KR100222701B1 - High voltage power circuit - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

The present invention relates to a high voltage power supply circuit for generating a stabilized high voltage DC output power supply from an unstable commercial AC input power supply or a DC input power supply.

I. The technical problem to be solved by the invention

Provides a high voltage power supply circuit that simplifies configuration.

All. Summary of Solution of the Invention

The high voltage DC output power is generated by PWM control in which the switching duty is determined to correspond to the voltage level of the output power. Then, FM control is performed in which the switching frequency is determined to correspond to the voltage level of the input power source.

la. Important uses of the invention

It is used for a display device provided with a CRT.

Description

High voltage power circuit

The present invention relates to a power supply device for generating a high voltage power supply, and more particularly, to a high voltage power supply circuit for generating a high voltage DC output power stabilized from an unstabilized commercial AC input power supply or a DC input power supply.

Typically a television (Television: "TV") receiver, a display device such as a monitor includes a CRT (Cathode Ray Tube). A high voltage DC power supply is applied to the anode of the CRT. If the high voltage fluctuates, the size of the screen may change, or the focus or convergence may be degraded. Accordingly, the display device having a CRT includes a high voltage power supply circuit for generating a high voltage DC output power stabilized from an unstabilized commercial AC input power or DC input power.

An example of a high voltage power supply circuit that has been conventionally used for a TV receiver is shown as the circuit diagram of FIG. 1. The high voltage power supply circuit of FIG. 1 includes an input rectifier 100, a switching mode power supply (SMPS) 102, a voltage step-down unit 104, and a high voltage generator 106. The input rectifier 100 has a bridge diode 108 connected to the commercial AC input power ACin and a capacitor C1 connected to the output terminal of the commercial AC input power to rectify the commercial AC input power ACin to supply the DC power. Outputs At this time, the DC power output from the input rectifier 100 is applied to the SMPS 102 as the input power Vi as a power in an unstable state.

In the SMPS 102, the primary winding Lp of the transformer T1 is connected between the output terminal of the input rectifier 100 and the ground through the transistor Q1, which is a switching element, and the secondary winding Ls is connected to the diode (S). It is connected between the anode of D1) and ground, and capacitor C2 is connected between the cathode of diode D1 and ground, and two resistors R1 and R2 are connected in series. In this case, the transistor Q1 has a collector connected to the primary winding Lp of the transformer T1, an emitter connected to ground, and a base connected to an output terminal of a pulse width modulation (PWM) control unit 110. The connection point between R2 is connected to a feedback input terminal of the PWM control unit 110. The SMPS 102 is a conventional power supply device that generates a stable DC power supply by DC-DC conversion by switching a DC input power source and is widely used since it can always obtain a stable output voltage against voltage variations of the input power source.

In the voltage step-down part 104, the collector of the transistor Q2 is connected to the output terminal of the SMPS 102, and the output terminal of the operational amplifier 112 is connected to the base terminal of the transistor Q2. The reference voltage Vref is applied to the non-inverting input terminal (+), and the inverting input terminal (-) is connected to the connection point of the two resistors R3 and R4 of the high voltage generator 106.

In addition, the high voltage generator 106 has a primary side winding L1 of the high-voltage transformer T2 through the output terminal of the voltage step-down unit 104, that is, an emitter of the transistor Q2 and a ground through the transistor Q3, which is a switching element. Connected between the secondary windings L2 to L5 of the transformer T2 between the anode of the diode D2 and ground, and between the secondary windings L2 to L5 between the diodes D3 to D5. The capacitors C3 are connected between the cathode of the diode D2 and the ground, and two resistors R3 and R4 are connected in series. In this case, the transistor Q3 is connected to the primary winding L1 of the transformer T2, the emitter is grounded, and the base is connected to the output terminal of the horizontal driver 114. The diode D6 and the capacitor C4 are connected in parallel with the transistor Q3, respectively, and the series-connected deflection coil L _DY and the capacitor C5 are connected in parallel with the transistor Q3. The high voltage generator 106 is a configuration of a conventional high voltage output deflection circuit, and the high voltage transformer T2 is called a flyback transformer (FBT).

