JPH01241979A - High voltage generating circuit - Google Patents

Abstract

PURPOSE:To make a high voltage stable by opening a gate by a control current having a pulse width corresponding to the drop of a high voltage output due to a high voltage current and boosting an added voltage by a multiple voltage circuit so as to apply the resulting voltage to a high voltage output coil. CONSTITUTION:When a high voltage output current flows to an anode 16 of a cathode ray tube 15 and a high voltage output voltage is lowered, the voltage detected by a voltage detection section 9 is also reduced. Thus, when a comparator amplifier 22 compares its detection voltage and a triangle wave voltage, since the level of the detected voltage is lowered, the period of the triangle wave voltage in excess of the detected voltage is increased. Since the width of a rectangle control signal outputted from a differential amplifier 32 is increased, the period to open the gate of a switching circuit is extended and the summing voltage applied to the high voltage coil is increased. The summing voltage outputted from the switching circuit 23 is boosted by plural times by a multiple voltage circuit 46 and then the resulting voltage is fed to the high voltage coil. Thus, the high voltage is made stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high voltage generation circuit that stabilizes the high voltage output voltage applied to the anode of a cathode ray tube by so-called pulse width control.

[Conventional technology]

FIG. 8 shows a conventional high voltage generation circuit.

This high voltage generation circuit includes a horizontal deflection output circuit 1 and a flyback transformer 2.

The horizontal deflection output circuit 1 includes a horizontal output transistor 4, a damper diode 5, a resonant capacitor 6, a horizontal deflection coil 7, and an S-shaped correction capacitor 8. The horizontal output transistor 4 performs a switching action in response to a voltage pulse sent from the horizontal drive circuit, and applies a sawtooth wave current to the horizontal deflection coil 7 in cooperation with the damper diode 5. On the other hand, the resonant capacitor 6 and the horizontal deflection coil 7 generate flyback pulses by their resonance action, which are applied to the flyback transformer 2 .

The flyback transformer 2 consists of a core 10 wound with a low voltage coil 11 and a high voltage coil 12.
One end of the coil 11 is connected to the collector side of the horizontal output transistor 4, and the other end of the coil 11 is connected to the input power source 13. The high voltage side of the high voltage coil 12 is connected to the anode 1 of the cathode ray tube 15 via the high voltage rectifier diode 14.
6, and the other end of the coil 12 is connected to A B L (A
automatic Brightness Lim1t
er) side. The flyback transformer 2 boosts the flyback pulse applied from the horizontal deflection output circuit 1 and applies the boosted output (high output voltage) to the anode 16 of the cathode ray tube 15.

Generally, the high-voltage coil 12 is wound in multiple layers through a diode 17 as shown in FIGS. 8 to 10, and the coils between each layer are wound with the same number of turns, the same winding width, and the same winding pitch.
Furthermore, if the end of winding of each layer and the start of winding of the next layer are made to have the same polarity using the diode 17, the potential difference between the coils of each layer becomes zero in terms of alternating current. Therefore, the insulation process between each layer only needs to consider the DC potential difference, and there is no need to consider heat generation due to dielectric loss, making the insulation process easy.

Furthermore, if the high voltage coil 12 is wound in multiple layers as described above, the insulation distance between the low voltage coil 11 and the high voltage coil 12 can be made smaller compared to other section wound coils.
The finished outer diameter of the outermost layer of the coil can also be made smaller. As a result, as shown in FIG. 11, there is an advantage that the cage inductance of the high voltage coil 12 can be reduced.
For this reason, the flyback transformer 2 in which the coil 12 is of a multi-layer winding type is widely used.

