Patent GB-693438-A (GB)
Title: Photographic cameras
IPC: G03B17/42
Filed: 1950-05-12
Abstract: 693,438. Photographic camera shutter mechanisms. DEBRIE, A. V. L. C. May 12, 1950 [May 21, 1949], No. 11959/50. Class 98 (i). In a photographic camera, the opening of the shutter simultaneously engages a continuouslyrotating constant-speed shaft with a member which is thereby moved along a parallel shaft, this member, after a predetermined movement, operating mechanism to close the shutter, and immediately thereafter causing mechanism to operate to wind the film through a pre-selected distance. The camera may comprise a shutteroperating member movable between shutteropening and shutter-closing positions, a device for automatically feeding a film after each exposure, and a timing device operatively connected to the shutter-operating member for holding it in the shutter-opening position for a pre-determined length of time after the shutteroperating member has been pushed by an operator to its opening position, and also operatively connected to the feeding device to control it so as to feed a pre-determined length of film. The shutter is operated by mechanism including a shaft 1 rotated continuously at constant speed and carrying a worm-wheel 2, and a square-sectioned shaft 17 journalled in fixed bearings such as 21. A cam 29, fast with a sector 28, is slidable along shaft 17. A spring 31 encircling shaft 17 is connected to bearing 21 and to cam 29. A fork 35 bridging shaft 17 is attached to a plate 36 slidably mounted on the camera wall. Sector 28 is normally pressed by spring 31 against fork 35 and is also rocked in the direction of arrow 34, so that it is clear of worm 2 and a spring-pressed pin 46 mounted therein is engaged under a fixed plate 49. When an exposure is to be made, the knob 27 of a flexible release 26 is pressed, moving a rack 23 longitudinally; this also opens the shutter and shuts off light entering a view-finder by action through a push-rod 24. Rack 23 meshes with a pinion 22 fast on shaft 17 which is thereby rocked, so that screw threads 45 on sector 28 mesh with worm 2. When knob 27 is released, return of shaft 17 and closure of the shutter is prevented, since pin 46 is pushed up and engages a face 51 of plate 49. The rotation of worm 2 causes sector 28 to move along shaft 17 until pin 46 slips off plate 49, when the shaft rocks until pin 46 meets another plate 54, closing the shutter. The time taken for this operation depends on the initial position of sector 28, i.e. of fork 35. This can be adjusted by moving plate 36 by means of a rack-and-pinion 41, 42 operated by a knob on the camera casing. Sector 28 still engages worm 2, and cam 29 is rocked to engage a cam-plate 15 on a shaft 5. This shaft is constantly rotated as it is slidably splined in a helical gear-wheel 4 driven by another gear-wheel 3 on shaft 1, and carries a locking-drum 7 and pin 8 which are normally held out of engagement with the star-wheel 11 of a Geneva mechanism by a spring 14 surrounding shaft 5. When cam 29 bears on cam-plate 15, shaft 5 is moved axially to engage the Geneva mechanism, which operates filmfeeding sprockets 12. The mechanism is engaged as long as pin 46 moves along plate 54, and this plate is movable by a rack-and-pinion 55, 56 so that the cam may operate while the Geneva mechanism operates once or twice. Pinion 56 is connected to a knob on the camera casing which normally has two positions, and is connected to movable screens which vary the length of the film gate.