When the commercial AC input power ACin is input to the input rectifier 100 in the high voltage power circuit of FIG. 1, the DC input power Vi is output from the input rectifier 100 and applied to the primary side winding Lp of the SMPS 102. do. At this time, the DC input power Vi is only a power supply in which the AC input power ACin is rectified and is a power in an unstable state. In this state, the PWM control unit 110 of the SMPS 102 generates a PWM signal and is applied to the base of the transistor Q1. Accordingly, the switching operation of the transistor Q1 is performed, the power is induced to the secondary winding Ls of the transformer T1, rectified by the diode D1 and the capacitor C2, and then output to the DC power supply V1. At this time, the resistors R1 and R2 divide the voltage of the DC power supply V1 by a predetermined voltage and apply it to the PWM control unit 110 as the output detection voltage Vf1. The PWM control unit 110 outputs the voltage detected by the resistors R1 and R2. The voltage of the DC power supply V1 is stabilized by adjusting the duty of the PWM signal in accordance with the variation of the voltage level of the DC power supply V1 by the detection voltage Vf1. Therefore, the DC power supply V1 output from the SMPS 102 remains stable even if the voltage of the input power supply Vi varies.

As described above, the DC power supply V1 output from the SMPS 102 is stepped down by the transistor Q2, and the stepped-down power supply V2 is applied to the primary side winding L1 of the transformer T2 of the high voltage generation unit 106. In the high voltage generator 106, the horizontal driver 114 switches the transistor Q3 by the horizontal synchronous pulse Hp, and accordingly, the sawtooth wave is horizontal to the primary winding L1 of the deflection coil L _DY and the transformer T2. Deflection current is generated by transistor Q3, diode D6, and capacitors C4 and C5. This operation is a common horizontal deflection and high pressure generating operation. As described above, when the sawtooth wave deflection current is generated in the primary winding L1 of the transformer T2 by the horizontal synchronizing pulse Hp, the diode is connected to the secondary windings L2 to L5 of the transformer T2 during the return period of the horizontal synchronization pulse Hp. The voltage pulse signal in the forward direction is induced to the fields D2 to D5 and charged to the capacitor C3. As a result, a high voltage direct current output power Vo is output from both ends of the capacitor C3. At this time, the resistors R3 and R4 divide the voltage of the output power Vo by a predetermined voltage and apply the output detection voltage Vf2 to the inverting input terminal (−) of the operational amplifier 112. Accordingly, the transistor Q2 stabilizes the voltage of the output power Vo by stepping down the DC power supply V1 in response to the variation of the voltage level of the output power Vo by the output detection voltage Vf2 detected by the resistors R3 and R4.

As described above, the high voltage power supply circuit of FIG. 1 stabilizes the DC input power Vi in an unstabilized state by the SMPS 102 first, and then stabilizes when the high voltage is generated in the high voltage generator 106 again. Power Vo is obtained. However, the configuration was complicated by having a two-stage stabilization configuration. Accordingly, when a large number of parts is required, and a large power capacity is required, it has been difficult to use because the size must be large. In particular, the heat sink, which is a heat sink for heat dissipation of the switching element Q1, has become very large, thereby increasing the overall size. In addition, stabilization was lowered when the variation of the input / output was large because only stabilization by the duty variable with respect to the input power Vi was adopted.

As described above, the conventional high voltage power supply circuit has a two-stage stabilization configuration, which is complicated in configuration and requires a larger power capacity, which is difficult to use, and stabilization decreases when the input / output variation is large. There was this.

Accordingly, an object of the present invention is to provide a high voltage power supply circuit which can simplify the configuration.

Another object of the present invention is to provide a high voltage power supply circuit that can be used to require a large power capacity without increasing the size of the components, and can be stabilized even when the input / output variation is large.

