JPH05183769A - Horizontal deflection circuit - Google Patents

Abstract

PURPOSE:To realize a circuit system where a proper power source is supplied while monitoring a horizontal deflection circuit state and also to prevent horizontal output voltage pulse abnormality which transitionally occurs and the destruction of an output transistor even if a horizontal synchronizing signal rapidly changes as against an equipment. CONSTITUTION:The state of a horizontal deflection circuit 12 is detected from the state adding the width of a horizontal output pulse, the pulse width and a fixed pulse which is obtained from the rear edge of the pulse are addition- integrated so as to be averaged, a power source voltage is applied to the horizontal deflection circuit 12 by a curve in proportion to the voltage and longitudinal pincushion compensation quantity is controlled. At the same time, the reference voltage of an error amplifier circuit 19 being the control circuit of a power source circuit is changed at the time of horizontal output abnormality so as to be instantaneously escaped from the abnormality state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal deflection circuit system in a horizontal multi-frequency display monitor or the like.

[0002]

2. Description of the Related Art In recent years, personal computers, etc.
With the progress of high resolution with technological innovation, the horizontal frequency is also increasing accordingly, and there are various horizontal frequency personal computers in the market.
Display monitors corresponding to these are coming out.

A conventional horizontal deflection circuit system for a display monitor will be described below. FIG. 3 shows a conventional horizontal deflection circuit method, and the horizontal amplitude and vertical pincushion correction is a method of controlling the power supply voltage to the horizontal deflection system. In FIG. 3, a block 1 is a chopper control type power supply circuit, a block 2 is a horizontal deflection circuit, and a block 3
Is for detecting the collector pulse of the horizontal output transistor, block 4 is for the peak rectification of the pulse, block 5 is the horizontal amplitude control circuit, block 6 is the vertical pincushion correction waveform generation circuit, and block 7 is the error that controls the chopper power supply output level. It is an amplifier circuit.

The operation of the horizontal deflection circuit system configured as described above will be described below. First, in this circuit system, when the horizontal frequency of the input signal changes, the drive pulse frequency to the horizontal output transistor Q1 changes, and the peak value of the collector pulse of the horizontal output transistor Q1 changes. The peak value of this pulse is detected in blocks 3 and 4, which is controlled by the DC voltage level of the horizontal amplitude control circuit output of block 6 and input to the negative terminal of block 7. Resistors R1 and R are on the positive terminal side of block 7.
Although the reference voltage is generated by 2, the output of the vertical pincushion correction waveform generation circuit of the block 6 is modulated through the capacitor C1 and the output of the error amplification circuit of the block 7 is determined by comparing the waveforms of both input terminals. AC is modulated in a vertical pincushion correction waveform form, and DC is determined by the DC voltage level on the negative terminal side of the block 7. The output of the block 7 controls the output of the chopper control type power supply, and this voltage is supplied to the horizontal deflection circuit.

[0005]

However, in the above-mentioned conventional configuration, the collector pulse of the horizontal output transistor modulated into the parabolic waveform by the vertical pincushion is detected to supply an appropriate power supply voltage level to the horizontal deflection circuit. Therefore, the detection pulse is controlled by peak rectification. However, when the horizontal frequency changes, this rectified waveform characteristic changes, and it is difficult to control this waveform characteristic with respect to the horizontal frequency. Also, if the integration time constant is increased, the power supply response characteristics against a sudden change in the horizontal frequency Is deteriorated and the horizontal output transistor is destroyed, so that a sufficient integration time constant cannot be provided. As a result, the waveform characteristics of the power supply voltage supplied to the horizontal deflection circuit change with the horizontal frequency, which affects the vertical pincushion characteristics and causes the image receiving signal on the surface of the cathode ray tube to appear bent. Was there.

The present invention solves the above-mentioned problems of the prior art by changing the control method of the power supply voltage applied to the horizontal deflection circuit from the conventional one, and by transiently generating a horizontal output voltage pulse when the horizontal frequency of the input signal changes. It is an object of the present invention to provide a circuit system that also solves the problem of preventing abnormalities and destruction of output transistors.

[0007]

To achieve this object, the present invention has a chopper control type power supply circuit, a collector pulse of a horizontal output transistor, or a pulse obtained from a flyback transformer, a pulse transformer or the like. Circuit, a monostable multivibrator circuit that outputs a constant pulse width using the trailing edge of the signal as a trigger, a circuit that adds the monostable multivibrator output voltage and the output of the previous waveform shaping circuit, and integrates the added output It has a circuit, a circuit for detecting the collector pulse of the horizontal output transistor, a circuit for peak rectifying this pulse, and an error amplification circuit for controlling the output voltage of the chopper power supply. It is composed of a circuit that changes the parabolic output level of the amplifier.

