JPH0556289A - High-voltage stabilizing circuit - Google Patents

Abstract

PURPOSE:To realize the improved high-voltage stabilizing circuit of the dynamic regulation of a stable fast response by making a differential amplifier to output the error voltage to modulate the supply voltage to a flyback transformer into a gain variable type not to give a bad influence to a dynamic range by the set value of a reference voltage for comparison, in the high-voltage generating circuit of a television receiver. CONSTITUTION:A detection voltage B by high voltage HV output bleeder resistances 3 and 4 of a flyback transformer FBT 2 is sample-held, delayed for 1 horizontal scanning period, the difference of the detection voltage B is obtained by a differential amplifier 7 and by a control signal 14 to make the same difference voltage into an absolute value, the gain of a gain variable type differential amplifier 10 is controlled. An error voltage 15 of the output of the differential amplifier 10 is fed back to a voltage modulating circuit 11 of a power voltage Vc, and a supply power 16 of the FBT 2 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to stabilization of a high voltage circuit in a horizontal deflection circuit of video related equipment such as a television receiver and a television monitor.

[0002]

2. Description of the Related Art FIG. 5 shows a block diagram of a high voltage stabilizing circuit in a conventional television receiver. 1 is a horizontal output circuit that receives the horizontal drive HD signal A. 2 is a flyback transformer FBT that generates a high voltage HV for a cathode ray tube CRT anode.
Is a bleeder resistance for detecting fluctuations in the high voltage HV, 12 is a filter circuit for integrating the detection voltage B of the bleeder resistance 4, 7 is a differential amplifier based on the reference voltage Vref for comparison of the output of the bleeder resistance 12, and 11 is the same differential This is a power supply voltage modulation circuit that feeds back the error voltage 15 output from the amplifier 7 and modulates the power supply voltage Vc. The circuit operation detects the fluctuation of the high voltage HV by the bleeder resistor 4, pulls a constant voltage by the differential amplifier 7 and amplifies it to an error voltage 15, which is fed back to the power supply voltage modulation circuit 11 and a predetermined correction voltage 16 is flyback. The circuit is stabilized by supplying it to the transformer. Since the difference from the reference voltage Vref is taken in the differential amplifier 7 as described above, the dynamic range of the differential amplifier 7 may not be wide depending on the set value of the reference voltage Vref. In addition, the response characteristic is changed by inserting the filter circuit 12 in the feedback loop, and if the time constant is increased, the phase is delayed, so that oscillation easily occurs.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional example, and outputs an error voltage for modulating a supply voltage to a flyback transformer in a high voltage generating circuit of a television receiver or the like. The differential amplifier is a gain variable type that does not adversely affect the dynamic range depending on the set value of the reference voltage for comparison, and a stable high-speed response and high voltage stabilization circuit with improved dynamic regulation are realized.

[0004]

According to the present invention, the voltage detected by a high-voltage output bleeder resistor of a flyback transformer is sample-held and delayed by one horizontal scanning period to obtain the difference between the detected voltages. Is used to control the gain of the variable gain type differential amplifier, and the error voltage of the differential amplifier output is fed back to the voltage demodulation circuit of the power supply voltage to control the power supply of the flyback transformer.

[0005]

As shown in FIG. 1, a horizontal output circuit 1, a flyback transformer FBT 2 for generating a high voltage HV, a bleeder resistor 3, 4 for detecting fluctuations in the high voltage HV output, and a timing 1H.
(1 horizontal scanning) Sample-hold circuits 5 and 6 having a phase difference of 2H period, differential amplifier 7 of the sample-hold circuits 5 and 6 output, absolute value circuit 8 of the differential amplifier 7 output,
Switch circuit 9 for switching and outputting the outputs of the sample and hold circuits 5 and 6 for each 1H, a differential amplifier with variable gain
10. It comprises a voltage modulation circuit or the like for modulating the power supply voltage Vc to supply power to the flyback transformer 2. The detection voltage B of the output of the bleeder resistor 4 is sample-held and delayed for 1H period by the differential amplifier 7. The difference between the voltages is calculated, the gain of the differential amplifier 10 is controlled by the control voltage 14 that is the absolute value of the difference voltage, the power supply voltage Vc is modulated by the error voltage 15 of the output of the differential amplifier 10, and the flyback transformer 2 It suppresses the fluctuation of high voltage HV output.

