GB448311A - Improvements in cinematographic projectors - Google Patents

Abstract

448,311. Kinematograph projectors. JARVA, Y. T., Lappeenranta, Finland. Sept. 3, 1935, No. 24555. [Class 97 (i)] In continuous-feed apparatus wherein the projection lens is reciprocated for compensation, and the return stroke is more rapid than the operative stroke, the lens mount is coaxial with a rod which is guided in a cam wheel chamber and carries a member engaging the track of the cam wheel. As shown, the lens components 16, 17, 18 are mounted in a tube 20 secured to a body 19 carrying a mirror 15 and fixed on a rod 24 provided with a roller 26 engaging the track 25 in a cam wheel 7 in a chamber 4. The wheel 7 is mounted on a shaft 2 driven by a belt pulley 5 and carrying a worm wheel 6 driving a sprocket 10. The film 28 is continuously drawn through a gate 13 by the sprocket 10, and is illuminated by light passing through a channel 11 and reflected by a mirror 12. The lens tube 20 may have three guide rails 23 engaging channel rails 22 in a cylindrical housing 21, and carries an apertured mask 43. The cam track may reciprocate the lens once during each revolution, the operative stroke taking three or four times as long as the return stroke, or may produce two or four reciprocations. Focusing is effected by adjusting the height of the gate arm 33 in a support 34 by a screw 36. The support 34 is pivoted on a pin 35 connected by a link 41 to a spring lock 40 associated with a safety shutter 38 ; when the film becomes loose owing to stoppage of its movement, the gate is turned to the position 13a, and the shutter 38 is closed, to reduce risk of fire. A second safety shutter 37 is closed magnetically if rotation of a roller 31, driven by the film, ceases, the roller being provided with a centrifugal switch 42 which then completes the circuit of a magnetic lock 39 for the shutter 37.