JP3389635B2 - High voltage generation circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a high-voltage generating circuit used for a CRT display or the like. 2. Description of the Related Art A conventional high voltage generating circuit will be described with reference to the drawings. FIG. 2 is a circuit diagram of a high-voltage generation circuit conventionally used for a CRT display or the like. In FIG. 2 , 1 is a main transformer. In the main transformer 1, 2 is a primary winding, 3 is a core, 4 is a secondary winding, and 5 is a rectifier diode on the secondary side. Reference numeral 7 denotes an auxiliary winding for driving the switching element. Reference numeral 6 denotes a correction transformer for correcting a high voltage output. In the correction transformer 6, 8 is a primary winding,
9 is a core, 10 is a secondary winding, 11 is a diode for rectifying a pulse voltage generated in the secondary winding 10, and 12 is a secondary winding 1
This is a capacitor for smoothing the voltage generated at zero. [0004] 13 is a switching element, 14 and 15
Is a DC power supply. Reference numeral 17 denotes a high-voltage detection resistor, and reference numeral 18 denotes a detection circuit. Reference numeral 20 denotes a switching element for correction, which performs a switching operation by a pulse voltage generated in the auxiliary winding 7. 16 is a condenser. Auxiliary winding 7
Is applied to the DC level output from the detection circuit 18, and the correction switching element 20 is turned on by a slight sinusoidal portion at the top of the pulse voltage. As described above, conventionally, the main transformer 1 composed of 2, 3, 4, 5 and 8, 9, 10, 11, 12
Are operated by the switching element 13 and the correction switching element 20, respectively, to obtain a high voltage output. The correction switching element 20 is supplied with a flyback pulse from the auxiliary winding 7 of the main transformer 1, and is turned on in a small section at the top of the flyback pulse. As described above, conventionally, the correction switching element 2
0 stabilized the high output voltage by conducting through a slight sinusoid at the top of the flyback pulse. However, in such a conventional high-voltage generating circuit, when a CRT display operates recently in synchronization with various kinds of video signals (hereinafter, referred to as a multi-scan operation). It was difficult to generate sufficient performance. That is, the correction switching element 2
The loss of 0 varies depending on the operating frequency, making it difficult to cope with a wide range. In addition, the ON time of the correction switching element 20 is at most less than the pulse width of the flyback pulse of the main transformer 1, and the ON time of the correction switching element 20 cannot be lengthened. I was In addition, the DC power supply 14 for the main transformer and the DC power supply 15 for the correction transformer are separately required, which increases the cost. According to the present invention, to solve these problems, a first diode is provided between a switching element and a primary winding of a main transformer, and the switching element and a correction transformer are provided. A second diode is connected between each of the primary windings, and a resonance capacitor is connected to each of the primary winding of the main transformer and the primary winding of the correction transformer. When connected so that power is supplied from a common power supply and the switching element is turned off
The resonance current flows to the main transformer and the high output voltage
In response, a resonance current is also supplied to the correction transformer to generate a pulse voltage.
It has a configuration for generating . SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a switching element for flowing a resonance current to a main transformer and a correction transformer, and supplying power from a common power supply to both transformers. It is an object of the present invention to provide a high-voltage generating circuit capable of performing the following. With the above configuration, during the ON period of the switching element, the first diode and the second diode conduct, and magnetic energy is accumulated in both the primary side of the main transformer and the primary side of the correction transformer. The potential of the primary winding of the transformer and the potential of the primary winding of the correction transformer rise. When the switching element is turned off, LC resonance is started by the primary winding of each transformer and the resonance capacitor connected to each, and a flyback pulse is generated. The switching element that flows the resonance current to the main transformer also allows the resonance current to flow to the correction transformer, and the first and second diodes block the mutual influence. Therefore, the switching element can be shared, and the main transformer and the correction transformer can be used. Can be supplied from a common power supply. Further correction
The switching-on time for the transformer is
Switch-on time for
Can be. FIG. 1 is a circuit diagram of a high voltage generating circuit according to an embodiment of the present invention. In FIG. 1, reference numeral 21 denotes a main transformer. In the main transformer 21, reference numeral 22 denotes a primary winding;
Is a core, 24 is a secondary winding, and 25 is a rectifier diode on the secondary side. 26 is a correction transformer for correcting high voltage output. In the correction transformer 26, 27 is a primary winding, 28
Is a core, 29 is a secondary winding, 30 is a diode for rectifying a pulse voltage generated in the secondary winding 29, and 31 is a secondary winding 29
This is a capacitor for smoothing the voltage generated in. 32 is a switching element, and 33 and 34
Is a resonance capacitor. A diode 35 is provided between the switching element 32 and the primary winding 22 of the main transformer 21.
