JPH077628A - High voltage generation circuit - Google Patents

Abstract

PURPOSE:To inexpensively supply a high voltage generation circuit having high voltage stability performance. CONSTITUTION:A diode 35 is connected between a switching element 32 and the primary winding wire 22 of a main transformer 21, and a diode 36 between the switching element 32 and the primary winding wire. 27 of a correction transformer 26 Resonance capacitors 33 and 34 are respectively connected to the primary winding wire 22 and the primary winding wire 27, and they are connected in such a way that power is supplied from a common DC power source 39 to the primary winding wires 22 and 27. Since resonance current is caused to flow in the transformers by the common switching element 32 and the diodes 35 and 36 interrupt mutual influence, the switching element can be shared and power can be supplied from the common DC power source to the transformers. Then, the high voltage generation circuit superior in high voltage stability performance can inexpensively be supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a high voltage generating circuit used in a CRT display or the like.

[0002]

2. Description of the Related Art A conventional high voltage generating circuit will be described below with reference to the drawings. FIG. 2 is a circuit diagram of a high-voltage generating circuit used in a conventional CRT display or the like. In FIG. 1, 1 is a main transformer, and in the main transformer 1, 2 is a primary winding, 3 is a core, 4 is a secondary winding, and 5 is a rectifying diode on the secondary side. Reference numeral 7 is an auxiliary winding for driving the switching element. Reference numeral 6 is a correction transformer for correcting the high voltage output.

In the correction transformer 6, 8 is a primary winding,
Reference numeral 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.
It is a capacitor that smoothes the voltage generated at 0.

13 is a switching element, and 14 and 15
Is a DC power supply. Reference numeral 17 is a high voltage detection resistor, and 18 is a detection circuit. Reference numeral 20 denotes a correction switching element, which performs a switching operation by the pulse voltage generated in the auxiliary winding 7. 16 is a condenser. Auxiliary winding 7
The pulse voltage generated at 1) is applied to the DC level output from the detection circuit 18, and the correction switching element 20 is turned on by the slight sinusoidal portion at the top of the pulse voltage.

Thus, conventionally, the main transformer 1 composed of 2, 3, 4, 5 and 8, 9, 10, 11, 12 are used.
And the correction transformer 6 configured by are operated by the switching element 13 and the correction switching element 20, respectively, to obtain a high voltage output.

Then, the correction switching element 20 is supplied with a flyback pulse from the auxiliary winding 7 of the main transformer 1 and conducts in a slight interval at the top of the flyback pulse. As described above, the correction switching element 2 is conventionally used.
Zero was conducting by the slight sinusoidal portion of the top of the flyback pulse to stabilize the high voltage output voltage.

[0007]

However, in such a conventional high voltage generating circuit, when the CRT display operates in synchronization with various video signals (hereinafter referred to as multi-scan operation), it is sufficient. It was difficult to generate performance. That is, the correction switching element 2
The loss of 0 changed depending on the operating frequency, and it was difficult to deal with it in a wide range. Further, the on-time of the correction switching element 20 is less than the pulse width of the flyback pulse of the main transformer 1 at the maximum, and the on-time of the correction switching element 20 cannot be lengthened, so that there is a problem that the control width is limited. Was there. Further, 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.

[0008]

In order to solve these problems, the present invention provides a first diode between a switching element and a primary winding of a main transformer, and a primary diode of the switching element and a primary transformer. A second diode is connected between each winding and a resonance capacitor is connected to each of the primary winding of the main transformer and the primary winding of the correction transformer, and a common power source is used for both primary windings of both transformers. Connected to supply power from.

The present invention has been made in view of the above problems, and shares a switching element for supplying a resonance current to a main transformer and a correction transformer, and supplies power to both transformers from a common power source. It is an object of the present invention to provide a high voltage generating circuit capable of

[0010]

With the above construction, during the ON period of the switching element, the first diode and the second diode conduct, and magnetic energy is accumulated on both the primary side of the main transformer and the correction transformer, and The potential of the secondary winding 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 resonant capacitor connected to each, and a flyback pulse is generated. The switching element that allows the resonance current to flow to the main transformer also causes the resonance current to flow to the correction transformer, and the first and second diodes block mutual effects, so that the switching element can be shared, and the main transformer and the correction transformer can be shared. Power can be supplied from a common power source.

