Sony Corporation

Nobuyuki Okamoto

Haruhisa Iida

Kenichiro Kawanami

Koji Kambayashi

An amplifier circuit in a display device for a monitor unit in a computer system or the like, includes first active element whose control electrode is supplied with a signal from an input terminal; a second active element cascade-connected to the first active element; a third active element so connected to the second active element that a junction thereof is connected to an output terminal; an impedance element disposed between the input terminal and the third active element and capable of changing the impedance in accordance with the frequency of the input signal; a first resistance element connected between the junction of the second and third active elements and the control electrode of the first active element; and a second resistance element connected between the input terminal and the control electrode of the first active element and serving to determine the signal amplification factor in cooperation with the first resistance element. Since the second active element is cascade-connected to the first active element, no manipulation is necessary for adjusting the component elements, and generation of any smear or sag resulting from variation of the feedback capacitance can be suppressed at low cost.

Amplifier with a second active element being cascode connected to a

A method and apparatus for adjustment of the white balance of a CRT display system enabling white balance adjustment to be performed in a short time and a television receiver using the same. The white balance adjustment apparatus has a level adjustment circuit, an attenuation resistor, a video signal output circuit, a coupling capacitor, and a synchronous-signal-tip level clamp circuit and is connected to the cathode electrode. The level adjustment circuit has a variable amplifier which amplifies only the video signal component V, a synchronous signal separation circuit, a variable amplifier for causing attenuation of the horizontal synchronous signal H-SYNC, a signal addition circuit, and an AND gate. In the white balance adjustment mode, the ratio of levels of the video signal and synchronous signal is changed from the usual 0.714:0.218 to, for example, 0.714:0.005. By this, even when the drive voltage is adjusted in the synchronous-signal-tip level clamp circuit after the adjustment of the background in the level adjustment circuit, there is less change of the horizontal synchronous signal and there are, therefore, less number of tracking operations needed between the adjustment of the background and the adjustment of the drive voltage.

Method of adjusting white balance of CRT display, apparatus for same,

A display device testing circuit includes a false video signal generator for producing a false video signal from a blanking pulse of the display device in a state where no video signal is connected to an input terminal of the display device, so that such false video signal is supplied to the video amplifier. A false clamp pulse generating circuit produces a false clamp pulse from the blanking pulse and supplies the false clamp pulse to a pedestal clamper in the video amplifier, thereby realizing a simplified test of the video amplifier at low cost.

Display device testing circuit using false video signal generator

A monitor interface circuit for adapting a color display monitor to a selected one of various types of computers which generate different types of color display data receives the display data and one of several horizontal scanning frequency signals from the computer and mixes the display data as a function of the one horizontal scanning frequency to thereby generate a proper display signal for the monitor.

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Tokyo, Japan

Nobuyuki Okamoto