White balance circuit for electronic endoscope

Abstract

Abstract PURPOSE:To display the object of image pickup in color with fidelity by obtaining the color temperature of a light source lamp and controlling the gain with respect to the signal of each wavelength in an image pickup signal of a solid-state image pickup element so as to apply white balance. CONSTITUTION:Sequential illuminating lights R, G, B reflected in a half mirror 66 are received by a photodetector 67, the, quantity of light is converted into an electric signal, inputted to an RGB synchronizing circuit 69 via an amplifier 68 to synchronize the R, G, B sequential signal electrically. Then the difference of the signals R, B with respect to the signal G is detected by differential amplifiers 91, 92 and its output signal forms R and B control signals controlling the gain at the input of R, G image pickup signal in the R, B sequential illumination picked up by a CCD 57. Then the R and B control signals are applied to a signal processing circuit processing the image pickup signal to obtain white balance. Thus, the white-balancing state is always maintained.

Inventors

• 👤 Masao Uehara
• 👤 上原　政夫

Bibliographic Details