Patent GB-720194-A (GB)
Title: Improvements in or relating to film winding and locking mechanism for photographic roll film cameras
IPC: G03B17/42
Filed: 1952-01-18
Abstract: 720,194. Photographic roll film cameras. KODAK, Ltd. Jan. 18, 1952 [Jan. 23, 1951], No. 1496/52. Class 98 (1). A roll film camera includes a forward locking device and a reverse locking device for a film winding member, said devices being rendered operative alternately by a single blocking member which upon being disengaged from one of said locking devices is moved automatically into engagement with the other of said locking devices. As shown, on the inside of the wall 11 the take-up spool is connected to a shaft 20 by a slipping clutch, the driving member of which meshes with a gear on a stub shaft bearing a gear 80 which meshes with a gear freely rotated on a reduced part of the shaft 20. This gear is secured to a ratchet-wheel 33 and is provided with a pair of similarly disposed arcuate flanges 38 having inclines 50 and steps 42 and forming between them openings 39 into which a tongue 40 on a freely-mounted coaxial plate 41 may seat. Over the gear, ratchet, and plate is a spring 53 and over it is an assembly consisting of a ratchet 62 having anticlockwise latching teeth 66 and a chordal portion 69, a plate 54 of different semi-circular parts 58, 59, part 59 being concentric with the tips 66 of the teeth 65, and a second ratchet 43 having a chordal portion 102, clockwise locking teeth 113, and a reduced diameter portion 117, concentric with which is a depending circular flange 45 which fits over the arcuate flanges 38 on the ratchet 33 and which is interrupted at 49 to accommodate the tongue 40. In the position shown after film-winding but prior to exposure, a clockwiseurged pawl 90, mounted on an upwardly-urged rotatable plunger 92 (Fig. 2) located in a well in the wall 11, lies in the plane of the ratchet 62 preventing anti-clockwise movement of the arm 24 to wind the film. By depressing the shutter release button 112, a plate 106 is moved downwardly against a return spring surrounding an integral guiding rod 109 passing through the wall 11 and a rod 105 on it passing through the wall 11 trips the shutter, while the arm 108 of the plate engages the upper end of the plunger 92 to move the pawl 90 downwardly past the part 64 of the ratchet 62 and the part 58 of the plate 54 so that it bears against the chord 102 of the ratchet 43, return of the pawl on release of the button being prevented by engagement beneath the plate 54. The film is then wound by rotating the arm 24 anticlockwise when by reason of the mating square sections of the end 23 of the shaft 20 and of the hole 63 in the ratchet 62 and also of the engagement by the flange 45 on ratchet 43 with the tongue 41 on plate 40, which tongue in turn abuts the step 42 of the right hand arcuate flange 38 on the ratchet 33, the gear 30 is rotated to feed the film and to rotate via gear 85 a film feeding and measuring sprocket. The film winding may also effect tensioning of the shutter. When the reduced portion 117 on ratchet 43 comes opposite the pawl 90, this rises since the portion 58 on plate 54 is concentric with the portion 117, thus releasing the arm 24 for clockwise return movement which may be effected by a return spring surrounding the shaft 20 and tensioned by the film winding movement. During the return movement, the gear 30 is held stationary by engagement with the ratchet 33 of an anticlockwise urged pivoted pawl 118. Thus the tongue 40 on plate 41 rides up the left hand arcuate flange 38 and finally drops into the right hand opening 39 between the flanges 38, ready for a further film winding after an exposure has been made. If after the start of winding it is not desired to complete it, the arm 24 may be returned to the rest position shown by depressing a button 125 which moves the pawl 90 downwardly clear of the clockwise latching teeth 113 on ratchet 43 to bear against the flange 45. At the end of the return movement, the pawl is still held beneath the plate 54 and the tongue 40 lies on one of the arcuate flanges 38. On later moving the arm 24 for completing the winding, before or after a further exposure, the members 62, 54, 43, 41 rotate idly until the tongue 40 drops into an opening 39, when the winding restarts.