Television receiver with picture-in-picture

Claim 2

A television receiver capable of simultaneously displaying a picture signal by at least first and second picture images on a cathode ray tube, characterized by that it is provided with: means for generating the first and second picture signal; a first APL detector for receiving the first picture signal to detect an average picture level of the first picture signal thus producing a first detection signal; a second APL detector for receiving the second picture signal to detect an average picture level of the second picture signal thus producing a second detection signal; a first picture signal processing means responsive to a first control signal for controlling the first picture signal in at 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 at 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 first 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.

Claim 3

A television receiver as claimed in claim 2, wherein the controller further comprising; a differential amplifier including first and second transistors having their emitters connected with each other in common; means for supplying the base of the first transistor with the first detection signal from the first APL detector; means for supplying the base of the second transistor with the second detection signal from the second APL detector; a current source circuit coupled in common to the emitter of the first and second transistors so as to be controlled its current in response to the for being is connected in common, for controlling the current amount in response to the detection voltage from the ABL detector; means for supplying the first picture signal processing means with the first control signal as a collector output of the first transistor;, and means for supplying the second picture signal processing means with the second control signal as a collector output of the second transistor.

Claim 4

A television receiver capable of simultaneously displaying a picture signal by at least first and second picture images on a cathode ray tube, characterized by that it is provided with; means for generating the first and second picture signal; a first APL detector for receiving the first picture signal to detect an average picture level of the first picture signal thus producing a first detection signal; a second APL detector for receiving the second picture signal to detect an average picture level of the second picture signal thus producing a second detection signal; a first picture signal processing means responsive to the first detection signal for controlling the first picture signal in its gain; a second picture signal processing means responsive to the second detection signal for controlling the second picture signal in its gain; 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 controlling at least one of a contrast and a brightness of an output picture signal from the superimposer in response to the detection voltage from the ABL detector.