Photographic camera with externally accessible drive coupling having releasable anti-backup feature
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to the following commonly assigned applications: 
     (1) Ser. No. 08/370,592 filed 9 Jan. 1995 by Dennis R. Zander for FILM LOADING/UNLOADING DESIGN FOR PHOTOGRAPHIC CAMERA; 
     (2) Ser. No. 08/391,757 filed 21 Feb. 1995 by Dennis R. Zander for FILM ROLL ACCUMULATING DEVICE; 
     (3) Ser. No. 60/001,515 filed 18 Jul. 1995 by Jeffrey C. Robertson for LIGHT TIGHT CHAMBER WITH CLOSURE AND SENSOR FOR POSITION OF CLOSURE AND CASSETTE IN CHAMBER; 
     (4) Ser. No. 60/002,644 filed 22 Aug. 1995 by Jeffrey C. Robertson for EXTERNALLY DRIVEABLE CASSETTE FOR LIGHT SENSITIVE WEB MATERIAL, INCLUDING KNIFE FOR CUTTING MATERIAL; 
     (5) Ser. No. 60/002,645 filed 22 Aug. 1995 by Jeffrey C. Robertson for EXTERNALLY DRIVEABLE CASSETTE FOR LIGHT SENSITIVE WEB MATERIAL, INCLUDING KNIFE FOR CUTTING MATERIAL AND METHOD OF OPERATION; 
     (6) Ser. No. 60/002,646 filed 22 Aug. 1995 by Jeffrey C. Robertson, Bradley S. Bush and Eric P. Hochreiter for EXTERNALLY DRIVEABLE CASSETTE FOR LIGHT SENSITIVE WEB MATERIAL, INCLUDING KNIFE FOR CUTTING MATERIAL AND METHOD OF OPERATION; 
     (7) Ser. No. 60/002,647 filed 22 Aug. 1995 by Jeffrey C. Robertson for EXTERNALLY DRIVEABLE CASSETTE FOR LIGHT-SENSITIVE WEB MATERIAL, INCLUDING KNIFE FOR CUTTING MATERIAL AND LATCHING CASSETTE DRIVE AFTER CUTTING; 
     (8) Ser. No. 60/002,854 filed 28 Aug. 1995 by Dennis R. Zander, Eric P. Hochreiter and William A. Bergstresser for METHOD AND APPARATUS FOR PRECISELY POSITIONING A CAMERA OR CAMERA FRAME; 
     (9) Ser. No. 08/569,634 filed 8 Dec. 1995 by Dennis R. Zander, William A. Bergstresser, Bradley S. Bush, Eric P. Hochreiter, Jeffrey C. Robertson and Paul Teremy for APPARATUS AND METHOD FOR LOADING AND UNLOADING A CAMERA WITH A DISCRETE FILM STRIP (Docket 71956CES); 
     (10) Ser. No. 08/569,054 filed 8 Dec. 1995 by William A. Bergstresser, Bradley S. Bush, Eric P. Hochreiter and Dennis R. Zander for APPARATUS FOR ACTUATING AND TESTING A CAMERA; 
     (11) Ser. No. 08/569,957 filed 8 Dec. 1995 by Dennis R. Zander, Paul Teremy and Eric P. Hochreiter for APPARATUS AND METHOD FOR LOADING A CAMERA; 
     (12) Ser. No. 08/569,557 filed 8 Dec. 1995 by Dennis R. Zander and Paul Teremy for PHOTOGRAPHIC CAMERA WITH COUNTERWHEEL HAVING OFFSET MARK; 
     (13) Ser. No. 08/569,543 filed 8 Dec. 1995 by Dennis R. Zander, Paul Teremy, William A. Bergstresser, Eric P. Hochreiter and Scott H. Schwallie for APPARATUS AND METHOD FOR LOADING AND PARTIALLY UNLOADING A CAMERA WITH A DISCRETE FILM STRIP; 
     (14) Ser. No. 08/569,558 filed 8 Dec. 1995 by Dennis R. Zander for PHOTOGRAPHIC CAMERA INCLUDING FEATURES FOR POSITIONING AN EXTERNAL FILM LOADING AND UNLOADING DEVICE (Docket 73228CES); 
     (15) Ser. No. 08/569,464 filed 8 Dec. 1995 by Eric P. Hochreiter, Bradley S. Bush, Stephen M. Granby and Dennis R. Zander for APPARATUS FOR LOADING AND UNLOADING PHOTOGRAPHIC FILM INTO OR FROM A CAMERA; 
     (16) Ser. No. 08/569,633 filed 8 Dec. 1995 by William A. Bergstresser, Eric P. Hochreiter, Paul Teremy and Dennis R. Zander for APPARATUS AND METHOD FOR OPENING AND CLOSING A PHOTOGRAPHIC CAMERA. 
     TECHNICAL FIELD 
     The invention relates to cameras into or from which a discrete film strip can be loaded or unloaded, the discrete strip not requiring a separate light shielding cartridge or other light shielding wrapper within the camera. More particularly, the invention concerns such a camera having features which enable the camera to cooperate with an external camera drive assembly for driving film into or from the camera. 
     BACKGROUND OF THE INVENTION 
     Conventional photographic cameras are designed to accept unexposed film which has been enclosed in a light shielding cartridge or other light shielding wrapper, to facilitate loading and unloading the camera without exposing the film. Many consumers find such cartridges or wrapped film to be difficult to load into or unload from a camera. The costs of such a cartridge or other wrapper and associated commercial packaging are significant components of the cost to the ultimate consumer. In addition, this known practice requires a film manufacturer to maintain an inventory of cartridges or rolls of film with various pre-selected lengths of film. 
     In recent years, so-called single use or disposable cameras have become popular, such as those disclosed in commonly assigned U.S. Pat. Nos. 4,890,130 and 5,235,366. While such cameras do not require the consumer to load or unload the film, the costs to the manufacturer continue to be high for disassembling such cameras to remove a factory-installed film cartridge and recover reusable parts. And, an inventory of cameras with various lengths of film still must be maintained. 
     Commonly assigned U.S. patent application Ser. No. 08/370,592 discloses a unique type of camera which can be loaded with a discrete length of unexposed film of a length selected by the consumer and subsequently unloaded of a discrete length of exposed film. Since such cameras do not use a cartridge or pre-wound spool of film to facilitate loading and unloading, there is a general problem of driving the film strip into or from the camera. Thus, a need has arisen for the camera to include features which will cooperate with an external camera drive assembly to drive film into or from the camera. 
     SUMMARY OF THE INVENTION 
     The primary objective of the invention is to provide a camera which can be driven externally to drive a discrete film strip into or from the camera. 
     A further objective of the invention is to provide such a camera in which an anti-backup feature, normally engaged during use of the camera by a consumer, can be released to enable a discrete film strip to be driven in either direction within the camera. 
     These objectives are given only by way of illustrative examples; thus other desirable objectives and advantages inherently achieved by the disclosed invention may occur or become apparent to those skilled in the art. Nonetheless, the scope of the invention is to be limited only by the appended claims. 
     A photographic camera according to the invention may include an external housing having a movable closure giving access to a film guide track within the camera, the guide track extending between an unexposed film chamber and an exposed film chamber, a rotatable sprocket for driving film along the guide track, and a driven gear operatively connected to rotate the sprocket. The camera of the invention is characterized by a coupling accessible externally of the housing and operatively connected to the driven gear, the driven gear and the coupling being mounted for axial movement in the housing; an anti-backup gear mounted for rotation and axial movement with the driven gear; and means for preventing reverse rotation of the driven gear in a first axial position of the coupling and for allowing rotation of the driven gear in either direction in a second axial position of the coupling. 
     The means for preventing and allowing may include a pawl resiliently mounted within the housing, the pawl comprising a locking tooth for engaging the anti-backup gear in the first axial position and a cam surface engaged by the anti-backup gear as the coupling moves to the second axial position, the cam surface being configured to move the pawl and pull the locking tooth out of engagement with the anti-backup gear. Preferably, the coupling, anti-backup gear and driven gear are mounted coaxially. The cam surface may move radially inwardly at one end of the anti-backup gear, to enable the locking tooth to reengage the anti-backup gear when the coupling moves to the first axial position. The sprocket may be mounted coaxially with an intermediate gear which meshes with the driven gear, the driven gear having an axial length sufficient to enable the driven gear to remain meshed with the intermediate gear as the driven gear moves between the first and second axial positions. The driven gear and the sprocket may be geared one to one. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objectives, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings. 
     FIG. 1 shows a perspective view of a camera loading and unloading apparatus according to the invention. 
     FIG. 2 shows the apparatus of FIG. 1, with the control console pivoted back to permit removal of the upper housing. 
     FIG. 3A shows the apparatus of FIG. 1, with the upper and lower housings removed. 
     FIG. 3B shows a fragmentary perspective view of the apparatus of FIG. 3A, looking from the right end of FIG. 3A and from below the level of the mechanism support plate. 
     FIG. 4 shows a perspective, partially broken away and partially exploded view of the cassette for unexposed film. 
     FIG. 5 shows an enlarged, fragmentary view of features for driving and guiding film from the cassette. 
     FIG. 6 shows a fragmentary view of the underside of the film cutter of the cassette. 
     FIG. 7 shows a view along line 7--7 of FIG. 4. 
     FIG. 8 shows a view along line 8--8 of FIG. 4. 
     FIG. 9 shows an enlarged, fragmentary perspective front view of features for actuating the film cutter of the cassette and for operating the cassette, and of the cutter and cartridge for exposed film. 
     FIG. 10 shows an enlarged, fragmentary perspective rear view of the features for actuating the film cutter of the cassette and for operating the cassette. 
     FIG. 11 shows a view along line 11--11 of FIG. 10. 
     FIG. 12 shows an enlarged, perspective rear view of the film loading and unloading tracks, looking from the perspective of the cassette. 
     FIG. 13 shows a view along line 13--13 of FIG. 12, with details of the loading and unloading tracks. 
     FIG. 14 shows an enlarged, perspective front view of the camera nest, the camera actuating and testing station, and the exposed film cutter and cartridge. 
     FIG. 15 shows the camera nest with a camera installed, prior to movement of the nest to the camera testing and actuating station. 
     FIG. 16 shows a perspective view of the back and bottom surfaces of the camera. 
     FIG. 17 shows a schematic view of film advancing gearing within the camera. 
     FIG. 18 shows an enlarged, partially broken away view of the externally accessible drive coupling, prior to engagement by the drive spindle. 
     FIG. 19 shows the features of FIG. 18, after engagement with the drive spindle. 
     FIG. 20 shows an enlarged, perspective view of the anti-backup pawl of FIGS. 18 and 19. 
     FIG. 21A shows a fragmentary, partially broken away perspective back view of the camera, indicating features of the thumbwheel, zero locking pawl and counterwheel. 
     FIGS. 21B and 21C show alternative embodiments of the counterwheel of FIG. 21. 
     FIG. 22 shows the features of FIG. 21 and also the opened back door of the camera, revealing internal features which cooperate with the structure of FIGS. 12 and 13. 
     FIG. 23A shows a view along line 23--23 of FIG. 22, revealing how the guide track cooperates with the camera. 
     FIG. 23B shows a fragmentary perspective view from the back of the camera, with the back of the camera housing removed to reveal details of the film guide track and stop ledge. 
