JP2692445B2 - Horizontal deflection high voltage generation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal deflection high voltage generating circuit for horizontal deflection and high voltage generation in a television receiver using a picture tube.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram showing a conventional horizontal deflection high voltage generating circuit. In FIG. 3, the horizontal output transistor 1 is supplied with the excitation pulse Vd from the preceding stage (not shown),
Switching operation of the horizontal deflection cycle is performed by the excitation pulse Vd. The first and second capacitors 2 and 3 are retrace resonance capacitors, and together with the auxiliary retrace resonance capacitor 4, they are part of the element that determines the retrace time of horizontal deflection. Further, the first and second damper diodes 5 and 6 cooperate with the horizontal output transistor 1 to perform switching operation of the horizontal deflection cycle. The third capacitor 8 connected between one end of the horizontal deflection coil 7 and the connection points of the first and second capacitors 2 and 3 and the first and second damper diodes 5 and 6 is an S-shaped correction capacitor. It operates and corrects the waveform of the current flowing through the horizontal deflection coil 7. With this configuration, a substantially sawtooth current Iy having a horizontal deflection period flows through the series circuit. Since the horizontal deflection coil 7 is attached to the neck portion of the picture tube not shown here, the horizontal deflection coil 7 performs the operation of horizontally deflecting the electron beam of the picture tube.

Further, a smoothing inductor 9 and a parallel circuit of a fourth capacitor 10 and a variable load circuit 11 are connected between the connection point of the first and second capacitors 2 and 3 and the ground. The current I flowing through the variable load circuit 11
Sawtooth current I flowing in the horizontal deflection coil 7 depending on the magnitude of ct
y is controlled. For example, if the current Ict is increased to reduce the charge of the fourth capacitor 10 and thus the charge of the second capacitor 3 connected in parallel to the second damper diode 6 on the ground side, both ends of the horizontal deflection coil circuit are reduced. The voltage value increases, the pp value of the sawtooth current Iy flowing through the horizontal deflection coil 7 increases, and the horizontal amplitude of the picture tube increases.

The variable load circuit 11 is controlled by an electric signal from the outside. For example, as shown in the drawing, a parabolic waveform Vpb having a vertical deflection period tv is applied to the variable load circuit 11. By doing so, the value of the load current Ict is increased in the central portion as compared with the both ends of the deflection cycle, and the horizontal amplitude of the central portion can be widened as compared with the both ends of the vertical screen, and the side pincushion distortion correction effect is obtained. You can have it. Further, the magnitude of the entire horizontal amplitude can be changed according to the DC level of the waveform Vpb, that is, the value of the DC component of the current Ict. As described above, the larger the value of the DC component of the current Ict is, the more horizontal deflection occurs. The value of the sawtooth current Iy flowing through the coil 7 increases.

One end of the primary winding 12a of the flyback transformer 12 is connected to the collector of the horizontal output transistor 1, and the other end of the primary winding 12a is connected to a DC power source Eb.
It is connected to the. When the switching operation between the horizontal output transistor 1 and the damper diodes 5 and 6 is performed in this way, a sawtooth current Iy flows through the horizontal deflection coil 7 and a flyback pulse Vc is generated at the collector of the horizontal output transistor 1. To do. This flyback pulse Vc is boosted by the flyback transformer 12 and appears as a high voltage pulse Vhv on the secondary winding 12b. Further, this high-voltage pulse Vhv is rectified by the high-voltage rectifier diode 13 to become a DC high voltage EHT, which is applied to the anode of a picture tube not shown.

[0006]

The anode current Ia flows through the anode of the picture tube according to the brightness of the picture tube.
In this case, since the horizontal deflection high voltage generating circuit including the flyback transformer 12 which is regarded as the power source of the high voltage EHT generally has an internal output impedance, the value of the high voltage EHT is increased by the anode current Ia as shown by the solid line in FIG. That is, it is lowered according to the brightness of the picture tube. When the high voltage EHT is lowered in this way, the deflection efficiency of the picture tube is increased, and the size of the image on the image receiving surface is widened, which is a practical problem. Further, when the cathode ray anode current Ia is increased and the high voltage EHT is lowered when trying to brighten the picture tube image,
There is a problem that not only sufficient brightness cannot be obtained, but also focus quality deteriorates.

