US 5,675,391 A · Contrast/brightness control circuit for television receiver

Abstract

The invention is subjected for a television receiver which is capable of simultaneously displaying a picture signal by at least first and second picture images on a cathode ray tube and including means for generating the first and second picture signal, a superimposer for selectively supplying the first and second picture signal to the cathode ray tube, an APL detector for receiving the first and second picture signals to detect respective average picture levels of the first and second picture signals respectively thus producing first and second level detection signals, an ABL detector for generating a detection voltage responsive to a variation in an anode current of the cathode ray tube, and control means for controlling at least one of contrasts and brightnesses of the first end second picture signals by commonly operating on the first and second picture signals in response to the detection voltage from the ABL detector as well as for independently controlling at least one of contrasts and brightnesses of the first and second picture signals in response to the first and second detection signals from the APL detector.

Claims4

Dependent claims

A television receiver capable of displaying a picture signal representing first and second picture images on a cathode ray tube, comprising:

means for generating first and second picture signals;
a superimposer for selectively supplying the first and second picture signals to the cathode ray tube;
an APL detector for receiving the first and second picture signals and detecting respective average levels thereof thus producing first and second level detection signals;
an ABL detector for generating a detection voltage responsive to a variation in anode current of the cathode ray tube;
and
control means for controlling at least one of contrasts and brightnesses of the first and second picture signals by commonly operating on the first and second picture signals in response to the detection voltage from the ABL detector, as well as for independently controlling at least one of contrasts and brightnesses of the first and second picture signals in response to the first and second detection signals from the APL detector.

3 more elements

A television receiver capable of simultaneously displaying a picture signal representing first and second picture images on a cathode ray tube, comprising:

means for generating first and second picture signals;
a first APL detector for receiving the first picture signal, detecting an average picture level thereof and producing a first detection signal;
a second APL detector for receiving the second picture signal, detecting an average picture level thereof and producing a second detection signal;
a first picture signal processing means responsive to a first control signal for controlling the first picture signal in a least one of its contrast and brightness;
a second picture signal processing means responsive to a second control signal for controlling the second picture signal in a least one of its contrast and brightness;
a superimposer for selectively supplying the first and second picture signals from the first and second picture signal processing means to the cathode ray tube;
an ABL detector for generating a detection voltage responsive to a variation in an anode current of the cathode ray tube;
and
a controller for supplying the first control signal responsive to the detection signal from the ABL detector and the first detection signal from the APL detector, as well as for supplying the second control signal responsive to the detection signal from the ABL detector and the second detection signal from the second APL detector.

6 more elements

Dependencies are inferred from the claim text.

Contrast/brightness control circuit for television receiver

Life of this patent

Contrast/brightness control circuit for television receiver

Life of this patent

Abstract

Claims4