     FIG. 24 shows a view along line 24--24 of FIG. 15, revealing features of the camera drive assembly. 
     FIG. 25 shows fragmentary, partially broken away perspective back view of the camera, the camera actuating and testing station and the camera door opening mechanism. 
     FIG. 26 shows a perspective back view of the camera door opening mechanism. 
     FIG. 27 shows a perspective front view of the camera door opening mechanism. 
     FIG. 28 shows a fragmentary sectional view of the camera door and the door opening mechanism, just prior to engagement. 
     FIG. 29 shows the features of FIG. 28, just after engagement. 
     FIG. 30 shows the features of FIG. 28, just after opening the door. 
     FIG. 31 shows a front perspective view of the camera actuating and testing station. 
     FIG. 32 shows a sectional view of the camera and guide track, just before opening the camera door. 
     FIG. 33 shows a fragmentary back perspective view of the camera and guide track, just after opening the camera door, with the film guide ramps contacting the film within the camera. 
     FIG. 34 shows the features of FIG. 33, just after the film has been wound back toward the unexposed film chamber and the film guide ramps have moved further into position within the camera. 
     FIG. 35 shows a fragmentary back perspective view of the nest and camera, the camera actuating and testing station, the film guide tracks, the exposed film cutter and the transfer cartridge, with the camera door open and a strip of film entering the camera. 
     FIG. 36 shows a perspective view of the transfer cartridge. 
     FIG. 37 shows a sectional view along line 37--37 of FIG. 36. 
     FIG. 38 shows a sectional view along line 38--38 of FIG. 37. 
     FIG. 39 shows an exploded, perspective view of the transfer cartridge. 
     FIG. 40 shows an exploded, front perspective view of the exposed film cutter. 
     FIG. 41 shows an exploded, back perspective view of the exposed film cutter. 
     FIG. 42 shows a front perspective view of the mechanism for actuating the exposed film cutter and driving the transfer cartridge. 
     FIG. 43 shows a front perspective view of the features of FIG. 42, plus the exposed film cutter and transfer cartridge. 
     FIG. 44 shows a back perspective view of the exposed film cutter and transfer cartridge. 
     FIG. 45 shows a front perspective view of the exposed film cutter and transfer cartridge. 
     FIG. 46 shows a fragmentary top view of the exposed film cutter and transfer cartridge with the mouth into the cartridge still closed. 
     FIG. 47 shows the features of FIG. 46 with the mouth into the cartridge open. 
     FIG. 48 shows a view along line 48--48 of FIG. 3, indicating features of the drive mechanism of the apparatus. 
     FIGS. 49, 50, 51, 52, 53A, 53B, 53C, and 54 show flow charts of the control logic for the apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a detailed description of the preferred embodiments of the invention, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several Figures. 
     OVERALL ARRANGEMENT AND OPERATION 
     FIGS. 1 to 3A show front perspective views of the overall apparatus 10. As used in this description, &#34;front&#34; views are taken essentially from the perspective of FIGS. 1 to 3A; whereas, &#34;back&#34; views are taken essentially from the opposite perspective. A central mechanism support plate or frame 12 is positioned between a lower housing 14 provided with hand holds 16 and an upper housing 18. For light tightness, the housings should be made from a suitable opaque material such as metal or molded plastic. A peripheral groove 19 is provided in an upper surface of support plate 12 and a similar groove, not illustrated, is provided in an under surface of the support plate. These grooves respectively receive a mating land on a lower edge of upper housing 18 and a mating land on an upper edge of lower housing 14, to provide a light-tight interior. Though the illustrated embodiment includes a housing suitable for a type of counter top apparatus, those skilled in the art will appreciate that the internal apparatus of the invention also could be incorporated into any light tight environment, such as a larger, vending machine format or a darkened room, all without departing from the scope of the invention. 
     At the left end of the upper housing, as viewed in FIGS. 1 and 2, a movable closure, such as an L-shaped end door 20, is mounted by a hinge 22, to provide access to a compartment for a cassette 24 for unexposed photographic film. Although a closed cassette is preferred for a source of unexposed film, those skilled in the art will appreciate that a discrete roll of film also could be used in accordance with the invention, though loading of the apparatus would then need to be accomplished in a darkened environment, where the film could not be exposed by ambient radiation. At the right end of the upper housing, a top door 26 is mounted by a hinge 28, to provide access to an irregularly shaped recess 30 in a top wall of upper housing 18. Suitable gaskets or land and groove seals, not illustrated, should be provided around end door 20 and top door 26 to ensure light tightness when the doors are closed. A catch 44 on top door 26 and catches 46 on end door 20 are provided to hold the doors shut when the apparatus is in use. 
     Through a bottom wall of recess 30 is provided an essentially rectangular opening 32 for insertion and removal of a camera to be loaded or unloaded. Also through the bottom wall of recess 30 is provided an oblong opening 34 for insertion and removal of a transfer cartridge for exposed film. Rigidly affixed to an under side of top door 26 is a downwardly depending actuating lever 36 which extends through an opening 38 in the bottom wall of recess 30 to coact with a camera nest to be described subsequently. Attached to an underside of door 26 is a retainer bracket 40 which supports a resilient pad 42 in position to engage a front surface of a camera positioned within the apparatus when the door is closed. Pad 42 thus is compressed and holds the camera down and toward the back of the apparatus. A grille 48 is provided on lower housing 14 to cover a cooling air inlet to the electronic controller of the apparatus. A pivotable control console or operator interface 50 is supported on a back edge of support plate 12 and includes a key pad 52 for entering customer and other information and a visual display 54. 
     As shown in FIGS. 2 and 3A, console 50 can be pivoted up and back to permit removal of the upper housing for access to the internal components of the apparatus. Support plate 12 is mounted within lower housing 14 on a plurality of downwardly extended support legs 60. On an upper surface of the support plate, a compartment for cassette 24 is defined, in part, by a rear wall 62 and a front wall 64. A ledge 66 may be provided on back wall 62 to support a guide flange 68 extended along one side of cassette 24 as seen best in FIG. 5. Ledge 66 and flange 68 thus cooperate to ensure proper orientation of the cassette. An interior stop wall 70 extends from front wall 64 toward back wall 62, to limit movement of the cassette into the apparatus. 
     As shown in FIG. 3A, cassette 24 is positioned to feed unexposed film into an unexposed film loading means such as a track 72 which extends essentially to the right on support plate 12. Toward the right end of the apparatus, a camera nest 74 is pivotably mounted at 76. In the position shown in FIG. 3A, nest 74 is directly below opening 32, to permit insertion or removal of a camera. As will be discussed in greater detail subsequently, a spring 78, visible in FIG. 3B, biases nest 74 to rotate clockwise from the position of FIGS. 3A and 15, toward the back of the apparatus to the position of FIGS. 3B, 25 and 35. In the latter position, an electromagnet assembly 81, visible in FIG. 3B, secures the nest to enable the camera to cooperate with film loading track 72 and with features of a camera actuating and testing station 80. Although a pivoted nest is illustrated, those skilled in the art will appreciate that nest 74 could be mounted to slide without pivoting between a position for receiving a camera and a position for actuating and testing the camera. Alternatively, actuating and testing station 80 could be mounted to move into engagement with a stationary nest, without departing from our invention. An exposed film unloading means such as a track 82 is provided to accept exposed film from the camera and guide the film through a cutter 84 to a transfer cartridge 86 where the exposed film is wound on a spool. Those skilled in the art will appreciate that transfer cartridge 86 could be omitted and unloading track 82 configured to guide the exposed film directly to a photographic processor, not illustrated. 
     From the foregoing description, those skilled in the art will understand the general operation of the apparatus. A cassette 24 of unexposed film is inserted into the apparatus and door 20 is closed and latched. A camera to be loaded or unloaded is inserted through opening 32 into nest 74. Assuming the camera is to be completely or partially unloaded, a transfer cartridge 86 is inserted through opening 34. Top door 26 is then closed and latched. To prevent opening of doors 20 and 26 during operations of the apparatus, solenoid actuated locks, not shown, may be used. Closure of the top door causes actuating lever 36 to pivot toward the back of the apparatus, thereby permitting spring 78 to rotate nest 74 into position before camera actuating and testing station 80, where electromagnet 81 secures the nest. Customer information and information about the status of the camera are then entered via console 50. If the camera has a flash feature and is to be loaded with film, the flash may be tested at this time. A door on the camera is opened and then: 
     (a) If the camera is empty, unexposed film is driven from cassette 24 and guided along loading track 72 into the camera. When a desired length of film has been loaded, a knife in the cassette cuts the film and a discrete cut strip is driven into the camera. In accordance with the invention, the discrete strip does not require any separate light shielding cartridge or paper within the camera. 
     (b) If the camera is full of exposed film, the exposed film is driven from the camera and guided along unloading track 82, through cutter 84 and into transfer cartridge 86. The camera then may be reloaded, if desired. 
     (c) If the camera contains a partially exposed length of film, the exposed portion is driven from the camera into transfer cartridge 86 and the film is cut by cutter 84. The remaining unexposed film is then driven back into the camera. 
     After the camera has been loaded or unloaded, as the case may be, the door on the camera is closed. Electromagnet 81 is deenergized and the solenoid locks, if provided on doors 20 and 26, are released. Top door 26 may then be opened, which causes actuating lever 36 to engage nest 74 to swing the nest back beneath opening 32 where the camera may be removed. Transfer cartridge 86 also may be removed and sent to a photographic processor. 
     CASSETTE 24 
     Referring now to FIGS. 4 to 8, those skilled in the art can understand the structure and operation of one cassette 24 suitable for use in apparatus 10. The cassette comprises a rigid, opaque body or housing 100 which may be made from any suitable material such as molded plastic, metal or the like. A bottom wall 102 is L-shaped at one end where the cassette mates with stop wall 70 and rounded at the other end where a roll of photographic film is mounted. Extended upwardly from and around bottom wall 102 is a peripheral wall 104. A removable cover 106 mates with an upper edge of wall 104 to close the cassette. Within the cassette, a roll 108 of photographic film, shown fragmentarily in FIG. 5, is wound on a central core 110 which is rotatably supported on a stub shaft 220, shown in FIG. 8. As shown in FIG. 5, a lead end 112 of the film is wrapped partially around an idler roller 114 supported for rotation on an upwardly extended shaft 116 mounted to bottom wall 102. Means are provided in the cassette for engaging the lead end to drive the web material from the cassette. The lead end wraps partially around a driven sprocket roller 118 supported for rotation with an upwardly extended drive shaft 120 whose lower end extends through an opening in bottom wall 102 for a purpose to be discussed subsequently. A plurality of teeth 122 on the sprocket roller engage edge perforations 124 along at least one edge of the film. A spring-biased keeper 126 is pivotably mounted on an upwardly extended shaft 128. A pair of contact pads 130, only one of which is visible in FIG. 5, engage the edges of the film to hold the film in engagement with the sprocket roller. An anti-backup pawl 132, formed integrally with the keeper, engages a saw toothed ratchet wheel 134 attached at an upper end of the sprocket roller, to prevent reverse rotation. Those skilled in the art will appreciate that a pair of nip rollers could be used rather than a sprocket roller, without departing from the scope of the invention. Alternatively, a toothed belt drive or a reciprocating vacuum shuttle could be used for short lengths of web. An exit slit 136 extends through peripheral wall 104 opposite sprocket roller 118. A raised lip 137 extends substantially around an upper surface of peripheral wall 104 to mate with a corresponding groove, not illustrated, on an under side of cover 106, thereby providing a seal against entry of light into the cassette. 
