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US 6,549,238 B1Granted
Sample-and-hold iris control system
AssigneeKoninklijke Philips Electronics N.V.
InventorJohannes B. M. Nooijen
Life of this patent
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Abstract
An iris control system uses a sample-and-hold circuit to provide a constant image signal to control an iris of a camera. To facilitate active iris control, a DC-AC converter is used to convert the constant image signal to an AC iris control having a peak amplitude that is based on the DC amplitude of the constant image signal.
Claims6
A method of generating an iris control signal comprising the steps:
- furnishing an image signal,
- subjecting the image signal to a sample-and-hold operation to form the iris control signal, and
- subjecting the iris control signal to a DC-AC (direct-current to alternating-current) conversion to form an AC (alternating-current) iris control signal.
A circuit comprising:
- a sensor that converts an image to an image signal,
- a sample-and-hold circuit that forms a DC (direct-current) iris control signal from the image signal, and,
- a DC-AC (direct-current to alternating-current) converter that provides an AC (alternating-current) iris control signal from the DC iris control signal.
A camera comprising:
- a lens having a controllable iris coupled to receive an AC (alternating current) iris control signal;
- a sensor that provides an image signal, based on an image from the lens;
- a sample-and-hold circuit that forms a DC (direct-current) iris control signal from the image signal;
- and
- a DC-AC (direct-current to alternating-current) converter that provides a DC-AC conversion of the iris control signal to form the AC iris control signal.
2 more elements
Dependencies are inferred from the claim text.