a first embodiment of the present invention will be described with reference to drawings . fig1 is a front view showing a phase - contrast haploscope according to the present embodiment . fig2 is a rear view showing the haploscope . fig3 is a right - hand side view showing the haploscope . fig4 is a plan view showing a control box . fig5 is an enlarged front view showing a rotary disc of the present embodiment . fig6 is a partially omitted perspective front view showing a disc case with its stationary front plate removed . fig7 is an enlarged plan view of essential portions of the disc case with its top plate removed when a halogen lamp is attached into a left - hand beam emitting hole . fig8 and 9 are enlarged plan views showing other examples of a rotary disc . in the figures , reference symbol a denotes a phase - contrast haploscope according to the present embodiment . b , b &# 39 ; and b &# 34 ; denote rotary discs used in the present embodiment . reference numeral 1 denotes a disc case . 1a denotes a front plate , 1b denotes a rear plate , and 1c and 1d denote right - and left - hand side plates . designators 2 and 3 denote a pair of circular left - and right - hand look - through holes which face left and right eyes , respectively , and which are formed in the front plate 1a at the center of its lower half portion . designators 4 denotes a through window provided in the rear plate 1b at the lower half portion thereof . designators 5a - 5d denote through holes which have the same diameter as the left - and right - hand look - through holes 2 , 3 and which are formed in the rotary disc b on concentric circular path α equally spaced at 90 degrees . designators 6a - 6d denote rectangular arc - shaped inner project - through holes which correspond to the left - hand look - through hole 2 and which are formed in the rotary disc b on concentric circular path γ equally spaced at 90 degrees . designators 7a - 7d denote rectangular arc - shaped outer project - through holes which correspond to the right - hand look - through hole 3 and which are formed in the rotary disc b on concentric circular path β equally spaced at 90 degrees . designators 8 and 9 denote left - hand connectors which are coaxially mounted to a left - hand beam incident hole 10a and a left - hand beam emitting hole 10 at their outer ends . the holes 10a and 10 are formed in the front plate 1a and rear plate 1b at opposed positions where the holes face on one of inner project - through holes 6a - 6d when one of through holes 5a - 5d instantaneously coincides with the left look - through hole 2 . the beam emitting end of a left - hand optical fiber 11 and the beam incident end of the left - hand transmitting optical fiber 12 are inserted into the left - hand connectors 8 , 9 and fixed thereto with set screws 13 , 14 . designators 15 and 16 denote right - hand connectors which are coaxially mounted to a right - hand beam incident hole 17a and a right - hand beam emitting hole 17 at their outer ends . the holes 17a and 17 are formed in the front plate 1a and rear plate 1b at opposed positions where the holes face on one of outer project - through holes 7a - 7d when one of through holes 5a - 5d instantaneously coincides with the right look - through hole 3 . the beam emitting end of a right - hand optical fiber 18 and the beam incident end of a right - hand transmitting optical fiber 19 are inserted into the right - hand connectors 15 , 16 and fixed thereto with set screws 20 , 21 . reference designator 22 denotes a variable speed motor mounted on the rear plate 1b at its center . the end of a motor shaft 22a extending through the rear plate 1b is fixed to the rotary disc b at its center . reference designator 23 denotes a forehead rest attached to a slide rod 23a which is inserted into a guide cylinder 24 mounted on the front plate 1a above the middle between the left - and right - hand look - through holes 2 , 3 . the slide rod 23a as an unillustrated guide groove extending along its upper edge , and the tip end of an adjusting set screw 25 is engaged with the guide groove for fixing . designators 26 and 27 denote glass or plastic transparent plates stuck on left - and right - hand cylindrical frames 28 , 29 whose stoppers 28a , 29a are mounted to the outer ends of the left - and right - hand look - through holes 2 , 3 , respectively . designator 30 denotes a lift support standing upright at the center of a horizontally h - shaped base frame 31 equipped with casters 31a which can be locked . designator 30a denotes a cylindrical support . 30b denotes a screw rod . 