JP2002135616A - High-voltage control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-voltage stable circuit having improved reliability of a circuit by reducing the power loss of a controlling transistor by a simple circuit configuration. SOLUTION: Detection voltage Er proportional to a high-voltage HV is obtained by resistors R3 and R4 and is applied to an arithmetic amplifier (comparator) OP.AMP 1 as Er to be compared with a reference voltage Es, to obtain output voltage Eo. PWM control is performed by this voltage to control the on-time of a switching transistor within a horizontal fly-back period. The voltage Eo is inputted to the second arithmetic amplifier (comparator) OP.AMP 2 to be compared with a fly-back pulse Vt from the third coil of a fly-back transformer (TBT) T1, to obtain a switching pulse Vsw. This pulse Vsw is inputted to a transistor Q2 to switch load resistors R1 and R2 on an FBT first side from ON to off within a horizontal fly-back period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage control circuit for controlling a high voltage applied to an anode of a picture tube in a display device using a picture tube, and more particularly to controlling a high voltage by using a simple circuit configuration. While being able to
The present invention relates to a high voltage control circuit suitable for a computer display device having various horizontal deflection frequencies.

[0002]

2. Description of the Related Art Conventionally, various high voltage control circuits for controlling a high voltage have been proposed. For example, JP-A-61-
No. 95672 discloses that a transistor for stabilizing a high voltage is connected to a horizontal output circuit via a diode,
A technique is described in which the transistor is turned on only during a horizontal pulse period to stabilize a high voltage without adversely affecting a horizontal deflection operation.

[0003]

However, in the conventional high voltage control circuit described above, the high voltage control transistor is
Since the transistor operates in a class, the power loss in the transistor is large. For this reason, not only is a large-capacity transistor required, but also a large heat radiating plate is required, and there is a problem that the substrate occupation area increases.

The present invention has been made in view of such circumstances, and provides a high-voltage control circuit capable of reducing power loss of a transistor, reducing the size of a heat sink, and reducing the area of a mounting substrate. The purpose is to:

[0005]

The high voltage control circuit according to the present invention has the following features to solve the above-mentioned problems.

That is, a high voltage control circuit according to the present invention comprises a resistor connected in series between a collector of a horizontal output transistor in a horizontal deflection high voltage generating circuit and a reference potential, and a detection voltage proportional to the high voltage output of the horizontal deflection high voltage generating circuit. And a high-voltage control circuit for performing control to stabilize the high-voltage output using the detection voltage,
A first comparator for comparing a detection voltage obtained by the detection circuit with a reference voltage; and an electronic switch having a control unit for performing PWM control based on an output voltage of the first comparator. It is characterized by having.

The high voltage control circuit of the present invention further comprises a resistor connected in series between the collector of the horizontal output transistor in the horizontal deflection high voltage generation circuit and a reference potential, and a detection voltage proportional to the high voltage output of the horizontal deflection high voltage generation circuit. A high-voltage control circuit for performing control to stabilize the high-voltage output using the detection voltage, wherein a first voltage for comparing the detection voltage obtained by the detection circuit with a reference voltage is provided. A comparator, a second comparator for comparing an output voltage of the first comparator with a horizontal retrace pulse, and a collector of the horizontal output transistor and a reference potential based on an output of the second comparator. An electronic switch for controlling the on / off time in the horizontal flyback period for the resistor connected in series between the electronic switches is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high voltage control circuit according to the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of a high-voltage stabilizer using a high-voltage control circuit according to the present invention. FIG. 2 is a circuit diagram showing a second embodiment of a high-voltage stabilizer using a high-voltage control circuit according to the present invention. It is a circuit diagram showing an example. FIG. 3 is a circuit diagram showing a conventional high-voltage stabilizer using a high-voltage control circuit. In addition,
1 to 3, the portions having the same functions are denoted by the same reference numerals and described.

[0010] high voltage stabilizing device using a high voltage control circuit according to a first embodiment of the <First embodiment> The present invention, as shown in FIG. 1, the base of the horizontal output transistor Q _1, shown not from the previous stage (drive stage) the drive pulses V _h of the horizontal deflection period is supplied, the horizontal output transistor Q ₁
Is applied between the base and the emitter. The collector of the horizontal output transistor Q _1, the series circuit of the damper diode D _1, a horizontal deflection coil L _y and the horizontal linearity correction coil L ₂ and the S-correction capacitor C _2, retrace resonant capacitor C _1, the flyback transformer (FBT) T ₁ is connected to form a well-known horizontal deflection high voltage generating circuit.