FIG. 4 shows an example of a conventional horizontal deflection high voltage generating circuit which solves this problem. 4, the same parts as those in FIG. 3 are designated by the same reference numerals. In the circuit shown in FIG. 4, voltage dividing resistors 14 and 15, a comparison circuit 16, a voltage control circuit 17, and a reference voltage Es1 are newly added. With the configuration shown in FIG. 4, the high voltage EHT is divided by the voltage dividing resistors 14 and 15 to become the reference voltage Erf, which is input to one of the comparison circuits 16. The reference voltage Es1 is input to the other side of the comparison circuit 16. And this comparison circuit 1
The output voltage Eov of 6 is applied to the voltage control circuit 17. The voltage control circuit 17 changes the direct current (power) voltage Eb to the direct current voltage Ebo.
And convert this DC voltage Ebo into a flyback transformer 1
2 to one end of the primary winding 12a. The direction of control by the comparison circuit 16 and the voltage control circuit 17 is such that when the high voltage EHT, that is, the reference voltage Erf rises and tries to exceed the reference voltage Es1, the output voltage of the comparison circuit 16 changes.
Is acted on to reduce the value of the voltage Ebo. With this configuration, the entire circuit operates so that the reference voltage Erf, which is the result of dividing the high voltage EHT, always matches the reference voltage Es1, and as a result, the high voltage EHT is made constant.

At this time, the movement of the high voltage EHT with respect to the anode current Ia becomes almost constant as shown by the broken line in FIG. 5, and the above-mentioned inconvenience due to the change of the high voltage EHT disappears. However, another problem arises here. That is, as shown by the solid line in FIG. 5, the characteristic of the high voltage EHT that should originally decrease with the increase of the anode current Ia is made flat as shown by the broken line, which means that the primary winding of the flyback transformer 12 is It is shown that the DC voltage Ebo, which is the power supply voltage of the circuit substantially applied to one end of 12a, is controlled to increase as the anode current Ia increases, as shown in FIG. However, since this DC voltage Ebo also works to create the sawtooth current Iy for horizontal deflection,
In this case, it means that the sawtooth current Iy also increases as the anode current Ia increases, and eventually the horizontal amplitude of the image widens. Therefore, the circuit configuration shown in FIG. 4 cannot correct the high-voltage EHT too much.

This problem can be solved if the circuit shown in FIG. 4 is a circuit only for generating a high voltage and is independent of horizontal deflection. At that time, the horizontal deflection coil 7 may be a dummy yoke coil which is a simple inductor which is not attached to the picture tube. However, in this case, in addition to the high-voltage generating circuit, a circuit for performing horizontal deflection, for example, a portion related to high-voltage generation from the circuit shown in FIG.
A circuit without the secondary winding 12b and the rectifying diode 13 is required. Therefore, the entire circuit scale becomes enormous, and there is a problem in terms of cost.

[0010]

In order to solve the above-mentioned problems of the prior art, the present invention has primary and secondary windings, one end of which is connected to a DC power supply, 2 above
A flyback transformer for applying a DC high voltage obtained by rectifying the pulse generated in the next winding to the anode of the picture tube, and the DC high voltage is divided, and the supply voltage of the DC power supply is controlled according to this divided voltage. A voltage control circuit, a collector connected to the other end of the primary winding of the flyback transformer, an excitation pulse of a horizontal deflection cycle is supplied, and a horizontal output transistor that performs a switching operation in response to the excitation pulse; First and second damper diodes connected in series in the same polarity direction between the collector and emitter of the horizontal output transistor, and first and second capacitors connected in parallel to the first and second damper diodes With water
In the flat deflection high-voltage generating circuit, the horizontal output transistor
Collector and the first and second damper diodes
The horizontal deflection coil and the third
First series circuit including a capacitor and a current detection circuit
And the emitter of the horizontal output transistor and the first and second
And the connection point of the second damper diode
In addition, the second direct capacitor consisting of the inductor and the fourth capacitor
A column circuit may be connected in parallel with the fourth capacitor.
The variable load circuit, the output of the current detection circuit and the reference voltage
Compare and control the variable load circuit according to the comparison result
And a comparator circuit for
And a secondary winding, wherein the primary winding is the horizontal deflection coil.
Pulsed voltage generated in the secondary winding connected in series
Horizontal deflection current flowing in the horizontal deflection coil depending on the pressure value
The present invention provides a horizontal deflection high-voltage generating circuit characterized by using a transformer for detecting the current value of .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A horizontal deflection high voltage generating circuit of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing an embodiment of a horizontal deflection high voltage generating circuit of the present invention, and FIG.
It is a concrete circuit diagram of the main part of. In FIG. 1,
The same parts as those in FIGS. 3 and 4 are designated by the same reference numerals, and in FIG. 2, the same parts as those in FIGS. 1, 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, the parts newly added by the present invention are a current detection circuit 18, a second comparison circuit 19, and a second reference voltage Es2. Here, the current detection circuit 18 uses the pp of the sawtooth current Iy flowing in the horizontal deflection coil 7.
A detection voltage Edi proportional to the value is generated. This detection voltage E
di is input to one of the second comparison circuits 19. The second reference voltage Es2 is input to the other one of the second comparison circuits 19. Then, the second comparison circuit 19 compares the voltage Edi with the voltage Es2. The voltage Eoi, which is the comparison result of the second comparison circuit 19, is applied to the variable load circuit 11. The variable load circuit 11 supplies a current Ict corresponding to the voltage Eoi,
The value of the sawtooth current Iy flowing through the horizontal deflection coil 7 is adjusted.