1 is a high voltage power supply circuit diagram of a conventional television receiver;

2 is a high voltage power supply circuit diagram according to an embodiment of the present invention;

3 is an operational waveform diagram of each part of FIG. 2;

The present invention for achieving the above objects generates a high voltage direct current output power by PWM control in which the switching duty is determined corresponding to the voltage level of the output power. Then, FM (Frequency Modulation) control is performed in which the switching frequency is determined to correspond to the voltage level of the input power.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the annexed drawings, numerous specific details are set forth in order to provide a more thorough understanding of the present invention, such as specific circuit configurations, types of elements or components, and the like. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

2 illustrates a high voltage power supply circuit diagram according to an exemplary embodiment of the present invention, which is configured to have only one stage of stabilization configuration, unlike the power supply circuit of FIG. 1, and includes an input rectifier 200 and an input voltage detector 202. The high voltage generator 204 and the output voltage detector 206 are configured. The input rectifier 200 is configured in the same manner as the input rectifier 100 of FIG. 1 described above. A bridge diode 208 is connected to a commercial AC input power ACin and a capacitor C11 is connected to an output terminal of the bridge diode 208. Connected to rectify commercial AC input power ACin to output DC power. At this time, the DC power output from the input rectifier 100 is applied to the high voltage generator 204 as the input power Vi as a power in an unstabilized state.

The input voltage detector 202 is composed of two resistors R11 and R12 connected in series between the input power Vi side and the ground, and divides the input power Vi at a predetermined level to correspond to the voltage level of the input power Vi. Generate an input detection voltage Vf1. The output voltage detector 206 is composed of two resistors R14 and R15 connected in series between the output power Vo side outputted from the high voltage generator 204 and the ground, and the output power Vo is divided by a predetermined voltage. An output detection voltage Vf2 at a level corresponding to the voltage level

The high voltage generator 204 has a high voltage transformer T12 for inputting the input power Vi output from the input rectifier 200 to the primary winding L1, and inputs an input detection voltage Vf1 and an output detection voltage Vf2. To the secondary windings L2 to L5 of the transformer T12 by switching the primary winding L1 according to the frequency that varies in response to the voltage variation of the input power Vi and the duty varying corresponding to the voltage variation of the output power Vo. The voltage pulse signal is induced and rectified to generate output power Vo. The high voltage generator 204 includes an FM controller 210, a PWM controller 212, a switching unit 214, a transformer T12, and an output rectifier 216.

The FM control unit 210 inputs the input detection voltage Vf1 from the input voltage detection unit 202 and generates a switching signal having a frequency that is variable to correspond to the voltage variation of the input power source Vi. When the voltage of the input power Vi decreases, the FM controller 210 lowers the frequency of the switching signal correspondingly, and increases the frequency of the switching signal correspondingly when the voltage of the input power Vi increases. In this way, the switching signal generated from the FM control unit 210 is commonly applied to the PWM control unit 212 and the switching unit 214. The PWM control unit 212 inputs a switching signal from the FM control unit 210, inputs an output detection voltage Vf2 from the output voltage detection unit 206, and outputs a PWM signal having the same frequency synchronized with the switching signal to change the voltage of the output power Vo. It is generated by varying in the on section of the switching signal with a duty corresponding to. When the voltage of the output power Vo decreases, the PWM control unit 212 varies the duty of the PWM signal correspondingly to a larger duration. If the voltage of the output power Vo increases, the PWM controller 212 changes the duty of a PWM signal smaller correspondingly. . The switching unit 214 switches the primary side winding L1 of the transformer T12 by a switching signal to induce a voltage pulse signal to the secondary side windings L2 to L5 of the transformer T12 and to raise the level of the voltage pulse signal. Variable according to the duty of the PWM signal. The output rectifier 216 has four diodes D14 to D17 connected in series, one between each of the secondary windings L2 to L5 of the transformer T12, and a capacitor C14 between the cathode of the diode D14 and ground. Is connected to rectify the voltage pulse signal induced in the secondary windings L2 to L5 of the transformer T12 to generate the output power Vo.