     On the exterior of housing 100 adjacent slit 136 is provided an essentially L-shaped recess 138 which extends along side wall 104 and also wraps around onto an under surface of wail 102. Recess 138 slideably receives a knife comprising a sliding knife holder 140 on which is mounted a flat knife blade 142 having a leading, angled cutting edge 144. A front surface of recess 138 in peripheral wall 104 is angled inwardly at an acute angle α between a plane of wall 104 and a plane of the recess, to enable blade 142 to provide a tapered or angled leading edge 145 on the film. Preferably, angle α is about 10°. See FIG. 5. The lead end of the film leaving the cassette must thread along film loading track 72. Angled leading edge 145 eases entry into and passage along the loading track and into the camera. Within recess 138 and adjacent exit slit 136 is provided an essentially J-shaped recess 146. A correspondingly shaped knife bed 148 is fixedly mounted in recess 146 with an edge 150 essentially aligned with an edge of exit slit 136. During cutting, knife blade 142 and edge 150 are in close sliding engagement, thereby cooperating to scissor the film as the blade moves to a closed position. As a result of the illustrated arrangement of sliding knife blade 142 and knife bed 148, a cut end of the film remains within the cassette just behind blade 142, ready to be dispensed during a later cycle of operation, there being no wasted portion of the film left extended from the cassette after cutting. 
     As shown in FIG. 6, a tab 152 near an inside lower edge of knife holder 140 is attached to one end of a tension spring 154, whose opposite end is attached to an anchor 156 on an under edge of peripheral wall 104, thus urging the knife holder and blade to the right, as viewed in FIGS. 4 to 6, to close exit slit 136. On an outside surface of knife holder 140, as shown in FIGS. 4 to 6, a pair of actuator tabs 166 are formed which extend laterally through a horizontal slot 168 formed in a knife cover plate 170 which is fixedly mounted against a pair of stop surfaces 172 spaced outboard of recess 138. The stop surfaces are shown best in FIG. 6 where cover plate 170 has been omitted for ease of illustration. The cover plate comprises along an upper edge a lip 174 for engaging an upper edge of peripheral wall 104; and along a lower edge, a bottom flange 176 for engaging a recess 178 into bottom wall 102, as shown in FIG. 6. As illustrated, recess 178 is the lower wall portion of L-shaped recess 138. An exit slit 180 extends through the cover plate, in alignment with exit slit 136. To hold the assembly of holder 140 and blade 142 firmly within recess 138 and against knife bed 148, a pair of leaf springs 182, 184 are formed integrally in the cover plate, as shown in FIG. 7. Suitable fasteners 186, 188 extend through bottom flange 176 into the body of the cassette to secure the cover plate, the fasteners but not the cover plate being shown in FIG. 6. 
     As shown in FIGS. 4 and 8, means are provided for preventing rotation of core 110 or movement of knife 140, 142 from a closed position, during handling and shipment of the cassette. An actuator plunger 190 is slidably mounted in a passage 192 through peripheral wall 104. Within the cassette, a channel 194 is defined along bottom wall 102 between a pair of parallel guide walls 196, 198. A coil spring 200 is slideably received on plunger 190 and is captured between a retainer flange 202 on the plunger and a transverse stop 204 extended between walls 196, 198. A cover plate 206 is attached by suitable fasteners to close the upper side of channel 194. Plunger 190 is used to actuate an anti-backup lever 208 having at one end a pivot axle 210 whose ends are pivotably received in a pair of notches 212, 214 formed in walls 196, 198. A pair of tabs 216 on one end of cover plate 196, only one tab being visible in FIG. 4, retain axle 210 in notches 212, 214. Between lever 208 and bottom wall 102 is positioned an essentially V-shaped leaf spring 218, one end of which bears against stop 204 and the other of which bears on bottom wall 102, just outside of a stub shaft 220. Spring 218 thus forces lever 208 to pivot upwardly, as viewed in FIG. 8. At its end opposite axle 210, lever 208 includes an upwardly extended latching finger 222 which is forced by spring 218 to extend into one of a plurality of recesses 224 formed in core 110, to keep the core from rotating on the stub shaft during handling or shipment of the cassette. Plunger 190 includes a sliding cam surface 226 which engages lever 208. 
     When the cassette is installed in apparatus 10, as shown fragmentarily in FIG. 8, a probe 228 on stop wall 70 of the apparatus engages plunger 190 and forces the plunger to move to the left as seen in FIG. 8. This movement causes lever 208 to pivot downwardly, thereby withdrawing latching finger 222 from recess 224 and freeing the roll of film to rotate. The same movement also releases knife 140, 142. A knife release arm 230 extends laterally from plunger 190 and includes a latching finger 232 which, before engagement of the plunger by probe 228, extends through an opening 234 in recess 138 into an opening 236 in knife holder 140, to prevent movement of the knife during handling or shipment. When plunger 190 is moved to the left in the manner just described, latching finger 232 is pulled out of opening 236, thus freeing the knife for movement to cut the film. 
     In use of the cassette of FIGS. 4 to 8, the cassette is inserted by sliding it into apparatus 10, thereby moving plunger 190 and freeing both core 110 and knife 140, 142. Tabs 166 are then engaged by a mechanism shown in FIGS. 9 and 10 to move the knife away from the knife bed against the action of spring 154, thus opening exit slit 136. Driven sprocket roller 118 is then rotated to drive the film from the cassette. When a sufficient length has been driven from the cassette, knife 140, 142 is driven back toward knife bed 148, thereby cutting the film and blocking exit slit 136. To prevent a trailing end of the just-cut film from being captured between knife 140, 142 and knife cover plate 170, the knife may be cycled open to release the trailing end, if captured, and then closed again. The leading end of the film remains within the cassette just behind blade 142, ready to be dispensed during a later cycle of operation, there being no wasted portion of the web material left extended from the cassette after cutting. 
     ACTUATOR MECHANISM FOR CASSETTE 24 
     FIGS. 9 to 11 show an actuator mechanism for the cassette. A rotary actuator 250, typically electrically operated, is supported from the under side of support plate 12 by a mounting flange 252. For ease of illustration, support plate 12 is shown fragmentarily. A drive shaft 254 of the actuator extends upwardly through an opening, not illustrated, in the support plate and rotatably supports an essentially circular cam follower plate 256. An arcuate cutout 258 is provided through plate 256 to engage rotational stop pins, not illustrated, which extend from support plate 12 to limit rotational movement of the actuator mechanism. A V-shaped notch 260 is provided through plate 256 for cooperation with a wedge cam 302 to be described subsequently. On an upper end of shaft 254, a radial actuator arm 262 is fixedly mounted, the arm having a radially extending actuating finger 264 which is positioned between actuator tabs 166, as seen in FIG. 9. 
     As shown in FIGS. 9 and 11, beneath the cassette, a cassette drive assembly 266 is mounted to the under side of support plate 12. Assembly 266 includes a tubular housing 268 having a radial mounting flange 270 at its upper end. Within housing 268, a pair of bearings 272, 274 rotatably support a hollow shaft 276 having a splined counter bore 278 at its upper end. A through bore 280 in shaft 276 slideably receives a driver shaft 282 having splines 283 to engage the splines of counter bore 278. A spring 284 is captured between a shoulder 286 on shaft 276 and a shoulder 288 on shaft 282, thus tending to force shaft 282 to move upward. At the bottom of shaft 282, a stop ring 290 limits upward movement. A timing pulley 292 is fixedly attached to the lower end of shaft 276; so that, rotation of shaft 276 will rotate shaft 282, due to the splined coupling 278, 283. 
     FIGS. 9 and 10 show the position of the parts when knife 140, 142 has closed exit slit 136. Actuator 250 rotates counter-clockwise to open the exit slit. An actuator lever 294 is pivoted at one end to a pivot block 296 recessed into support plate 12, the lever extending downward through a slot in the support plate, as shown fragmentarily in FIG. 44. At its other end, lever 294 comprises a fork 298 which receives the upper end 300 of shaft 282. Just below cam follower plate 256, lever 294 supports a wedge cam 302 which tapers toward fork 298. Thus, when actuator 250 rotates counter-clockwise, a leading edge of notch 260 will slide along cam 302, thus allowing lever 294 to pivot upward in response to expansion of spring 284 and movement of shaft 282, to permit end 300 to engage an externally accessible drive coupling 304 for sprocket roller 118, shown in FIG. 6. As shown in FIG. 10, a sensor flag 306 is mounted on follower plate 256. Thus, as the follower plate rotates during actuation of knife 140, 142, flag 306 cooperates with adjacent sensors 310, 312 mounted on support plate 12, as shown in FIGS. 3A and 10, to indicate whether exit slit 136 is open or closed. Sensors 310, 312 preferably each comprise an infrared light source and detector pair. Thus, when sensor flag 306 passes between the source and the detector, the outputs of the sensors will indicate the status of exit slit 136. Similar sensors are used throughout the apparatus to detect presence of a film strip or sensor flag, as will be understood by those skilled in the art from the remainder of this description. 
     FILM LOADING AND UNLOADING TRACKS 
     FIGS. 12 and 13 show various features of film loading track 72 and film unloading track 82. In FIG. 12, the view is from the back of the apparatus, just down stream from exit slit 136. For a more compact arrangement, a shallow V-shaped frame member 320 is provided, extending from near exit slit 136 toward the back of the camera when the camera is in position at actuating and testing station 80. A plurality of mounting brackets 322 support frame member 320 just above support plate 12. An upper side rail block 324 and a lower side rail block 326 are attached to respective upper and lower edges of frame member 320. Upper retainer flanges 328, 330 and lower retainer flanges 332, 334 are attached to the rail blocks to define between the blocks and flanges a lower film guide slot 336 and an upper film guide slot 338. To ease movement of a film strip into the guide slots, flared inlets 340 and 342 are provided which, as seen in FIG. 3A, are positioned closely to exit slits 136, 180 to readily receive a leading end of film as it is driven from cassette 24. As shown in FIG. 12, inlets 340, 342 are flared both horizontally and vertically to ensure ease of entry of a film strip. Along guide slot 336, a sensor 344 is located to detect the presence of film within the track. 
     Side rail blocks 324, 326 each include a tapered downstream end 346 positioned in close proximity, respectively, to an upper side rail block 348 and lower side rail block 350 of film unloading track 82. A frame plate 352 extends between rail blocks 348, 350 and is supported by one of brackets 322. An upper retainer flange 353, shown in FIG. 12, and a similar lower retainer flange 355, shown in FIG. 13, cooperate with rail blocks 348, 350 to define guide slots 336&#39; and 338&#39;. Downstream ends 354, 356 of retainer flanges 330, 334 extend beyond tapered ends 346. Each tapered end 346 includes a slot 358, shown in phantom in FIG. 13, in which a film diverter spring 360 is mounted on a pin 362. When no film is moving down slots 336, 338, an end of spring 360 extends outward through a slot 364 in the adjacent retainer flange. When film is moving down the tracks from the cassette, the leading edge of the film pushes spring 360 aside, thus allowing the film to move on toward ends 354, 356. 
