Patent ID: RE41144

Claim:
In a signal amplifying circuit system for a charge coupled device camera the improvement comprising ; : a first automatic gain control auxiliary amplifying circuit (m 1 ) having a low amplification degree and high signal to noise ratio; a second separate automatic gain control auxiliary amplifying circuit (m 2 ) 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 (m 1 ) having a low amplification degree and a high signal to noise ratio to said second separate automatic gain control auxiliary amplifying circuit (m 2 ) 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 (m 1 ) 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 (m 2 ) 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.