Automatic tracing circuit for white balance of color video camera

Abstract

Abstract PURPOSE:To attain photographing with an appropriate white balance, by providing 3rd and 4th comparator circuits to which output signals of 1st and 2nd integration circuits are supplied and by which said output signals and reference level signals are compared, and an exclusive 'OR' circuit to which the output signal of each comparator circuit is supplied. CONSTITUTION:Regardless of color temperature, logic of the output signals at respective output terminals of comparators 21 and 22 is such that the logic of one output signal is 'L' when the logic of the other output signal is 'H', and vice versa. Therefore, the output signal of an exclusive 'OR' circuit 23 becomes 'H' in logic and a start/stop controlling circuit 24 sets up-down circuits 8 and 16 and counters 9 and 17 to operable states. Therefore, when a whole picture becomes green of lawns in a state where white balance is maintained, gain controlling circuits 2 and 11 are held at the gains immediately before the whole picture turns to green and photographing can be carried out without spoiling the white balance.

Inventors

• 👤 Koshiro Hamada
• 👤 浜田　耕四郎
• 👤 Yoshiro Hieda
• 👤 稗田　善郎

Bibliographic Details