Film carrying roller
This is a continuation of application Ser. No. 704,617, filed July 12, 1976, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a film carrying roller, and particularly, to a film carrying roller which can be used for carrying two films of different sizes, for example 16 mm and 8 mm films. 
     Hitherto, as a roller for carrying two films of different sizes, a roller having an outer annular groove, both the inner walls of which are provided with two annular steps for receiving the two films, is known, but such roller cannot be used for driving a connected film consisting of such two films. 
     Further, a similar roller having an outer annular groove, and an annular soft rubber tire provided with a great many small projections on its upper surface and fit within the groove is known. This roller can drive the aforesaid connected film, but has various disadvantages to be described hereinafter. 
     SUMMARY OF THE INVENTION 
     It is a chief object of the invention to overcome such disadvantages and to provide a film carrying roller comprising an outer annular groove for receiving a film, an annular recess formed at the central portion of the bottom of the groove, an elastic tire having an upper convex surface, such tire fitting in the recess, and two annular slopes or inclined surfaces formed at both the remaining portions of the bottom of the groove, each such slope ascending from a respective upper annular edge of the recess to a respective outer annular end of the groove bottom, and each such end being positioned higher than the peak of the convex surface of the tire. 
     Further objects and advantages of the invention are as follows: 
     1. The aforesaid roller according to the invention can be effectively used for driving and guiding respectively two films of different sizes. 
     2. Such roller hardly gives any damage to the films, and particularly, to the picture and sound recording parts thereof. 
     3. Such roller is of comparatively simple construction, and can be supplied at a low cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will be apparent from the following description, taken with the accompanying drawings, wherein: 
     FIG. 1 is a half sectioned elevational view of a known film carrying roller, which is used for carrying two films of different sizes; 
     FIG. 2 is a view similar to FIG. 1 of another known film carrying roller; 
     FIG. 3 is a view similar to FIG. 1, but of a film carrying roller according to the invention, which is used for carrying a 16 mm film; 
     FIG. 4 is a view similar to FIG. 3, but of such roller used for carrying a 8 mm film; and 
     FIG. 5 is an elevational view of a series of driving rollers and a series of guide rollers, which are arranged up and down, a film being spirally wound therearound. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One known film carrying roller used for carrying two films of different sizes, is shown in FIG. 1. Roller 1a has an outer annular groove 2 for receiving films, both the inner walls of which groove are provided with two annular steps 3 and 3&#39;, and the two upper steps 3 serve to receive a film of a larger size, for example a 16 mm film 4a, while the two lower steps 3&#39; serve to receive a film of a smaller size, for example an 8 mm film 4b. 
     When carrying a connected film consisting of the two films the roller 1a cannot be used as a driving roller 1 (FIG. 5) because the circumferential speeds at the upper steps 3 and the lower steps 3&#39; are different, and therefore, such roller can be used only as a guide roller 1&#39; (FIG. 5) in the above case. 
     In an ordinary film processor, as shown in FIG. 5, a series of the driving rollers 1 are fixedly mounted on a driving shaft 5, while a series of the guide rollers 1&#39; are rotatively mounted on a fixed shaft 5&#39;, and a film 4 is spirally wound or hung over the driving and guide rollers, and in this case the film runs in the direction indicated by a arrow 6. 
     Another known film carrying roller 1b is shown in FIG. 2. Roller 1b has the outer annular groove 2, and an annular soft rubber tire 7a provided with a great many small projections 8 on its upper surface fits in the bottom of the groove. Roller 1b can be used for driving and guiding even the aforesaid connected film, but dust, refuse and the like easily adhere to the many projections 8, and when adhered to such projections, the back of the film is soiled, and further, when the projections became uneven in height due to wear, the back of the film is damaged. 
     Such defects as above mentioned are not only overcome, but also several advantages are obtained by the invention as hereinafter described. 
     The preferred embodiment of the invention is shown in FIGS. 3 and 4. 
     A film carrying roller 1e according to the invention has an outer annular groove 2 for receiving a film. An annular recess or indentation 9 is formed at the central portion of the bottom of groove 2, and an annular elastic tire 7b, for example of rubber, fits within the indentation 9, and an upper convex surface 10 of the tire projects upwardly therefrom. Formed at both the remaining portions of the bottom of groove 2 are annular slopes are inclined surfaces 11, each of which ascends from a respective upper annular edge of the indentation 9 to a respective outer annular end of the groove bottom, the outer end of each slope 11 being positioned higher than the peak of the convex surface 10 of the tire 7b. 
     The roller 1c is thus constructed, and its operation is as follows. 
     As shown in FIG. 3, the 16 mm film 4a of a larger size is received by both the end outer portions of the slopes 11 of the groove bottom, and then the film exists at such a high position as not to touch the convex surface 10 of the tire 7b. 
     The film 4a is driven by the roller 1c because of the friction between the side portions of the film and said the outer portions of the slopes 11, and the picture and sound recording parts of of the film suffer no damage. 
     Next, the 8 mm film 4b of a smaller size (FIG. 4) is first received by the convex surface 10 of the tire 7b, and soon traverses in one direction due to the horizontal component of force of the torque of the driving shaft 5, thereby leaning or drifting to one of the inner walls of the groove 2. In the case of FIG. 5 such horizontal component of force as indicated by arrow 6&#39; causes the film 4b to move to the left inner wall of the groove 2, as shown in FIG. 4. 
     Then the film 4b is received by one outer end portion of one slope 11 and the peak portion of the convex surface 10, and is driven by the roller 1c due to friction at the receiving portions. Therefore, the picture and sound recording parts of the film suffer no damage. 
     When driving a connected film consisting of two films of different sizes by the roller 1c, there is no difference between the circumferential speeds at each film receiving portion for the two films, as is easily seen from the above description, and therefore, the roller can be effectively used for driving connected films of different sizes. 
     Further, since the upper surface 10 of the tire 7b of the roller 1c is smooth and convex, dust, refuse and the like hardly adhere to such surface, and accordingly, the back of a film to be driven is not soiled and damaged. 
     Moreover, the roller 1c is of comparatively simple construction, and can be supplied at a low cost. 
     In the above description 16 mm and 8 mm films are exemplified as the two films of different sizes, but 35 mm and 16 mm films and the like can be also effectively carried by the roller 1c of corresponding sizes.