Here, if the sawtooth current Iy increases, the movement of the detection voltage Edi of the current detection circuit 18 and the movement of the output voltage Eoi, which is the comparison result of the second comparison circuit 19, are the current of the variable load circuit 11. Suppose that it is configured to reduce Ict. Then, as described above, this is the sawtooth current Iy.
Acts to reduce. Therefore, after all, the sawtooth current Iy cannot move from the value where the voltage Edi matches the second reference voltage Es2, and is stabilized at this voltage value. Therefore, as described above, even if the voltage Ebo increases with the increase of the anode current Ia for stabilizing the high voltage, the value of the sawtooth wave current Iy flowing through the horizontal deflection coil 7 is not affected and maintains a constant value. In this circuit, the change of the current Ict of the variable load circuit 11 influences the value of the sawtooth current Iy, but since it has little influence on the collector pulse Vc, and hence on the high voltage EHT, it does not depend on the high voltage correction and is independent. The stabilization of the wave current Iy can be achieved. Here, if the sawtooth current I
To change the value of y, the value of the second reference voltage Es2 may be changed.

Next, a further explanation will be given with reference to FIG. FIG.
FIG. 4 is a concrete circuit diagram of a main part of the present invention, that is, a part relating to stabilization of a sawtooth current Iy. First, the current detection circuit 18 will be described. The current detection circuit 18 is the current detection transformer 2
0, a rectifying diode 21, a smoothing capacitor 22, and voltage dividing resistors 23 and 24. The primary winding 20a of the current detection transformer 20 is inserted in series with the circuit of the horizontal deflection coil 7, and the sawtooth current Iy is applied to the primary winding 20a.
Flows as is. And 2 of the current detection transformer 20
A pulse Vn proportional to the pp value of the sawtooth current Iy is generated in the secondary winding 20b. The pulse Vn is rectified and divided by the rectifying diode 21 to the voltage dividing resistor 24. The voltage En across the voltage dividing resistor 24 has a polarity as shown and has a voltage value proportional to the pp value of the sawtooth current Iy.

Then, this voltage En is applied to the comparison circuit 19. The comparison circuit 19 includes voltage dividing resistors 25 and 26, an operational amplifier 27, and an AC dividing feedback capacitor 2 for preventing oscillation.
8, a direct current feedback resistor 29, and a coupling resistor 30 connecting the operational amplifier 27 and the next stage. The DC power supply voltage E is divided by the resistors 25 and 26 to become a positive DC voltage Ep. Then, the voltage obtained by adding the voltage Ep and the voltage En is input to the inverting input terminal of the operational amplifier 27. Then, the voltage value at the inverting input terminal is positive, and the characteristic is such that it decreases in the zero direction as the sawtooth current Iy increases. On the other hand, a control voltage Ei for adjusting the horizontal amplitude is externally input to the non-inverting input terminal of the operational amplifier 27.

Further, a specific circuit configuration of the variable load circuit 11 will be described. The variable load circuit 11 includes a pnp transistor 31, an output npn transistor 32, a collector resistor 33 of the transistor 31, sensitivity setting resistors 34 and 35, and a protective resistor 36 of the transistor 32. With such a configuration, when the potential of the base (point p) of the transistor 31 decreases, the collector current of the transistor 32, that is, the load current Ict described above, increases, and the sawtooth current Iy acts in the direction of increasing. Further, a parabolic waveform Vpb having a vertical deflection period is applied to the point p via the coupling capacitor 37. By doing so, the side pincushion distortion in which the load current Ict increases in the central portion compared to the upper and lower ends of the vertical deflection and the horizontal amplitude in the central portion increases compared to the upper and lower ends is corrected.

In FIG. 2, if the value of the sawtooth current Iy flowing through the horizontal deflection coil 7 is increased from a steady value for some reason, the absolute value of the voltage En obtained by rectifying and dividing the pulse Vn also increases. As a result, the operational amplifier 27
Therefore, the voltage at the inverting input terminal of the above becomes lower than the voltage Ei at the non-inverting input terminal. Then, the voltage of the output suddenly increases,
Since this forms a feedback loop that acts to reduce the load current Ict, the sawtooth current Iy cannot move, and the sum of the voltage En and the voltage Ep always matches the input voltage Ei from the outside. Stabilize. This is the same even if the power supply voltage Ebo of the circuit actually changes as a result of the control circuit working for the high voltage correction as described above, and the sawtooth current Iy is a predetermined value. Does not change from In order to change the sawtooth current Iy, the value of the external voltage Ei is changed and controlled.