[0011] In this arrangement, when one end of the primary winding L _p of a flyback transformer T ₁ is added a DC power supply voltage + B, the well-known principles, the current I _y sawtooth the horizontal deflection coil L _y Flows to deflect the electron beam of the picture tube (not shown) in the horizontal direction. Further, the collector of the horizontal output transistor Q ₁ generated horizontal retrace pulse V _cp.
The horizontal retrace pulse V _cp may flyback transformer T ₁
Boosted by the secondary winding L _s of, next to the high pressure HV is rectified by a high voltage rectifying diode D _2, it is guided to the anode of the picture tube.

Further, the high voltage HV is divided by the high voltage fluctuation detecting resistors R ₃ and R ₄ , and is divided as a detection voltage _{Er into the} operational amplifier OP. Input to the non-inverting input terminal of AMP1. The high-voltage fluctuation detection resistors R ₃ and R ₄ operate as a detection circuit that obtains a detection voltage _Er proportional to the high voltage HV. Operational intensifier O
P. The AMP1 inverting input terminal of the reference voltage E _s is inputted, the arithmetic increase congestion unit OP. AMP1 is the detection voltage _Er.
Is compared with the reference voltage Es to output a DC voltage _Eo . This operational amplifier OP. AMP1 functions as a first comparator.

Here, in the conventional high voltage stabilizer using the high voltage control circuit shown in FIG. 3, this DC voltage _Eo is connected in series with the load resistors R ₁ and R ₂ on the primary side of the flyback transformer T _1. are connected high-voltage stabilizing transistors Q directly to _two of the base, the internal resistance of the high voltage stabilizing transistors Q ₂ controls a class controls the load impedance of the primary side of the flyback transformer T _1, a high pressure Had stabilized.

On the other hand, in the high-voltage stabilizing apparatus using the high-voltage control circuit according to the first embodiment of the present invention, the PWM slice level is controlled by the DC voltage _Eo , and the high-voltage stabilization during the flyback period is performed. controls the on timing of the transistor Q ₂ for reduction, generates a switch pulse V _sw, so on-time increases in the blanking period of the transistor Q ₂ When pressure rises, heavier load on the primary side of the FBT Then, the pressure is controlled in a direction of decreasing the high pressure.

The high voltage stabilizing device using a high voltage control circuit according to a second embodiment of the <Second embodiment> In the present invention, as shown in FIG. 2, the base of the horizontal output transistor Q _1, shown not from the previous stage (drive stage) the drive pulses V _h of the horizontal deflection period is supplied, the horizontal output transistor Q ₁
Is applied between the base and the emitter. The collector of the horizontal output transistor Q _1, the series circuit of the damper diode D _1, a horizontal deflection coil L _y and the horizontal linearity correction coil L ₂ and the S-correction Kontensa C _2, retrace resonant capacitor C _1, the flyback transformer (FBT) T ₁ is connected to form a well-known horizontal deflection high voltage generating circuit.

In such a configuration, the one end of the primary winding L _p of a flyback transformer T ₁ is added a DC power supply voltage + B, the well-known principles, the current I _y sawtooth the horizontal deflection coil L _y Flows to deflect the electron beam of the picture tube (not shown) in the horizontal direction. Further, the collector of the horizontal output transistor Q ₁ generated horizontal retrace pulse V _cp.
The horizontal retrace pulse V _cp may flyback transformer T ₁
Boosted by the secondary winding L _s of, next to the high pressure HV is rectified by a high voltage rectifying diode D _2, it is guided to the anode of the picture tube.

Further, the high voltage HV is divided by the high voltage fluctuation detection resistors R ₃ and R ₄ , and is divided as a detection voltage _{Er into the} operational amplifier OP. Input to the inverting input terminal of AMP1. The high-voltage fluctuation detection resistors R ₃ and R ₄ provide a detection voltage E proportional to the high voltage HV.
_It operates as a detection circuit that obtains _r . Operational intensifier O
P. The non-inverting input terminal of the AMP1, a reference voltage E _s is inputted, the arithmetic increase spokes unit ○ P. AMP1 is the detection voltage E
by comparing the _r and the reference voltage E _s to output a DC voltage E _o.
This operational amplifier OP. AMP1 functions as a first comparator.

Here, in the conventional high-voltage stabilizer using the high-voltage control circuit shown in FIG. 3, this DC voltage _Eo is connected in series with the load resistors R ₁ and R ₂ on the primary side of the flyback transformer T _1. are connected high-voltage stabilizing transistors Q directly to _two of the base, the internal resistance of the high voltage stabilizing transistors Q ₂ controls a class controls the load impedance of the primary side of the flyback transformer T _1, a high pressure Had stabilized.