However, as shown in FIG. 11, if the high-voltage coil 12 is simply made of multi-layer winding (laminate winding), the high-voltage current IM flowing from the coil 12 to the anode 16 of the cathode ray tube 15 will be zero.
It fluctuates rapidly in the range of ~200 μA, causing undesirable phenomena. Therefore, in recent years, as shown in FIG. 8, a fixed resistor 18 and a variable resistor 20 are arranged in series between the high voltage output side (the anode side of the cathode ray tube 15) and the ground, and the high voltage output current 1, Approximately 10% of the current is shunted, and the first
As shown in Figure 2, sudden fluctuations in the high voltage output current are prevented.

That is, in the characteristic diagrams shown in FIGS. 11 and 12, high voltage current 1. If the variable setting range of is set in the range of 0 to 1000 μA, the output impedance Z will be the same if no means for diverting the high voltage current IN is taken. 1 is the 11th
From the figure, zo, = (27-25) KV/1000μA
=2MΩ. On the other hand, if a 1□ divider is used, the output impedance will be Z. 2 is from Figure 12, Z o
z= (26,124,9) KV/1000μA
= 1.2MΩ, which means that the output impedance has been significantly improved.

[Problems to be Solved by the Invention] However, today, there is an increasing demand for higher definition in the image quality of the cathode ray tube 15, and it is desired to further reduce the output impedance. Moreover, when lowering the output impedance, a means that does not involve power loss is strongly desired, and as described above, 1. The method of diverting the energy resources has already become incapable of meeting such demands and is no longer accepted by the market.

The present invention was made in view of the above circumstances, and its purpose is to significantly reduce output impedance without power loss, in other words, to stabilize high voltage against changes in high voltage current. The purpose of the present invention is to provide a high-pressure generating device that can.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention boosts a flyback pulse applied from a horizontal deflection output circuit using a flyback transformer, and applies a high-voltage output voltage from the high-voltage side of a high-voltage coil constituting the transformer to the anode of a cathode ray tube. An addition voltage generation coil is wound around the core of the bank transformer and generates an addition voltage, and a triangular wave voltage with a constant waveform whose zero value is approximately at the start point of the retrace period and its peak value is approximately at the end point of the retrace period is generated. a reference voltage generation circuit; a voltage detection unit that detects a change in the high voltage output voltage by extracting the high voltage output voltage or the high voltage output current; and a detection voltage detected by the voltage detection unit and a triangular wave voltage of the reference voltage generation circuit. a comparator circuit that compares and outputs a control signal only in an area where the triangular wave voltage exceeds the detected voltage; and an amplifier that converts the signal into a rectangle (hereinafter referred to as a comparator amplifier);
Opening a gate in the section of the control signal applied from the comparator amplifier from the rising position of the rectangle to the end point of the retrace period and outputting the added voltage generated by the added voltage generating coil;
In other sections, a switching circuit that closes the gate to prevent the output of the added voltage is inserted between the switching circuit and the high voltage coil of the flyback transformer, which amplifies the added voltage applied from the switching circuit to create a high voltage. It is characterized by having a multi-voltage circuit applied to the low-voltage end side of the coil.

[Operation] In the present invention configured as described above, when the high voltage output current flows to the anode of the cathode ray tube and the high voltage output voltage decreases, the voltage detected by the voltage detection section also decreases. Therefore, when the comparison amplifier compares the detected voltage with the triangular wave voltage, the level of the detected voltage decreases, so the section of the triangular wave voltage that exceeds the detected voltage becomes larger. Along with this, the rectangular width of the control signal output from the differential amplifier increases, so the period during which the gate of the switching circuit is open becomes longer, and the additional voltage applied to the high voltage coil also increases. Since the added voltage output from this switching circuit is boosted by a plurality of times by the multiplier circuit and applied to the high-voltage coil, it becomes possible to control the high-voltage output voltage in a direction that stabilizes it.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on concave surfaces. In the description of this embodiment, circuit parts that are the same as those of the conventional example are denoted by the same reference numerals, and redundant explanation thereof will be omitted.

FIG. 1 shows a circuit configuration showing one embodiment of the present invention.

