JPH07123286A - Power supply voltage generating circuit for horizontal deflection circuit - Google Patents

Abstract

PURPOSE:To apply a power supply voltage to a horizontal deflection circuit to correct a horizontal trapezoidal distortion on a screen. CONSTITUTION:A monostable multivibrator A10 outputs a pulse having a duty cycle proportional to a vertical vertical deflection frequency and the pulse is converted into a DC voltage at a 1st smoothing circuit (R10, C10). The DC voltage is applied to a collector of a transistor(TR) Q10 via a buffer amplifier 12. A pulse whose duty is inversely proportional to a horizontal deflection frequency is fed to a base of the TRQ10 from a monostable multivibrator B14. A collector output of the TRQ10 is converted into a DC voltage by a 2nd smoothing circuit (R12, C12) and the DC voltage is fed to an integration circuit (R18, C14, 20) via a buffer amplifier 16 and an inverse amplifier circuit (R14, R16, R18). A TRQ12 is turned on by a vertical synchronizing signal to discharge the charge in the capacitor C14. Thus, a sawtooth voltage having a vertical synchronizing signal period is outputted from the integration circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply voltage generation circuit for a horizontal deflection circuit.

[0002]

2. Description of the Related Art In a television receiver, a displayed image may be distorted into a trapezoidal shape. Especially when displaying an image on a large screen such as a projection type receiver (projector), due to the difference in the projection distance to the screen,
The horizontal trapezoidal distortion is conspicuous because the horizontal amplitude is different between the upper side and the lower side. In order to correct the horizontal trapezoidal distortion, the power supply voltage to be supplied to the horizontal deflection output circuit is modulated by the sawtooth voltage of the vertical period, and a certain constant ratio of the sawtooth voltage of the PP period is required. . Further, when the scanning frequency of the input video signal is different, it is necessary to perform automatic scanning, and the power supply voltage of the horizontal deflection output circuit also needs to be changed in proportion to the horizontal deflection frequency. Further, even if the vertical deflection frequency changes, the PP value of the sawtooth voltage in the vertical cycle must be constant. FIG. 2 shows a conventional example of a circuit that outputs such a power supply voltage.

In FIG. 2, a vertical synchronization signal is a monostable multivibrator (hereinafter referred to as monomulti) A.
Input to 1. The monomulti A1 outputs a pulse having a constant pulse width. This output pulse has a duty that is proportional to the vertical deflection frequency. The output pulse of the monomulti A1 is converted into a DC voltage by the first smoothing circuit including the resistor R1 and the capacitor C2. The voltage converted into the direct current is amplified by the first buffer amplifier 2. The output voltage of the first buffer amplifier 2 is a DC voltage proportional to the vertical deflection frequency. The output of the first buffer amplifier 2 includes resistors R3 and R4 and a first operational amplifier
It is inverted and amplified by the inverting amplifier circuit including the amplifier 3.
The output of this inverting amplifier circuit is a resistor R5 and a capacitor C3.
And the second operation amplifier 4 are supplied to the integration circuit. Further, the transistor Q1 is connected in parallel with the capacitor C3. This transistor Q1 has a vertical synchronizing signal period O depending on the vertical synchronizing signal input to its gate.
N, the electric charge charged in the capacitor C3 is quickly discharged. As a result, the output of the integrating circuit becomes a sawtooth voltage having a vertical cycle in which the PP value does not change even if the vertical deflection frequency changes. The output of the integrating circuit is supplied to one input terminal of the multiplier 7.

A horizontal synchronizing signal is input to the monomulti B5. The monomulti B5 outputs a pulse having a constant pulse width. This output pulse has a duty proportional to the horizontal deflection frequency. The output pulse of the monomulti B5 is converted into a DC voltage by the second smoothing circuit including the resistor R2 and the capacitor C2. The voltage converted into the direct current is amplified by the second buffer amplifier 6. Second
The output voltage of the buffer amplifier 6 is a DC voltage proportional to the horizontal deflection frequency. The output of the second buffer amplifier 6 is supplied to the other input terminal of the multiplier 7. The multiplier 7 calculates both input voltages and outputs a voltage which is proportional to the horizontal deflection frequency and which is modulated in the vertical cycle. In this case, a voltage that gradually changes from the beginning to the end of the vertical cycle is output. If this voltage is supplied as the power supply voltage of the horizontal deflection circuit of the next stage, the trapezoidal distortion can be corrected.

The above circuit can correct the horizontal trapezoidal distortion described above, but the multiplier 7 is expensive and
There was a problem that it was necessary to adjust the offset of the multiplier.

[0006]

Since the conventional power supply circuit for the horizontal deflection circuit uses the multiplier, it has a drawback that the cost is high and the offset adjustment is required.

It is an object of the present invention to generate a power supply voltage supplied to a horizontal deflection circuit with a simple circuit configuration in order to correct the horizontal trapezoidal distortion on the screen.

