Auxiliary amplifier selection circuit for a CCD camera
AssigneeWatec Co., Ltd.
InventorShigeto Igarashi
Life of this patent
Estimating the term…
Abstract
Object: To broaden the range of photographing of object, until illumination of 0.02 lux. Construction: In the case of sufficient bright object, photographing is performed by a conventional circuit at a high S/N ratio, at a high degree. In the case of an insufficient bright object, inserting auxiliary amplifying circuit m, m1, m2 or em and ignoring the S/N ratio, and raising the amplification degree. In the case of sufficient bright object, photographing is performed by high S/N ratio, and high degree, in the case of insufficient bright object, an auxiliary amplifying circuit m, m1, m2 or em is inserted ignoring the S/N ratio until utility noise composite of 20 dB (10%).
Claims5
In a signal amplifying circuit system for a charge coupled device camera the improvement comprising;
- a first automatic gain control auxiliary amplifying circuit (m1) having a low amplification degree and high signal to noise ratio;
- a second separate automatic gain control auxiliary amplifying circuit (m2) having a high amplification degree and a low signal to noise ratio that is less than about the minimum signal to noise ratio of said auxiliary amplifying circuit with a high signal to noise ratio;
- a detector for detecting a change of object illumination;
- and,
- a switch activated by said detector for switching from said first automatic gain control auxiliary amplifying circuit (m1) having a low amplification degree and high signal to noise ratio to said second separate automatic gain control auxiliary amplifying circuit (m2) having a high amplification degree and a low signal to noise ratio when said object illumination produces a signal-to-noise ratio that is less than the minimum signal to noise ratio of said first automatic gain control auxiliary amplifying circuit (m1) with said high signal to noise ratio;
- whereby said charge coupled device camera is switched to said second separate automatic gain control auxiliary amplifying circuit (m2) having a high amplification degree when ambient illumination of said object is extremely low thereby substantially broadening the range of light levels suitable for photographs by said charged coupled device camera.
Dependencies are inferred from the claim text.