GB1507909A - Film cartridge - Google Patents

Abstract

1507909 Motion picture viewing cartridge MONTRON CORP 16 Dec 1975 [23 Dec 1974] 51492/75 Heading B8M A cartridge 10 suitable for viewing motion pictures comprises a viewing aperture 24, an endless length of film 26 having perforations along one edge, a sprocket 56 for advancing the film past the aperture and an indexing plate 29 having a pair of indexing projections 28 disposed on opposite sides of the aperture and flange 38 and ribs 39, 41, Fig. 7, for guiding the film over the index plate and past the aperture. In the embodiment of Figs. 1-7 the indexing is facilitated by a pair of pivot arms 81 having arcuate film guiding portions 81c and arms 81a that are urged together by leaf spring 86. As sprocket 56 is rotated say counter-clockwise the upper run 67 of the film is tensioned and pulls its guide 81c towards sloping mirror 51 by rotation of arm 81 about its pivot 82. When the movement is sufficient to free the film from the adjacent projection 28 the tension advances the film until the next perforation is engaged by projection 28. This engagement is facilitated by spring 86 causing counter-clockwise rotation of pivot arm 81. The cycle of relatively slow build up of film tension followed by relatively rapid indexing of the film by one perforation and thus one picture frame is repeated. The indexing plate 29 is curved so as to bow the film as shown in Fig. 6. Movement of pivot arm 81 therefor does not cause the film adjacent the aperture to move out of focus. In the embodiment of Fig. 8 spring 86 and pivot arms 81 are replaced by a plastics member 151 having spring-like arms 157 whose curved surfaces 158 urge the film into engagement with plate 29 and projections 28. As the film is advanced one of the arms is flexed inwardly until the film is released from one of the projections 28 and is advanced one frame. The film may be formed into a roll 91 which is disposed on a spool 92. The spool has a hub 97 in the shape of a truncated cone, an annular roll supporting surface 93 and an upstanding rim 94. Helical spring 106 engages a notch 108 on the inner side of hub 97 and a rib 107 on cartridge side wall 14 to allow the spool to rotate counter-clockwise but not clockwise. Ribs (127, 128, 132, 133, Fig. 4, not shown) in the top wall 12 of the cartridge form channels (127, 138) to guide the film between spool 92 and sprocket 56. Further guidance is provided by slots 72 in ribs 69, 71 and by ribs 76. The guides are themselves ribbed so as to contact only the margins of the film and thus avoid scratching the picture frames. A viewer 141 for receiving the cartridge is shown in broken lines in Figs. 1, 2. The cartridge sprocket 56 is driven via crank 144 and pins 147. The cartridge is assembled by inserting all the components through the top and then fixing the top wall 16.