[0006]

1 is a block diagram of a high voltage stabilizing circuit for feeding back a detection voltage obtained by dividing a flyback transformer output of a high voltage generating circuit by a high resistance. Further, FIG. 2 shows an operation timing chart of each part of FIG. Reference numeral 1 is a horizontal output circuit that receives the horizontal drive HD signal A shown in FIG. 2A and generates a high-voltage pulse. Reference numeral 2 is a high-voltage rectifier circuit using a boost winding of the high-voltage pulse and a secondary winding for a medium-voltage power supply. Picture tube CR
Flyback transformer FB that outputs high voltage HV to T anode
T, 3 and 4 are bleeder resistors that detect fluctuations in the high-voltage HV output and output as detection voltage B shown in B of FIG. 2. Reference numeral 5 is a sampling pulse C of 2H (2 horizontal scanning) period shown in C of FIG. A sample and hold circuit for the detection voltage B, 6 is shown in FIG.
Of D, a sample-and-hold circuit for the detection voltage B by the sampling pulse D having a phase difference of 1H and a 2H period, 7 is a differential amplifier of the sample-and-hold circuit 6 output and the sample-and-hold circuit 5 output, and 8 is the same differential amplifier. An absolute value circuit for converting 7 outputs into an absolute value and outputting it as a control signal 14, 9 is a switch circuit for selectively outputting the sample and hold circuits 5 and 6 every 1H by a switching signal E shown in E of FIG.
Reference numeral 10 is a differential amplifier of variable gain for inputting the reference voltage Vref and the output of the same switching circuit 9 and controlling the gain by a control signal 14 based on the variation of the high voltage HV of the output of the absolute value circuit 8 to output an error voltage 15. , 11 feeds back the error voltage 15 of the output of the same variable gain differential amplifier 10, so that
Power supply of flyback transformer 2 when HV rises
The power supply voltage modulation circuit modulates the power supply voltage Vc in the direction in which the 16 voltage is lowered and, when the high voltage HV is lowered, the voltage of the power supply 16 is increased.

When the timing for sampling and holding the detection voltage B of the output of the bleeder resistor 4 is shifted by 1H and sampled and held for 2H as shown in C and D of FIG. 2, a variation amount from the previous 1H appears in the output of the differential amplifier 7. (The larger the fluctuation, the more the correction must be made). The gain of the differential amplifier 10 that outputs the error voltage 15 is changed according to the magnitude of the fluctuation, and the gain is increased when the fluctuation is large. In the control relating to the direction close to the reference voltage Vref of the differential amplifier 10, the gain becomes small and the control is delayed, and if the normal gain is raised to cope with a rapid change, it also causes oscillation, so that the change amount is detected. Therefore, it is effective to change the gain of the differential amplifier 10.

FIG. 3 shows a block diagram of another embodiment of the high voltage stabilizing circuit for feeding back the detection voltage of the high voltage fluctuation. Further, FIG. 4 shows an operation timing chart of each part of FIG. 1 is a horizontal drive HD shown in A of FIG. 4 (same as FIG. 2)
A horizontal output circuit for inputting the signal A and generating a high voltage pulse F shown in F of FIG. 4 is a flyback transformer FBT, 3, 4
Is a bleeder resistance for detecting fluctuations in high voltage HV, and 5 is C1 in FIG.
A sample and hold circuit for detecting the bleeder resistance 4 detected voltage B by the sampling pulse C1 of 1H cycle shown in FIG. 7, 7 is a differential amplifier based on the reference voltage Vref for comparison of the output of the sample and hold circuit 5, and 11 is an error voltage of the output of the differential amplifier 7. A power supply voltage modulation circuit that feeds back 15 to modulate the power supply voltage Vc. In FIG. 4, the detection voltage B is sampled at the central portion of the horizontal scanning where the influence of the horizontal pulse F shown by C1 is small, and the filter circuit is unnecessary, thereby improving the response of the system.
Further, since the peak value of the detection voltage B is not smoothed, a correct value can be sampled. As described above, improvement of dynamic regulation and improvement of high voltage output accuracy with respect to high voltage fluctuation are recognized.

