Patent GB-692313-A (GB)
Title: Improvements in or relating to roll film photographic cameras
IPC: G03B19/04
Filed: 1950-09-04
Abstract: 692,313. Photographic roll film cameras. KODAK, Ltd. Sept. 4, 1950 [Sept. 2, 1949], No. 21787/50. Class 98 (i). In a camera in which film is propelled across the exposure gate from a spool in a supply chamber to form a loose coil in a take-up chamber a film winding control mechanism comprises a ratchet on the winding knob, a pawl mounted for movement towards and away from the ratchet, and a pivoted lever for moving the pawl into engagement with the ratchet to prevent further unwinding movement of the knob when a lug on said lever engages in and is moved by a stop aperture in the film strip when the film is unwound. Means are also provided for ensuring that only one frame at a time is rewound on to the supply spool. As shown, a film F, provided with apertures A<SP>1</SP>, A<SP>2</SP> ... at intervals of one exposure length and an unwinding stop aperture O displaced relatively to the line of the apertures A, and coiled on a supply spool 14 having inwardly directed beads 17 on its flanges, is fed across the camera exposure gate into a chamber 22 having a spring 23 which guides the film into a coil by means of a winding knob 18. A lever 32 loosely mounted on a stud 31 is provided with a lug 35, disposed so as to engage in the aperture O when the film is almost completely unwound to prevent the film from being detached from the spool, and bevelled so as to move out of the aperture on rewinding the film; and with a further bevelled lug 36 adapted to trail over the apertures A during unwinding but to engage them in succession on rewinding the film. The aperture in the front plate 60 of the exposure gate is extended to accommodate the lug 35 and the front plate is also apertured to receive the lug 35, the portion of the plate between the lug-receiving apertures being engaged by a third lug 37 on the lever 32 which lug acts as a fulcrum about which the lugs 35, 36 may see-saw towards or away from the plane of the film, the lug 35 being urged away from the film by a spring 61. An arm 38 of the lever 32 passes through a slot 39 in a slide 40, pin-and-slot mounted at 42, 43 and having pawl teeth 44, 45 for engaging a ratchet 46 on the film winding knob, the slide being normally spring-urged to the rest position shown in Fig. 3. On unwinding the film into the chamber 22, the lug 36 is engaged by the film end to rock the lug 35 against the film so that the film is unwound until the lug engages in the aperture O pivoting the lever 32 anticlockwise to move the slide 40 to the right as seen in Fig. 3 so that the pawl tooth 44 latches the ratchet 46. The film is then rewound for exposure, this action causing the lug 36 to re-engage the film as the lug 35 leaves the aperture O, so that the lug 36 engages in the aperture A<SP>1</SP> at the end of the feed of one frame and thereby causes the arm 38 to move the pawl tooth 45 to lock the winding knob against further rewinding. To rewind a further frame, the projecting end 48 of a slidable member is first depressed, engaging the arm 49 of the lever 32 and returning the slide 40 to its rest position so releasing the ratchet 46 from the tooth 45. Specifications 558,515, 645,169 and 651,414 are referred to.