JPH0514754A - Vertical image position control circuit - Google Patents

Abstract

PURPOSE:To attain a vertical image position control by which a trapezodial distortion is not generated even at the time of moving the image position up and down by interlocking a vertical image position control signal with a trapezodial distoration correction control signal at the time of moving the image up and down by the pertinent vertical image position control signal. CONSTITUTION:Vertical deflecting currents from a vertical deflection output circuit 6, and direct currents 10 for a vertical position control, are inputted to a trapezodial distortion correction signal generating circuit 7, and a vertical deflection output 11 whose amplitude is changed according to the size of the currents 10, is outputted. This output 11 is turned to a waveform corresponding to the positive, zero, and negative of the direct currents from a variable resistor 1 for a vertical position control. And also, As for a horizontal deflection output circuit 8, a saw-tooth-wave signal is amplitude-modulated by the output 11, and output currents are running through a horizontal deflecting coil 9. Thus, the vertical image position control is interlocked with the trapezodial distortion correction, so that the vertical image position control by which the trapezodial distoration is not generated even at the time of moving the image position up and down can be operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver having a vertical screen position control circuit and a computer display monitor.

[0002]

2. Description of the Related Art Generally, the vertical position of a screen on a CRT is adjusted by passing a current in which a vertical deflection current and a direct current are superimposed on a vertical deflection coil and changing the magnitude of the direct current.

FIG. 2 shows a conventional vertical screen position control circuit. Reference numeral 1 is a vertical position control variable resistor. This control voltage is amplified by a DC amplifier 2 and a direct current is supplied to a vertical deflection coil 4 through a control resistor 3. Is superimposed to control the vertical position of the screen. In the figure, 5 is a coupling capacitor, and 6 is a vertical deflection output circuit.

[0004]

However, in the vertical screen position control circuit configured as described above, when the vertical position control variable resistor 1 is turned to raise or lower the screen position, the CRT from the deflection center to the CRT surface, Due to the characteristics of the deflection coil, as shown in FIG. 3, when the screen is moved upward, the upper part of the screen expands and the lower part contracts. Conversely, when the screen is moved downward, the lower part of the screen expands and the upper part of the screen expands. It has a problem that trapezoidal distortion such as shrinkage occurs. In view of such a point, the present invention, even if the vertical screen position is changed,
It is an object of the present invention to provide a vertical screen position control circuit that does not generate trapezoidal distortion.

[0005]

In order to achieve the above object, the vertical screen position control circuit of the present invention is such that a vertical screen position control signal and a trapezoidal distortion correction signal are interlocked with each other.

[0006]

According to the present invention, when the screen is moved up and down by the vertical screen position control signal, the vertical screen position control signal is interlocked with the trapezoidal distortion correction control signal to change the horizontal deflection amount to correct the trapezoidal distortion. Will be done.

[0007]

1 is a block diagram of a vertical position control circuit according to an embodiment of the present invention.

The vertical deflection coil 4 has a vertical deflection output circuit 6
The vertical deflection current from the above and the direct current from the vertical position control variable resistor 1 are supplied as described in the conventional example. In the trapezoidal distortion correction signal generation circuit 7, the vertical deflection current and the vertical position control DC current from the vertical deflection output circuit 6 are input, and the vertical deflection output whose amplitude changes according to the magnitude of the vertical position control DC current 10. 11 is output. The output 11 of the trapezoidal distortion correction signal generation circuit 7 is shown in FIGS. 4, 5 and 6 depending on when the direct current from the vertical position control variable resistor 1 is positive, zero or negative. The waveform looks like this. In the horizontal deflection output circuit 8, the horizontal deflection sawtooth wave signal is amplitude-modulated by the output 11 of the trapezoidal distortion correction signal generation circuit 7, and the output current thereof flows in the horizontal deflection coil 9.

As described above, according to this embodiment, the vertical screen position control and the trapezoidal distortion correction are interlocked with each other, whereby the vertical screen position control can be performed without causing the trapezoidal distortion even when the screen position is moved up and down.

[0010]

As is apparent from the above description of the embodiments, the present invention changes the correction amount of the trapezoidal distortion by the vertical screen position control signal so that the trapezoidal distortion does not occur even if the screen position is moved up and down. It can be controlled, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 Conventional circuit diagram

FIG. 3 is a pattern diagram for explaining conventional problems.

FIG. 4 is an output waveform diagram of a trapezoidal distortion correction signal circuit.

FIG. 5 is an output waveform diagram of the trapezoidal distortion correction signal circuit.

FIG. 6 is an output waveform diagram of the trapezoidal distortion correction signal circuit.

FIG. 7 is a waveform diagram of a current flowing through the coil.

FIG. 8 is a waveform diagram of a current flowing through the coil.

FIG. 9 is a waveform diagram of a current flowing through the coil.

[Explanation of symbols]

 1 Variable resistor for vertical position control 2 DC amplifier 3 Control resistor 4 Vertical deflection coil 5 Coupling capacitor 6 Vertical deflection output circuit 7 Trapezoidal distortion correction signal generating circuit 8 Horizontal deflection output circuit 9 Horizontal deflection coil 10 Vertical position control signal 11 Trapezoidal distortion correction signal

Claims (1)

Claim: What is claimed is: 1. A vertical screen in which a horizontal deflection current amplitude-modulated by a trapezoidal distortion correction signal having a vertical period whose amplitude changes in accordance with a DC voltage for vertical position adjustment is passed through the horizontal deflection coil. Position control circuit