The switching element 32 and the primary winding 2 of the correction transformer
A diode 36 is inserted between the switching elements 7, and the two diodes 35 and 36 have their cathodes connected to the switching element 32. 37 and 38 are damper diodes. 39 is a DC power supply. 40 is a high-voltage detecting resistor, 41 is a control circuit,
Reference numeral 42 denotes transistors, which are provided for adjusting the output voltage. When the transistor 42 is turned on, the DC power supply 39 is applied to the primary winding 27 of the correction transformer 26 to generate a pulse voltage. The primary winding 22, the core 23, the secondary winding 24,
A main transformer 21 including a rectifier diode 25, a primary winding 27, a core 28, a diode 30, a capacitor 31,
The correction transformer 26 including the secondary winding 29 shares the switching element 32. The main transformer 21 and the correction transformer 26 also share a DC power supply 39. The outline of the operation will be described below. The switching element 32 performs a switching operation by a horizontal deflection synchronization signal. Due to this switching operation, the current in the primary winding 22 of the main transformer 21 is interrupted, and a very high pulse voltage is generated in the secondary winding 24. This pulse voltage is rectified by the rectifier diode 25, and a DC high-voltage output voltage is obtained. When the output voltage of the main transformer 21 changes due to a load change or the like, the change is detected by the high-voltage detecting resistor 40, and the control circuit 41 is operated.
To increase the input voltage. As a result, the output of the correction transformer 26 rises, and the high-voltage output can be stabilized. More specifically, when the switching element 32 is on, the diode 35 and the diode 36 are turned on, and magnetic energy is stored on the primary side of the two transformers (21, 26). When the switching element 32 is turned off, the primary windings (22, 2) of the respective transformers (21, 26)
LC resonance occurs between 7) and the resonance capacitors (33, 34). That is, on the transformer 21 side, LC resonance is started by the primary winding 22 and the resonance capacitor 33, and the transformer 2
On the sixth side, LC resonance is started by the primary winding 27 and the resonance capacitor 34 to generate flyback pulses. Therefore, the voltage Vb at the point b and the voltage Vc at the point c increase instantaneously. Even if a voltage such that Vb> Vc and Vc> Vb is generated with the passage of time, since the circuit is cut off by the diodes 35 and 36, the respective transformers (21, 2)
6) is not affected. Therefore, even if the voltage supplied from the DC power supply 39 to the correction transformer 26 for adjusting the output voltage is changed by the transistor 42, the main transformer 21 is not affected. According to the present invention, in a high voltage generating circuit,
A first diode is connected between the switching element and the primary winding of the main transformer, and a second diode is connected between the switching element and the primary winding of the correction transformer, respectively.
Resonant capacitors are connected to the primary winding of the main transformer and the primary winding of the correction transformer, respectively, and the primary windings of both transformers are connected so that power is supplied from a common power supply. It is possible to use a single switching element for supplying a resonance current to the correction transformer, and power can be supplied from a common power supply to the main transformer and the correction transformer, so that only one type of power supply is required. Further, the switching-on time for the correction transformer can be made the same as the switching-on time for the main transformer, and high-performance high-pressure stabilization performance can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a high-voltage generating circuit according to an embodiment of the present invention. FIG. 2 is a circuit diagram of a conventional high-voltage generating circuit. Secondary winding 25 Rectifier diode 26 Correction transformer 27 Primary winding 29 Secondary winding 32 Switching element 33, 34 Resonant capacitor 35 Diode 36 Diode 39 DC power supply 41 Control circuit 42 Transistor

Claims (1)

(57) [Claims] [Claim 1] A main transformer and a high-voltage output of the main transformer
When the voltage changes, the DC power supply is turned on based on the high-voltage output voltage.
To generate a pulse voltage on the primary side, and from this secondary side
And a correction transformer for correcting the high-voltage output voltage with the output of the switching element. A first diode is connected between the switching element and the primary winding of the main transformer, and the switching element and the primary winding of the correction transformer are connected. A second diode is connected between the first diode and the second diode.
The cathode side of the anode is connected to the switching element,
And the anode side is the main transformer and the auxiliary transformer, respectively.
It is connected to a lance, connected to provide power from the DC power supply to both of the primary winding of the transformer with connecting each resonant capacitor to the primary winding of the correction transformer and the primary winding of the main transformer And the switching element
When turned off, a resonance current flows through the main transformer.
In addition, the correction transformer is also shared according to the high-voltage output voltage.
A high-voltage generating circuit for generating the pulse voltage by passing a vibration current .