The switching unit 214 has a transistor Q12, which is a main switching element, connected in parallel to the primary winding L1 of the transformer T12, and an output terminal of the switching controller 218 is connected to a base of the transistor Q12. do. The switching controller 218 switches the transistor Q12 according to the switching signal of the FM controller 210. The diode D11 is connected in the reverse direction to the input power supply Vi in parallel with the transistor Q12, and the capacitor C13 is connected in parallel with the transistor Q12, and the input power supply Vi side and the primary side of the transformer T12 are connected. A capacitor C12 is connected between the windings L1, and two diodes D12 and D13 are connected in series in the reverse direction between the input power supply Vi and ground, and switching between the connection point between the diodes D12 and D13 and ground. The transistor Q13, which is an element, is connected and switched by the PWM signal of the PWM control unit 212. Further, the first winding L11 of the transformer T13 is connected between the connection point between the transistor Q12 and the capacitor C13 and the transistor Q13, and the first winding L11 of the transformer T13 is connected between the primary winding L1 and the transistor Q12 of the transformer T12. Two windings L12 are connected. Here, the number of the second windings L12 of the transformer T13 is very small compared to the number of the primary windings L1 of the transformer T12 and is very small compared to the number of the first windings L11.

In addition, the switching control unit 218 is connected to the output terminal of the FM control unit 210, the base of the transistor Q11 is connected, the emitter of the transistor Q11 is grounded and the collector is the primary winding (Lp) of the transformer T11 Is connected to the supply voltage Vcc. The secondary winding Ls of the transformer T11 is connected between the base and the emitter of the transistor Q12 through the resistor R13.

3 is a waveform diagram of each part of FIG. 2, wherein FIG. 3A is a waveform of a switching signal generated from the FM controller 210, and FIG. 3B is a waveform generated from the PWM controller 212. 3C is a waveform of a PWM signal, FIG. 3C is a conduction current waveform of the primary winding L1 of the transformer T12, FIG. 3D is a collector current waveform of the transistor Q13, and FIG. Is a collector current waveform of transistor Q11, FIG. 3 (f) is an emitter voltage waveform of transistor Q11, and FIG. 3 (g) is a voltage waveform induced in secondary winding L2 of transformer T12. to be. 3 shows an example in which the duty of the PWM signal varies from Td1 to Td2.

The operation of the high voltage power supply circuit of FIG. 2 as described above will now be described in detail with reference to FIG. 3 showing an operation waveform of each part of FIG. 2. First, when the commercial AC input power ACin is input to the input rectifier 200 in the high voltage power circuit of FIG. 2, the DC input power Vi is output from the input rectifier 200. At this time, the DC input power Vi is only a power supply in which the AC input power ACin is rectified and is a power in an unstable state. In this state, the resistors R11 and R12 of the input voltage detector 202 divide the input power supply Vi by a predetermined voltage and output the input detection voltage Vf1 corresponding to the voltage level of the input power supply Vi to the FM controller 210.

Then, the FM controller 210 generates a switching signal having a waveform as shown in FIG. 3 (a) according to the input detection voltage Vf1, and changes the frequency of the switching signal to correspond to the voltage variation of the input power source Vi. At this time, the switching signal becomes the base driving signal of the transistor Q12 which is the main switching element through the switching controller 214 and is also applied to the PWM controller 212.

The PWM control unit 212 inputting the switching signal generates a PWM signal having a waveform as shown in FIG. 3 (b) and applies it to the base of the transistor Q13. And the duty is varied according to the voltage variation of the output detection voltage Vf2 applied from the output voltage detection unit 206. At this time, as shown in FIG. 3 (b), the duty ratio of the PWM signal is changed in the whole section of the switching signal as shown in FIG. 3 (a), that is, the section from t0 to t2 and the section from t1 'to t2'. Variable. 3 (b) shows an example of turning off from t0 to t1, turning on from t1 to t2, turning off from t2 to t1 ', and turning on from t1' to t2 '. In the description of the present invention, on means a state in which the transistor Q12 or the transistor Q13 is turned on, and off means a state in which the transistor Q12 or the transistor Q13 is turned off.

