Automatic white balance adjusting circuit

Abstract

Abstract PURPOSE:To provide an excellent transition response by shortening the period of a clock signal inputted to a counter driving circuit in a beginning period in which the counter driving circuit is made into an active condition. CONSTITUTION:According to whether the level of a luminance signal is in a prescribed scope or not, a first signal voltage and a second signal voltage are outputted, and when the second signal is outputted, an input signal switching means is switched so as not to input a color difference signal to an arithmetic means outputting white balance control signal. Further, a time, when a level detecting means outputs continually the second signal voltage, is detected, and when the continuation time exceeds a prescribed time, a third signal voltage is outputted and a switching is executed to inactivate an arithmetic means. When the arithmetic means is activated again, a clock generating means to give the clock signal to the arithmetic means gives the clock signal of the first period in the beginning prescribed period and simultaneously speeds up the action speed of the arithmetic means. Thus, white balance adjustment with good transition response can be executed.

Inventors

• 👤 Noboru Matsuda

Bibliographic Details