30c denotes a head portion which contains a known adjusting mechanism for raising and lowering the screw rod 30b inserted thereinto by turning a rotary handle 32 in a forward or reverse direction . designator 32a denotes an adjusting stopper screw for fixing the screw rod 30b at an adjusted position . reference designator 33 denotes a table type base and 34 and 35 denote left - and right - hand parallel support stands standing upright on the base 33 to support the disc case 1 thereon . designators 36 and 37 denote left - and right - hand parallel uprights standing in front of the left - and right - hand parallel support stands 34 , 35 . designator 38 denotes a cross - plate which bears a chin rest 38a at its central portion corresponding to the middle between the left - and right - hand look - through holes 2 , 3 and which stretches between the left - and right - hand parallel guide uprights 36 , 37 in such a manner that its both ends slide up and down along the uprights . designator 39 denotes a cylindrical slider which is slidably fit onto the right - hand guide upright and which is fixed at an adjusted position with an adjusting set screw 40 in order to position the cross - plate 38 via a sleeve 39a . designators 41a and 41b denote left - and right - hand light source boxes which are mounted on the bottom face of the base 33 at both sides thereof and to which beam incident ends of the left - and right - hand optical fibers 11 , 18 are connected . designator 42 denotes a control box attached to the right - hand end of the base 33 in a hanging manner with set screws 42a . designators 43 , 44 , 45 , 46 and 47 denote a main switch , a right - hand bright control , a left - hand bright control , a speed control , and a digital speedometer , respectively , arranged on a control panel 42b . designators 48 and 49 denote a pair of left - and right - hand projectors which upward penetrate the base 33 with a predetermined spacing . designators 50 and 51 denote left - and right - hand slide loaders which are incorporated into the left - and right - hand projectors 48 , 49 , respectively , at their top portions and which allow lantern slides n , o to be loaded thereinto or unloaded therefrom . designators 52 and 53 denote a pair of left - and right - hand zooms which are mounted on the left - and right - hand projectors 48 , 49 , respectively , at their top ends . designators 54 and 55 denote left - and right - hand connectors which are connected to the left - and right - hand projectors 48 , 49 , respectively , at their bottom ends and into which the beam irradiating ends of the left - and right - hand transmitting optical fibers 12 , 19 are inserted and fixed with set screws 56 , 57 . designators 58 and 59 denote a pair of left - and right - hand mirrors which are pivotally mounted in left - hand forked brackets 62 and right - hand forked brackets 63 with pivots 58a , 59a in such a manner that a vertical angle can be adjusted and set as desired and as to face the top ends of the left - and right - hand zooms 52 , 53 . the left - and right - hand forked brackets 62 , 63 stand upright on the left - and right - hand seat rings 60 , 61 , respectively . the left - and right - hand seat rings 60 , 61 are mounted rotatably on the top ends of the left - and right - hand projectors 48 , 49 in such a manner as to cover the lower portions of the left - and right - hand zooms 52 , 53 . designators 64 and 65 denote a pair of left - and right - hand right - angle handles for swinging the left - and right - hand mirrors 58 , 59 horizontally and vertically . the handles 64 , 65 are fixed to the inner neighboring sides of the left - and right - hand arms 66 , 67 which obliquely downwardly project from and are located at the middle portions of the back surfaces of the left - and right - hand mirrors 58 , 59 . designator 68 denotes a screw rod mounting hardware which is mounted on the bottom face of the base 33 at its center and into which the top end of the screw rod 30b is inserted to be fixed with a stopper screw 69 . designator 70 denotes a plug attached to the end of a power cord 71 extending from the control box 42 . as illustrated with a dash - and - two dots line in fig6 and shown in fig7 the left - and right - hand beam emitting holes 10 , 17 in the rear plate 1b may be enlarged to obtain left - and right - hand beam emitting holes 10 &# 39 ;, 17 &# 39 ; having a larger diameter , and left - and right - hand halogen lamps 72 , 73 may be inserted thereinto for attachment . in this case , electric cords ( not shown ) in place of the left - and right - hand optical fibers 11 , 18 are directly connected to the control box 42 , and the left - and right - hand light source boxes 41a , 41b become unnecessary . in the phase - contrast haploscope a according to the present embodiment described above , four holes of each kind , i . e . through holes 5a - 5d and rectangular arc - shaped