     Near tapered ends 346, a side surface 366 of each of rail blocks 348, 350 curves gently into essential parallelism with retainer flanges 330, 334, as shown in FIG. 13. At the ends of rail blocks 348, 350, a pair of film guide ramps 370, 372 are mounted on pivot pins 374, 376. Each guide ramp includes a central film guide slot 378 which, in the position of FIG. 13, essentially forms a continuation of one of slots 336, 338. On the opposite side of pivot 376 from guide slot 378, each guide ramp includes a radial arm 380, shown in phantom in FIG. 13. A pair of leaf springs 382, secured at one end to frame plate 352, bear upon respective arms 380 to bias each guide ramp to rotate clockwise as viewed in FIG. 13. Thus, when a camera is positioned at camera actuating and testing station 80 and an access door on the camera is opened, guide ramps 370, 372 will be pivoted under the action of springs 382 until a pair of transverse stops 384 on the guide ramps encounter at least one stop ledge 386 in the camera, as shown in phantom in FIG. 13. Stop ledge 386 will be described further with regard to FIGS. 16, 22, 23A and 23B. Finally, one of a pair of sensor flags 388, 390 is attached to each guide ramp, for cooperation with a pair of sensors to be described subsequently. When film is driven into the camera, the leading edge of the film presses diverter spring aside to allow the film to move into guide slots 378. When film is driven from the camera, springs 360 divert the film into guide slots 336&#39;, 338&#39; leading to cutter 84 for exposed film. Since photographic film being driven from the camera will tend to curl in a direction to move into guide slots 336&#39;, 338&#39;, use of diverter spring 360 is optional. As the film passes from guide slots 336&#39;, 338&#39;, a sensor 392 monitors its passage. 
     In the foregoing description, film loading track 72 and unloading track 82 have been shown and described as open tracks which must be enclosed within some sort of light-tight environment to prevent fogging of the film as it moves between cassette 24 and the camera and between the camera and cutter 84/cartridge 86. However, those skilled in the art will appreciate that, without departing from the scope of our invention, the loading and unloading tracks themselves could be made completely light tight and provided with light seals or gaskets at their ends engaging cassette 24, the camera and cutter 84. 
     The apparatus of the invention should be capable of operation over a considerable range of ambient temperature, for example, from about 20° to about 40° C. Over such a range, thermal expansion of the width of a film strip could lead to undesirable scraping or dragging of the edges of the film as the edges move through guide slots 336, 338. Conventional photographic film bases of the types suitable for use in accordance with the invention will have a coefficient of thermal expansion of about 8×10 -5  in/in/° C. Thus, by making frame member 320 and frame plate 352 from materials having substantially equal coefficients of thermal expansion, any potential for interference at high temperatures can be minimized. Conventional styrene plastic having a coefficient of thermal expansion in the range of 6 to 8×10 -5  in/in/° C., would be preferred for member 320 and plate 352. 
     COOPERATING FEATURES OF NEST 74 AND CAMERA 426 
     As shown in FIG. 14, camera nest 74 comprises an essentially rectangular base plate 410 on which positioning pins 412, 414 are mounted for engagement with features in the bottom of a camera. An aperture through the base plate allows passage of a camera drive spindle 418 which engages a drive coupling on the bottom of a camera. Flared end walls 420, 422 and a flared back support 424 ensure that when a camera 426 is lowered into the nest as shown in FIG. 15, the camera will settle closely onto pins 412, 414 and spindle 418. Because nest 74 is biased to rotate clockwise about pivot 76, back support 424 engages a lower end of actuating lever 36. Thus, when top door 26 is closed, spring 78 will cause the nest to swing into place before actuating and testing station 80, where electromagnet 81 will hold the nest in position. 
     Camera 426 is an example of many types of manually operated cameras which can be used in accordance with the invention. Those skilled in the art will appreciate, however, that features of nest 74 and its associated sensors soon to be described would require adjustment for other camera styles, including motorized cameras, without departing from the scope of the invention. An assembled photographic camera suitable for use in accordance with the invention would include an external housing having at least one movable closure which, in an open position of the at least one closure, would enable a discrete strip of film to be loaded from an exterior of the camera into the camera and a discrete strip of film to be unloaded from the camera to the exterior. Within such a camera, a guide track would extend between an unexposed film chamber and an exposed chamber. Means would be provided for moving a film strip back and forth between the unexposed and exposed film chambers. Those skilled in the art will appreciate that this means for moving could be a conventional toothed sprocket, a pinch roller drive, driven spools in the film chambers, or a combination of such known features for moving film. In the following description of camera 426, specific examples are given of various camera features; however, the apparatus and method of the invention are not limited to use of such a particular camera. 
     As shown in FIG. 15, the camera includes a front housing 428 having a lens opening 430. In the familiar manner, a lens cover actuator 432 extends through a slot 433 to enable the user to move the lens cover between a closed position, as illustrated, and an open position. In cameras with a flash feature, a flash opening 434 is provided along with a flash activation switch 436 which is moved out to the position of FIG. 15 to activate the flash. On top of the camera, a shutter trigger button 438 is provided in the familiar manner. 
     Referring to FIGS. 14 and 15, additional features of the apparatus can be understood. A &#34;camera present&#34; treadle assembly 440 is mounted on a pivot 442 at one end of nest 74. Assembly 440 includes a transversely extended treadle foot 444 which is depressed when the camera is placed in the nest. Movement of treadle foot 444 causes a sensor flag 446 to move to a position to actuate a sensor 448 when nest 74 is swung into position at actuating and testing station 80. At the front of the nest, a &#34;lens cover open&#34; treadle assembly 450 is mounted on a pivot 452. A transversely extended arm 454, normally spring-biased upward, extends from the pivot in position to be engaged by lens cover actuator 432 if the lens cover is open. Movement of arm 454 causes a downwardly extended, L-shaped sensor flag 456 to move to a position to actuate a sensor 458 suspended from the nest. Near the pivot end of the nest, a &#34;flash activated&#34; lever assembly 460 is mounted on a pivot 462 on support plate 12. Assembly 460 includes a transversely extended arm 464 in position to be engaged by flash actuator switch button 436 as the nest is swung into position at station 80. Movement of arm 464 causes a transversely extended arm 466 to move to a position where a sensor flag 468 can actuate a sensor 470 mounted on support plate 12. 
     As shown in FIG. 16, the bottom of the camera includes an aperture 472 which permits pin 412 to engage the internal frame of the camera, not illustrated, and an aperture 474 which permits pin 414 to engage the internal frame. An externally accessible drive shaft coupling 476 is recessed into the bottom of the camera for cooperation with spindle 418. A back housing 478 includes an opening 480 through which a &#34;flash ready&#34; light may be observed and a slot 482 for a thumbwheel 486. A movable closure, such as a sliding door 484, is provided to permit film to be loaded into or unloaded from the camera. 
     FIG. 17 shows schematically a gear train for advancing film into or out of the camera. Thumbwheel 486 is connected for rotation with a gear 488 and a conventional film takeup spool 490, all mounted for rotation on bearings within the camera, not illustrated. Gear 488 meshes with a gear 492 which is connected for rotation with a shutter reset cam 494, in a conventional manner. A smaller gear 496 meshes with gear 492 and is connected for rotation of a counterwheel advancing pawl 498 which meshes with a counterwheel 500. A window 501, visible in FIG. 15, is provided through the camera housing in the conventional manner, to enable a user to see the numbers on the counterwheel. The gear ratios are chosen so that one revolution of gear 496 will move counterwheel 500 sufficiently to indicate passage of a single frame of film. A shaft 502 supporting gear 492 extends downward in the camera and, via an axially extensible joint 504, is connected for rotation with a shaft 506. On the lower end of shaft 506 is mounted a sprocket drive gear 508. A spring 510 is captured between a stop 512 in the internal frame of the camera and gear 508; so that, drive gear 508 is normally biased toward a first position near the bottom of the camera. As shown in FIGS. 17 to 19, an anti-backup gear 514 is formed coaxially with drive gear 508 and normally is engaged with an anti-backup pawl 516 to prevent reverse rotation. See FIG. 18. A gear 526 is meshed with drive gear 508 and mounted coaxially on a shaft with a film drive sprocket 530 which engages the perforations in the film. Preferably, gears 508, 526 and 530 are geared one to one. 
     When the camera is lowered into nest 74, spindle 418 engages coupling 476 and pushes the coupling upward from the first position of FIG. 18 into the camera to a second position of FIG. 19. This upward movement causes gear 514 to move out of engagement with pawl 516 and into engagement with an angled cam surface 518 shown in FIG. 20. Pawl 516 and cam surface 518 are mounted at a free end of a flexible cantilevered arm 520 extended from a base 522 attached to the internal frame of the camera. As shown in FIGS. 18 and 20, base 522 is molded integrally with a frame plate 523 having at one end a right angle stiffener wall 524. An unillustrated bore extends through frame plate 523 next to wall 524 to enable the frame plate to be installed over a mounting pin 525 extended downward from the internal frame of the camera. When gear 514 moves upward and engages cam surface 518, arm 520 flexes and pawl 516 swings out of engagement with gear 514. Gear 508 has an axial length sufficient to enable driven gear 526 to remain meshed as gear 508 moves up and down. Continued contact between gear 514 and cam surface 518 holds the pawl out of engagement with gear 514. When gear 514 moves downward when the camera is removed from the nest, it slides down along cam surface 518, thus allowing arm 520 to return to its original position and permitting pawl 516 to reengage gear 514. Because gear 514, as illustrated, is somewhat larger in diameter than gear 508, cam surface 518 moves radially inward above gear 514 when pawl 516 is engaged with gear 514. 
     FIGS. 21A, B, C and 22 show features of the frame counting and zero locking mechanisms. A zero locking pawl 532 is mounted on a pivot 534 near thumbwheel 486 and is spring-biased to rotate counter-clockwise. Pawl 532 includes a tangentially extended stop finger 536 which usually slides against a cylindrical surface 538 of the counterwheel. However, when the last frame of film has been exposed, finger 536 moves into a radial slot 540 formed in an upper surface of the counterwheel, thus preventing further rotation of the counterwheel. Simultaneously, a locking tooth 542 on pawl 532, hidden from view in FIGS. 21A and 22, engages an inwardly facing saw toothed ratchet 544 provided in the upper surface of thumbwheel 486, to prevent its further rotation. However, to enable the camera to load and unload film in accordance with the invention, means are provided for releasing the zero locking pawl. A release lever 546 extends radially from pivot 534 just inside an access hole 548 through back housing 478. Thus, when the camera is positioned at camera actuating and testing station 80, a probe 684 shown in FIG. 31 will enter hole 548 and push on release lever 546. This causes the zero locking pawl to rotate clockwise and to disengage finger 536 from slot 540 and tooth 542 from ratchet 544. Thus, the gear train of FIG. 17 can be rotated freely in either direction. 
     FIG. 22 also shows how sliding door 484 moves to one side to reveal ledge 386, shown in FIG. 13, and a pair of notches 550, 552 formed at the ends of the ledges to receive the ends of guide ramps 370, 372. Also visible in FIG. 22 is an entrance 554 into a film track 566 within the camera. Ledge 386 and notches 550, 552 thus comprise a means at entrance 554 for positioning an external film loading or unloading device for guiding film into or receiving film from guide track 566. FIG. 23A illustrates schematically additional internal details of a camera suitable for use in the apparatus of the invention. In the familiar manner, camera 426 includes an unexposed film chamber 562, an exposed film chamber 564, with film guide track 566 running between chambers 562, 564 to present unexposed film to an exposure chamber 568. Within unexposed film chamber 562, a flexible film scroller 563 may be provided to guide the film strip into a scroll within the chamber. Such a scroller may be of the type shown in U.S. Pat. No. 3,288,388, the contents of which are incorporated by reference into this description. 