This embodiment is different from the conventional example in that it includes a reference voltage generation circuit 3, a voltage detection section 9, and an addition voltage generation coil 21.
In addition, a comparison amplifier 22, a switching circuit 23, and a voltage multiplier circuit 46 are provided.

The additional voltage generating coil 21 is wound around the core 10 of the flyback transformer 2 insulated from other coils, and an input tap 19 is provided at the winding start end of the coil 21. An output tap 24 is provided on the output end side (winding end side) of the coil 21. This output tap 24 outputs the added voltage generated in the coil 21.

On the other hand, the high voltage side of the high voltage coil 12 (high voltage rectifier diode 1
One end of a fixed resistor 28 is connected to the cathode side of the resistor 29 , and a variable resistor VR for adjusting the focus output, a fixed resistor 29 . Variable resistor VHS for adjusting screen voltage, fixed resistor 30. Variable resistor VR for adjusting high voltage output voltage.

are connected in series in order to constitute a voltage detection section 9 for high voltage output voltages F and s. The other end of the variable resistor VR3 is connected to a reference potential (earth side in this case).

The variable resistor VR detects the high voltage output voltage E through its sliding terminal, and applies this detected voltage e6 to the first input terminal of the comparison amplifier 22.

The reference voltage generation circuit 3 includes a control voltage generation coil 25,
It consists of a rectifier 26, a rectangular wave output circuit 27, and an integrating circuit 31, and the rectangular wave output circuit 27 consists of an amplifier 32 and a clip circuit 33.

The control voltage generating coil 25 is wound around the core 10 of the flyback transformer 2 on the low voltage side insulated from other coils.
Control voltage e2 of flyback pulse waveform shown in figure (a)
occurs. The high voltage side (winding end side) of this control voltage generating coil 25 is connected to a reference potential (earth side in the figure = 10-), and the low voltage side (winding start side) of the control voltage generating coil 25 is connected to a rectifier (diode in the figure). It is connected to the negative terminal of the amplifier 32 via 26.

Note that the positive terminal of the amplifier 32 is connected to a reference potential (earth side in the figure). Note that when the input of the amplifier 32 is constituted by the base of a transistor, the input waveform is rectified by an equivalent diode between the base and emitter of the transistor, so the rectifier 26 is not necessary.

The rectifier 26 rectifies the voltage e2 generated by the control voltage generating coil 25 and transmits only the positive component of the voltage e2 to the amplifier 32.
Input to the inverted input terminal, that is, the negative terminal.

Amplifier 32 amplifies this input voltage and applies its output to clip circuit 33. The clipping circuit 33 cuts off the top of the voltage waveform amplified by the amplifier, as shown in FIG.
), the voltage e4 is a rectangular wave (in this specification, rectangular wave is used in a broad sense including not only rectangular waveforms but also square waveforms) whose pulse width is the retrace period T. is generated and added to the integrating circuit 31.

This integrating circuit 31 integrates the rectangular wave voltage e4 over the blanking period T1, and as shown in FIG. 2(c), the starting point of the blanking period is zero, and the ending point of the same period is Creates an upward-sloping waveform with a peak value. In this case, since integration is not performed in the range exceeding the retrace period Tr, the waveform is discharged from the peak position (discharge from the capacitor of the integrating circuit).
As a result, the voltage waveform slopes downward to the right, and a triangular wave (sawtooth wave) voltage e is created that peaks at the end point of the retrace period Tr. This triangular voltage waveform maintains a constant shape during any retrace period T. This triangular wave voltage e, is applied to the second input terminal of the comparator amplifier 22.

The comparator amplifier 22 compares the triangular wave voltage e with the detection voltage e6 applied from the variable resistor VRI of the voltage detection section 9 (FIG. 2(c)), so that the triangular wave voltage es becomes the detection voltage e.
, only the interval Δt exceeding , (in the figure, the interval t3 to t5 and t
, ~t)) The control signal e7 becomes a constant positive voltage, and otherwise becomes a constant negative level voltage including the scanning period.
is added to the switching circuit 23.