project - through holes 6a - 6d and 7a - 7d are arranged with an inter - hole phase angle of 90 . the number of holes of each kind is not limited to 4 . one hole may be provided , or multiple holes may be arranged at the same phase angle . in detail , in the rotary disc b for the phase - contrast haploscope according to the present invention , four holes of each kind , i . e . through holes 5a - 5d and project - through holes 6a - 6d and 7a - 7d are arranged . a rotary disc having a single hole of each kind arranged with an inter - hole angle of 360 degrees , rotary disc b &# 39 ; having two holes of each kind arranged with an inter - hole angle of 180 degrees as shown in fig8 and rotary disc b &# 34 ; having three holes of each kind arranged with an inter - hole angle of 120 degrees as shown in fig9 may be acceptable . in these cases , when the motor 22 coupled directly with the motor shaft 22a rotates at a speed of 120 c / s or 7200 rpm , the changeover speed is calculated as follows : ______________________________________1 hole 7200 times / minute2 holes 7200 × 2 = 14400 times / minute3 holes 7200 × 3 = 21600 times / minute4 holes 7200 × 4 = 28800 times / minute______________________________________ ______________________________________1 hole 7200 rpm2 holes 7200 / 2 rpm = 3600 rpm3 holes 7200 / 3 rpm = 2400 rpm4 holes 7200 / 4 rpm = 1800 rpm______________________________________ thus , as the number of holes increases , the speed of the motor can be lowered . accordingly , a torque load can be reduced , and a cheaper motor can be employed . of course , in place of one large through hole 4 in the present embodiment , a pair of left - and right - hand through holes corresponding to the left - and right - hand look - through holes 2 , 3 may be used . the present embodiment has the above - described concrete structure . operations of the present embodiment will now be described . the apparatus according to the present embodiment is moved to a desired place . the apparatus is locked using the locks 31a &# 39 ; of a group of casters 31a . the plug 70 of the power cord 71 is inserted into a power connector ( not shown ). after loosening the adjusting stopper screw 32a , the rotary handle 32 is turned in the forward or reverse direction to project or retract the screw rod 30b according to the sitting height of examinee p who sits on a separately prepared chair , so that an appropriate height is attained . the adjusting stopper screw 32a is thereafter tightened . according to the face profile of the examinee p , after loosening the adjusting set screw 25 , the forehead rest 23 is advanced or retracted along the guide cylinder 24 until an appropriate position is reached , and the adjusting set screw 25 is then tightened . also , after loosening the adjusting set screw 40 , the cylindrical slider 39 is vertically slid along the left - and right - side parallel guide uprights 36 , 37 until the chin rest 38a together with the cross - plate 38 reaches an appropriate position , and the adjusting set screw 40 is then tightened , thus determining the height of the chin rest 38a . thus , the face of the examinee p with respect to the front plate 1a is set so that both eyes of the examinee p are properly seen from the central portions of the left - and right - hand transparent plates 26 , 27 of the left - and right - hand look - through holes 2 , 3 . after turning on the power switch 43 on the control panel 42b , the left - and right - hand brightness controls 44 , 45 are adjusted , and the speed controller 46 is adjusted while checking a speed displayed on the digital speedometer 47 . next , the left - and right - hand slide boxes 50a , 51a are pulled out , and the left - and right - hand lantern slides n , o used for an examination are loaded thereinto . the slide boxes are inserted back into the left - and right - hand slide loaders 50 , 51 . the handles 64 , 65 for swinging the left - and right - hand mirrors are operated horizontally and vertically so that for example , the targets h , g : on the left - and right - hand lantern slides are projected ion the plane of projection m at a desired position . at the same time , the left - and right - hand zooms 52 , 53 are operated to zoom in or out the projected left - and right - hand targets h , g . after the adjusting operations : have been completed , when the rotary disc b is rotated , for example , at a speed higher than the critical fusion frequency ( 100 - 120 c / s or higher ) as in the conventional phase - contrast haploscope , the left and right changeover speed becomes twice that of the conventional synchronous type phase - contrast haploscope . as the rotary disc b rotates at a high speed in the direction of an arrow as illustrated , the centers