US 2004/0000874 A1 · Circuit and method of controlling vertical and horizontal screen sizes of cathode ray tube monitor

Abstract

In a circuit and method of controlling the horizontal and vertical screen sizes of a cathode ray tube (CRT) monitor, the circuit includes a horizontal screen size compensation circuit, an east-west correction signal controller, a vertical screen size compensation circuit, and a vertical screen size correction signal controller. The horizontal screen size compensation circuit compares the voltage value of a horizontal screen size correction signal with the voltage value of a horizontal reference voltage to obtain first and second horizontal current signals. In response to a horizontal control signal, the horizontal screen size compensation circuit outputs a horizontal correction current signal obtained by subtracting a horizontal variable current signal from the first horizontal current signal. The vertical screen size compensation circuit compares the voltage value of a vertical screen size correction signal with the voltage value of a vertical reference voltage to obtain first and second vertical current signals. In response to a vertical control signal, the vertical screen size compensation circuit selects one of first and second vertical correction current signals and outputs the selected signal as a vertical correction current signal.

Claims24

Dependent claims

A circuit for controlling the horizontal and vertical sizes of a screen of a cathode ray tube (CRT) monitor, the circuit comprising:

a horizontal screen size compensation circuit which compares the voltage value of a horizontal screen size correction signal with the voltage value of a horizontal reference voltage to obtain first and second horizontal current signals and, in response to a horizontal control signal, generates a horizontal correction current signal by subtracting a horizontal variable current signal from the first horizontal current signal, and outputs the horizontal correction current signal;
an east-west correction signal controller which generates an east-west direct current (DC) correction signal by combining the horizontal correction current signal with an east-west DC gain signal;
a vertical screen size compensation circuit which compares the voltage value of a vertical screen size correction signal with the voltage value of a vertical reference voltage to obtain a vertical current signal, generates a vertical correction current signal as a function of the vertical current signal and a vertical control signal, and outputs the vertical correction current signal;
and
a vertical screen size correction signal controller which compares a sawtooth voltage signal with a sawtooth reference voltage, amplifies the difference, converts the amplified signal into a sawtooth current signal, and generates a vertical screen size control signal by subtracting the vertical correction current signal from the sawtooth current signal.

2 more elements

A method of controlling the vertical screen size of a CRT monitor, the method comprising:

(a) comparing the current value of a vertical screen size correction signal with the current value of a vertical reference voltage to obtain first and second vertical current signals;
(b) converting a digital vertical control signal into an analog vertical control current signal;
(c) generating a vertical variable current signal by dividing the current value of the second vertical current signal by the current value of the vertical control current signal;
(d) selecting one of a value obtained by subtracting the current value of the vertical variable current signal from the current value of the first vertical current signal and a value obtained by adding the current value of the vertical variable current signal to the current value of the first vertical current signal, and outputting the selected signal as a vertical correction current signal;
and
(e) comparing a sawtooth voltage signal with a sawtooth reference voltage to determine the difference therebetween, amplifying the difference, outputting the amplified signal as a sawtooth current signal, and generating a vertical screen size control signal by subtracting the vertical correction current signal from the sawtooth current signal.

3 more elements

Dependencies are inferred from the claim text.

Circuit and method of controlling vertical and horizontal screen sizes of cathode ray tube monitor

Life of this patent

Circuit and method of controlling vertical and horizontal screen sizes of cathode ray tube monitor

Life of this patent

Abstract

Claims24