When the transistor Q12 is turned on while the high voltage power supply circuit of FIG. 2 is in normal operation, a resonance current of the capacitor C12 and the primary winding L1 of the transformer T12 is generated to the transistor Q12. This is the same operation as a normal horizontal deflection current generation. At this time, the influence by the second winding L12 of the transformer T13 becomes very small. Then, when the transistor Q12 is switched from the on state to the off state, the counter electromotive force is generated at the primary side winding L1 of the transformer T12 by the current flowing through the capacitor C12 and the primary side winding L1 of the transformer T12. The resonance current is generated in the primary winding L1 and the capacitor C13 of the capacitor C12 and the transformer T12. Accordingly, a high pulse voltage is generated at both ends of the capacitor C13. At this time, the collector of the transistor Q12 is maintained at the voltage of the input power supply Vi and the emitter of the transistor Q12 is operated by a pulse of high negative voltage, which is different from the operation of a conventional horizontal deflection pulse. same. At this time, the influence by the second winding L12 of the transformer T13 becomes very small.

As described above, when a resonant current is generated in the primary winding L1 and the capacitor C13 of the capacitor C12 and the transformer T12 and the voltage between both ends of the capacitor C13 becomes equal to or higher than the forward voltage of the diode D12, the diode D12. ) Is turned on and a resonance current of the capacitor C12 and the primary winding L1 of the transformer T12 flows through the diode D12. This is the same operation as a normal horizontal deflection current generation. In addition, the voltages of the secondary windings L2 to L5 of the transformer T12 during a period in which a resonance current is generated in the primary winding L1 and the capacitor C13 of the capacitor C12 and the transformer T12 and the pulse voltage is induced. The diodes D14 to D17 are discharged in the forward direction and rectified by the capacitor C14 to generate a high voltage output power Vo. At this time, the conduction current waveform of the primary winding L1 of the transformer T12 is as shown in Fig. 3 (c), and the induced voltage waveform of the secondary windings L2 to L5 is as shown in Fig. 3 (g).

As described above, as the transistor Q12 and the diode D12 are turned on, a resonance current is generated at the primary winding L1 of the capacitor C12 and the transformer T12, and the capacitor C12 and the transformer T12 A resonance current is generated in the primary winding L1 and the capacitor C13, and the resonance current also flows in the second winding L12 of the transformer T13, thereby controlling the resonance current flowing in the primary winding L1. Will be.

Meanwhile, as the transistor Q11 of the switching controller 214 is turned on / off by the switching signal of the FM controller 210, the transistor Q12 is equally turned on / off via the transformer T11. Accordingly, the voltage waveform of FIG. 3A is the same as the operation period of the transistor Q12. Resonant currents of the capacitor C12 and the primary winding L1 of the transformer T12 from the time t0 at which the transistor Q12 is turned on to the time t2 at which the transistor Q12 is turned off are generated through the transistor Q12 as shown in FIG. . At this time, when the transistor Q13 is turned on by the PWM signal of FIG. 3 (b) of the PWM control unit 212 in the period from the time t1 to the time t2, the input power supply is provided at both ends of the first winding L11 of the transformer T13. The voltage of Vi is applied and a charging current is generated. At this time, the voltage across each of the transistors Q12 and Q13 can be ignored. The counter current is generated in the second winding L12 by the charging current generated in the first winding L11 of the transformer T13, and thus the resonance current of the capacitor C12 and the primary winding L1 of the transformer T12. The counter electromotive current is induced to rise in combination with Accordingly, the total resonance current of the capacitor C12 and the primary winding L1 of the transformer T12 is increased as shown in FIG. 3 (c). However, in the period from the time t0 to the time t1, an organic current is generated in the first winding L11 and the diode D12 of the transformer T13 by the current of the second winding L12 of the transformer T13.

