GB722587A - Improvements in and relating to photographic roll-film cameras - Google Patents

Abstract

722,587. Photographic roll-film cameras. VOIGTLANDER AKT.-GES. Dec. 16, 1952 [Dec. 15, 1951], No. 31782/52. Class 98 (1). In a lock for preventing unintentional opening of a photographic roll-film camera a feeler member is provided which is spring-urged towards the film and is movable perpendicularly to the direction of movement of the film but is not directly accessible from outside the camera, which feeler member when a film is in place in the camera is pressed aside by the film and thereby directly or indirectly holds the rear wall of the camera locked from the inside while when no film is in the camera the locking is released. As shown in Fig. 1, a film 2 is wound from a cassette 21 to a take-up spool 5 by means of a sprocket drum 4. A spring 6, mounted on a part 1 of the camera casing, carries a lug 8 bearing on the margin of the film 2. The camera back slides up over the casing and has a pin which engages a bent lug 13 on spring 6 and forces the spring forward until the pin engages a hole 10 in the spring. So long as the film extends across the camera, the spring is pressed back by lug 8 engaging the film so that the pin is engaged and the back cannot be slid off. Preferably the end of lug 8 enters the take-up spool chamber so that if the film is detached from the cassette and wound wholly on spool 5, the lock still operates. When the film is wound back into the cassette 21, spring 6 moves forward by its own resilience and the hole 10 is cleared from the pin on the camera back, which may be slid off. A lever may be provided on the camera back to be operable as by a screw-driver or coin to engage lug 13 and to move the spring 6 forward and disengage the lock, even when the film is in place. A mark 17 on spring 6 is pressed against a ground-glass window, so as to be visible therethrough when the film is in place. When the lever moves forward, the mark cannot be seen, and this indicates that the film has been wound back into the cassette. In the embodiment shown in Fig. 5, the camera back 33 is hinged to the camera. A pivot 45 journalled in the back 33 carries an arm 44 and an arm 46 with a pin 47. The camera is latched by bolts 40, urged apart by spring 41 and having lugs 42 engaging slots 43 in the camera body. When the camera is closed and the film is in place, arm 44 is engaged by the backing paper 35 of the film and is thus pressed back so that pin 47 enters a slot 48 in one of the bolts 40, preventing the camera from being opened until the film is wound completely on to its take-up spool. If it is s necessary to open the camera while the film is still in position, a pointed tool is inserted through an opening in wall 33 to press the arms 44, 46 along their common pivot against a spring (not shown), so that 47 is moved endwise out of slot 48. Arm 44 may be formed as, or connected to, a film pressure-plate.