     Further details of ledge 386 are illustrated in FIGS. 16, 22 and 23B. As best seen in FIG. 23B, in which the camera back has been removed, ledge 386 preferably is coplanar with guide track 566. In the conventional manner, guide track 566 includes a pair of parallel side rails 570, 572 on which the film is supported just outside of the image area. Similarly, ledge 386 preferably includes a pair of parallel side rails 574, 576 which are located just inboard of notches 550, 552 and form respective extensions of side rails 570, 572. Just outboard of the notches, a pair of guide wedges 578, 580 preferably are provided to engage the longitudinal edges of a film strip to guide and center the strip as it moves through entrance 554 into guide track 566. Between side rails 574, 576, ledge 386 is recessed to avoid contact with the image area of the film. Thus, those skilled in the art will appreciate that the ledge need not be continuous across the width of entrance 554 and that the portion of the ledge between side rails 574, 576 may be omitted without departing from our invention. 
     Turning now to FIG. 24, features of the camera drive assembly can be understood. Nest 74 includes a downwardly extended boss 582 on which a drive assembly 584 is mounted. Assembly 584 includes a tubular housing 586 having at its upper end an integral mounting flange 588. Within housing 586, a pair of beatings 590, 592 rotatably support camera drive spindle 418, the upper end of which engages an internally splined bore 594 within drive coupling 476. To ensure positive engagement between spindle 418 and coupling 476, a torque transmission pawl 596 is pivoted at 598 within a slot formed in the spindle. A spring 600 biases pawl 596 to rotate outwardly. When a camera is lowered into the nest, pawl 596 will retract into the spindle unless it happens to align initially with groove within coupling 476. Then, when spindle 418 is rotated, pawl 596 will spring outward into the first available groove to provide the necessary positive engagement. 
     As shown in FIGS. 3B and 24, at the lower end of spindle 418 is mounted a driven gear 602 whose operation will be discussed subsequently. Beneath gear 602 is mounted an encoder disk 604 having a plurality of radially extended sensor flags 605 which cooperate with a sensor 606 suspended beneath support plate 12 on a bracket 608. The number of sensor flags 605 corresponds to the number of teeth on film drive sprocket 530. For example, if the film strip has eight perforations per frame and the drive sprocket has eight teeth, a single rotation of gear 602 will cause eight sensor flags 605 to pass sensor 606, which provides a corresponding output to the controller of the apparatus. A single sensor flag could be used to indicate completion of a rotation; however, a plurality of sensor flags enables the apparatus to advance a partial frame. 
     In the foregoing description, the camera drive assembly is particularly adapted for use with manually operated cameras. Those skilled in the art will appreciate, however, that our invention is readily adaptable for use with motorized cameras. For example, rather than including the assembly of parts 582 to 604, a motorized camera and nest 74 could be provided electrical interconnections, not illustrated, to enable the controller of the apparatus of operate the motor of the camera to drive film back and forth between chambers 562, 564 during loading and unloading of the camera. 
     CAMERA DOOR OPENING MECHANISM 
     Referring now to FIGS. 25 to 30, those skilled in the art will understand the structure and function of a door opening mechanism 610 for sliding open door 484. An L-shaped frame member 612 includes a horizontal mounting flange 614 which is attached to the under side of support plate 12. An electrical rotary actuator 616 is mounted to frame member 612 below flange 614 and includes an output shaft, not illustrated, which extends horizontally through the frame member. A cylindrical spacer 618 is mounted for rotation with the output shaft and supports a depending sensor flag 620 having an arcuate portion 622 positioned to actuate a pair of sensors 624, 626 mounted on the frame member. Outboard of spacer 618 is mounted a door opening arm 628 which also rotates with the shaft of actuator 616. A linear actuator and a pivoted arm, not illustrated, also could be used within the scope of our invention. 
     As seen in FIG. 25, a slot 630 extends through support plate 12 to permit a door engaging hook 632 on arm 628 to come into engagement with sliding door 484, when the nest is swung into position at actuating and testing station 80. Hook 632 includes an angled ramp portion 634 having an acute ramp angle 13 which preferably is greater than 30°, most preferably about 60°, as seen in FIG. 28. A thrust washer 635, flat washer 637 and bolt 639 secure arm 628 to the end of the output shaft. Due to the presence of thrust washer 635, arm 628 is permitted to flex or rock slightly on the output shaft when hook 632 engages a sliding door. 
     When a camera is swung into the position shown in FIG. 25, hook 632 enters into a slot 636 formed near an outboard side edge of door 484 and arm 628 rocks slightly toward the back of the apparatus against thrust washer 635, to provide a secure engagement. Within slot 636, an angled side wail 638 is positioned to coact with ramp portion 634 in a manner soon to be explained. Side wall 638 is set at an acute angle γ, which preferably is less than angle β, to ensure that an outside edge 641 of side wall 638 first contacts ramp portion 634. As seen in FIG. 28, door 484 includes on an inner surface a catch protrusion 640 which forms an extension of angled side wall 638 and, when the door is closed, extends into an aperture 642 formed in the housing of the camera. Door 484 should be flexible enough to allow catch 640 to slide along the camera housing and snap into aperture 642 when the door is installed initially; however, catch 642 should be substantial enough to prevent the user from opening the door by pushing sideways. 
     In operation of mechanism 610, arm 628 initially is rotated counter-clockwise, as viewed in FIG. 26, until a stop 646 and sensor 626 are engaged by arcuate portion 622. Then arm 628 is rotated clockwise until both sensors 624, 626 are engaged. To open the door, arm 628 is rotated further clockwise until arcuate portion 622 moves out of engagement with sensor 626 but remains in engagement with sensor 624. This movement brings ramp portion 634 into contact with edge 641 of angled side wall 638. The camming action of ramp portion 634 during rotation of arm 628 causes door 484 to flex outwardly enough to allow catch protrusion 640 to pull out of aperture 642 and the door to slide to the position of FIG. 30. To close the door, arm 628 is rotated counter-clockwise until stop 646 again is engaged and the catch protrusion once again snaps into the aperture. 
     CAMERA ACTUATING AND TESTING STATION 80 
     As shown in FIGS. 25 and 31, station 80 includes an upwardly extended frame member 654 having a lower mounting flange 656 secured to the upper surface of support plate 12. Frame 654 includes a backwardly extended support flange 658 on the under side of which is mounted an electrical linear actuator 660. An actuator shaft 662 extends upwardly through flange 658 to engage an actuation end 664 of a camera trigger actuating lever 666 pivoted at 668 to the upper end of frame member 654. On the opposite side of pivot 668, lever 666 includes an engagement end 670 which, when a camera is in the position of FIG. 25, is positioned to engage and actuate shutter trigger button 438. 
     As shown in FIG. 31, behind engagement end 670, a cross bar 672 is provided to support a sensor 674 having an emitter and receiver pair. A suitable sensor is Model P3062-01 made by Hamamatus Corporation of Japan. Such sensors are provided in a single package and typically include an infrared light emitting diode, a photodiode, an amplifier, a Schmitt trigger, an output transistor and a focusing lens. Such a sensor can detect changes in the average reflectance of a surface, as would occur when a surface changes from a dark to a light color, or vice versa. Such a sensor also can detect the presence of a dark-colored mark on a light-colored counterwheel having dark-colored numbers, as in FIG. 21A; or a light-colored mark on a counterwheel having light colored numbers on a dark background, not illustrated. 
     Thus, as shown in FIGS. 25 and 35, sensor 674 is positioned opposite and sufficiently close to window 501 to enable the sensor to detect the presence of an optically detectable feature on counterwheel 500. As shown in FIG. 21A, such a feature may be a darkened sector 676 on a light-colored counterwheel 500, sector 676 being between the first and last frame numbers and having a leading edge 676a. Sector 676 can be provided in any suitable manner, but must have a reflectance which contrasts with the remainder of the surface of the counterwheel. Alternatively, the feature may be a black or darkened mark 676b of contrasting reflectance at any place on a light-colored counterwheel which passes beneath window 501, as shown in FIG. 21B. Or, the feature may be a mark 676c of an infrared absorbing material at any place on a light-colored counterwheel which passes beneath window 501 as shown in FIG. 21C. Such infrared absorbing materials are conventional and familiar to those skilled in the art and will allow visible light to pass but will absorb infrared. The contrasting reflectance of features 676, 676b or 676c should be such that sensor 674, shown in FIG. 31, can optoelectronically distinguish the mark from a frame number on the counterwheel. A frame number may fill approximately 10% of the field of view at window 501; whereas, mark 676, 676b or 676c preferably should fill approximately 40 to 60% of the field. 
     As will be discussed in more detail subsequently, feature 676, 676b or 676c can be offset from a first frame indicator on the counterwheel so that presence of the feature beneath window 501 will indicate that all of the film has been exposed. Or, the feature may be offset from a first frame indicator on the counterwheel so that presence of the feature beneath window 501 will indicate that counterwheel 500 has been offset, before loading of fresh film into the camera, to account for the number of frames between cassette 24 and the camera and the length of a leader trailer portion on the film strip. 
     For example, when sector 676 is positioned between the first and last frame numbers as shown in FIG. 21A, to account for a length of film between cassette 24 and the camera after actuation of knife 140, 142 and a length of a leader portion, sector 676 may have an arcuate extent corresponding to a number of frames of film equal to the sum of such lengths. Either edge of the darkened sector is distinguishable from the typically white color of the remaining surface of the counterwheel, due to a low reflectivity of the darkened sector. 
     Although the detectable feature most conveniently is located on the counterwheel in the manner just described, those skilled in the art will appreciate that without departing from the invention the feature alternatively could be located on a separate wheel, not illustrated, which would be geared to rotate synchronously with counterwheel 500. In such a case, a separate window, not illustrated, would be provided in the camera housing for viewing the feature. Or, the detectable feature could be provided on a peripheral, vertical edge surface of the counterwheel and viewed, for example, through opening 548 by providing probe 684 with a suitable sensor. 
     Referring again to FIG. 31, near actuation end 664 a sensor flag 678 is positioned to actuate a sensor 680 supported on an upwardly extended mounting bracket 682. Thus, when actuator 660 is energized, shaft 662 pushes upward on end 664 which causes end 670 to press downward on trigger button 438 to operate the shutter mechanism of the camera. At the same time, flag 678 actuates sensor 680 to confirm that the shutter has been operated. 
     On a front surface of frame member 654 is mounted a probe 684 having a semicylindrical tip 686 and a stop surface 688. When a camera is swung into the position of FIG. 25, tip 686 passes through access hole 548 and engages release lever 546 to release zero locking pawl 532. Stop surface 688 engages a stop in the camera casing or frame, not illustrated, to limit tilting of the camera within the nest and to prevent over insertion of the probe. 
     Also mounted on the front surface of frame member 654 is a bracket 690 having a vertical member 692 on which are mounted a pair of sensors 694, 696 which are positioned to cooperate with sensor flags 388, 390, respectively, on film guide ramps 370, 372. Thus, when the ramps have moved into the camera to a position for film loading or unloading, sensors 694, 696 will signal that event. 
