Patent GB-712941-A (GB)
Title: Improvements in or relating to photographic roll film cameras
IPC: G03B17/42
Filed: 1952-05-08
Abstract: 712,941. Photographic roll film cameras. HEIDECKE, R., [trading as FRANKE & HEIDECKE]. May 8, 1952 [June 26, 1951], No. 11633/52. Class 98(1) In a camera in which the shutter tensioning mechanism may be coupled to the drive for the film winding mechanism and means are provided whereby on completion of the shutter tensioning the connection is broken to allow continued feed of the film, the drive from film winding mechanism to the shutter tensioning mechanism includes a pawl and ratchet device, and the means for decoupling said device comprising a member positioned to about the pawl on completion of the shutter tensioning operation, said member being movable away from the pawl by the actuation of a shutter release member to permit the pawl to reengage the ratchet. As shown, on depressing the slidable shutter trigger 25, the finger 27 of a pivoted bell-crank lever 26 moves out of a recess 28 in the apertured shutter blade 18 pivoted at 36 whereupon a tensioned spring 29 moves the blade anticlockwise to uncover the camera exposure aperture 30. Simultaneously the downward movement of the trigger carries with it a pivoted lever 20 urged anticlockwise towards a fixed stop 32 by a spring 22. On release of the trigger the finger 27 engages in a second recess 31 on the blade and the nose of the lever 20 becomes located clockwise of a projection 19 on an anticlockwise-urged pawl 8 pivoted on a crank 7 on a shaft 6 which through gears 12, 13 and a crank 14 moves a slide 15 to set the shutter, the shaft 6 being driven by the pawl 8 engaging an internal ratchet 5 on one face of a gear 4 meshing with a gear 3 on the shaft of a film take-up spool, the gear ratio being such that in winding on one film frame the gear 4 always makes at least one revolution. On rotating the film spool by a knob 1, the slide 15 rises and a peg 16 on it moves clockwise a lever 34 freely mounted on the shutter blade pivot to tension a spring 29 between the lever and a similarly mounted lever 35 held against clockwise movement by a pin 37 on the shutter blade, the shutter being held set after one complete revolution of the shaft 6 between the peg 16 and the latch 27 engaging the shoulder 31 on the shutter blade. At this point the projection 19 on the pawl 8 engages the nose of the lever 20 turning this clockwise and so tensioning the spring 22 until the tail 23 of the lever engages a fixed lug 24 whereafter on continued film winding the pawl 8 is turned clockwise by the nose 32 disconnecting the shutter tensioning means from the film wind. A film measuring device of any known type may be caused after a fresh film frame has been wound on to lock the film wind and to release the shutter trigger which has previously been locked against a second actuation. On now depressing the trigger, the shutter moves in the opposite direction to that described above to make an exposure, and on subsequently operating the film wind the shutter is set by action of the lug 17 on the lever 35 as the slide 15 is moved downwardly, the ratio of gears 12, 13 being such that the slide moves in opposite directions on successive revolutions of the shaft 6. Intentional double exposures may be effected by rotating the shaft 6 manually by means of a knob 33 to set the shutter without winding the film, this knob also disengaging the trigger lock controlled by the film measuring device.