[0011]

1 is a circuit diagram of a high voltage generating circuit according to an embodiment of the present invention. In FIG. 1, 21 is a main transformer, and in the main transformer 21, 22 is a primary winding, and 23
Is a core, 24 is a secondary winding, and 25 is a rectifying diode on the secondary side. Reference numeral 26 is a correction transformer for correcting the high voltage output. In the correction transformer 26, 27 is a primary winding and 28
Is a core, 29 is a secondary winding, 30 is a diode for rectifying the pulse voltage generated in the secondary winding 29, 31 is a secondary winding 29
This is a capacitor that smoothes the voltage generated in the.

32 is a switching element, and 33 and 34.
Is a resonant 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 7 and the cathode side of each of the two diodes 35 and 36 is connected to the switching element 32. 37 and 38 are damper diodes. 39 is a DC power supply.

Reference numeral 40 is a high voltage detecting resistor, 41 is a control circuit,
Reference numeral 42 is a transistor, which is 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.

Primary winding 22, core 23, secondary winding 24,
A main transformer 21 including a rectifying 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 according to the horizontal deflection synchronizing 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. The 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, this is detected by the high voltage detecting resistor 40, the control circuit 41 is operated, and the correction transformer 26 is operated.
Increase the input voltage of. As a result, the output of the correction transformer 26 rises and the high voltage output can be stabilized.

More specifically, during the ON period of the switching element 32, first, the diode 35 and the diode 36 become conductive, and magnetic energy is stored in the primary side of the two transformers (21, 26).

When the switching element 32 is turned off, the primary winding (22, 2) of each transformer (21, 26) is turned on.
LC resonance occurs between 7) and the resonance capacitor (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 6 side, LC resonance is started by the primary winding 27 and the resonance capacitor 34, and flyback pulses are generated respectively. Therefore, the voltage Vb at the point b and the voltage Vc at the point c instantaneously increase.

Even if a voltage such that Vb> Vc, Vc> Vb is generated with the passage of time, since the circuits are cut off by the diodes 35 and 36, the respective transformers (21, 2) are
It does not affect 6). 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.

[0021]

According to the present invention, in the 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.
By connecting resonant capacitors to the primary winding of the main transformer and the primary winding of the correction transformer, and connecting the primary windings of both transformers so that power is supplied from a common power source, Since it is possible to use only one switching element for supplying a resonance current to the correction transformer, and since power can be supplied from a common power supply to the main transformer and the correction transformer, only one power supply is required. Furthermore, 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-voltage stabilization performance can be realized.

[Brief description of 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 generation circuit.

[Explanation of symbols]

 21 Main Transformer 22 Primary Winding 24 Secondary Winding 25 Rectifying Diode 26 Correction Transformer 27 Primary Winding 29 Secondary Winding 32 Switching Element 33, 34 Resonance Capacitor 35 Diode 36 Diode 39 DC Power Supply 41 Control Circuit 42 Transistor

Claims (2)

[Claims] 1. A main transformer and an auxiliary transformer for high-voltage output correction, wherein a first diode is connected between a switching element and a primary winding of the main transformer, and the switching element and the correction are provided. A second diode is connected between the primary winding of the transformer and resonant capacitors are connected to the primary winding of the main transformer and the primary winding of the correction transformer, and the primary windings of both transformers are connected. A high-voltage generation circuit characterized in that it is connected so as to supply electric power to a line from a common power source. 2. The high voltage generating circuit according to claim 1, wherein cathode sides of the first and second diodes are connected to a switching element, and anode sides of the diodes are connected to a main transformer and an auxiliary transformer, respectively. .