Patent GB-1471638-A (GB)
Title: Power-operated actuator for a film advance mechanism of a camera
IPC: G03B1/12
Filed: 1975-11-11
Abstract: 1471638 Camera mechanism and drive NIPPON KOGAKU KK 11 Nov 1975 [13 Nov 1974] 46573/75 Heading G2A A motor-driven actuator has a shaft adapted to be coupled to the film advance mechanism of a camera, a first gear connected to the motor and a second gear connected to the shaft, the first gear being engaged during part of its rotation with the second gear, and disengaged during a further part of its rotation. As shown, the actuator is a separate unit 20 which is coupled to the camera 1. The camera has a film advance shaft 3 to which is secured reset member 4. Attached to member 4 via an intermediate crank 6 is a slide bar 7. As shaft 3 rotates clockwise, bar 7 moves to the right, which actuates the film advance mechanism and shutter cocking. At the end of the film advance, a spring 12 biases the shaft 3 anti-clockwise, and member 4 and bar 7 are returned to their original, Fig. 1 positions. At this stage a bifurcated plate 8 is spring-urged so that one limb 8a engages in a notch 7a in bar 7, so preventing a further film advance movement until the shutter release 14 has been pressed, when plate 8 is pivoted clockwise out of the notch 7a. The unit 20 has a shaft 21 which, on attachment of the unit to the camera, is coupled by connectors 22 and 15 to the member 4. Thus rotation of shaft 21 actuates the film advance mechanism. The drive derives from a motor M, which, through a train of gears 41, 40, 39, 38 and a friction clutch 37, drives a shaft 36 and a gear 35. Gear 35 meshes with a gear 34 rotatably mounted on shaft 21, gear 34 being integral with another gear 33. Gear 33 meshes with a gear 32 fixed to a shaft 31, to which is also fixed a stepped gear 30. Thus gear 30 is driven directly by the motor M via the gear train. A collar 24 secured to shaft 21 has an offset portion 24a which over-lies a stepped gear 25 rotatably mounted on the shaft, the gear having a plate 26 secured to one face. A torsion spring 27 has one end fixed to the offset portion 24a and its other end fixed to a projection 26a on plate 26. Thus the collar 24 and the plate 26, and hence gear 25 are biased in opposite directions with respect to each other by spring 27. When the shutter button 14 is released after being depressed to make an exposure, the motor is energized, and stepped gear 30 is rotated, anti-clockwise as shown. Gear 30 meshes with stepped gear 25, which is accordingly driven clockwise, and its motion is transmitted to shaft 21, and hence to member 4, so that film advance and shutter cocking is effected. Continued rotation of gear 30 eventually brings a cut-away portion 30p towards gear 25, so that it is no longer in engagement with gear 25. Thus spring 12 is able to restore bar 7, member 4, and shaft 21 to their original Fig. 1 positions. Since the cut-away portion of gear 30 is facing gear 25, some rotation of gear 30 will take place before any of its teeth will mesh with gear 25. Thus motor M can be started under low load conditions, allowing it to accelerate before a load is imposed thereon by meshing of the two gears. If the film advance is effected by hand, by rotating lever 2, although gear 25 will be rotated, no movement is imparted to gear 30 because the cut-away portion 30p is presented to gear 25. Thus the gear train between gears 30 and 41 remains idle.