JPH05344372A - Screen center position adjustment circuit - Google Patents

Abstract

PURPOSE:To save the power for adjustment in a production line and to stabilize the screen by automatically adjusting the screen center position. CONSTITUTION:In the horizontal screen center position adjustment, a horizontal pulse FP is made a tooth-shaped wave and a center position is detected by a center position detecting circuit 6. A dot counter 7 determines a count value E corresponding to the center position from a horizontal synchronizing signal A separated by a synchronizing separator circuit 1, and a phase comparator supplies the value compared with a detection signal D of the position detection circuit to a phase comparator 2a of a horizontal drive circuit 2. The comparator 2a controls a horizontal pulse oscillation circuit 2b by means of it and the comparison output with the horizontal synchronizing signal A, and controls the entire device to make the horizontal center position coincide with the center position at the dot counter 7. The vertical screen center position adjustment is similarly performed by a vertical center point detection circuit 12, a line counter 13, and a phase comparator 14. Thus, the center position can be automatically adjusted during the operation of a television receiver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for adjusting the screen center position of a picture tube used in a television receiver, a monitor television or the like.

[0002]

2. Description of the Related Art In the conventional example shown in FIG. 7, a composite video signal input from a terminal 50 is separated by a sync separation circuit 1 into a horizontal sync signal and a vertical sync signal. The horizontal synchronizing signal (A) is given to the horizontal drive circuit 2, and the vertical synchronizing signal is given to the vertical drive circuit 9. The horizontal drive circuit 2 includes a phase comparator 2a and a horizontal drive pulse oscillation circuit 2b.
And consists of. The horizontal synchronizing signal (A) is given to the phase comparator 2a, and the phase is compared with a horizontal sawtooth wave given separately here. And this phase comparator 2
The horizontal drive pulse oscillation circuit 2b is controlled by the output of a.

The output of the horizontal drive pulse oscillation circuit 2b is given to the horizontal deflection coil L1 of the deflection yoke DY through the horizontal output circuit 3 of the next stage and also to the flyback transformer 4. The high voltage output of the flyback transformer 4 is supplied to the anode of the picture tube CRT. At the same time, a horizontal pulse (flyback pulse) FP is also taken out from the flyback transformer 4, and the horizontal pulse FP is converted into a sawtooth wave voltage by an integrating circuit 5 and then sent to the phase comparator 2a of the horizontal drive circuit 2 described above. Given.

On the other hand, the vertical deflection system is provided with a vertical drive circuit 9 and a vertical output circuit 10. Through the vertical drive circuit 9 and the vertical output circuit 10, a vertical deflection coil L2 is provided.
A vertical deflection current is applied to. The configurations of the vertical drive circuit 9 and the vertical output circuit 10 are similar to those of the horizontal drive circuit 2 and the horizontal output circuit 3, respectively. However, as the vertical sawtooth wave voltage applied to the phase comparator 9a in the vertical drive circuit 9, the sawtooth wave voltage obtained from point (a) of the vertical deflection circuit is used. In FIG. 7, the center position of the screen is the variable resistor VR1, the center position of the sawtooth wave voltage,
It was adjusted by varying with VR2 or the like.

[0005]

However, since such a screen center position adjustment is manually preset, the circuit design must be performed in consideration of the variation of the circuit elements in each circuit shown in FIG. In addition to that, there is a drawback in that an adjustment process must be provided in the production line. In addition, there are drawbacks in that there are variations in adjustment and it is not possible to sufficiently deal with the constant fluctuation of each circuit element after adjustment.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a screen center adjustment circuit which can save labor in adjustment in a production line and stabilize an output screen by adopting an automatic adjustment method. To aim.

[0007]

The screen center position adjusting circuit according to the present invention which achieves the above object detects the center point of the horizontal sawtooth wave of the horizontal deflection output circuit within the horizontal scanning period. Circuit, a second detection circuit that counts a clock given from the clock oscillation circuit using a horizontal synchronization signal as a count start signal, and detects a horizontal center point, and a center point obtained from the first and second detection circuits. Of the horizontal deflection drive signal through the phase control circuit.

Further, the screen center position adjusting circuit of the present invention comprises a first detection circuit for detecting the center point of the horizontal sawtooth wave of the horizontal deflection output circuit within the horizontal scanning period, and a clock supplied from the clock oscillation circuit. By using the horizontal synchronizing signal as a count start signal to detect a horizontal center point, and a center point obtained from the first and second detecting circuits as a phase control circuit for a horizontal deflection drive signal. Horizontal center position adjusting means to match through,
A third detection circuit for detecting the center point of the vertical sawtooth wave of the vertical deflection output circuit within the vertical scanning period, and a fourth detection circuit for detecting the vertical center point by counting the number of horizontal scanning lines of the video signal. And a vertical center position adjusting means for matching the center points obtained by the third and fourth detection circuits through a phase control circuit for a vertical deflection drive signal.