[0008]

With this configuration, when the collector pulse of the output transistor of the horizontal deflection circuit becomes abnormally large, the reference voltage level of the error amplification circuit for controlling the output level of the power supply circuit of the chopper control system is changed to instantly change the horizontal deflection circuit. The power supply voltage is lowered to prevent this. Normally, the voltage level supplied to the horizontal deflection system is based on the voltage obtained by adding and integrating the pulse width of the horizontal output transistor of the horizontal deflection circuit and the output of the monostable circuit triggered by the trailing edge of the pulse. The vertical pincushion correction level is controlled by the addition output of the vertical pincushion correction level. By these, the said subject is solved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a block 11 is a chopper control type power supply circuit for supplying power to the horizontal deflection circuit of the block 12, a horizontal output transistor Q1.
Collector pulse or flyback transformer FB
Circuit block 14 for shaping the waveform of a pulse obtained from T, pulse transformer, etc., monostable multivibrator circuit block 1 for producing a constant pulse width from the trailing edge of the signal
5. A circuit for adding the output voltage of the monostable multivibrator and the output of the above waveform shaping circuit by the diodes D1 and D2, a circuit for integrating the added output by the resistor R1 and the capacitor C1, and vertical pincushion correction Parabolic waveform generation circuit block 16, a differential amplifier 17 for varying its output level, and this output level is controlled by the terminal voltage of the capacitor C1. The differential amplifier 1
The output of 7 is mixed circuit 1 through capacitor C4.
8 is input to the other terminal, and the terminal voltage of the capacitor C1 is applied to the other terminal. The mixing circuit 18 modulates the DC voltage of the capacitor C1 with a vertical pincushion waveform. The output of this mixing circuit is input to the next error amplifier 19, and the resistor R is connected to one input terminal.
The reference voltage defined by 1 and R2 is supplied. The operation of the embodiment configured as described above will be described. First, the collector pulse of the horizontal output transistor Q1 is detected by the capacitors C2 and C3, peak rectification is performed by the diode D3 and the capacitor C4 through the transistor Q2, and this voltage is received by the emitter follower circuit. In the normal state where a stable horizontal synchronizing signal is received, the voltage at point a in FIG. 1 is set higher than the emitter of the transistor Q3. In addition, the collector pulse of the horizontal output transistor is shaped by the circuit block 14, a constant pulse width is created by the monostable multivibrator circuit block 15 from the trailing edge of the signal, and the monostable multivibrator output voltage and the preceding waveform shaping. The output of the circuit is added by the diodes D1 and D2, and the added output is integrated by the resistor R1 and the capacitor C1 to detect the horizontal oscillation frequency at which the device is operating and to change the power supply voltage to be supplied to the horizontal deflection circuit. Get the characteristics. This changing voltage characteristic is applied to one of the input terminals of the block 18,
On the other hand, a vertical pincushion correction waveform is added through the capacitor C4, and the block 18 modulates the previously changed voltage characteristic with the vertical pincushion correction waveform. It should be noted that the above-mentioned change voltage is only a DC voltage as long as the signal is constant and stable regardless of the signal. The output voltage of the block 18 is input to the plus terminal of the error amplifier circuit, and the reference voltage is determined by the resistors R1 and R2 on the minus terminal side. This error amplifier circuit amplifies the difference applied to both input terminals, and if the voltage on the positive terminal side rises above the negative terminal voltage, the output voltage also rises with the negative terminal voltage as the reference. If the minus terminal voltage rises, the output voltage will fall with the plus terminal voltage as the reference. The output of the chopper power supply circuit is controlled by the operation of the error amplification circuit. In this embodiment, if the output of the error amplifier circuit rises, the output voltage of the chopper power supply circuit rises. Further, the control method of the vertical pincushion correction amount is to supply the output of the vertical pincushion correction parabolic waveform generation circuit block 16 to the input terminal of the differential amplifier 17 and to the other side the addition output by the resistor R1 and the capacitor C1. The integrated voltage is supplied to control the vertical pincushion correction output gain of the differential amplifier. In this case, the gain is controlled to increase as the control voltage increases. The output of the differential amplifier 17 is the mixing circuit 18
Is input to the terminal. The subsequent operation is performed in the same manner as described above, and the voltage waveform for the horizontal deflection circuit is modulated by the vertical pincushion correction waveform, and the vertical pincushion is correctly corrected on the surface of the cathode ray tube.

Next, when the input horizontal synchronizing signal changes abruptly, there is a moment when the power supply voltage to be applied to the horizontal deflection circuit with respect to the horizontal synchronizing signal is at an abnormally high moment. Unusually high,
In FIG. 1, the voltage at point a is exceeded by the emitter of the transistor Q3. In this case, the output voltage level of the error amplifier 19 is lowered by the circuit operation described above,
The voltage supplied to the horizontal deflection system is instantaneously lowered, the collector pulse of the horizontal output transistor is lowered, and the element is not destroyed.

