Mirror mechanism for a film projector
AssigneeVireco, A.G.
InventorGordon McNally
Life of this patent
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Abstract
A mirror mechanism for a continuous-motion cinematograph film projector. A drive shaft is mechanically coupled to the film transport and is coupled through a slipping clutch to drive a cam. A cam follower riding on the cam profile oscillates a compensating mirror. Frame synchronization of the mirror scan is effected by detection of optical synchronizing marks on the film. Release pulses are generated in response to the synchronizing marks to energize a solenoid to release a blocking member which otherwise blocks movement of the cam.
Claims8
A mirror mechanism for a continuous-movement cinematograph film projector, which projector has means for driving the film continuously and a drive shaft driven in synchronism with the film, the mirror mechanism comprising a compensating mirror;
- a pivot axis about which the mirror oscillates;
- a lever arm coupled to the mirror to oscillate the mirror;
- a cam-follower portion on the lever arm;
- a cam having a profile on which the cam-follower portion rides;
- a spring for urging the cam-follower portion into contact with the profile of the cam;
- a slipping clutch for coupling the cam to the drive shaft and allowing the cam to be arrested while the drive shaft continues to rotate;
- a blocking member having a blocking position where it engages the cam and a release position where it is clear of the cam, the cam being arrested by the blocking member when in the blocking position;
- and a solenoid which, when energised by an electrical release pulse, withdraws the blocking member to the release position to release the cam.
Dependencies are inferred from the claim text.