of the through holes 5a - 5d revolve traveling along out the concentric circular path α . the through holes 5a - 5d pass one by one in front of the left - and right - hand look through holes 2 , 3 whose centers are located on the concentric circular path α . one of the through holes 5a - 5d coincides instantaneously with the left - hand look - through hole 2 , and then after the elapse of a predetermined instantaneous time , it coincides instantaneously with the right - hand look - through hole 3 . thus , as a result of the through holes 5a - 5d in the rotary disc b revolving counterclockwise and passing in front of the left - and right - hand look - through holes 2 , 3 , the left - and right - hand look - through holes 2 , 3 alternately coincide with one of the through holes . while the rotary disc b makes one rotation , the alternation occurs 4 times for instantaneous coincidence . in synchronism with the above , as the rotary disc b rotates , the rectangular arc - shaped inner project - through holes 6a - 6d and the rectangular arc - shaped outer project - through holes 7a - 7d rotate between the left - hand beam emitting end of the left - hand optical fiber 11 or the left - hand halogen lamp 72 and the beam incident end opposed thereto of the beam incident hole of the left - hand transmitting optical fiber 12 on the front plate 1a or between the right - hand beam emitting end of the right - hand optical fiber 18 or the right - hand halogen lamp 72 and the beam incident end opposed thereto of the beam incident hole 17a ( not shown ) of the right - hand transmitting optical fiber 19 on the front plate 1a , and travel along the inner concentric circular path γ and the outer concentric circular path β , respectively . synchronously with the instantaneous coincidence of one of the through holes 5a - 5d with the left - hand look - through hole 2 , one of the rectangular arc - shaped inner project - through holes 6a - 6d corresponding to the one of the through holes 5a - 5d passes between the beam emitting end of the left - hand optical fiber 11 or the left - hand halogen lamp 72 and the beam incident end opposed thereto of the left - hand transmitting optical fiber 12 . at that time , a left - hand projecting beam l emitted from the beam emitting end of the left - hand optical fiber 11 or the left - hand halogen lamp 72 passes through one of the rectangular arc - shaped inner project - through holes 6a - 6d and enters the beam incident end opposed thereto of the left - hand transmitting optical fiber 12 . the beam irradiates the lantern slide n inserted into the left - hand projector 48 via the left - hand transmitting optical fiber 12 . the beam from the left - hand projector passes through the left - hand zoom 52 . then , a projecting beam q reflected on the left - hand mirror 58 projects the left - eye target h on the plane of projection m . thus , the left eye can visually recognize the left - eye target h through the left - hand look - through hole 2 and one of the through holes 5a - 5d coinciding instantaneously therewith and the through window 4 . on the other hand , synchronously with the instantaneous coincidence of one of the through holes 5a - 5d with the right - hand look - through hole 3 , one of the rectangular arc - shaped outer project - through holes 7a - 7d corresponding to the one of the through holes 5a - 5d passes between the beam emitting end of the right - hand optical fiber 18 or the right - hand halogen lamp 73 and the beam incident end opposed thereto of the right - hand transmitting optical fiber 19 . at that time , a right - hand projecting beam l emitted from the beam emitting end of the right - hand optical fiber 18 or the right - hand halogen lamp 73 passes through one of the rectangular arc - shaped outer project - through holes 7a - 7d and enters the beam incident end opposed thereto of the right - hand transmitting optical fiber 19 of the right - hand beam incident hole . the beam irradiates the right - hand lantern slide o inserted into the projector 49 via the right - hand transmitting optical fiber 19 . the beam from the projector 49 passes through the right - hand zoom 53 . then , a projecting beam r reflected on the right - hand mirror 59 projects the right - eye target g on the plane of projection m . thus , the right eye can visually recognize the right - eye target g through the right - hand look - through hole 3 and one of the through holes 5a - 5d coinciding instantaneously therewith and the through window 4 . thus , the left - and right - hand projecting beams l are intermittently blocked as the rotary disc b rotates . also , synchronously with the coincidence between the left - or right - hand look - through hole 2 , 3 and one of the through holes 5a - 5d , the targets h and g of the left and right eyes can be alternately changed over at a high speed and separated completely from each other . an examiner such as a doctor adjusts the orientation of the left - and right - hand mirrors 58 , 59 and examines in a third party &# 39 ; s manner or objectively various binocular functions including the state of fusing the targets h , g in the vertical and horizontal directions . a second embodiment of the present invention will now be described with reference to drawings . fig1 is a front view showing essential portions of a phase - contrast haploscope according to the present embodiment . fig1 is a right - hand side view of the haploscope . the same members as the first embodiment are denoted by the same reference numbers to avoid redundant description . in the figures , a &# 39 ; denotes the phase - contrast haploscope according to the present embodiment . designator 74 denotes a gantry stand which comprises left - and right - hand supports 74a , 74b standing upright on a base 33 to pass the intermediate portions of left - and right - hand optical fibers 11 , 18 therethrough and a top plate 74c . designators 75 and 76 denote left - and right - hand right - angled triangle shaped auxiliary cases which stand on the top plate 74c of the gantry stand 74 on both sides of a disc case 1 standing on the top plate 74c in such a manner as to support the sides of the disc case and which allow the intermediate portions of the left - and right - hand optical fibers 11 , 18 and left - and right - hand transmitting optical fibers 12 , 19 to pass therethrough for neat arrangement . designator 77 denotes a chin rest fixed to a top - end head 80a of a screw rod 80 which passes through the end portion of a stepped crank bracket 78 , whose base end is fixed on the bottom face of the top plate 74c of the gantry stand 74 below the middle between left - and right - hand look - through holes 2 , 3 , and which rises or lowers by turning a cylindrical adjusting nut 79 having knurls 79a and engaging therewith . designators 81 and 82 denote left - and right - hand pivoting pins which pivot the left - and right - hand projectors 50 , 51 in a vertically swinging manner between left - hand forked brackets 87 and between right - hand forked brackets 88 , respectively . the left - and right - hand forked brackets 87 , 88 stand on forked bracket base coupling portions 85 , 86 , respectively , in a horizontally rotatable manner , which coupling portions are located on the top ends of left - and right - hand support stands 83 , 84 studded upright into a base 33 . designators 89 and 90 denote a pair of handles , as operating means , projecting downward at right angles to auxiliary plates 91 , 92 at their rear ends , which auxiliary plates are attached to the bottom portions of slide loaders 50 , 51 of left - and right - hand projectors 48 , 49 . designators 93 and 94 denote equilibrating tension springs one end of which is attached to the end of the left - or right - hand auxiliary plate 91 , 92 with a retaining pin 95 and the other end of which is attached to the forked bracket base coupling portion 85 , 86 with a retaining pin 96 , thereby horizontally biasing the left - and right - hand projectors 48 , 49 and the left - and right - hand auxiliary plates 91 , 92 . other portions are configured in the same manner as the first embodiment . the present embodiment has the above - described concrete structure . operations of the present embodiment will now be described . while adjusting a forehead rest 23 , the vertical position of the chin rest 77 is set according to the face profile of examinee put by turning the cylindrical adjusting nut 79 in the forward or reverse direction to raise or lower the screw rod 80 . thus , the face of the examinee p is set with respect to the front plate la so that both eyes of the examinee p are properly seen from the central portions of the left - and right - hand transparent plates 26 , 27 of the left - and right - hand look - through holes 2 , 3 . the left - and right - hand handles 89 , 90 are moved right and left or up and down to horizontally swing the left - and right - hand forked brackets 87 . 