     As shown in FIG. 3A, a flash sensor 698 is positioned above support plate 12 on a bracket 700, to detect operation of the flash feature of the camera. And, as shown in FIG. 35, a sensor 701 is positioned on a bracket 702 above support plate 12 and opposite opening 480, to detect illumination of the flash ready light of the camera. To prevent light from the ready light from fogging film entering the camera, sensor 701 preferably should be provided with a resilient gasket, not illustrated, to engage the camera around opening 480 and prevent leakage of light. 
     FILM LOADING AND UNLOADING OPERATIONS 
     FIG. 32 shows the configuration of the film loading and unloading tracks and a camera, when the camera has been swung into station 80. Until door 484 has been opened in the manner previously described, guide ramps 370, 372 will be pivoted toward the back of the apparatus due to contact with the door. When the door has been opened, the guide ramps will be swung by springs 382 through the open door toward notches 550, 552, which are shown in FIG. 22. If, as shown in FIG. 33, a film strip 704 in the camera is blocking access to notches 550, 552, then the guide ramps will come to rest on the film strip and sensor flags 388, 390 will not actuate sensors 694, 696. In this event, the controller of the apparatus, to be discussed later, will cause camera drive assembly 584 to be actuated to drive the film strip back toward unexposed film chamber 562. An angled lead edge 706 of the film strip, shown in FIG. 34, eventually will move past ramp 370 and permit ramp 370 to drop into notch 550. As a result, sensor flag 388 will actuate sensor 694 to indicate that the end of the film is nearing sprocket 530. Drive assembly 584 will continue to rotate just far enough to ensure that ramp 390 drops into notch 552. Sensor flag 390 then will actuate sensor 696 to indicate that the film should be stopped while the film strip remains engaged with sprocket 530. At this time, drive assembly 584 can advance angled lead edge 706 into film guide slot 378 of each guide ramp, as shown in FIG. 34. 
     As seen in FIGS. 3B and 35, a drive motor 708 is mounted to support plate 12. A downwardly extended drive shaft 710 supports a driver gear 874, also shown in FIG. 48. Gear 874 meshes with driven gear 602 on camera drive assembly 584 when nest 74 has been pivoted to locate a camera in the position of FIGS. 3B and 35. Motor 708 can be energized to rotate in either direction, to drive film from the camera into film unloading track 82 or to drive film into the camera from film loading track 72. 
     As mentioned previously, an electromagnet assembly 81 holds the nest in the position of FIGS. 3B and 35. As seen in FIG. 3B, assembly 81 comprises a flat-faced ferromagnetic block 81a attached to tubular housing 586 of drive assembly 584 and a flat-faced electromagnet 81b supported on a bracket 712 beneath support plate 12. An eye bolt 714 is attached to block 81a and an eye bolt 716 is attached to magnet 81b, with spring 78 extended between the two eye bolts. Contraction of spring 78 thus will pivot nest 74 to the position of FIG. 3B and pull block 81a into contact with electromagnet 81b to hold the nest in that position. 
     TRANSFER CARTRIDGE 86 
     The features of transfer cartridge 86 are shown in FIGS. 36 to 39. Cartridge 86 conveniently may be made from primarily injection molded plastic parts. An outer, opaque shell half 720 includes opposing end disks 724, 726 and a radially extended lip 728. A strip of conventional light lock material 730 is attached to an inwardly facing side of lip 728, as best seen in FIG. 38. At the ends of lip 728, a pair of depending actuation lips 732, 734 are provided, for a purpose to be described later in this specification. Nested partially within shell half 720 is an inner, opaque shell half 736 having opposing end disks 738, 740 which slidably engage end disks 724, 726. Shell half 736 also includes a radially extended lip 742 on an inwardly facing side of which a strip of light lock material 744 is attached for cooperation with strip 730. At the ends of lip 742, a pair of depending snap flanges 746, 748 are provided to secure the cartridge in its closed configuration. Within the shell formed by halves 720, 736, is rotatably mounted a conventional take-up spool 750. A row of radially extended teeth 752 are provided at one or both ends of spool 750 to engage corresponding perforations on a film strip. Extended around the spool and anchored at one end beneath strip 744 is a film threadup scroll or guide 754 which directs film passing between lips 728, 742 into engagement with the spool. A central bore within the spool retains a triangular friction clutch spring 758. A central drive shaft 760 extends through the spool. A cylindrical portion 762 on shaft 760 closely engages clutch spring 758. A retainer cap 764, suitably attached to a free end of shaft 760, and an externally accessible drive shaft coupling 766 secure shaft 760 for rotation in bores through end disks 724, 726. An internally splined counter bore 768 is provided within coupling 766. 
     In use of cartridge 86, lips 728, 742 are separated enough to permit insertion of a leading end of a film strip and spool 750 is rotated to engage the film with teeth 752. However, should excessive torque be required to draw film into the cartridge, shaft 760 will slip relative to clutch spring 758 to prevent damage to the film or the cartridge. When a film strip has been wound into the cartridge, lips 728, 742 are pressed toward each other to engage light lock strips 730, 744, thus providing a light tight enclosure for the film. 
     FILM CUTTER 84 
     The features of film cutter 84 are shown in FIGS. 40, 41 and 43 to 47. Referring initially to FIGS. 40 and 41, a rigid knife frame member 780 preferably is made from metal such as black anodized aluminum and includes along its lower side a mounting bracket 782 for attachment to support plate 12. On its side facing film unloading track 82 are a pair of parallel guide rails 784, 786 which cooperate with a mating pair of rails 785, 787 (seen in FIG. 41) on a facing side of a knife holder 788. A stainless steel knife blade 790 with an angled cutting edge 792 is mounted to holder 788. An actuator finger 794 extends from the holder between rails 785, 787 and passes through a horizontal through slot 796 provided in frame member 780. Near one end of the frame member, a J-shaped knife bed 798 is mounted with an edge 800 aligned with a corresponding edge of a slot 802 through the frame member. A pair of actuator tabs 804 extend from knife holder 788 through a slot 806 provided in a knife cover plate 808. A top lip 810 of the cover plate engages a top edge of frame member 780, while a bottom flange 812 includes a pair of fastener tabs 814 used to attach the cover plate to an under side of frame member 780. An exit slit 816 extends through the cover plate opposite slot 802. A pair of leaf springs 818, 820 are formed in the cover plate to engage the knife holder and press it into contact with the frame member. For simplicity, knife 788, 790 is oriented to cut the film straight across, rather than at an angle as in the cutter of FIG. 4; however, those skilled in the art will appreciate that cutter 84 also could be oriented to provide an angled cut, without departing from the scope of the invention. 
     As seen in FIG. 41, a horizontal slot 822 is provided on the side of frame member 780 opposite rails 784, 786. At the end of slot 822 closer to slot 796, a pair of spring pockets 824, 826 are provided, one on each side of slot 796. A slider 828 is positioned in slot 822. As shown in FIG. 41, pair of springs 827 are positioned in pockets 824, 826 and compressed between a right end of slider 828 and a keeper plate 829 attached to frame member 780. A horizontal through slot 830 in slider 828 receives the free end of actuator finger 794. Slot 830 is slightly shorter than slot 796, for a purpose to be discussed subsequently. At its end opposite slot 830, slider 828 supports an outwardly angled, horizontal arm 832 which extends through a slot 834 formed in a back cover plate 836. Arm 832 is seen best in FIGS. 40 and 45 to 47. Back cover plate 836 includes a top flange 838 which extends over frame member 780 in the assembled cutter. At an edge opposite to slot 802, cover plate 836 supports a pair of film strip edge guides 840, 842 between which extends an image relief recess 844, best seen in FIG. 41. 
     At an outer end of arm 832 is mounted a hinge 846 having a rotatable hinge pin 847 on which are fixedly mounted a pair of hooks 848, 850 positioned to engage actuation lips 732, 734 on an adjacent transfer cartridge 86. As best seen in FIG. 45, hook 848 includes a downwardly depending rotational stop 852 which can engage arm 832 to limit the range of movement of the hooks. As seen in FIGS. 41 and 45 to 47, each of film strip guides 840, 842 includes a backwardly angled ramp 854 which contacts a respective one of hooks 848, 850. On an opposite side of slot 802 from guides 840, 842 is mounted a film strip guide member 856 which includes a pair of film strip edge guides 858, 860 positioned opposite to guides 840, 842, respectively. An image relief recess 862 extends between guides 858, 860. A horizontal tab 864 projects from guide member 856 just below edge guide 860 to guide a lower longitudinal edge of the film strip between edge guides 842, 860. Finally, a top plate 866 is mounted to the assembly above flange 838. 
     As seen in FIGS. 43 and 44, an essentially cylindrical nest 868 is mounted to the top surface of support plate 12 to receive transfer cartridge 86. The nest is open along one side to allow radial lips 728, 742 of the cartridge to extend toward cutter 84; so that, hooks 848, 850 can engage actuation lips 732, 734 as the cartridge is lowered into the nest. As seen in FIG. 44, a cartridge retainer lever 867 is supported at one end of top plate 866 on a pivot 867a. Lever 867 includes a spring mounting post 867b spaced radially from the pivot. A spring 867c extends from the mounting post to an attachment point, not illustrated, on support plate 12. With lever 867 in the elevated position shown in FIG. 44, spring 867c passes above the pivot; however, when the lever is rotated clockwise as viewed in FIG. 44, the spring passes over the pivot and then contracts to force the lever into engagement with cartridge 86. A retainer finger 867d extends from the lever in position to engage end disk 724 of cartridge 86 and hold the cartridge securely within nest 868. In the assembled apparatus, lever 867 extends upward through opening 34, shown in FIG. 1, so that the upper end of the lever is engaged by the underside of top door 26. Thus, as top door 26 is closed by the operator of the apparatus, lever 867 will be pivoted in the manner just described to retain the cartridge in the nest. 
     FIGS. 42 to 47 show features of an actuator 250&#39; to 264&#39; for cutter 84 and a drive assembly 266&#39; to 302&#39; for cartridge 86. Except for the diameters of timing pulleys 292, 292&#39;, this actuator and drive assembly are essentially identical to those illustrated in FIGS. 10 and 11 and therefore will not be described again. As shown in FIG. 48, pulley 292&#39; may be smaller than pulley 292, causing takeup spool 750 in transfer cartridge 86 to rotate at a higher speed than sprocket roller 118 in cassette 24. As shown in FIGS. 42 and 43, a pair of sensor flags 870, 872 are mounted on cam follower plate 256&#39; in positions to actuate a corresponding pair of sensors 871, 873 visible in FIG. 3A. 