Further, in the circuits of FIGS. 1 and 2 according to the present invention, even if the value of the high voltage EHT is adjusted by changing the adjustment state of the voltage control circuit 17 to change the value of the voltage Ebo, the sawtooth current Iy is changed. The value is not affected. Of course, even if the value of the sawtooth current Iy is changed by changing the value of the control voltage Ei from the outside, the high voltage EHT is not affected by this. That is, it is a feature of the present invention that not only the high voltage EHT and the sawtooth current Iy are made constant, but also the high voltage EHT and the sawtooth current Iy can be adjusted independently of each other. Further, except for some of the components in the current detection circuit 18, even if the circuit elements in the feedback loop described above drift due to temperature or other factors, they are automatically corrected, and the value of the sawtooth current Iy is not affected, and horizontal. The amplitude is always kept stable.

In FIG. 2, the smoothing capacitor 22
And the time constant of the AC feedback capacitor 28 is set to be sufficiently longer than the vertical period, and the feedback loop described above considers only the DC component. Therefore, the average amplitude of the sawtooth current Iy is mainly controlled and stabilized. However, the smoothing capacitor 2 is shortened by shortening this time constant.
An envelope waveform of the pulse Vn, that is, a side pincushion distortion correction waveform may appear at both ends of 2. In this case, the parabolic waveform Vpb is added to the amplitude control DC voltage Ei by superimposing it from the point q, not the point p. By doing so, the sawtooth current Iy is modulated faithfully to the parabolic waveform of the input. If the characteristics of the current detection transformer 20 are good, the stability of side pincushion distortion correction is better.

[0020]

As described in detail above, since the horizontal deflection high voltage generating circuit of the present invention is constructed as described above,
The DC high voltage applied to the cathode of the picture tube can be made constant regardless of the brightness of the picture of the picture tube, and the horizontal amplitude can also be made constant. Further, the DC high voltage and the horizontal amplitude can be adjusted independently of each other. Also, these are stable regardless of temperature and drift of circuit constants, and have an extremely excellent practical effect that they can be configured by a relatively small-scale circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a horizontal deflection high voltage generating circuit of the present invention.

FIG. 2 is a specific circuit diagram of a main part of a horizontal deflection high-voltage generating circuit according to the present invention.

FIG. 3 is a circuit diagram showing a conventional horizontal deflection high-voltage generating circuit.

FIG. 4 is a circuit diagram showing a conventional horizontal deflection high-voltage generating circuit.

FIG. 5 is a characteristic diagram for explaining a conventional horizontal deflection high voltage generation circuit.

FIG. 6 is a characteristic diagram for explaining a conventional horizontal deflection high-voltage generating circuit.

[Explanation of symbols]

1 Horizontal Output Transistor 2, 3, 8, 10 Capacitor 5, 6 Damper Diode 7 Horizontal Deflection Coil 9 Inductor 11 Variable Load Circuit 12 Flyback Transformer 12a Primary Winding 12b Secondary Winding 17 Voltage Control Circuit 18 Current Detecting Circuit 19 Comparison circuit 20 Current detection transformer 20a Primary side winding (primary winding) 20b Secondary side winding (secondary winding)

Claims (1)

(57) [Claims] 1. A picture tube having primary and secondary windings, wherein one end of the primary winding is connected to a DC power source, and a DC high voltage obtained by rectifying a pulse generated in the secondary winding is received. A flyback transformer to be applied to the anode of the flyback transformer, a voltage control circuit that divides the DC high voltage and controls the supply voltage of the DC power supply according to the divided voltage, and a collector has a primary winding other than the primary winding of the flyback transformer. A horizontal output transistor which is connected to one end of the horizontal output transistor and which is supplied with an excitation pulse having a horizontal deflection period and performs a switching operation in response to the excitation pulse; and a horizontal output transistor connected in series in the same polarity direction between the collector and the emitter of the horizontal output transistor. Horizontal deflection high voltage including first and second damper diodes, and first and second capacitors connected in parallel to the first and second damper diodes
In the generation circuit, the collector of the horizontal output transistor and the first and
It was connected between the connection point of 2 damper diodes,
The horizontal deflection coil, the third capacitor, and the current detection circuit
The first series circuit, the emitter of the horizontal output transistor, and the first and second
It was connected between the connection point of 2 damper diodes,
A second series circuit consisting of an inductor and a fourth capacitor
And a variable load circuit connected in parallel with the fourth capacitor.
And the output of the current detection circuit and the reference voltage are compared, and the ratio thereof is compared.
A comparison circuit for controlling the variable load circuit according to the comparison result;
And a primary and secondary winding as the current detection circuit,
The primary winding is connected in series with the horizontal deflection coil,
Note that the horizontal deviation is determined by the pulse voltage value generated in the secondary winding.
Detecting the horizontal deflection current flowing in the coil
A horizontal deflection high voltage generating circuit characterized by using a sensor .