The switching circuit 23 includes a drive transistor 34, diodes 35 and 36, resistors 37 and 38, a capacitor 40, a drive type 21iii41, a drive transformer 42, and an ill? It consists of a wholesale transistor 43. The drive transistor 34 has its base side connected to the output terminal of the comparator amplifier 22, and its emitter side connected to a common connection between one end side of the resistor 37 and the capacitor 40 and the negative side of the drive type IAU. The common connection is further connected to a reference potential (ground side in the figure).

The other end sides of the resistor 37 and the capacitor 40 are commonly connected to the cathode side of a diode 35, and the anode side of the diode 35 is connected to the collector of the drive transistor 34 and the primary coil 4 constituting the drive transformer 42.
It is commonly connected to the connection part with the high voltage side (winding end side) of No. 4. These, the resistor 37 and the capacitor 40,
Diode 35 forms a snubber circuit. Also, -
The low voltage side (winding start side) of the secondary coil 44 is connected to the positive side of the drive power source 41 via the resistor 38 .

On the other hand, the low voltage side (the winding start side) of the secondary coil 45 of the drive transformer 42 is connected to the base side of the control transistor 43, and the high voltage side (winding end side) of the secondary coil 45 is connected to the emitter side of the control transistor 43. and diode 3
6, and this common connection becomes an output end of the switching circuit 23 and is connected to an input end of the multiplier circuit 46. control transistor 4
The collector side of 3 is connected to the cathode side of the diode 36, and the connecting portion between the two 43 and 36 is connected to the output tap 24 of the addition voltage generating coil 21. Also,
The low voltage side (winding start side) of the addition voltage generating coil 21 communicates with the ABL side via the input tap 19.

Note that the diode 36 is for flowing a current in the opposite direction from the emitter side to the collector side of the control transistor 43. Therefore, the control transistor 43 is constituted by a type of transistor through which reverse leakage current flows, such as a bipolar transistor. Sometimes the diode 36 is not necessarily required and can be omitted. When the control signal e is a positive voltage, this switching circuit 23 opens the gate for a predetermined period, which will be described later, to generate a pulse voltage e as shown in FIG. 2(h).
. is applied to the multiplier circuit 46.

The multiplier circuit 46 includes first to fifth diodes 47.
．． 48, 49, 50, 51, and each of the first to fifth capacitors 52, 53, 54, 55, 56. Foreword - The anode side of the first diode 47 is connected to the emitter side of the control transistor 43,
The cathode (!1.!l) of the same diode 47 is connected to the anode side of the second diode 48, the cathode side of the same diode 48 is connected to the anode side of the third diode 49, and similarly, the third diode 49 is connected to the fourth diode 49. The fourth diode 50
The diodes are each connected to a fifth diode 51 to form a series connection body of a group, and the cathode side of the fifth diode 51 is connected to the low voltage side of the high voltage coil 12.

Further, one end of the first capacitor 52 is connected to a common connection between the emitter of the control transistor 43 and the anode of the first diode 47, and the other end of the capacitor 52 is connected to the cathode of the second diode 48. and the anode side of the third diode 49.

Also, one end of the fourth capacitor 55 is connected to a common connection between the emitter of the control transistor 43 and the anode of the first diode 47, similar to the one end of the first capacitor 52. The other end side is connected to a connection portion between the fourth diode 50 and the fifth diode 51. One end side of the second capacitor 53 is connected to the cathode of the first diode 47 and the second diode 4.
It is connected to the connection part with the anode of B, and also the third
One end of the capacitor 54 is connected to the connection between the cathode of the third diode 49 and the anode of the fourth diode 50, and similarly, one end of the fifth capacitor 56 is connected to the connection between the cathode of the third diode 49 and the anode of the fourth diode 50. The other end sides of the second capacitor 53, the third capacitor 54, and the fifth capacitor 56 are all connected to the ABL side. Further, the anode side of the diode 57 is connected to this ABL side, and the cathode side of the diode 57 is connected to the first diode 47 and the second diode 48.
or the connection between the second diode 48 and the third diode 49 (the connection between the first diode 47 and the second diode 48 in FIG. 1).

