Device for automatically controlling a protective filter in a fi

Details Device for automatically controlling a protective filter in a fi Device for automatically controlling a protective filter in a fi

1974-08-20

1976-02-03

Hayes, Monroe H.

Optics: motion pictures

With film strip fire prevention or isolation

Film cooling

G03B 2116

Patent

active

039361675

ABSTRACT:
In a film projector of the type wherein film advance is controlled by pulse signals generated by a tape recorder or the like, a protective filter is automatically inserted into the optical path between the projection lamp and the film when the time interval between successive pulse signals exceeds a predetermined time limit. The filter is automatically removed from the optical path only when two successive time intervals have a duration less than a predetermined duration.

REFERENCES:
patent: 1385162 (1921-07-01), Tillyer
patent: 1954844 (1934-04-01), Scheinfeld

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