Individual frames on a photographic film strip in a projector are automatically positioned by a simple circuit. The circuit uses a photodiode that senses frame registry position and a relay that stops the film-advance motor to suspend the film at point of registry

Silver, R. H.

English

NASA Technical Reports Server

it Source 
To Motor 
Switch 
Light Source 
Photodiode'...
Latching
Relay 
Photodli 
May 1965	 Brief 65-10132 
NASA TECH BRIEF H 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Simple Circuit Positions Film Frames in Projector
The problem: Automatically positioning individual 
frames on a strip of photographic film in a projector, 
viewer, or an enlarger. 
The solution: A circuit employing a photodiode 
that senses frame registry position and a relay that 
cuts off the film-advance motor to stop the film at the 
point of registry. 
How it's done: One edge ofa standard 35-mm film 
is masked to cover all of the perforations in each 
frame but one, which serves as a registry marker. A 
photodiode placed between the masked edge of the 
advancing film and a light source senses the registry 
perforation adjacent to a frame and opens the contacts 
of a latching relay to cut off the film-advance motor 
at the proper point. The open relay contacts also pre-
vent the motor from restarting until the reset button is
pressed to reengage the latching relay and advance the 
film to the next frame. 
Note: Inquiries concerning this innovation may be 
directed to:
Technology Utilization Officer 
Jet Propulsion Laboratory 
4800 Oak Grove Drive 
Pasadena, California, 91103 
Reference: B65-10132 
Patent status: NASA encourages commercial use

of this innovation. No patent action is contemplated.

Source: Robert H. Silver

(J PL-508) 
Category No. 02 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000131 2020-03-11T17:22:47+00:00Z


Simple circuit positions film frames in projector

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