Since the transistors Q11 and Q12 are turned off in the period from the time t2 to the time t3, the resonance current of the capacitor C12 and the primary winding L1 of the transformer T12 is reduced by the capacitor C13, the capacitor C12, and the transformer. It is converted into the resonance current of the pulse voltage of the primary winding L1 of T12 and induced to the negative pulse voltage -Vp as shown in FIG. At this time, the counter electromotive force is also generated in the primary winding L1 of the transformer T12 and the second winding L12 of the transformer T13. At this time, since the number of the first windings L11 of the transformer T13 is much larger than the number of the second windings L12, a high voltage is induced in the first winding L11 of the transformer T13. Accordingly, the diode D12 is turned on and is limited to a voltage of -Vp + Vi at both ends of the first winding L11 of the transformer T13, that is, a voltage at both ends of the capacitor C13, and thus, the second winding L12 of the transformer T13. The voltage at both ends of the s) is also limited to a constant voltage by the turns ratio, and a large pulse voltage is induced at both ends of the primary winding L1 of the transformer T12. Accordingly, the voltage of the output power Vo can be obtained at a high voltage.

Next, the period from the time t3 to the time t4 is the period during which the diode D11 conducts due to the back electromotive force of the primary winding L1 of the transformer T12, and the primary winding L1 of the capacitor C12 and the transformer T12. ) Is generated by conducting the diode D11. At this time, an induced voltage is generated across the first winding L11 of the transformer T13 by the counter electromotive force of the second winding L12 of the transformer T13, and the diode D13 and the first winding L11 of the transformer T13 are generated. ) An organic current is generated.

As described above, by increasing the resonance current of the capacitor C13 and the primary winding L1 of the transformer T12 in a period from the time t1 to the time t2, the primary winding of the capacitor C12 and the transformer T12 is increased. Resonant current between L1 and transistor Q11, primary side winding of capacitor C12 and transformer T12, resonant current between L1 and capacitor C13, primary winding of capacitor C12 and transformer T12 The voltage stabilization of the output power Vo can be achieved by controlling the resonance current between the L1 and the diode D11.

Next, the operation for a period from the time t0 'to the time t4' at which the duty of the PWM signal varies is also performed as described above. However, in the period from time t0 'to time t4', when the voltage of the output power Vo decreases, the duration of the PWM signal generated by the PWM control unit 212 as the output detection voltage Vf2 detected by the output voltage detection unit 206 decreases. This example shows an increase from Td1 to TD2. In this case, as shown in FIG. 3C, the conduction current of the transformer L1 increases by ΔI and the collector current of the transistor Q11 further increases. As a result, the output power Vo becomes high, resulting in stabilization. If the voltage of the output power Vo increases, the opposite operation is performed. Accordingly, stabilization occurs even when the voltage of the output power Vo changes.

In addition, when the voltage of the input power source Vi decreases, the input detection voltage Vf1 detected by the input voltage detector 206 is lowered, and the FM controller 210 lowers the frequency of the switching signal. Then, as the on time of the transistor Q12 is longer, the voltage of the output power Vo increases as the peak current, that is, the resonance current increases. On the contrary, when the voltage of the input power source Vi is increased, the input detection voltage Vf1 detected by the input voltage detector 206 is increased, and accordingly, the FM controller 210 increases the frequency of the switching signal. Then, as the on-time of the transistor Q12 becomes shorter, the voltage of the output power Vo decreases as the resonance current decreases. As a result, stabilization occurs even when the input power source Vi varies.

Therefore, the high voltage DC output power Vo stabilized by the FM control in which the switching frequency is determined according to the voltage of the input power Vi and the PWM control in which the switching duty is determined by the voltage of the output power Vo are generated. At this time, the configuration is simpler by having a single-stage stabilization configuration without using the SMPS 102 and the voltage step-down part 104 used in the related art, whereby a large power capacity is required as the number of components is reduced. Even smaller than the conventional size. In addition, by stabilizing the output by the switching frequency and the stabilization of the output by the duty variable at the same time can be stabilized even if the variation of the input / output is large.

Meanwhile, in the above description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Particularly, in the embodiment of the present invention, the PWM control in which the switching duty is determined to correspond to the voltage level of the output power and the FM control in which the switching frequency is determined to correspond to the voltage level of the input power are applied. If this is not large, the FM control may be omitted. In this case, instead of omitting the input voltage detector 202 and the FM controller 210, a switching signal of a predetermined frequency may be applied to the transistor Q11 and the PWM controller 212. In addition, the input rectifier 200 is used when the commercial AC input power ACin is input. However, when directly inputting the DC input power Vi, the input rectifier 200 does not need to be used. Therefore, the scope of the invention should not be defined by the described embodiments, but should be defined by the equivalent of claims and claims.