The above horizontal deflection system voltage control will be described in detail. If the circuit constant of the horizontal deflection block 12 is constant, if the horizontal frequency increases, the peak value of the collector pulse of the horizontal output transistor decreases in inverse proportion. To keep the crest value constant, a crest value is kept constant by supplying a voltage proportional to the horizontal frequency.
In the present method, since the collector pulse of the horizontal output transistor and the trailing edge of the pulse are used as a trigger to add a pulse having a constant width, the voltage obtained by integrating the added voltage, that is, the average voltage is proportional to the horizontal frequency. If the power supply voltage is supplied to the horizontal deflection circuit in proportion to the horizontal frequency, and if the resonance capacitor of the horizontal deflection circuit is switched with relays at various points along with the horizontal frequency, the voltage to be supplied is Since it is no longer proportional to the horizontal frequency, it has to be switched.
However, with this method, the collector pulse of the horizontal output transistor Q1 or the flyback transformer F
Circuit block 14 for shaping the waveform of a pulse obtained from BT, pulse transformer, etc., monostable multivibrator circuit block 1 for producing a constant pulse width from the trailing edge of the signal.
5. To monitor the width of the collector pulse of the horizontal output transistor Q1 even at the same frequency by adding the output voltage of the waveform shaping circuit to the output voltage of the monostable multivibrator and integrating and averaging the added output. The circuit state of the horizontal deflection system is also detected, and the voltage to be supplied to the horizontal deflection system can be appropriately supplied. This characteristic is shown in FIG. 2A is a voltage characteristic curve to be supplied to the horizontal deflection circuit, and B is a voltage characteristic curve at point a in FIG.

[0013]

As described above, the present invention has the following advantages. A circuit system that can supply an appropriate power supply voltage while monitoring the state of the horizontal deflection circuit can be realized, and at the same time, a horizontal output voltage pulse abnormality that occurs transiently even if the horizontal synchronization signal for the device changes suddenly, destruction of the output transistor Can be prevented.

2. Further, since the power supply voltage characteristic is stabilized by the above-mentioned circuit system, the vertical pincushion correction amount also realizes a proper gain characteristic suitable for the horizontal deflection circuit state.

[Brief description of drawings]

FIG. 1 is a diagram of a horizontal deflection circuit system according to a first embodiment of the present invention.

FIG. 2 is a waveform characteristic diagram in the first embodiment of the present invention.

[Fig. 3] Conventional horizontal deflection circuit system diagram

[Explanation of symbols]

 11 chopper control type power supply circuit 12 horizontal deflection circuit 14 waveform shaping circuit 15 monostable multivibrator circuit 16 parabolic waveform generation circuit 17 differential amplifier 18 mixing circuit 19 error amplifier FBT flyback transformer V voltage

Claims (3)

[Claims] 1. A power supply circuit for a chopper control system, a circuit for detecting a collector pulse of a horizontal output transistor, a circuit for peak rectifying the pulse, and an error amplification circuit for controlling an output voltage of a chopper power supply. Even if the horizontal sync signal changes abruptly, the reference voltage of the error amplification circuit is changed to supply an appropriate power supply voltage to the horizontal deflection circuit so that the peak value of the collector pulse of the horizontal output transistor does not become abnormal. The horizontal deflection system circuit is characterized by preventing horizontal output voltage pulse abnormalities that occur transiently and destruction of the output transistor even if the horizontal synchronization signal for the device suddenly changes. 2. A chopper control type power supply circuit, a circuit for shaping a collector pulse of a horizontal output transistor, or a pulse obtained from a flyback transformer, a pulse transformer or the like, and a constant pulse width with a trailing edge of the signal as a trigger. A monostable multivibrator circuit that outputs, a circuit that adds the monostable multivibrator output voltage and the output of the above waveform shaping circuit, a circuit that integrates the added output, a vertical pincushion correction parabolic waveform generation circuit,
It is equipped with a differential amplifier that amplifies this, and an error amplifier circuit that controls the output voltage of the chopper power supply, and the vertical pincushion correction parabolic output level of the differential amplifier is changed with the added integrated output voltage to change the vertical pincushion. Horizontal deflection system circuit characterized by realizing characteristics. 3. A circuit for shaping a collector pulse of a horizontal output transistor or a pulse obtained from a flyback transformer, a pulse transformer or the like, and a monostable multivibrator circuit for outputting a constant pulse width by using a trailing edge of the signal as a trigger. A circuit for adding the monostable multivibrator output voltage and the output of the above waveform shaping circuit, a circuit for integrating the added output, and controlling the voltage supplied to the horizontal deflection circuit by the output voltage. Horizontal deflection system circuit.