[0009]

According to this structure, the horizontal center position of the screen or the center position of the screen itself is automatically adjusted during the operation of the television receiver, the monitor TV or the like having the structure.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. In FIG. 1 in which the present invention is implemented, the same parts as those in the conventional example of FIG. First, the horizontal screen center position adjustment will be described. In this embodiment, after the horizontal output pulse FP is integrated by the integrating circuit 5 to form a sawtooth wave voltage, the center point of horizontal scanning is set to the horizontal center from the sawtooth wave voltage. It is detected by the point detection circuit 6. The detection signal is shown in FIG.

On the other hand, the dot counter 7 to which the horizontal synchronizing signal (A) separated by the synchronizing separating circuit 1 is applied, counts the clock from the clock oscillating circuit 51 as the horizontal synchronizing signal as a count start signal (reset signal) and When counting up to the value corresponding to the center position, the count value is held until the next horizontal synchronizing signal is input.

The phase comparator 8 compares the center position detection signal (E) given from the dot counter 7 with the center position detection signal (D) given from the horizontal center position detection circuit 6 and outputs the comparison output. To the phase comparator 2a of the horizontal drive circuit. The phase comparator 2a compares the phase of the given signal and the horizontal synchronizing signal (A), and outputs the comparison output from the horizontal drive pulse oscillation circuit 2b.
To control. As a result, the whole is controlled so that the horizontal center position coincides with the center position of the dot counter 7.

Regarding the vertical screen center position adjustment,
Vertical center point detection circuit 12 and line counter 13
And a phase comparator 14 for performing phase comparison between a center point detection signal (not shown) detected by them and the center point detection signal (not shown). The horizontal center position described above is that the line counter 13 counts the horizontal sync signal up to a predetermined value (position corresponding to the vertical center point) using the vertical sync signal as a count start signal (reset signal). The configuration is basically the same, with only a slight difference from the adjustment.

Next, FIGS. 3 and 4 showing a concrete configuration example of the horizontal center point detection circuit 6 in FIG. 1 will be described. First, in FIG. 3, the sawtooth wave voltage (C) given from the integration circuit 5 (FIG. 1) and its inverted voltage (C ′) by the inverter 52 are input to the comparator 53 and compared, respectively. An output as shown in G) is obtained. This output is further processed through the differentiating circuit 54 and the waveform shaping circuit 55, and becomes a detection pulse as shown in FIG.

On the other hand, in FIG. 4, a sawtooth wave voltage (C ') obtained by cutting the direct current component by the capacitor C1 is obtained from the sawtooth wave voltage (C) given from the integrating circuit 5, and this is supplied to the (+) terminal. It is input to the (-) terminal of the comparator 53 connected to the ground point, and the comparison output as shown in FIG. 6 (G) is obtained by the simple zero-cross detection operation.

[0016]

As described above, according to the center position adjusting circuit of the present invention, the center position of the screen is automatically adjusted during the operation of the television receiver or the monitor television having the circuit. Therefore, the center position of the screen is realized with high accuracy. Moreover, it is not necessary to design the screen center position adjusting circuit in consideration of the variation of the circuit elements, and the design can be facilitated accordingly, and the adjustment process can be saved in the production line.

[Brief description of drawings]

FIG. 1 is a block diagram of a screen center position adjustment circuit embodying the present invention.

FIG. 2 is an operation waveform diagram of each part thereof.

FIG. 3 is a diagram showing a specific configuration example of a part thereof.

FIG. 4 is a diagram showing another example of a specific configuration of a part thereof.

5 is an explanatory diagram of the operation of FIG.

6 is an explanatory diagram of the operation of FIG.

FIG. 7 is a block diagram of a conventional example.

[Explanation of symbols]

 1 sync separation circuit 2 horizontal drive circuit 3 horizontal output circuit 4 flyback transformer 5 integration circuit 6 horizontal center point detection circuit 7 dot counter 8 and 14 phase comparator 9 vertical drive circuit 10 vertical output circuit 12 vertical center point detection circuit 13 lines Counter 51 Clock oscillation circuit

Claims (2)

[Claims] 1. A first detection circuit for detecting a center point of a horizontal sawtooth wave of a horizontal deflection output circuit within a horizontal scanning period, and a clock supplied from a clock oscillation circuit is counted by using a horizontal synchronization signal as a count start signal. And a means for matching the center points obtained from the first and second detection circuits through a phase control circuit for the horizontal deflection drive signal, and a second detection circuit for detecting the horizontal center point. Center position adjustment circuit. 2. A first detection circuit for detecting a center point of a horizontal sawtooth wave of a horizontal deflection output circuit within a horizontal scanning period, and a clock supplied from a clock oscillation circuit is counted by using a horizontal synchronization signal as a count start signal. And a second detection circuit for detecting the horizontal center point, and horizontal center position adjusting means for matching the center points obtained from the first and second detection circuits through a phase control circuit for the horizontal deflection drive signal. A third detection circuit for detecting the center point of the vertical sawtooth wave of the vertical deflection output circuit within the vertical scanning period, and a fourth detection circuit for detecting the vertical center point by counting the number of horizontal scanning lines of the video signal. A detection circuit and a vertical center position adjusting means for matching the center points obtained by the third and fourth detection circuits via a phase control circuit for a vertical deflection drive signal. Screen center position adjustment circuit consisting of.