| 摘要 |
PROBLEM TO BE SOLVED: To provide a video camera system that reduces power consumption and suppresses quantization noise, when a high gain is required. SOLUTION: An AGC circuit 3 amplifies an analog signal from a sensor 2, an analog/digital converter 4 converts the signal into a digital signal, which is amplified by an AGC circuit 5 and processed by a signal processing circuit 6. A level detection circuit 9 detects the level of an output luminance signal Y of the signal-processing circuit 6, a microcomputer 7 compares the detected value with a reference value and generates an aperture control signal of an iris 1, a gain control signal 73 of the AGC circuit 3, and a gain control signal 75 of the AGC circuit 5, depending on the comparison result. The microcomputer 7 minimizes the gain of the AGC circuits 3, 5, to make the detected value match with the detected value under the control of the aperture of the iris 1 at low illuminance, the microcomputer 7 fully opens the iris, minimizes the gain of the AGC circuit 5 and makes the detected value match with the reference value under the gain control of the AGC circuit 3 at medium illuminance, and the microcomputer 7 fully opens the iris 1, maximizes the gain of the AGC circuit 3 and makes the detected value match wit the reference value under the gain control of the AGC circuit 5 at high illuminance.
|
