Patent GB-611233-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B19/04
Filed: 1946-02-06
Abstract: 611,233. Photographic roll film cameras. KODAK, Ltd. Feb. 6, 1946, No. 3738. Convention date, Nov. 10, 1944. [Class 98 (i)] A camera includes film winding mechanism which comprises a rack 8 mounted on the camera back and movable by a handle 7 protruding through a slot 6 therein which drives, through two coaxial gears 10, 12 engaging the rack 21 and mounted on a light-excluding plate behind the slot, a slidable member 20, a rack 22 carried thereby driving the take-up spool 4 through gearing 23 including two coaxial mutilated gears 35, 46 so mounted that, when mutilated portion 36 lies opposite gear 37, mutilated portion 47 lies opposite the rack 22. The take-up spool is locked against reverse winding by a spring-biassed pawl 43 engaging a ratchet-wheel 42 on the spool shaft, and the gears 35, 46 are urged towards their operative positions by a spring 49, but are held inoperative by a latch 32 engaging a pin 33 on gear 35. As described, the mechanism is combined with means for preventing double exposures. The latch 32 pivoted at 30 and urged anti-clockwise by spring 31 has a transversely crooked finger 28 on its opposite arm 29 and the " knuckle " of said finger engages in a slot 27 (Fig. 7, not shown) cut in the shutter trigger 25. A second latching lever 60 pivoted on the top cover of the camera is also spring-urged against the trigger. With the camera as shown ready for exposure, depression of the trigger rotates the arm 29 and releases the latch 32 so that gears 35, 46 rotate into mesh with gear 37 and rack 22 which is moved slightly thereby, as also is the rack 8 through the coaxial gears 10, 12. Thus, on releasing the trigger, a clockwisebiassed lever 54 turns the lever 60 anti-clockwise so that the latch end 63 slips into an annular recess 26 on the trigger, locking it against a second actuation while the arm 29 of latch 32 re-engages in the slot 27. The film must then be wound on by sliding the handle 7 to its full extent, the pawl 43 preventing back movement before the completion of the stroke. Once the stroke is complete the handle 7 may be moved back and forth without affecting the winding, due to the mutilated portions of gears 35, 46. When the handle returns to its rest position, the end 57 of rack 22 engages the end 56 of the lever 54 and turns it anti-clockwise to rotate lever 60 clockwise and disengage the latch 63 from the shutter trigger which may then be depressed again. In a modification, the release knob operates the rod controlling the shutter through a pivoted lever having a rectangular aperture, into which on depressing the release knob the end of a locking lever slips, said locking lever being released as before. An exposure counting mechanism is provided comprising a slide 73 having an aperture 72 engaged once per revolution of the feed sprocket shaft 67 by a single toothed gear 71 thereon, said engagement moving slide 73 to the right and causing spring arm 76 to engage a tooth of the counter disc 79 to rotate it one unit against the action of a flat spiral spring 81, which is prevented from rotating the disc by a pawl 84. Two teeth are removed from the disc at 88a so that when the full number of exposure frames has been wound on, further winding will not affect the counter disc, informing the operator of this fact. The Specification also describes means for rewinding the exposed film on to the supply spool in a manner described and claimed in Specification 610,730 to which reference is made.