JPS6042546Y2 - Horizontal phase variable circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a horizontal phase variable circuit that corrects a horizontal positional shift between a raster and an image in a CRT display device or the like.

CRT display devices are used as computer terminals, but unlike home television receivers, the screen is underscanned, so the positional relationship between the raster image and the image becomes a problem.

Signals used in computers, etc. are inferior to broadcast television signals in that the accuracy of the phase relationship between the video signal and the synchronization signal is inferior, and even in the CRT display device itself, there are loops between retrace bases and phase correction circuits. Due to variations in gain and the like, a phase shift occurs between the video signal and the horizontal deflection pulse, which inevitably causes a position shift between the raster and the image.

For this reason, conventionally, the positions of the raster and the screen have been adjusted by changing the component constants of the comparison waveform circuit that generates the sawtooth wave of the sawtooth wave AFC circuit.

Therefore, it takes time to attach and detach parts, and since the constants of the parts are changed, the constant changes are gradual changes, making it impossible to set the image at the optimum position.

The present invention was conceived in view of the above problems, and aims to achieve continuous image quality position adjustment using a simple circuit configuration.

An embodiment of the present invention is shown in FIG. 1 and will be described below.

1 is a horizontal synchronization signal input terminal, 2 is a phase difference detection circuit, 3
4 is a horizontal oscillator circuit, 4 is a horizontal deflection output circuit, 5 is an output terminal for taking out horizontal deflection pulses, and 6 is a part of the horizontal deflection output pulse from the horizontal deflection output circuit, and a sawtooth wave for comparison is made for comparison. It is a waveform circuit.

Since the above is a horizontal deflection circuit using a well-known sawtooth wave AFC circuit, a description thereof will be omitted.

In the present invention, the above comparison waveform circuit 6 has the following configuration.

The horizontal deflection pulse input terminal 7 is connected to the horizontal deflection output circuit 4, and the sawtooth wave output terminal 8 is connected to the phase difference detection circuit. A resistor R1 is connected to the input terminal 7 side, and a resistor y is connected to the sawtooth wave output terminal 8 side.

A capacitor C□ and a variable resistor ■3 are connected in parallel between the sawtooth wave output terminal 8 and the ground, and the movable piece 9 of the variable resistor ■1 is connected to the resistors R1 and R2. The configuration is such that a capacitor C2 is connected between the point a and the point a.

In the above configuration, if the movable piece 9 of the variable resistor vR is brought as close as possible to the ground side, the capacitor C2 will be grounded, resulting in an equivalent circuit as shown in FIG. 2 A1.

In this circuit, a resistor R□ and a capacitor C2 form an integrating circuit, and a resistor R2 and a capacitor C□ form an integrating circuit, thereby forming a double integrating circuit.

Next, when the movable piece 9 of the variable resistor VR is brought as close as possible to the connection point between the variable resistor VR and the resistor B2, an equivalent circuit as shown in FIG. 2B is obtained.

In this circuit, a differentiation circuit is formed by the capacitor C2 and the variable resistor VR, and an integration circuit is formed by the resistor 1□, R2 and the capacitor C1, thus forming a differentiation/integration circuit.

In the case of the double integration circuit shown in FIG. 2A above, when a horizontal deflection pulse like that shown in FIG. Become.

This integrated waveform is integrated again by resistor R2 and capacitor C1 to produce a bulging sawtooth wave as shown in FIG. 3 S1.

When this sawtooth wave is applied to the phase difference detection circuit, and a synchronization signal is added from the other input terminal 1 such that the phase difference between the video signal and the synchronization signal is T1 as shown in FIG. is the average value S of the sawtooth wave S1.

□ point, t. Locked at 1 point.

Similarly, in the case of FIG. 2B, the horizontal deflection pulse P1 applied to the input terminal 7 is differentiated by the variable resistor R and the capacitor C2.

Furthermore, this differential waveform is created by resistor (R1+R2) and capacitor C.
The average value S of the sawtooth wave S2 is integrated by the process to form a thin sawtooth wave as shown in FIG. 3, S2, and as shown in FIG. 3, P2'.

2 or t. Locked at point 2. That is, variable resistor ■8
The horizontal synchronization point is determined by t.

1 to t. Can move continuously up to 2.

Therefore, the position of image quality can be similarly moved within that range.

As explained above, the horizontal phase circuit of the present invention consists of a variable resistor, a plurality of resistors, and a capacitor, and the circuit is simple.
Further, by using a variable resistor, there is no need to replace component constants, and the image can be easily set at the optimum position.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of the horizontal phase variable circuit of the present invention, FIG. 2 is an equivalent circuit diagram during its operation, and FIG. 3 is a waveform diagram for explaining its operation. 6: Comparison waveform circuit, 7: Horizontal deflection pulse input terminal, 8:
Sawtooth wave output terminal, R□, R2: Resistor, C1, C2: Capacitor, vR = variable resistor.

Claims (1)

[Scope of utility model registration request] In a horizontal deflection circuit in which the horizontal oscillation wave number is controlled by a sawtooth wave AFC circuit, a variable resistor and a plurality of resistors and capacitive elements are used in the comparison waveform circuit constituting the sawtooth wave AFC circuit, and the comparison A horizontal phase variable circuit characterized in that the horizontal position of an image is continuously moved by continuously changing the circuit equivalently from a double integration circuit to a differentiation/integration circuit.