On the other hand, according to a second embodiment of the present invention.
In the high-voltage stabilizer using the high-voltage control circuit, the DC power
Pressure E_oIs the operational amplifier OP. Input to the inverting input terminal of AMP2
Tertiary winding L from which positive pulse of FBT is output_tYo
The positive polarity pulse is supplied to the operational amplifier OP. Non-inverted input of AMP2
Input to the input terminal of the operational amplifier OP. Switch to AMP2 output
Switch pulse V_swIs generated and the high-voltage
Transistor Q for stabilization _TwoControl the on-time of
High voltage stabilization transistor Q_TwoWithin the retrace period of
To increase on-time and flyback tiger
Once T₁To increase the primary side load and reduce the high pressure
Is controlled. This operational amplifier OP. A
MP2 functions as a second comparator.

Although not described in detail in the above embodiments, in FIGS. 1, 2 and 3, D ₃ is a switch diode, C ₃ is an ABL capacitor, and R ₅ and R ₆ are A.
BL resistance is shown.

[0021]

As described in detail above, the high voltage control circuit of the present invention comprises a first comparator for comparing a detection voltage obtained by a high voltage detection circuit with a reference voltage, and a first comparator for comparing the first voltage with the reference voltage. An electronic switch having a control unit for performing PWM control based on the output voltage of the heater.

Further, the high voltage control circuit of the present invention comprises a first comparator for comparing a detection voltage obtained by a high voltage detection circuit with a reference voltage, and an output voltage of the first comparator and a horizontal retrace. A second comparator for comparing a pulse and a resistor connected in series between the collector of the horizontal output transistor and the reference potential based on the output of the second comparator, turn on during a horizontal blanking period. And an electronic switch for controlling the off time.

Therefore, it is possible to reduce the loss of the electronic switch transistor (of course, the FET is also possible), to use a transistor having a small capacity, and to reduce the mounting board area by reducing the size of the heat sink. Further, the reliability of the electronic switch transistor can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a high-pressure stabilizer using a high-voltage control circuit according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of a high-pressure stabilizer using a high-voltage control circuit according to the present invention.

FIG. 3 is a circuit diagram showing a high-voltage stabilizing device using a conventional high-voltage control circuit.

[Explanation of symbols]

Q ₁ : Horizontal output transistor Q ₂ : High voltage stabilizing transistor (electronic switch) D ₁ : Damper diode D ₂ : High voltage rectifier diode D ₃ : Switch diode C ₁ : Return resonance capacitor C ₂ : S-shaped correction capacitor C ₃ : ABL capacitor L _y: horizontal deflection coil L _2: the horizontal linearity correction coil L _p: fBT1 winding L _s: FBT2 winding L _t: FBT3 winding T _1: flyback transformer (FBT) R _1, R ₂ : FBT primary side load resistance R ₃ , R ₄ : High-voltage fluctuation detection resistance R ₅ , R ₆ : ABL resistance OP. AMP1: Operational amplifier (first comparator) OP. AMP2: operational amplifier (second comparator) PWM: PWM control circuit V _h: horizontal drive pulse V _cp: horizontal retrace pulse V _t: FBT3 winding Pulse V _sw: Switch Pulse HV: high E _r: detection voltage E _s : reference voltage E _o : output voltage of operational amplifier (first comparator)

Claims (2)

[Claims] 1. A horizontal deflection high voltage generation circuit comprising: a resistor connected in series between a collector of a horizontal output transistor and a reference potential in a horizontal deflection high voltage generation circuit; and a detection circuit for obtaining a detection voltage proportional to a high voltage output of the horizontal deflection high voltage generation circuit. A high-voltage control circuit for performing control for stabilizing the high-voltage output using the detection voltage; a first comparator that compares a detection voltage obtained by the detection circuit with a reference voltage; An electronic switch having a control unit for performing PWM control based on an output voltage of the comparator. 2. A horizontal deflection high voltage generation circuit comprising: a resistor connected in series between a collector of a horizontal output transistor and a reference potential in a horizontal deflection high voltage generation circuit; and a detection circuit for obtaining a detection voltage proportional to a high voltage output of the horizontal deflection high voltage generation circuit. A high-voltage control circuit for performing control for stabilizing the high-voltage output using the detection voltage; a first comparator that compares a detection voltage obtained by the detection circuit with a reference voltage; A second comparator for comparing an output voltage of the comparator with a horizontal retrace pulse, and a resistor connected in series between a collector of the horizontal output transistor and a reference potential based on an output of the second comparator. On the other hand, an electronic switch for controlling ON and OFF times during a horizontal flyback period is provided.