Automatic white balance adjusting device of color video camera

Abstract

Abstract PURPOSE:To reduce color shifting even for an optical source including a bright line spectrum and to make it possible to use the titled device also for a camera using a shutter by simply constituting the device of two light receiving elements. CONSTITUTION:The spectroscopic sensitivity distribution of visible light type silicon photodiodes 3, 5 receiving light from a white diffusion plate 1 is made close to visibility distribution and a filter fitted to the diode 5 transmits the center wavelength of said distribution, i.e. wavelength longer than 550nm. The output signals Wa, Ra of the diodes 3, 5 are supplied to a subtractor 8 through logarithm compressing circuits 6, 7 respectively. Therefore, the output signal of the circuit 8 has chromatic temperature information. The output signal is A/D converted and its digital signal is supplied to a microcomputer 10. In the microcomputer 10, a white balance control signal is previously determined in accordance with the chromatic temperature information. In this example, red and blue signal control signals obtained from the microcomputer 10 are A/D converted respectively and their analog signals are supplied to red and blue gain control circuits 12R, 13B respectively. Thus, the white balance is automatically adjusted at a real time.

Inventors

• 👤 Norio Koyama
• 👤 紀男 小山

Bibliographic Details