JPS62234189A - Image phase circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to a video phase circuit that moves and adjusts the screen position in the horizontal direction in a display device that automatically follows a plurality of horizontal scanning frequencies.

(2) Conventional technology Conventionally, 15Kl-1z, 15.75KHz, 24
Display devices such as monitors and TV receivers that automatically follow a plurality of horizontal scanning frequencies such as KHz, 31.5 KHz, etc. are known.

In such display devices, in order to move and adjust the screen position in the horizontal direction, a one-shot mono multivibrator or the like is used to delay the horizontal IUI signal and then supply it to the horizontal deflection circuit. There is. The amount of delay is determined according to the horizontal movement adjustment ffff1.

(3) Problems to be Solved by the Invention In this type of circuit that delays the horizontal synchronizing signal, since the delay 1 is fixed, it cannot support multiple types of horizontal scanning frequencies as described above, and If you adjust delay 1 according to the frequency and adjust the screen position horizontally,
With other horizontal scanning frequencies, there is a problem that the horizontal deflection position shifts.

(4) Means for Solving the Problems The present invention has been made in view of the above points, and an object thereof is to obtain a constant horizontal screen position even at a horizontal scanning frequency such as In order to achieve this purpose, a sawtooth wave generation circuit that generates a sawtooth wave with the period of the input horizontal synchronization signal, a frequency signal conversion circuit that converts the frequency of the input horizontal synchronization signal into an electrical signal, and a sawtooth wave generation circuit that converts the frequency of the input horizontal synchronization signal into an electrical signal. It is configured to include a comparator that compares the output voltage of the generation circuit with a predetermined voltage value, and a one-shot mono-multivibrator whose output pulse width is controlled by the output of the frequency signal conversion circuit triggered by the comparator.

(5) Effect In this configuration, a reference signal is created by a combination of a sawtooth wave generation circuit and a comparator, and the inversion time of the one-shot mono multivibrator triggered by this reference signal is determined by the input horizontal open 1! It acts to control according to the frequency of l tOi'.

(6) Examples Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a block diagram showing an embodiment of a video phase circuit according to the present invention.

In FIG. 1, a horizontal synchronization signal A as shown in FIG. The signal is supplied to the generating circuit 7.

The F/V conversion circuit 5, together with the voltage-current conversion circuit 6, increases or decreases the pulse width of a one-shot monomultivibrator 11, which will be described later, in accordance with the frequency of the horizontal synchronizing signal A supplied to the input terminal l. ing. That is, a voltage corresponding to the frequency of the horizontal synchronizing signal is created by the F/V conversion circuit 5, and after this voltage is converted into a current by the voltage-current conversion circuit 6, the one-shot mono multivibrator 11
The output pulse width of the one-shot mono-multivibrator 11 is changed by supplying the signal to a time constant circuit that determines the inversion time. This pulse width is 1/2 of the period of the horizontal synchronizing signal, for example, when the horizontal scanning frequency is 15.7
It is set to approximately 0°03 m5ec at 5KHz, approximately 0.02msec at 24KHz, and approximately 0.015m5ec at 31.5KHz.

The sawtooth wave generation circuit 7 is used to generate a sawtooth wave signal together with the peak detection circuit 8 and the amplifier circuit 9, and is shown in FIG.
), a sawtooth wave B is created at the frequency of the horizontal synchronization signal. By applying feedback, the peak detection circuit 8 and the amplifier circuit 9 keep the amplitude of the sawtooth wave B constant even when the frequency of the horizontal synchronizing signal A supplied to the input terminal l differs. As a result, the output of the sawtooth wave generating circuit 7 becomes -V as shown in FIG. 2(b).
It becomes a sawtooth wave with a peak of , and a peak of +■ (■ is a fixed value).

The sawtooth wave B created in this way is transmitted to the comparator 1.
is compared with the reference DC voltage at 0, and the comparator lO
outputs a pulse signal C that becomes "H" level when the sawtooth wave B is higher than the reference DC voltage (see Fig. 2 (C)).
)). This reference voltage value is level-adjusted by a DC voltage applied to the input terminal 2 from the outside. By this level adjustment, when the voltage value rises to the positive side, the rise of the pulse signal C becomes slower, and when it falls to the minus side, the rise of the pulse signal C becomes faster.

By this adjustment, it is possible to adjust the output of the one-shot mono-multivibrator 12, which will be described later, ie, the position of the pulse signal E shown in FIG. 2(e).

The pulse signal C, which is the output of the comparator IO, is supplied as a trigger signal to the one-shot mono multivibrator 11, and the one-shot mono multivibrator
11 is inverted to "H" level at the rise of pulse signal C. As mentioned above, the inversion time T (Fig. 2 (d)) of the one-shot mono multivibrator 11 is controlled by the output of the voltage-current conversion circuit 6, and is set to be short when the frequency of the horizontal synchronization signal A is high. , and when the frequency to the horizontal synchronizing signal is low, M control is performed so that it becomes long.

The output of one-shot mono multivibrator-11 is
It is supplied to the one-shot mono multivibrator 12 as a trigger signal. The inversion time of the one-shot mono multivibrator 12 is fixed, and it goes to the ``LIt level with the rise of the pulse signal, and returns to the IIHIt level after a predetermined period of time (Fig. 2(e)).
). The output of this one-shot mono multivibrator 12 is used as a horizontal synchronization signal after adjusting the image position.
It is supplied to the outside from the output terminal 3.

According to the circuit shown in FIG. 1, if the horizontal image position is adjusted by changing the DC voltage supplied to the input terminal 2 at a certain horizontal scanning frequency, even if the horizontal scanning frequency is subsequently changed, the DC voltage will change from -■ to Time to reach value (Figure 2 (b)
) and the rotation of the sawtooth wave B does not change. Moreover, the output pulse width of the one-shot mono multivibrator 11 is controlled according to the horizontal scanning frequency by the functions of the F/V conversion circuit 5 and the voltage-current conversion circuit 6.
There is no need to adjust the horizontal image position again.

(7) Effects of the Invention As explained above, the present invention provides a sawtooth wave generation circuit that generates a sawtooth wave based on the period of an input horizontal synchronization signal, and a frequency signal that converts the frequency of the input horizontal synchronization signal into an electrical signal. A conversion circuit, a comparator that compares the output voltage of the sawtooth wave generation circuit with a predetermined voltage value, and a one-shot mono-multivibrator whose output pulse width is controlled by the output of the frequency signal conversion circuit triggered by the comparator are provided. With this configuration, it is possible to always obtain a constant horizontal screen position for any horizontal scanning frequency.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the video phase circuit according to the present invention, and FIG. 2 is a waveform diagram illustrating the operation of the circuit shown in FIG. 1. 5...F/V conversion circuit 6...Voltage/current conversion circuit 7...Sawtooth wave generation circuit 10...Comparator 11...One-shot mono multivibrator

Claims (1)

[Claims] A sawtooth wave generation circuit that generates a sawtooth wave with the period of an input horizontal synchronization signal, a frequency signal conversion circuit that converts the frequency of the input horizontal synchronization signal into an electrical signal, and an output voltage and a predetermined voltage value of the sawtooth wave generation circuit. and a one-shot mono multivibrator whose output pulse width is controlled by the output of the frequency signal conversion circuit triggered by the comparator.