| 摘要 |
1,133,409. Slide projectors. BELL & HOWELL CO. Aug.31, 1967 [Sept.28, 1966], No.39809/67. Heading G2J. Apparatus for maintaining the focus of a slide projector when the slide film "pops" comprises a pivoting slide holder 65 lightly spring-biased by spring 69 towards a meniscus lens 23 biased in its frame 27 towards a fixed stop 38 by a much stronger spring 31, the frame 27 being cammed out of contact with the film when slide-changing takes place. Stop 38 is the upper horizontal rail of the manual slide changing pusher, and is engaged by a limit screw 33. Cam surface (45), Fig.2 (not shown) on rail (38) engages screw (33) as the pusher is withdrawn and tilts frame 27 about pivot 29, ears (71) limiting the forward tilt of holder 65 as the lens is removed. When the slide "pops", holder 65 is pivoted somewhat while the lens 23 remains stationary and in contact with the film. The meniscus lens is tilted away from the film before the slide commences the slide-changing movement by a lost-motion connection between slide and pusher. This connection is made by a spring-loaded tip (47) of the lower rail (39) of the pusher, Fig.1 (not shown), allowing a further displacement of the pusher after the slide reaches the projection position, this displacement disengaging cam (45) from frame 27, and allowing lens 23 to engage the film. A shutter (49), Fig.1, is pushed by the slide as it enters the slide tracks (61, 63), Fig.1, and is withdrawn to cover the gate as the pusher is withdrawn, a pin on rail (38) engaging a recess in a wire member attached to shutter (49) with a lost motion contact. Rail 38 is thus able to move sufficiently to cam the lens away from the film before shutter 49 pushes the slide out. |