     In operation of the cutter and transfer cartridge, a film strip is fed from the camera along film unloading track 82 in the manner previously described. When the leading edge of the film strip actuates sensor 392, shown in FIG. 13, a signal is sent to the controller to energize rotary actuator 250&#39; to rotate actuator arm 262&#39; counterclockwise, as viewed in FIG. 43. Thus, knife blade 790 slides to the left to open a passage for the film strip to pass through cutter 84 into transfer cartridge 86. Rotation of cam follower plate 256&#39; simultaneously permits actuator lever 294&#39; to rise, thereby allowing upper end 300&#39; of drive shaft 282&#39; to move upward and engage coupling 766 of the transfer cartridge to rotate spool 750 and wind the film strip into the transfer cartridge. Movement of knife blade 790 simultaneously causes actuation finger 794 to move away from slot 802 through slot 796 and slot 830. But, before finger 794 reaches the end of slot 796, the finger engages the end of slot 830 and pulls slider 828 away from slot 802. As slider 828 moves, springs 827 are compressed and hooks 848, 850 pull on actuation lips 732, 734. Movement of actuation lips 732, 734 begins in the position of FIG. 46, where the transfer cartridge is closed and ends in the position of FIG. 47, where the transfer cartridge is open and finger 794 has reached the end of slot 796. Thus, cutter 84 and cartridge 86 are opened simultaneously. During movement between the closed and open conditions, hooks 848, 850 are guided by ramps 854. 
     Movement of the film strip into the transfer cartridge is controlled by snip guides 840, 842 and 858, 860 and by tab 864, which direct the film into an entrance slit defined between light lock strips 730, 744 of the cartridge. Winding into the cartridge continues until a desired length of film has been wound into the cartridge, either the entire strip from the camera or a portion of that snip, as will be discussed in further detail. At that point, rotary actuator 250&#39; is energized to slide knife blade 790 back to its starting position, thereby cutting the film snip, if only a portion has been unloaded from the camera, and closing the passage through cutter 84. Springs 827 extend to force slider 828 back toward slot 802, causing hooks 848, 850 to close the entrance slit between light lock snips 730, 744. At the same time, drive shaft 282&#39; is disengaged from coupling 766 to stop rotation of spool 750. 
     DRIVE TRAIN FOR APPARATUS 10 
     FIG. 48 shows a view taken just below support plate 12. A driver gear 874 is connected to output shaft 710 of motor 708, in position to mesh with driven gear 602 when nest 74 is swung into position at camera actuating and testing station 80. Output shaft 710 also supports a timing pulley 876 which engages a timing belt 878 which also engage pulleys 292 and 292&#39;; so that the drives of cassette 24, nest 74 and transfer cartridge 86 share the single motor 708. See also FIG. 3B, where the timing belt has been omitted for simplicity. To maintain tension in belt 878, a further timing pulley 880 is mounted on an adjustment lever 882 pivoted at 884 to the under side of support plate 12. Also visible in FIG. 48 are a support member 886 for control console 50 and a conventional programmable controller 888 separated from the light tight portions of the apparatus by a dividing wall 890. 
     LOADING AN EMPTY CAMERA 
     The overall operational logic of the apparatus is shown in the interconnected flow charts of FIGS. 49 to 54. Controller 888 receives inputs from the various sensors of the apparatus and controls operation of the various motors and actuators. To prepare the apparatus for use, cassette 24 is loaded past open door 20; a camera 426 is loaded past open door 26 into nest 74; and a cartridge 86 is loaded into nest 868. The doors are closed. The operator then uses console 50 to enter data concerning the camera and any operations to be performed on the camera. For example, the operator might indicate that the camera contains only exposed film and is to be completely unloaded; that the camera contains exposed and unexposed film and is to be partially unloaded of only the exposed frames; that the camera is empty and is to be loaded with a selected number of frames of unexposed film; that the camera is simply to be tested; or that the camera has no flash feature. With this information, as shown in FIGS. 49 and 50, the controller then checks the appropriate sensors to confirm that the doors are closed; a camera is present; the lens cover is open; the flash switch has been turned on; and the flash ready light is illuminated. 
     Camera door 484 is then opened. If ramps 370, 372 are able to swing into place against ledge 386 inside the camera, sensors 694, 696 will signal the controller that no film is present in the camera, meaning that a loading sequence may begin, following the logic of FIGS. 50 to 52. Actuator 660, shown in FIG. 25, is then energized to depress shutter trigger button 438. If sensor 698, shown in FIG. 3A, does not detect a flash, sprocket drive gear 508 is rotated to advance the film one frame and actuator 660 again is energized to depress the shutter trigger button. If no flash is detected again, the camera must be removed for repair. 
     If sensor 698 detects a flash, the camera must be initialized following, for example, the logic of FIG. 54. Assume that the camera includes counterwheel 500 having a darkened sector 676 as shown in FIG. 21. If sensor 674 detects the presence of sector 676 essentially blocking window 501, motor 708 is energized to drive sprocket drive gear 508 and counterwheel 468 counter clockwise until leading edge 676a of sector 676, shown in FIG. 21, is detected at window 501, at which point motor 708 is stopped. If sensor 674 does not detect the presence of sector 676 blocking window 501, motor 708 is energized to drive the sprocket drive gear and counterwheel clockwise until leading edge 676a is detected, at which point motor 708 is stopped. Sprocket drive gear 508 is then driven clockwise a fixed number of frames corresponding to the length of film between the cassette and the camera, plus a length of any leader portion to be provided on the film strip, at which point motor 708 is stopped. The counterwheel now has been offset to account for the distance from the cassette to the camera and the leader portion. 
     Alternatively, assume the camera includes counterwheel 500 having a black mark 676b or an infrared absorbing mark 676c, such as shown in FIGS. 21B and 21C. Assume further that mark 676b or 676c is positioned on the counterwheel so that, when the mark is detected at window 501, the counterwheel is offset to account for the distance from the cassette to the camera and the leader portion. In these embodiments, initializing an empty camera prior to loading is accomplished simply by rotating counterwheel 500 until the mark is detected at window 501. 
     Returning from FIG. 54 to the logic of FIG. 51, actuator 250 and motor 708 are energized to drive film from cassette 24, along loading track 72 into the camera, where the film is scrolled into unexposed film chamber 562. Loading continues until chamber 562 has received a number of frames equal to the total selected by the operator, plus the leader portion and minus the distance from the cassette to the camera. Actuator 250 is then energized to move knife 142 to cut the film and stop rotation of sprocket roller 118. The film still in loading track 72 is then driven into the camera and the film transport is stopped while the film is still engaged with sprocket drive 530. As camera door 484 is shut, it engages ramps 370, 372 and pivots them out of the camera to the position of FIG. 32. The film is advanced a partial frame to be sure that at least one of ramps 370, 372 will encounter the film should camera door 484 be reopened. Door 26 is opened and the loaded camera is removed. 
     FULLY AND PARTIALLY UNLOADING A CAMERA 
     Refer again to the flow chart of FIG. 50. If a camera with at least some exposed frames is placed in the apparatus, the exposed frames will have been wound into exposed film chamber 564. The flash switch will be turned off before the camera is inserted in nest 74. Due to the presence of exposed frames, as shown in FIG. 33, ramps 370, 372 will not be able to swing into place against ledge 386 inside the camera; and sensors 694, 696 will signal the controller that exposed film is present in the camera, meaning that an unloading sequence is ready to begin. Referring to the flow chart of FIGS. 53A, B and C, motor 708 is energized to drive the exposed frames over to unexposed film chamber 562. The number of exposed frames is determined by counting the revolutions of encoder disk 604 in the manner previously described. As soon as the end of the film strip has moved just past ledge 386 but is still engaged with drive sprocket 530, the ramps will swing into place, causing flags 388, 390 to swing into engagement with sensors 694, 696 which signal the controller than the unloading sequence may continue, at which point the film transport is stopped. Using the just-counted number of exposed frames, the controller then determines a number of frames to be driven from the camera into unloading track 82. This number will be the number of frames rewound into chamber 562, plus two frames, plus a number of frames equal to the distance from the camera to cutter 84. Actuator 250&#39; is then energized to move knife blade 790 away from slot 802 and to engage cartridge 86 with its drive mechanism. The film is then driven from the camera one frame at a time and the shutter is tripped between frames, until the required number of frames has been driven out of the camera. 
     If the leading edge 676a of sector 676 is detected by sensor 674 before the required number of exposed frames has been driven out of the camera, this indicates that a complete unloading of the camera must be performed, following the left branch of the flow chart of FIG. 53. The remainder of the film is driven along unloading track 82 until sensor 392 indicates that the trailing end of the film has passed, at which point the film transport is stopped and actuator 250&#39; is de-energized. If the counterwheel bears one of marks 676b or 676c, rather than sector 676, then detection of that mark at window 501, before the required number of frames has been driven from the camera, also would indicate that a complete unloading must be performed. Following a complete unloading, the camera may be reloaded after turning on its flash switch, or door 26 may be opened and the empty camera removed for later reuse. 
     If the leading edge of sector 676 is not detected (or either of marks 676b or 676c), a partial unloading may be done. The required number of frames is driven from the camera and the film transport is stopped. Cutter 84 is actuated to cut the film. Because the drive to the transfer cartridge is disengaged when the cut is made, a short tab of film will be left extended from the closed transfer cartridge for use in subsequent photofinishing of the exposed film. The film transport is then actuated to drive the remaining, unexposed film back into the camera, stopping when the end of the film is still engaged with drive sprocket 530. Camera door 484 is shut. The film is advanced a partial frame, to be sure that at least one of ramps 370, 372 will encounter the film should door 484 be reopened. The customer later will advance the film into engagement with take up spool 490. Door 26 is opened and the partially unloaded camera is removed for further use. 
