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1. 发明专利

GB1105702A Improvements in or relating to film transport mechanisms 未知
公开(公告)号：GB1105702A
公开(公告)日：1968-03-13
申请号：GB537065
申请日：1965-02-08
申请人： GEN ELECTRIC CO LTD , THOMAS JOHN CANNON , WALTER RAYMOND GODDEN , IAN DONALD MACLEOD , RALPH DESMOND NIXON
IPC分类号： G03B1/18
摘要： 1,105,702. Educational appliance. GENERAL ELECTRIC CO. Ltd., T. J. CANNON, W. R. GODDEN, I. D. MACLEOD and R. D. NIXON. 7 Feb., 1966 [8 Feb., 1965], No. 5370/65. Heading G5G. [Also in Divisions F2 and G2] A visual teaching machine has a film transport mechanism by which a selected number of film frames may be wound on, and mechanical means for storing an indication of said number, the film then being wound back a number of frames in dependence upon the stored indication so that the previously viewed frame may be returned to. Film is wound from spool 8, through gate 5, and into open receptacle 26 by driving sprocket 14, selected frames being projected by lamp 2 and lenses 6, 7, on to a screen in the projection lid, via mirror 9. Guide 16 holds the film on to sprocket 14 and is retractable for film loading. The transport mechanism includes a clutch, Fig. 1 (not shown), whose driven member (45) is coupled to sprocket (14) and whose driving member (46) is driven by a lost-motion coupling to a position displaced from a datum position and corresponding to the extent of film wound on. Trip member (62) operates during the lost motion to disengage the clutch momentarily and so permit member (46) to return to its datum position before driving the member (45), this displaced position of member (46) then providing an indicaton of the extent of the preceding film wind-on at any time. Sprocket (14) rotates against a click-stop engagement of eight-toothed detent wheel (35) on sprocket shaft (15) with a wheel carried on arm (37) pivoted at (38), each click corresponding to one film frame. Shaft (15) is driven through bevel gears (34, 42) by shaft (43) on which member (46) freely rotates. Member (45) is locked to shaft (43) and has teeth which are engaged by a tooth (47) on a flange of member (46) which also has an arm (51) by which member (46) is itself driven. Initially, arm (51) rests against stop (54), the datum position, until rotated by engagement with member (52) extending from collar (44) fixed on the actuating shaft (53) which is manually driven by a dialling mechanism by which the number of frames to be advanced is selected. Arm (51) is biased against the rotation of shaft by a spring-loaded cam member (56) mounted on shaft (57). This spring-loading returns member (46) to the datum position when the clutch is dis-engaged by I-shaped trip member (62) which is displaced against member (46) when cam face (67) of member (62) is engaged by the radial extension (68) of member (52). During the dialling operation in which film is being moved, lamp 2 is turned off by a microswitch rotating with shaft (53) and actuated by a cam on shaft (60). If it is desired to return to the previously viewed frame, a lever on shaft (60) is manually turned to rotate shaft (57) and cam member (56) in the direction in which it is biased thereby overcoming the clip-stop mechanism and driving the film back to a position determined by the datum position of the member (46).

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