The present embodiment is constructed as described above, and the stabilizing effect of the high output voltage E11 will be explained below.

When the brightness of the cathode ray tube 15 is increased, a high-voltage current 111 flows through the anode 16, and the high-voltage output voltage E11 decreases due to the internal impedance of the high-voltage generating section, and accordingly, the voltage e6 detected by the voltage detection section 9 also decreases. do. When this detection voltage e6 decreases, the detection voltage e6 becomes a triangular wave voltage e generated by the integrating circuit 31, as shown in FIG.
, since it falls below the peak position of , the retrace period Δ
The triangular wave voltage e5 exceeds the detection voltage e6 in the interval t and the interval ΔL2 beyond the retrace period. In Figure 2 (C), t3
t7~L than the detection voltage e6 detected in the period ~t5
A case is shown in which the detection voltage e6 detected in the period , is lower, and the lower the detection voltage e6, that is, the high-voltage output voltage Ell, the lower the detection voltage e6, the more Δt (
t, Δt2) becomes wider, and the positive voltage range of the control signal e7 output from the comparison amplifier 22 becomes wider (FIG. 2(d)).

The circuit operation when the control signal e7 is applied to the switching circuit 23 will be described below.

First, during the retrace period T and the period 1 to L30, the detection voltage e6 is larger than the triangular wave voltage e5, so the comparator amplifier 22 applies the negative voltage e7 to the drive transistor 3.
Apply to the base of 4. As a result, the drive transistor 34 is cut off, and the collector voltage ee of the transistor 34 (FIG. 2(e)) becomes a positive voltage. As a result, no current flows from the drive power supply 41 to the primary coil 44 of the drive transformer 42, and the transformer 42 is turned off. Accordingly, the base voltage eq of the control transistor 43 (FIG. 2(f)) becomes negative. Therefore, the control transistor 43 is cut off and its gate is closed. Therefore, the addition voltage elG (FIG. 2(h)) is not applied from the addition voltage generating coil 21 to the multiplier circuit 46.

Next, in the section from t to L4 of the retrace period Tr, since the detection voltage e6 is smaller than the triangular wave voltage e, the comparison amplifier 22 applies a positive voltage e to the base of the drive transistor 34. As a result, the transistor 34 is turned on, and current flows from the drive power source 41 to the primary coil 44. Then, the control transistor 4 is connected via the secondary coil 45.
A positive pulse e is applied to the base of the transistor 43, and the transistor 43 is turned on. At this time, a flyback pulse eI of around 100 OV (Fig. 2 (g)) is generated at the output end of the addition voltage generating coil 21, and this addition voltage e1 is applied from the output tap 24 to the collector of the control transistor 43. has been done.

Therefore, since the transistor 43 is turned on and the gate is opened in the interval from t3 to t4 (the interval of Δt), the voltage e of the waveform portion of el in that interval. (FIG. 2(h)) is applied to the multiplier circuit 46 from the emitter side through the gate of the transistor 43.

Next, in the interval from t4 to is, the relationship 65>86 holds true as in the interval from t3 to t4, and a positive pulse e9 is applied to the base of the control transistor 43. Since the section is in the scanning period, the negative voltage component EN of the addition voltage e1 is applied to the collector side of the transistor 43, and the transistor 43 is turned off and the gate is closed. Therefore, the voltage e1° applied to the multiplier circuit 46 from the emitter side of the transistor 43 becomes zero.