[0009]

As described above, according to the present invention, in the high-voltage generating circuit of a television receiver or the like, the detection voltage by the high-voltage output bleeder resistance of the flyback transformer is sample-held and delayed for one horizontal scanning period, and the difference in the detection voltage is detected. The gain of the differential amplifier for error voltage detection is controlled by the absolute value (magnitude) of the same difference voltage, and the error voltage is fed back to the voltage demodulation circuit of the power supply voltage to control the power supply of the flyback transformer. As a result, it is possible to realize the intended purpose of a high-voltage stabilizing circuit with stable high-speed response and improved dynamic regulation.

[Brief description of drawings]

FIG. 1 is a block diagram of a high voltage stabilizing circuit that feeds back a detection voltage obtained by dividing a high voltage output with a high resistance.

FIG. 2 is a timing diagram of each part of the circuit for explaining FIG.

FIG. 3 is a block diagram of a high voltage stabilizing circuit for feeding back a detection voltage similar to FIG. 1 showing another embodiment.

FIG. 4 is a timing diagram of each part of the circuit for explaining FIG.

FIG. 5 is a block diagram of a conventional high voltage stabilizing circuit that feeds back a detected voltage.

[Explanation of symbols]

 1 horizontal output circuit 2 flyback transformer 3 bleeder resistance for detecting high voltage output fluctuation 4 bleeder resistance for detecting high voltage output fluctuation 5 sample and hold circuit 6 sample and hold circuit 7 differential amplifier 8 absolute value circuit 9 switch circuit 10 variable gain type Differential amplifier 11 Power supply voltage modulation circuit 12 Filter circuit 14 Control signal 15 Error voltage 16 Power supply

Claims (2)

[Claims] 1. In a high voltage generating circuit of a television receiver or the like, a load (primary) winding of a horizontal output circuit and a medium voltage power supply 2
The output of the high-voltage rectifier circuit of the flyback transformer, which consists of a high-voltage rectifier circuit composed of a secondary winding and a high-voltage winding, is divided into resistors for voltage fluctuation detection, and the detection voltage by the same resistor division is 2H
(Horizontal scanning) period first sample hold circuit and second
Connected to the sample and hold circuit of
Each of the sample and hold circuit outputs is connected to a first differential amplifier and a two-input switch circuit, and the output of the first differential amplifier is supplied to the switch circuit output and a reference voltage for comparison via an absolute value circuit. Is connected to a variable gain second differential amplifier, the second differential amplifier output is fed back to the voltage modulation circuit of the power supply voltage, and the modulation circuit output is used as the load supply power source of the flyback transformer. High voltage stabilization circuit. 2. In a high voltage generating circuit of a television receiver or the like, a load (primary) winding of a horizontal output circuit and a medium voltage power supply 2
The output of the same high-voltage rectifier circuit of the flyback transformer, which consists of a high-voltage rectifier circuit with a secondary winding and a high-voltage winding, is resistance-divided for voltage fluctuation detection, and the detected voltage by the same resistance division is connected to a 1H cycle sample-hold circuit, The output of the sample and hold circuit and the reference voltage for comparison are connected to a differential amplifier,
The differential amplifier output is fed back to the voltage modulation circuit of the power supply voltage,
A high-voltage stabilization circuit, wherein the output of the modulation circuit is used as a load supply power source of the flyback transformer, and a sample hold timing is set to a central position of a horizontal scanning period.