[0008]

A first DC voltage generating means for inputting a first signal having a vertical period and generating a first DC voltage proportional to the frequency of the first signal, and a horizontal DC voltage source on a base. The second signal of the cycle is input, and the first signal is input to the collector.
Generating a second DC voltage proportional to the frequencies of the first and second signals using the transistor supplied with the first DC voltage from the DC voltage generating means and the collector voltage of the transistor. A second DC voltage generating means and a charging / discharging capacitor, integrating the second DC voltage from the second DC voltage generating means, and charging / discharging cycle by the first signal. And an integrating means that is controlled.

[0009]

The first DC voltage generating means generates a DC voltage proportional to the vertical period and supplies it as the collector voltage of the transistor. Since a horizontal synchronizing input signal is supplied to the base of the transistor, a DC voltage proportional to the horizontal and vertical periods can be obtained by smoothing the collector voltage. The DC voltage is integrated by the integrating means, and the charging / discharging cycle is controlled by the signal of the vertical cycle. As a result, a trapezoidal distortion can be corrected by outputting a voltage, which is modulated in the vertical cycle and is proportional to the horizontal cycle, from the integration means and supplies it as the power supply voltage of the horizontal deflection circuit. In this case, the PP value of the power supply voltage that changes in the vertical cycle is constant.

[0010]

FIG. 1 shows a power supply voltage generation circuit for a horizontal deflection circuit according to the present invention. In FIG. 1, a vertical synchronizing signal is input to a monostable multivibrator (hereinafter referred to as monomulti) A10. The monomulti A10 outputs a pulse having a constant pulse width. This output pulse has a duty that is proportional to the vertical deflection frequency. Mono Multi A10
Output pulse is converted into a DC voltage by a first smoothing circuit composed of a resistor R10 and a capacitor C10. The voltage converted into the direct current is amplified by the first buffer amplifier 12. The output voltage of the first buffer amplifier 12 is a DC voltage proportional to the vertical deflection frequency. The output from the first buffer amplifier 12 is supplied to the collector of the first transistor Q10.

The horizontal synchronizing signal is input to the monomulti B14. The monomulti B14 outputs a pulse having a constant pulse width from the inverting output terminal. This output pulse has a duty inversely proportional to the horizontal deflection frequency. Mono Multi B
The inverted output pulse from 14 is supplied to the base of the first transistor Q10.

Therefore, the collector of the first transistor Q10 outputs a pulse whose duty is proportional to the horizontal deflection frequency and whose peak value is proportional to the vertical deflection frequency. The output pulse of the first transistor Q10 is converted into a DC voltage by the second smoothing circuit including the resistor R12 and the capacitor C12. The voltage converted into the direct current is amplified by the second buffer amplifier 16. The output voltage of the second buffer amplifier 16 is a DC voltage proportional to both the horizontal and vertical deflection frequencies. The output of the second buffer amplifier 16 is inverted and amplified by the inverting amplifier circuit including the resistors R14, R16 and the first operation amplifier 18. The output of this inverting amplifier circuit is a resistor R18, a capacitor C14 and a second operational amplifier.
It is supplied to the integrating circuit composed of the amplifier 20. A second transistor Q12 is connected in parallel with the capacitor C14. The second transistor Q12 is turned on by the vertical synchronizing signal inputted to its gate, during the vertical synchronizing signal period,
The electric charge charged in the capacitor C14 is quickly discharged.
As a result, when the horizontal deflection frequency changes, the output of the integrating circuit changes in proportion to the voltage, and the sawtooth voltage modulated in the vertical period is output. The PP value of the vertical cycle of this output voltage is constant. The voltage modulated in the vertical cycle is supplied as the power supply voltage of the horizontal deflection circuit in the next stage.

[0013]

As described above, according to the present invention, in order to correct the horizontal trapezoidal distortion on the screen described in the prior art, the power supply voltage supplied to the horizontal deflection circuit can be generated with a simple circuit configuration. .

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a power supply voltage generation circuit for a horizontal deflection circuit according to the present invention.

FIG. 2 is a diagram showing a configuration of a power supply voltage generation circuit for a conventional horizontal deflection circuit.

[Explanation of symbols]

10 ... Monostable multivibrator A, 12 ... First buffer amplifier, 14 ... Monostable multivibrator B, 16 ... Second buffer amplifier, 18 ... First operation amplifier, 20 ... Second operation amplifier Amplifier, R10, R12, R1
4, R16, R18 ... Resistor, C10, C12, C14 ... Capacitor, Q10 ... First transistor, Q12 ... Second transistor.

Claims (1)

[Claims] 1. A first DC voltage generating means for inputting a first signal of a vertical cycle and generating a first DC voltage proportional to the frequency of the first signal, and a second of a horizontal cycle for a base. Is input to the collector, and a collector voltage of the transistor is used to supply the first DC voltage from the first DC voltage generating means to the collector.
And a second direct current voltage generating means for generating a second direct current voltage proportional to the frequency of the second signal, and a capacitor for charging / discharging, the second direct current voltage generating means including the second direct current voltage generating means. While integrating the DC voltage,
A power supply voltage generation circuit for a horizontal deflection circuit, comprising: an integration unit whose charge / discharge cycle is controlled by the first signal.