Patent GB-1479491-A (GB)
Title: Film winding device for a photographic camera
IPC: G03B17/42
Filed: 1974-06-26
Abstract: 1479491 Camera film winder NIPPON KOGAKU KK 26 June 1974 [26 June 1973] 28274/74 Heading G2A A film-winding device for a camera comprises a rotatable film winding shaft, means limiting the angle through which the shaft can rotate in a filmwinding direction, gears for transmitting rotation of the shaft to a rotary driving member having an engaging part thereon, a film-engaging sprocket provided with an engaging member angularly spaced from said engaging part at the commencement of film-wind but engageable by the engaging part when the rotary driving member is rotated, whereby rotation of the winding shaft causes rotation of the sprocket after any backlash in said gears, and said angular spacing, have been taken up, and means for setting said angular spacing to a value ensuring that a predetermined amount of rotation is given to the sprocket by rotating the winding shaft to its limit in the film winding direction, whereby to compensate, in use for the effect of said backlash on the amount of film wound by full operation of the winding shaft. In a camera in which a lever 2 effects film wind by movement from position I to II, followed by automatic return movement to position III, shutter release by movement from position III to II, and shutter charging by movement from position II to I, accurate single frame advance, by single rotation of a sprocket 20, is effected by means of a sprocket rotation-limiting cam 24, notched part 24a being engaged by pawl 27a of an incomplete shutter charge prevention lever 27 preventing clockwise rotation of cam 24 before and after film wind and notched part 24b being engaged by pawl 26a of a sprocket rotationlimiting lever 26, preventing anti-clockwise rotation of cam 24 on completion of film wind. Lever 2 is permanently connected by a gear train Fig. 3 (not shown), to a sprocket wheel 18, anti-clockwise rotation of which is transmitted to sprocket 20 by contact of projections 18a and 20a, no contact being effected on initial clockwise rotation due to gear backlash. Lever 2 is similarly connected to a sun gear 5 which carries a spool-actuating lever 7 having a ratchet pawl 7a Figs. 4, 8 and 9 (not shown) adapted to rotate ratchet wheel 12 of a clockwise spring-biased spool 13 only during the winding stroke, a pawl 9 Figs. 5-7 (not shown), which prevents reverse rotation during the winding stroke, and a changeover lever 8. After film-wind, return rotation of lever 2 is stopped at position III by engagement of a pawl (7b) Figs. 13 and 14 (not shown), in a groove (34a) of a shutter cam (34) anti-clockwise rotation of which effects shutter release. Also after film-wind, clockwise rotation of a shutter release lever 29 by means of a pin 2c on film-wind shaft 2h allows pawls 26a and 27a to engage notches 24a and 24b and pawl 27b of lever 27 to engage ratchet teeth 2d of film-wind shaft 2h at position III, to prevent reverse rotation during shutter charging. At the beginning of filmwind, a ratchet pawl 29a of shutter release lever 29 engages sector type notch 2e of shaft 2h, preventing reverse rotation, in advance of engagement of pawl 9 with ratchet teeth 2b. Film-rewinding, with free rotation of sprocket 20, is effected by pressing down sprocket shaft 21 and also sprocket wheel 18 against the bias of springs 22 and 19 respectively.