Patent GB-1306318-A (GB)
IPC: G03B17/52
Filed: 1971-11-12
Abstract: 1306318 Film advancing mechanism POLAROID CORP 12 Nov 1971 [12 Aug 1971] 52737/71 Heading G2A A camera for use with a film assemblage of the type including a stack of thin flexible film units in a cassette has a first film advancing means which, when the cassette is mounted in the camera, engages the rear end of the foremost film unit through a rear opening of the cassette and pushes it through an exit opening at the front of the cassette to engage with a second film advancing means, both means being motordriven. As shown, the camera is of the folding reflex type for use with self-processing film units. A reflex member 46 having reflecting surfaces 54, 56 on either side can be pivoted from the viewing position shown in Fig. 1, in which it is positioned as a lighttight closure over the exposure opening 36 of the cassette 34, to a raised position in which the exposure is made. Its movement is controlled by a linkage system including a crank 58 and a ram 60. The film advancing mechanism includes a first means formed as a generally T-shaped slide 62 mounted on a fixed flange 64, the mounting being an arrangement of slots and pins so that slide 62 can have a reciprocating movement. The slide is biased to the left by a spring 84, and has a resilient cantilever arm 86 whose downward end 88 can engage behind the trailing end of a film unit 39 in preparation for moving it forwards out of the cassette through the forward exit 35 and into the bite of the rollers 40, 42. Extending along the camera housing is a gear train 44 beginning with a drive gear 92 which is coupled to a motor 38. The gear train divides into two paths, one path ending with a gear 118 which drives roller 40, and the other ending in a timing gear 110 which carries a cam 128. Initially, the camera is in the viewing or focusing mode, as in Fig.1. The release button 122 is then pressed to initiate operation of the camera. The motor 38 is energized for a time sufficient to rotate gear 110 anti-clockwise about 10 degrees. Ram 60 has a follower 124 which is in engagement with the high point of cam 128. As this cam rotates with gear 110, cam 128 moves clear of follower 124, thus allowing ram 60 to move to the right under the action of the reflex up springs, the reflex member so moving up to the exposure position. The shutter 120 then opens for a period of time determined by a photo-cell 121. After the shutter has been closed, motor 38 starts again. During this rotation of the gears, a pin 130 on gear 102 engages the flanged end 90 of slide 62 and pushes it to the right, so that end 88 of arm 86 engages behind the end 37 of film unit 39 and pushes it so that the leading end passes through exit slot 35 to the rollers 40, 42. The film unit has a pod of processing liquid (45), Fig. 5 (not shown) which is ruptured as it passes between the rollers, which spread the liquid between photosensitive and image-receiving sheets in the usual way. Eventually cam 128 rotates sufficiently to drive follower 124 and hence ram 60 to the left again, which drives reflex member 46 to the down position, opens shutter 120 and shuts off the motor 38, so that the cycle of operations is completed. Since the gear ratio is such that gear 102 must rotate through more than one revolution to complete the transport of the film unit, a latch 140 is provided to hold slide 62 in its extreme right position Fig. 4 (not shown), out of the path of movement of pin 130 until the film transport is complete.