Video camera iris control circuit

Details Video camera iris control circuit Video camera iris control circuit

1983-07-25

1987-03-10

Groody, James J.

Facsimile and static presentation processing

Facsimile

Recording apparatus

354451, 352141, H04N 5235

Patent

active

046494316

ABSTRACT:
An iris control circuit for a video camera in which only a single drive coil is employed so that the video camera employing the circuit can be more easily miniaturized. A first operational amplifier supplies drive current to a drive coil in proportion to the sum of an iris control signal and a feedback signal. A detecting circuit, preferably implemented as a voltage divider circuit, detects the counterelectromotive force developed across the drive coil. A feedback circuit, which may be implemented with a second operational amplifier, develops the feedback signal. The feedback signal can be made variable to adjust the feedback ratio, and hence the proportional braking force applied to the iris.

REFERENCES:
patent: 3896461 (1975-07-01), Higuma
patent: 4134653 (1979-01-01), Ishiguro et al.
patent: 4141043 (1979-02-01), Liu
patent: 4184757 (1980-01-01), Kondo
patent: 4399466 (1983-08-01), Stephenson
patent: 4410915 (1983-10-01), Yamamoto
patent: 4471383 (1984-09-01), Shiono
patent: 4473843 (1984-09-01), Bishop
patent: 4558368 (1985-12-01), Aoki et al.

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