     
         ______________________________________                                    
Parts List                                                                
______________________________________                                    
 10         apparatus for loading and unloading                           
            cameras                                                       
 12         central mechanism support plate or                            
            frame                                                         
 14         lower housing                                                 
 16         hand hold                                                     
 18         upper housing                                                 
 19         peripheral groove                                             
 20         L-shaped end door                                             
 22         hinge between 18 and 20                                       
 24         cassette for unexposed film                                   
 26         top door                                                      
 28         hinge between 18 and 26                                       
 30         recess in 18                                                  
 32         camera insertion and removal                                  
            opening                                                       
 34         transfer cartridge insertion and                              
            removal opening                                               
 36         actuating lever for camera nest                               
 38         opening through bottom of 30                                  
 40         retainer bracket                                              
 42         resilient pad                                                 
 44         catch on 26                                                   
 46         catch on 20                                                   
 48         grille on air inlet                                           
 50         pivotable control console                                     
 52         keypad                                                        
 54         visual display                                                
 60         support legs for 12                                           
 62         back wall of cassette compartment                             
 64         front wall of cassette compartment                            
 66         ledge on 62 to support                                        
 68         guide flange on 24                                            
 70         interior stop wall                                            
 72         film loading track assembly                                   
 74         camera nest                                                   
 76         pivot between 74 and 12                                       
 78         spring                                                        
 80         camera actuating and testing station                          
 81         electromagnet assembly                                        
 81a        ferromagnetic block                                           
 81b        electromagnet                                                 
 82         film unloading track assembly                                 
 84         cutter for exposed film                                       
 86         transfer cartridge                                            
100         opaque body or housing                                        
102         bottom wall                                                   
104         peripheral wall                                               
106         removable cover                                               
108         roll of film                                                  
110         central core                                                  
112         lead end of film                                              
114         idler roller                                                  
116         shaft for 114                                                 
118         driven sprocket roller                                        
120         driven shaft                                                  
122         teeth on 118                                                  
124         edge perforations on film                                     
126         spring-biased keeper                                          
128         shaft for 126                                                 
130         contact pad of 126                                            
132         anti-backup pawl                                              
134         saw toothed ratchet wheel                                     
136         exit slit                                                     
137         raised lip                                                    
138         L-shaped recess                                               
140         knife holder                                                  
142         knife blade                                                   
144         angled cutting edge                                           
α     acute angle between plane of 104 and                          
            plane of 138                                                  
145         angled leading edge on film                                   
146         J-shaped recess                                               
148         knife bed                                                     
150         edge of 148                                                   
152         tab on 140                                                    
154         tension spring                                                
156         anchor on 104                                                 
166         actuator tabs on 140                                          
168         slot in 170                                                   
170         knife cover plate                                             
172         stop surface                                                  
174         upper lip on 170                                              
176         bottom flange on 170                                          
178         recess into 104                                               
180         exit slit in 170                                              
182, 184    leaf springs                                                  
186, 188    fasteners                                                     
190         actuator plunger                                              
192         passage in 104                                                
194         channel along 102                                             
196, 198    guide walls                                                   
200         coil spring                                                   
202         retainer flange                                               
204         transverse stop                                               
206         cover plate                                                   
208         anti-backup lever                                             
210         pivot axle                                                    
212, 214    notches in 196, 198                                           
216         tabs on 206                                                   
218         leaf spring                                                   
220         stub shaft                                                    
222         latching finger                                               
224         recesses in 110                                               
226         cam surface on 190                                            
228         probe                                                         
230         knife release arm                                             
232         latching finger                                               
234         opening in 138                                                
236         opening in 140                                                
250, 250&#39;   rotary actuator                                               
252, 252&#39;   mounting flange to underside                                  
            of 12                                                         
254, 254&#39;   drive shaft                                                   
256, 256&#39;   cam follower plate                                            
258, 258&#39;   arcuate cutout in 256                                         
260         V-shaped notch in 256                                         
262, 262&#39;   radial actuator arm                                           
264, 264&#39;   actuating finger between 166                                  
266, 266&#39;   cassette/cartridge drive                                      
            assembly                                                      
268         tubular housing                                               
270, 270&#39;   mounting flange to underside                                  
            of 12                                                         
272, 274    bearings                                                      
276         hollow shaft                                                  
278         splined counter bore                                          
280         through bore                                                  
282, 282&#39;   driver shaft                                                  
283         splines on 282                                                
284         spring                                                        
286         shoulder on 276                                               
288         shoulder on 282                                               
290         stop on 282                                                   
292, 292&#39;   timing pulley on 276                                          
294, 294&#39;   actuator lever                                                
296, 296&#39;   pivot block                                                   
298, 298&#39;   fork                                                          
300, 300&#39;   upper end of 282                                              
302, 302&#39;   wedge cam on 294                                              
304         drive coupling for 118                                        
306         sensor flag                                                   
310         sensor                                                        
312         sensor                                                        
320         shallow V-shaped frame plate                                  
322         mounting bracket                                              
324         upper side rail block                                         
326         lower side rail block                                         
328, 330    upper retainer flanges                                        
332, 334    lower retainer flanges                                        
336, 336&#39;   lower film guide slot                                         
338, 338&#39;   upper film guide slot                                         
340         flared inlet to 336                                           
342         flared inlet to 338                                           
344         sensor pair to detect film presence                           
346         tapered downstream end of 324,                                
            326                                                           
348         upper side rail block                                         
350         lower side rail block                                         
352         frame plate                                                   
353         upper retainer flange                                         
354, 356    downstream ends of 330, 334                                   
355         lower retainer flange                                         
358         slot in 346                                                   
360         film diverter spring                                          
362         pin                                                           
364         slot in 354, 356                                              
366         curved end of 348, 350                                        
370, 372    film guide ramps                                              
374, 376    pivot pins                                                    
378         film guide slot in 370, 372                                   
380         radial arm 370, 372                                           
382         leaf spring                                                   
384         transverse stop                                               
386         stop ledge in camera                                          
388, 390    sensor flags                                                  
392         sensor                                                        
410         base plate                                                    
412         positioning pin                                               
414         positioning pin                                               
416         aperture                                                      
418         camera drive spindle                                          
420, 422    flared end walls                                              
424         central, flared back support                                  
426         camera                                                        
428         front housing                                                 
430         lens opening                                                  
432         lens cover actuator                                           
433         slot                                                          
434         flash opening                                                 
436         flash activation switch                                       
438         shutter trigger button                                        
440         &#34;camera present&#34; treadle assembly                             
442         pivot                                                         
444         transversely extended treadle arm                             
446         sensor flag                                                   
448         sensor for 446                                                
450         &#34;lens cover open&#34; treadle assembly                            
452         pivot                                                         
454         transversely extended treadle arm                             
456         downwardly extended L-shaped                                  
            sensor flag                                                   
458         sensor for 456                                                
460         &#34;flash activated&#34; lever assembly                              
462         pivot                                                         
464         transversely extended arm                                     
466         transversely extended arm                                     
468         sensor flag                                                   
470         sensor for 468                                                
472         bottom aperture for 412                                       
474         bottom aperture for 414                                       
476         externally accessible drive shaft                             
            coupling for 418                                              
478         back housing                                                  
480         opening for flash ready light                                 
482         slot for thumbwheel                                           
484         sliding door to permit                                        
            loading/unloading of film                                     
486         thumbwheel                                                    
488         gear                                                          
490         conventional film take-up spool                               
492         gear                                                          
494         shutter reset cam                                             
496         gear                                                          
498         counterwheel advancing pawl                                   
500         counterwheel                                                  
501         window in 428 to view frame                                   
            number                                                        
502         shaft                                                         
504         axially extensible joint                                      
506         shaft                                                         
508         sprocket drive gear                                           
510         spring                                                        
512         stop in camera frame                                          
514         anti-backup gear                                              
516         anti-backup pawl                                              
518         cam surface                                                   
520         flexible cantilever arm                                       
522         base                                                          
523         frame plate                                                   
524         right angle stiffener wall                                    
525         mounting pin                                                  
526         gear                                                          
530         film drive sprocket                                           
532         zero locking pawl                                             
534         pivot axle                                                    
536         stop finger on 532                                            
538         cylindrical surface on 500                                    
540         radial slot in upper surface of 500                           
542         locking tooth                                                 
544         inward facing saw toothed ratchet                             
            in 486                                                        
546         release lever                                                 
548         access hole in 478                                            
550, 552    notches in ledge 386                                          
554         entrance to film track within                                 
            camera                                                        
562         unexposed film chamber                                        
563         flexible film scroller                                        
564         exposed film chamber                                          
566         film guide track between 562 and                              
            564                                                           
568         exposure chamber                                              
570, 572    side rails on 566                                             
574, 576    side rails on 386                                             
578, 580    guide wedges at ends of 386                                   
582         downward boss on 74                                           
584         camera drive assembly                                         
586         tubular housing                                               
588         mounting flange                                               
590, 592    bearings                                                      
594         internally splined counter bore in                            
            476                                                           
596         torque transmission pawl                                      
598         pivot                                                         
600         spring                                                        
602         driven gear                                                   
604         encoder disk                                                  
605         sensor flag                                                   
606         sensor                                                        
608         bracket                                                       
610         camera door opening mechanism                                 
612         L-shaped frame                                                
614         mounting flange to underside of 12                            
616         rotary actuator                                               
618         cylindrical spacer                                            
620         sensor flag                                                   
622         arcuate portion                                               
624, 626    sensors                                                       
628         door opening arm                                              
630         slot through 12                                               
632         door engaging hook                                            
634         ramp portion                                                  
635         thrust washer                                                 
β      ramp angle                                                    
636         slot                                                          
637         flat washer                                                   
638         angled side wall                                              
639         bolt                                                          
640         catch protrusion                                              
γ     catch angle                                                   
641         outside edge of 638                                           
642         aperture in 478                                               
644, 646    stops for 622                                                 
654         frame member                                                  
656         mounting flange to 12                                         
658         backwardly extended support                                   
            flange                                                        
660         linear actuator                                               
662         actuator shaft                                                
664         actuation end of 666                                          
666         camera trigger actuating lever                                
668         pivot                                                         
670         engagement end                                                
672         cross bar                                                     
674         sensor to sense 676                                           
676         darkened sector on 500                                        
676a        leading edge of 676                                           
676b        black mark                                                    
676c        infrared absorbing mark                                       
678         sensor flag                                                   
680         sensor                                                        
682         mounting bracket                                              
684         probe                                                         
686         semi-circular tip                                             
688         stop flat                                                     
690         mounting bracket                                              
692         vertical member                                               
694, 696    sensors for 388, 390                                          
698         flash sensor                                                  
700         bracket                                                       
701         sensor for flash ready light                                  
702         bracket                                                       
704         film strip in camera                                          
706         angled end edge                                               
708         drive motor                                                   
710         drive shaft                                                   
712         bracket                                                       
714         eye bolt                                                      
716         eye bolt                                                      
720         outer shell half                                              
724, 726    end disks                                                     
728         radial lip                                                    
730         strip of light lock material                                  
732, 734    depending actuation lips                                      
736         inner shell half                                              
738, 740    end disks                                                     
742         radial lip                                                    
744         strip of light lock material                                  
746, 748    depending flanges                                             
750         spool                                                         
752         teeth                                                         
754         film thread up scroll or guide                                
756         central bore                                                  
758         triangular spring                                             
760         central shaft                                                 
762         cylindrical portion of 760                                    
764         retainer cap                                                  
766         externally accessible drive shaft                             
            coupling                                                      
768         internally splined counterbore                                
780         knife frame member                                            
782         mounting bracket                                              
784, 786    parallel guide rails on 780                                   
785, 787    parallel guide rails on 788                                   
788         knife holder                                                  
790         knife blade                                                   
792         angled cutting edge                                           
794         actuator finger                                               
796         slot in 780                                                   
798         J-shaped knife bed                                            
800         edge of 798                                                   
802         slot                                                          
804         actuator tabs on 788                                          
806         slot in 808                                                   
808         knife cover plate                                             
810         top lip                                                       
812         bottom flange                                                 
814         fastener tab                                                  
816         exit slit                                                     
818, 820    leaf springs                                                  
822         slot                                                          
824, 826    spring pockets                                                
827         springs                                                       
828         slider                                                        
829         keeper plate                                                  
830         slot                                                          
832         rearwardly angled arm                                         
834         slot                                                          
836         back cover plate                                              
838         top flange                                                    
840, 842    film strip guides                                             
844         image relief recess                                           
846         hinge                                                         
847         hinge pin                                                     
848, 850    hooks                                                         
852         rotational stop                                               
854         ramp                                                          
856         film guide member                                             
858, 860    film strip edge guides                                        
862         image relief recess                                           
864         tab                                                           
866         top plate                                                     
867         cartridge retainer lever                                      
867a        pivot                                                         
867b        spring mounting post                                          
867c        spring                                                        
867d        finger                                                        
868         nest for 86                                                   
870, 872    sensor flags                                                  
871, 873    sensors                                                       
874         driver gear                                                   
876         timing pulley                                                 
878         timing belt                                                   
880         timing pulley                                                 
882         tension adjustment arm                                        
884         pivot                                                         
886         hinge for 50                                                  
888         controller                                                    
890         light-tight dividing wall                                     
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     While my invention has been shown and described with reference to particular embodiments thereof, those skilled in the art will understand that other variations in form and detail may be made without departing from the scope and spirit of my invention. 
     While my invention has been shown and described with reference to particular embodiments thereof, those skilled in the art will understand that other variations in form and detail may be made without departing from the scope and spirit of my invention.