Patent GB-1408919-A (GB)
Title: Photographic cameras
IPC: G03B17/36
Filed: 1972-10-04
Abstract: 1408919 Film-controlled mechanisms EASTMAN KODAK CO 4 Oct 1972 [4 Oct 1971] 45736/72 Headings G2A and G2X In a camera for use with film having metering perforations, in which the said perforations are closer together in the leader portion than in the exposure portion, the shutter is prevented from being actuated while the leader is passing through the exposure area. As shown, the film is advanced from a supply chamber 22 to a take-up chamber 24 by pulling a spring-loaded slide 32 to the left. A locking member 42 having three notches a, b, c is secured to the slide. A stop member 64 is pivoted on the camera wall by a pin 66, and a spring 76 extends between the wall and a post 78 on member 64. A film sensing lever 50 is pivoted to the slide at 52, and is spring-urged clockwise so that a pawl 58 bears against the film 10. Initially, after a roll of film has been loaded into the camera, the leader portion will be in the exposure position. As shown in Fig. 1, the metering perforations in the leader portion 12 and the trailer portion 16 are spaced closer together than in the exposure portion 14, the trailer portion having at its end an elongated perforation 18. As slide 32 is pulled to the left, pawl 58 slides along the leader until it engages in a perforation, the leader then also being pulled to the left until the pawl reaches a stop position. Stop member 64, which has been in the inclined position of Fig. 6 (not shown), is engaged by a tab 46 on slide 32 and pivoted anticlockwise. When slide 32 is released, it is pulled to the right by its spring 36, and pawl 58 disengages from the leader perforation. The anticlockwise movement of lever 50 causes member 64 to pivot clockwise, because of tab 70 thereon, so that a bent-down tab 68 at its end is held clear of the notches a, b, c. When pawl 58 falls into the next leader perforation, member 64 pivots anticlockwise, and its tab 68 falls into notch b (as in Fig. 3). Slide 32 can move no further to the right, and a notch 48 at one end is out of alignment with a tab portion 84 of a shutter release 82, so that the latter cannot be operated. On pulling slide 32 to the right again, more of the leader is advanced into take-up chamber 24, and eventually the first frame of the exposure portion 14 is located in the exposure area of the camera. As pawl 58 now moves to the right again, on release of slide 32, it has to move a little further until it engages in the next perforation, because of the different perforation spacing. Thus tab 68 will now fall into notch a on member 42, and slide 32 can no longer again be pulled to the left. Slot 48 is now aligned with release 82, which can now be depressed to effect an exposure. At the same time a cam surface 86 on release 82 engages a leg 74 of member 64 and pivots it clockwise. As release 82 moves upwards again to its original position, spring 76, having already been moved past its centre position, pulls member 64 still further clockwise, so that another leg 72 thereof is below release 82, so preventing it from being depressed again. Slide 32 can now be pulled to the left again to repeat this sequence of operations until all the film frames have been exposed. As pawl 58 engages in the first perforation in the trailer portion 16, tab 68 falls once more, on the return of slide 32, into notch b. The shutter release is again prevented from being operated, and only further advance of the trailer by slide 32 can be made. When pawl 58 falls into the elongated perforation 18 at the end of the trailer portion, tab 68 rides over a bevelled portion of notch b and falls into notch c. Slide 32 can now no longer be moved in either direction, and release 82 cannot be operated. The film advance mechanism is thus completely locked, and the film can now be unloaded and replaced by a new film.