×

Automatic white adjusting circuit for a television camera

  • US 4,486,771 A
  • Filed: 03/14/1983
  • Issued: 12/04/1984
  • Est. Priority Date: 06/02/1980
  • Status: Expired due to Fees
First Claim
Patent Images

1. An automatic white adjusting circuit for a television camera having a color image pick-up device, said automatic white adjusting circuit comprising:

  • first variable gain amplifying means applied with a first primary color signal;

    second variable gain amplifying means applied with a second primary color signal,matrixing means applied with a third primary color signal and outputs of said first and second variable gain amplifying means;

    first, second, and third low-pass filters respectively applied with the outputs of said first and second variable gain amplifying means and said third primary color signal;

    first and second comparing means respectivey supplied with an output of said third low-pass filter to a single input terminal, and supplied with respective outputs of said first and second low-pass filters to their respective other input terminal;

    first and third reversible counter means respectivel supplied with an output of said first comparing means to their respective up/down input terminals;

    second and fourth reversible counter means respectively supplied with an output of said second comparing means to their respective up/down input terminals;

    first, second, third and fourth digital-to-analog converters respectively supplied with parallel outputs of said first, second, third, and fourth reversible counter means;

    first reference gain establishing means supplied with outputs of said first and third digital-to-analog converters;

    second reference gain establishing means supplied with outputs of said second and fourth digital-to-analog converters; and

    switching means for selectively switching over an incoming clock pulse, to supply said clock pulse to respective clock pulse input terminals of said first and second reversible counter means or said third and fourth reversible counter means,said clock pulse input terminals of said first and second reversible counter means being respectively connected to load terminals of said third and fourth reversible counter means,said first and second variable gain amplifying means respectively being supplied with gain varying control voltages from said first and second reference gain establishing means,said matrixing means producing a luminance signal and two color difference signals.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×