Next, in the interval from t5 to t6, the relationship is e,>es,
Drive transistor 34 and control transistor 43
is cut off and the transistor 43 closes its gate, so the voltage e, applied to the multiplier circuit 46. becomes zero.

As described above, the switching circuit 23 opens the gate only in the section of Δt1 from the position where the control signal e8 becomes a positive voltage within the retrace period to the end point of the retrace period, and the additional voltage e is The voltage e1° of the waveform part of is applied to the multiplier circuit 4
It is added to 6. In this case, as the high voltage output voltage EM becomes lower, the width of ΔL1 becomes larger and the time during which the gate is open becomes longer, so the voltage elo applied from the switching circuit 23 to the multiplier circuit 46 also becomes larger.

The multiplier circuit 46 boosts the voltage elO applied from the switching circuit 23 as follows and applies it to the high voltage coil 12 of the flyback transformer 2. This step-up operation can be explained in equivalent figures 3 to 5, which are extracted from the circuit in figure 1.
To explain based on the diagram, first, during the retrace period T, current flows through each route shown in FIG. The voltage of EIO+EN is charged by the voltage EIO+EN. Similarly, the voltage of Elo is applied to the second capacitor 53 due to the current of the b route, the voltage of 2E, o+EN is applied to the third capacitor 54 due to the current of the C route, and the voltage of 2E, o+EN is applied to the fourth capacitor 55 due to the current of the d route. 2 (El. 10 EN)
The fifth capacitor 56 is charged with a voltage of 3EIO+2EH by the current of route C.

Here, E+o is the voltage e. is the peak voltage value (Fig. 2 (h)), and E is the added voltage e+ (Fig. 2 (g)
)) The voltage of the negative component of the waveform 2l- = 20-.

Next, during the scanning period, current flows through each route shown in FIG. The second capacitor 53 is charged with a voltage of 10 E, the second capacitor 53 is charged with a voltage of E+o, the fourth capacitor 55 is charged with a voltage of 2 (EIO+EJ1), and the third capacitor 54 is charged with a voltage of 2E, o+E. be done. Next, when it comes to the retrace period again, the third
Current flows again through each route in the figure, and the fifth capacitor 56
The voltage of 3E, O+2E8 charged in the high voltage coil 12
added to. In other words, in the circuit shown in Fig. 1, the multiplier circuit 4
6 functions as a triple voltage circuit (if the AC component is included, it functions as a 5 double voltage circuit, but EN is sufficiently small compared to El. (You can think of it as a circuit).

Note that when the control transistor 43 is cut off, the high voltage current III flows through a route as shown in FIG.

By the way, when the circuit operates, the high voltage output voltage E.

It may be necessary to flow a high-voltage output current even when This purpose is achieved by arranging diodes 57 connected to the anode connections of the two.

As described above, according to this embodiment, the high voltage output voltage Ell
Since the time for opening the gate of the switching circuit 23, Δt, is controlled in accordance with the amount of drop in E, the greater the amount of drop in E, the longer the time the gate is open; therefore, it is added to E8. The voltage elo also increases, and this elo is amplified by the voltage multiplier circuit 46 and applied to the high voltage coil 12.

The circuit operates in the direction of keeping constant.

On the other hand, switching of the switching circuit 23 is performed by the on/off operation of the control transistor 43, and even if the operating voltage e is applied to the base side, the OFF operation is automatically turned off by entering the scanning period. So,
As far as the switching off action is concerned, the quality of the fall performance of the transistor 43 is irrelevant. Therefore, as for the performance of the transistor 43, only the rise performance of the on operation needs to be considered, and even if a transistor with poor fall performance is used, a good switching operation can be performed. Furthermore, since the voltage e applied to the control transistor 43 is boosted by the drive transformer 42, the withstand voltage of the control transistor 43 does not have to be extremely high, so-called (2). B. According to the standard, a product having a withstand voltage of about 1500 V can sufficiently achieve the purpose, and it is possible to reduce the cost of the transistor 43 used and to reduce the size of the transistor.

