Fade-over arrangement for a motion picture camera

Details Fade-over arrangement for a motion picture camera Fade-over arrangement for a motion picture camera

1974-12-05

1976-06-29

Hix, L. T.

Optics: motion pictures

Special effects

Transition effects

352 91S, 352141, G03B 2136

Patent

active

039663124

ABSTRACT:
A bridge circuit contains a photoelectric resistor positioned behind the diaphragm and thus having a resistance varying as a function of the light falling on the film. A second arm of the bridge circuit contains a resistor. The bridge circuit output is connected to the inputs of a differential amplifier whose output controls a step motor which adjusts the size of the aperture until the bridge is balanced. For fade-out, an additional resistor is inserted in the second arm by opening a short-circuiting switch, thus causing the bridge to become unbalanced and the step motor to change the aperture until it is again in balance. This balance will take place at a predetermined low illumination suitable for fade-out. Closing the switch will result in fade-in, namely an opening of the aperture until the circuit is again in balance. The output signal from the bridge circuit thus controls the aperture even during fade-in and fade-out.

REFERENCES:
patent: 3419325 (1968-12-01), Mayr et al.
patent: 3623989 (1971-11-01), Mayr et al.
patent: 3792920 (1974-02-01), Mayr et al.
patent: 3801194 (1974-04-01), Pelte et al.
patent: 3813680 (1974-05-01), Wagensonner et al.

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