88 and at the same time to vertically swing the left - and right - hand projectors 48 , 49 so that for example , the left - and right - hand targets h , g on the left - and right - hand lantern slides n , o are projected on the plane of projection m at a desired position . at the same time , operate left - and right - hand zooms 52 , 53 to zoom in or out the projected left - and right - hand targets h , g . other members and mechanisms are adjusted in the same manner as the first embodiment , and hence various examinations of the examinee p are executed in the same manner . as described above , a rotary disc according to the present invention provides a higher rotational speed above the critical fusion frequency of a single rotary disc to change over the vision of both right and left eyes and thus to separate targets of both right and left eyes from each other . hence , it becomes possible to set conditions quite similar to the ordinary vision for both right and left eyes . thus , under these conditions , it is possible to examine various functions of binocular vision , i . e . subjective angle of squint , retinal correspondence , fusion faculty , subjective vision , suppression , aniseikonia , circumflex deviation and others in near natural state . accordingly , it is possible to easily examine an examinee over a long period of time without causing uncomfortableness or pain and thus to obtain a higher diagnostic reliability . also , a phase - contrast haploscope according to the present invention allows one to adjust it according to the sitting height and face profile of an examinee irrespective of age or sex , and hence can immediately cope with any examinee . a small - sized , light , compact structure allows the apparatus to be moved to any location for use anywhere a power source and a required occupational space are available . when not in use , the apparatus can be stored in a compact manner . moreover , since only one motor is used to rotate a rotary disc , synchronous control is unnecessary , and hence a control technique is quite simple . as a result , the apparatus does not require much adjustment , is reliable , is very durable , and is easy to maintain . also , no special skills are required for operation , and an initial cost is lower . the phase - contrast haploscope according to the present invention is equipped with zooms and allows mirrors or projectors themselves to swing horizontally and vertically by handle operations . thus , left - and right - hand targets projected on the plane of projection can be individually zoomed in or out or moved vertically or horizontally . as a result , it is possible to freely examine various functions of binocular vision , i . e . subjective angle of squint , retinal correspondence , fusion faculty , subjective vision , suppression , aniseikonia , circumflex deviation and others . by changing over the vision of both right and left eyes at a higher rotational speed above the critical fusion frequency of a single rotary disc and accordingly separating targets of both right and left eyes from each other , it becomes possible to set conditions quite similar to the ordinary vision for both right and left eyes . as a result , examinations can be conducted in near natural state . accordingly , it is possible to easily examine an examinee over a long period of time without causing uncomfortableness or pain and thus to obtain a higher diagnostic reliability . moreover , since as compared with conventional apparatus , the apparatus according to the present invention is smaller in size and scale , is minimized in the number of parts , and uses only one motor , synchronous control is unnecessary , and hence a control technique is quite simple . as a result , the apparatus does not require much adjustment , is reliable , is very durable , and is easy to maintain . also , no special skills are required for operation , an initial cost is lower , and the apparatus does not occupy much space .
a haploscope has a housing defining left and right viewing apertures disposed to permit substantial alignment with a subject &# 39 ; s left and right eyes and permit viewing through the housing . projection light sources for projection of left and right images are provided and the housing defines first and second light source apertures for transmission of light from the sources therethrough . the haploscope has first and second projection devices for projecting images using the light passing through respective ones of the first and second light source apertures . the housing has a rotary disc and a motor for rotating the rotary disk within the housing at a position permitting occlusion of the first and second light source apertures and the left and right viewing apertures . the rotary disc has at least one viewing aperture disposed to align with the left and right viewing apertures during rotation of the rotary disc such that only one of the left and right viewing apertures is not occluded at a given time . the rotary disc also has first and second light source transmission apertures disposed to align with respective ones of the light source apertures during rotation of the rotary disc to permit transmission of light therethrough coincident with non - occlusion of respective ones of the left and right viewing apertures .