Note that the present invention is not limited to the above-mentioned embodiments, and can take various embodiments. For example, in the circuit shown in FIG.
The snubber circuit in 3 may be omitted if necessary.

Further, in this embodiment, a triple voltage circuit as shown in FIG. The double voltage circuit shown in the figure (3 times the voltage circuit if AC components are included) and the Kotscroft type triple voltage circuit shown in Part 7 (5 times the voltage circuit if AC components are included) are used. You can also use

However, the recent trend in CRT cathode ray tubes is toward higher definition and larger screens, and in order to achieve such higher definition and larger screens, taking into account variations in circuit manufacturing, high voltage current is required. When IH is 2 mA, a static correction voltage of 2 to 4 KV is required.

Furthermore, when taking into account the characteristics, an instantaneous voltage drop of about 4 to ν occurs due to an external load, etc., and this needs to be corrected. However, the additional voltage el output from the switching circuit 23.

Since el cannot be increased beyond the breakdown voltage of the control transistor 43. The maximum value of VCBO of the same transistor 43
Determined by the standard withstand voltage. However, even if the added voltage elo determined in this way is boosted by the double voltage circuit shown in FIG. 6, the high voltage E This will be insufficient to compensate for the decrease in . On the other hand, if a triple voltage circuit is used as in this embodiment, the high voltage E1. This means that the decrease of 24- can be sufficiently compensated for.

Of course, the decrease in EH can be compensated for by using the triple voltage circuit shown in FIG. When compared with the same capacitance, the circuit of this example is superior in that the output voltage can be regulated smaller (and therefore the output voltage can be increased). In this case, the multivoltage circuit of this embodiment has the advantage that it can be made smaller.

Furthermore, it is possible to use a circuit with four times the voltage or more in the DC component as a multiplier circuit, but in this case there is a disadvantage that the cage inductance increases. It is demonstrated that the circuit is most suitable as a multivoltage circuit.

Further, as a modification of this embodiment, the high voltage coil 12 may be wound in a multilayered manner in the first circuit, and in this case,
As shown in FIG. 8, a diode 17 is connected between the coils in each layer.
We will intervene.

Further, in the above embodiment, the voltage detection section 9 directly extracts the high voltage output voltage EI+ to obtain the detection voltage e6, but it may also extract the high voltage output current and indirectly obtain the detection voltage e6. In this case, the extracted high-voltage output current will be introduced from the ABL side to the comparison amplifier 22 via a resistor, which will require some circuit changes.

(Effects of the Invention) As explained above, the present invention handles the drop in the high voltage output voltage E□ due to the flow of the high voltage current IH by opening the gate with a control current having a pulse width corresponding to the drop, thereby increasing the additional voltage. Since the voltage is boosted by a multiplier circuit and applied to the high-voltage output coil, the additional voltage corresponding to the voltage drop is replenished to the high-voltage coil without any shortage, thereby stabilizing the high-voltage output voltage. Since distortion of the screen can be effectively prevented and the output impedance of the high voltage generation circuit can be made extremely small, it can fully meet the demands for higher definition and larger screens.

Furthermore, since the high voltage output voltage is controlled on the high voltage side (secondary side) of the flyback transformer, it does not adversely affect voltage fluctuations of the deflection coil, and therefore the screen does not deteriorate.

Furthermore, the present invention allows pulse width control within the retrace period with a small circuit configuration, and since this pulse width control is performed within the retrace period, there is no need to worry about switch noise from the switching circuit appearing on the screen. In addition, the transistors used for switch control generate less heat.

Furthermore, in the present invention, since the addition voltage generation coil and the control voltage generation coil used in the reference voltage generation circuit can be provided by being wound around the core of the flyback transformer, the entire circuit can be constructed using this core as a boundary. It becomes easy to insulate the hot side and the cold side in terms of alternating current.

