Title: Device for automatically controlling a protective filter in a film projector

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.

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Inventors: Wakahara, Shigeo (Yokohama, JA)

Application Number: 499079
Filing Date: 1974-08-20
Publication_date: 1976-02-03
Assignee: Nippon Kogaku K.K. (Tokyo, JA)
Primary Class(es): 352/148
Other Classes:
US Patent Ref:

1385162	Jul, 1921	Tillyer	352/148.
1954844	Apr, 1934	Scheinfeld	352/154.

Other Refs:
Primary Examiner: Hayes, Monroe H.
Assistant Examiner:
Attorney: Shapiro and Shapiro