| 摘要 |
<p>1288964 Cine apparatus; film threading SINGER CO 2 Sept 1969 [5 Sept 1968] 43355/69 Heading G2E In a cine projector, loop forming sprockets 36, 46 on either side of gate 20 are positioned so that film 16 may be threaded to a substantially straight line from idle roller 26 on the supply side to sprocket 36 and from sprocket 46 to idle roller 54 on the take-up side. After threading, pressure rollers 38, 48 move to the positions 42, 52 leaving free loops, while tensioning rollers 32, 60 are moved to positions shown in broken lines. Film is intermittently fed through gate 20 by sprocket 44. The projector has a fail-safe system whereby projection cannot begin until threading is completed correctly. Movement of arms 40, 50 carrying rollers 38, 48 to the operating position is sensed by switches 80, 84, while switch 82 senses film pressed against curved gate guides 70 by strips 76 in the operating position. Arms 62, 64 are moved by lever 68 to press film 16 round sound head 18, the movement of arm 62 being sensed by switch 78. Film tensioning. Tensioning arms 30, 58 are each mounted on a shaft such as 87, Fig.2, and are spring-urged to the operative position. A potentiometer 104 geared to shaft 86 senses the angular position of arm 30 and supplies a signal controlling the supply reel motor, or the take-up reel motor in the case of arm 58. Arms 30, 58 are moved to the loading position of Fig.1, by motors such as 118 geared to shaft 110 clutched to shaft 86. Reel drives. Each reel is carried on a shaft such as 136, Fig.3, connected by coupling 138 to the shaft of a D.C. motor 132. Rotation of shaft 136 is controlled by a brake 140 in which brake shoes 170, 172 are urged by spring 164 to engage diaphragm 168 rotating on the shaft until coil 162 is energized to draw armature 158 and shoe 172 from the diaphragm. The signals from potentiometers such as 104 are amplified and fed to the brake coils for each reel. Framing adjustment. Opaque disc (232), Fig.4 (not shown), has a transparent sector (236) and rotates on the shaft of motor (214) driving sprocket 44 through a Geneva mechanism. If any one of the sensing switches 78-86 are closed, the transport system is disabled by a relay (176), but motor (214) is only de-energized when sector (236) passes light from lamp (238) to photo-sensor (240) and a signal to generate to open switch (246). A film frame may then be positioned at gate 20, and framing is thereafter correct. During projection, motor (214) is energized by amplifiers (216) fed with a drive signal by computer (218). Tachogenerator (222) on the shaft of motor (214) provides feedback signals to amplifier (216) to control the motor speed.</p> |