Furthermore, since the grounding of the switching circuit of the present invention does not necessarily have to be the line on the ABL side, it is possible to increase the degree of freedom in circuit design.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
Waveform diagrams of each part of the circuit shown in the figure, Figures 3 to 5 are explanatory diagrams of circuit operation, Figures 6 and 7 are other circuit diagrams of the multivoltage circuit, and Figure 8 is a conventional high voltage generation circuit. A circuit diagram showing the circuit, Fig. 9 is a half-sectional view of a flyback transformer using a laminated type high voltage coil, Fig. 10 is a wiring diagram of the high voltage coil shown in Fig. 9, and Fig. 11 is added to the anode of a cathode ray tube. Figure 12 is a characteristic comparison diagram comparing the relationship between the high voltage output voltage EH and the high voltage current II+ when the high voltage coil has a laminated winding and when the high voltage coil has a section winding. 9 is a characteristic diagram showing the relationship between the high voltage output voltage EH and the high voltage currents 1, 1 of the circuit of FIG. 8, which is provided with a shunting means. DESCRIPTION OF SYMBOLS 1... Horizontal deflection output circuit, 2... Flyback transformer, 3... Reference voltage generation circuit, 4... Horizontal output transistor, 5... Damper diode, 6... Resonant capacitor, 7... ... Horizontal deflection coil, 8 ... S-shaped correction capacitor, 9 ... Voltage detection section, 10 ... Core, 11 ... Low voltage coil, 12 ... High voltage coil, 13
...Input power supply, 14...High voltage rectifier diode, 15
... Braun tube, 16 ... Anode, 17 ... Diode, 18 ... Fixed resistor, 19 ... Input tap, 20 ... Variable resistor, 21 ... Addition voltage generating coil, 22 ... Comparison amplifier, 23 ... Switching circuit, 24 ... Output tap, 25 ... Control voltage generation coil, 26 ... Rectifier, 27 ... Square wave output circuit, 28,29.30. ...Fixed resistor, 31... Integrating circuit, 32... Amplifier, 33... Clip circuit, 3
4... Drive transistor, 35.36... Diode, 37.38... Resistor, 40... Capacitor, 41... Drive power supply, 42... Drive transformer, 43... Control transistor , 44...-secondary coil, 45... secondary coil, 46... multiplier circuit, 47
...first diode, 48...second diode, 49...third diode, 50...fourth diode, 51...fifth diode, 52...first
capacitor, 53...second capacitor, 54...
・Third capacitor, 55...Fourth capacitor, 5
6...Fifth capacitor, 57...Diode.

Claims (1)

[Claims] The flyback pulse applied from the horizontal deflection output circuit is boosted by a flyback transformer, and the high voltage output voltage is applied to the cathode ray tube anode from the high voltage side of the high voltage coil that constitutes the transformer. a reference voltage generating circuit that generates a triangular wave voltage having a constant waveform having a zero value approximately at the starting point position of the retrace period and a peak value approximately the end point position of the retrace period; A voltage detection section detects a change in the high voltage output voltage by extracting the high voltage output voltage or high voltage output current, and compares the detection voltage detected by this voltage detection section with the triangular wave voltage of the reference voltage generation circuit, and detects the triangular wave voltage. A comparator amplifier that outputs a rectangular control signal only in the section exceeding the detection voltage, and a gate is opened in the section from the rising position of the rectangle to the end point of the retrace period of the control signal applied from the comparator amplifier to generate the addition voltage. A switching circuit that outputs the added voltage generated in the coil and closes the gate in other sections to prevent the output of the added voltage, and a switching circuit that is interposed between the switching circuit and the high-voltage coil in the flyback transformer. A high voltage generation circuit comprising: a multiplier circuit that amplifies an applied additional voltage and applies the amplified voltage to the low voltage end side of a high voltage coil.