JPS6437190A - White balance setting circuit - Google Patents

Abstract

PURPOSE:To suppress the occurrence of the variation in color difference signal amplitude and that of a vertical correlation error signal by making the output signal amplitudes of a first and a second gain controlled circuits that gain- control the output of an image pickup element equal to each other and constant against color temperature variation. CONSTITUTION:For a line for which a line switch 5 selects a white balance setting value 20, a white balance setting value 23 is selected by a line switch 6 simultaneously, a sample-hold signal 13 is gain-controlled by a white balance setting value 20, while a sample-hold signal 14 is also gain-controlled by a white balance setting value 23. White balance setting circuits 8, 11 control the white balance setting values 20, 23 so that output signals from the gain- controlled circuits 3, 4 goes to constant against the variation in color temperature at the time of image-picking-up of white, and similarly, white balance setting circuit 10, 9 set white balance setting values 21, 22 so that output signals from the gain controlled circuits 3, 4 goes to a prescribed constant value against the variation in color temperature at the time of image-picking-up of white.