Optics: motion pictures – With automatic diaphragm control
Patent
1982-09-29
1984-07-10
Hayes, Monroe H.
Optics: motion pictures
With automatic diaphragm control
G03B 708
Patent
active
044589921
ABSTRACT:
The present invention is an automatic exposure correction system for use in combination with a motion picture camera, which includes a lens barrel, a lens iris-ring and a first toothed pulley which is mechanically coupled to the lens iris-ring, for making automatic exposure corrections in response to continuous changes in camera speed of the motion picture camera. The automatic exposure correction system includes an iris-ring drive mechanism and a camera speed aperture computer. The iris-ring drive mechanism includes a servo motor and a reduction gearhead which has an output shaft and a multi-turn variable resistor which has a rear shaft which a torque limiting clutch mechanically couples to the output shaft of the servo motor and the reduction gearhead. The iris-ring drive mechanism also includes a second toothed pulley which mechanically couples the front shaft of the multi-turn variable resistor to the lens iris-ring through a toothed band and the first toothed pulley. The front shaft of the multi-turn variable resistor drives the lens iris-ring continuously through a plurality of f/stop settings. The camera speed aperture computer includes an electronic processing and control circuit for processing data relating to camera speed of the motion picture camera and the position of the front shaft of the multi-turn variable resistor. The electronic processing and control circuit sends a control signal to the servo motor in order to drive the shaft of the multi-turn variable resistor thereby driving the lens iris-ring to the correct f/stop setting for the camera speed.
REFERENCES:
patent: 4084893 (1978-04-01), Flandorfer
patent: 4142785 (1979-03-01), Saito
patent: 4175840 (1979-11-01), Kittag
Hayes Monroe H.
Johansen W. Edward
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