As described above, the present invention has the advantage that the overall size is smaller than the conventional case even when a large power capacity is required as the configuration is simpler and the number of parts is reduced accordingly with a single-stage stabilizing configuration. In addition, by stabilizing the output by the switching frequency and the stabilization of the output by the duty variable at the same time can be stabilized even if the variation of the input / output is large.

Claims (6)

In a high voltage power supply circuit which generates a stable high voltage DC output power supply from an unstable DC input power supply, An output voltage detector for generating an output detection voltage having a level corresponding to the voltage level of the output power; A PWM control unit which is generated by varying a PWM signal having the same frequency synchronized with a switching signal of a predetermined frequency within the warm period of the switching signal with a duty corresponding to the output detection voltage variation; A switching unit for switching the primary winding of the transformer by the switching signal to induce the voltage pulse signal on the secondary winding of the transformer and varying the level of the voltage pulse signal according to the duty of the PWM signal; A first switching element connected in parallel to the primary winding of the transformer, A switching controller for switching the first switching element according to the switching signal; A diode connected in a reverse direction to the input power supply side in parallel with the first switching element; A capacitor connected in parallel with the first switching element, A capacitor connected between the input power supply side and the primary winding of the transformer; Two diodes connected in series in a reverse direction between the input power supply side and ground; A second switching element connected between the connection point between the two diodes and the ground and switched by the PWM signal; A transformer in which a connection point between the primary winding of the transformer, the first switching element and the capacitor, and a first winding are connected between the second switching element, and a second winding is connected between the first switching element; And an output rectifier for rectifying the voltage pulse signal induced in the secondary winding of the transformer to generate the output power. The high voltage power supply circuit according to claim 1, further comprising an input rectifier for rectifying commercial AC input power to provide the DC input power. In a high voltage power supply circuit which generates a stable high voltage DC output power supply from an unstable DC input power supply, An input voltage detector for generating an input detection voltage having a level corresponding to the voltage level of the input power source; An output voltage detector for generating an output detection voltage having a level corresponding to the voltage level of the output power; It has a high voltage transformer for inputting the input power to the primary side winding, and inputs the input detection voltage and output detection voltage, and variable to correspond to the frequency and the voltage change of the output power that is variable corresponding to the voltage change of the input power And a high voltage generator configured to generate and output the output power by inducing and rectifying a voltage pulse signal on the secondary side winding of the transformer by the primary side winding switching according to the duty. The method of claim 3, wherein the high voltage generating unit, An FM controller for generating a switching signal of a frequency that is variable to correspond to the voltage variation of the input power source; A PWM controller which is generated by varying a PWM signal having the same frequency synchronized with the switching signal within a warm period of the switching signal with a duty corresponding to a voltage variation of the output power; A switching unit for switching the primary winding of the transformer by the switching signal to induce the voltage pulse signal on the secondary winding of the transformer and varying the level of the voltage pulse signal according to the duty of the PWM signal; And an output rectifier for rectifying the voltage pulse signal induced in the secondary winding of the transformer to generate the output power. The method of claim 4, wherein the switching unit, A first switching element connected in parallel to the primary winding of the transformer, A switching controller for switching the first switching element according to the switching signal; A diode connected in a reverse direction to the input power supply side in parallel with the first switching element; A capacitor connected in parallel with the first switching element, A capacitor connected between the input power supply side and the primary winding of the transformer; Two diodes connected in series in a reverse direction between the input power supply side and ground; A second switching element connected between the connection point between the two diodes and the ground and switched by the PWM signal; And a transformer having a first winding connected between the primary winding of the transformer, the connection point between the first switching element and the capacitor, and the first winding connected between the second switching element, and a second winding connected between the first switching element. Power circuit. The high voltage power supply circuit according to claim 5, further comprising an input rectifier for rectifying commercial AC input power to provide the DC input power.

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