KR19980082271A - Flyback transformer with diode protection during discharge - Google Patents

Abstract

The present invention relates to a flyback transformer that provides various voltages to large CRTs, CRTs, and the like. In particular, the present invention relates to a diode protection function for preventing a rectifying diode from being destroyed by an instantaneous discharge of an anode voltage. It relates to a flyback transformer provided.

When the anode voltage discharges inside the tube, the discharge voltage is a pulsed AC component whose magnitude rises rapidly and falls momentarily, and this discharge voltage is conventionally used in sequence of the focus voltage output stage, the bypass capacitor, and the capacitor in the set. In the present invention, the flyback transformer is lost due to the breakdown of the rectifying diode through the ABL stage, and the flyback transformer loses its function. However, in the present invention, a resistance is coupled between the bypass capacitor and the ground, and the magnitude of the resistance is discharged. By setting the voltage to such a degree that the voltage can be sufficiently reduced, the discharged voltage through the focus voltage output terminal and the bypass capacitor, and then at the discharge voltage blocking resistor R4 is significantly reduced to prevent the diode from being destroyed. will be.

Description

Flyback transformer with diode protection during discharge

The present invention relates to a flyback transformer that provides various voltages to large CRTs, CRTs, and the like. In particular, the present invention relates to a diode protection function for preventing a rectifying diode from being destroyed by an instantaneous discharge of an anode voltage. It relates to a flyback transformer provided.

In general, a flyback transformer having a double focus unit is used to supply a high voltage (approximately 30 kV) to a large CRT anode such as a CRT tube for a TV and a CRT tube for a CAD, and to provide a double focus (3 kV) and a screen voltage. do.

A schematic circuit diagram of such a conventional flyback transformer is shown in FIG. 1. Referring to FIG. 1, the flyback transformer is a primary coil L1 of a flyback transformer. The pulse generated at the collector side of the horizontal output transistor during the operation of the horizontal output transistor inside the horizontal output unit 10 by the power applied to the secondary coil (L2) from the primary coil (L1) of the flyback transformer Organic).

The voltage induced in the secondary coil L2 is rectified by the high-voltage rectifier diodes D1 to DN, and then, first, an anode voltage VA is provided to the anode of the CRT, and a voltage division resistor included in the focus unit. The focus voltages VF1 and VF2 and the screen voltage VS are supplied by R11, R12, R21, R22, VR11, VR21, R3, and VR3, respectively.

Meanwhile, in FIG. 1, the coupling capacitor C1 serves to provide an AC component included in the focus voltage to the parabola circuit, and the bypass capacitor C2 bypasses the AC signal included in the focus voltage to ground. Function to pass.

In such a conventional flyback transformer, when the high-voltage anode voltage of about 30 KV discharges momentarily to the focus voltage output terminal (VF1 or VF2) (also called in-tube discharge), the discharge voltage instantly bounces to about 30 KV. There is a problem such as through the bypass capacitor (C2) and the condenser (C3) in the set and then introduced into the diode along the ABL stage, the diode is destroyed.

The present invention has been made to solve the above problems.

Accordingly, an object of the present invention is to provide a flyback transformer having a diode protection function during an in-discharge discharge to prevent the rectified diode from being destroyed by an instantaneous discharge of the anode voltage.

It is another object of the present invention to provide a stronger flyback transformer for high pressure discharge.

1 is an internal circuit diagram of a conventional flyback transformer.

2 is an internal circuit diagram of a flyback transformer according to the present invention.

Explanation of symbols on the main parts of the drawings

10: horizontal output unit 20: flyback transformer

L1: Primary Coil L2: Secondary Coil

FC: Iron core D1 to DN: High pressure rectifier diode

R11, R12, R21, R22, R3: Resistor VR11, VR21, VR3: Variable resistor

C1: Coupling Capacitor C2: Bypass Capacitor

VA: Anode Voltage VF1, VF2: Focus Voltage

VS: Screen Voltage VP: Parabola Input Voltage

R4: Discharge high voltage blocking resistor

As a technical means for achieving the above object of the present invention, the flyback transformer of the present invention is voltage-converted from the primary coil to the secondary coil, and then supplies the anode voltage through the high-voltage rectifier diode, the secondary coil A flyback transformer comprising a bypass capacitor for dividing a voltage rectified from an intermediate tap of a predetermined size in a double focus unit to supply a focus voltage and a screen voltage, and bypassing an AC component of the focus voltage to ground. Through the focus voltage output terminal and the bypass capacitor, and through the capacitor between the ground and the ABL terminal in the set, the discharge voltage between the bypass capacitor and the ground to cut the high-voltage discharge voltage flowing into the rectifying diode after picking up the ABL terminal It is characterized by including a resistance for blocking.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the flyback transformer according to the present invention will be described in detail. In the drawings referred to in the present invention, components having substantially the same configuration and function will use the same reference numerals.

FIG. 2 is an internal circuit diagram of the flyback transformer according to the present invention. Referring to FIG. 2, the flyback transformer 20 shown in FIG. 2 is induced by the horizontal output unit 10 by the applied power. Primary and secondary coils L1 and L2 for transforming, High voltage rectifying diodes D1 to DN for rectifying the induced pulse to provide an anode voltage, and an intermediate tap MT of the secondary coil L2. And a double focus unit for variably dividing the voltage from the predetermined size to provide the focus voltages VF1 and VF2 and the screen voltage VS.

The double focus unit includes voltage divider circuits R11, R12, R21, R22, VR11, and VR21 (R3, VR3), and an intermediate tap MT and a voltage divider resistor circuit of the primary coil L1. A coupling capacitor C1 is connected between the contact of the parabolic circuit and the input terminal of the parabola circuit to provide an AC component in the focus voltage VF to the parabola circuit, and to supply the AC component of the focus voltage to ground. The bypass capacitor C2 to pass is comprised.

Through the focus voltage (VF) output terminal and the bypass capacitor (C2), through the condenser (C3) between the ground and the ABL terminal in the set, and after the ABL terminal to cut off the high voltage discharge voltage flowing into the rectifying diode (DN). The discharge voltage blocking resistor R4 is formed between the bypass capacitor C2 and the ground.

Here, RB, which is not described in the drawings, is a breather resistor, CH is a high voltage smoothing capacitor, and ABL is an abbreviation of Auto Beam Current Limiter or Auto Bright Limiter, which is a circuit block for detecting screen brightness and controlling screen voltage.

Operation according to the flyback transformer of the present invention configured as described above will be described in detail below based on the accompanying drawings.

Referring to the flyback transformer according to the present invention with reference to FIG. 2, the power supply voltage B + applied to the primary coil L1 of the flyback transformer 20 shown in FIG. The pulse generated at the output unit 10 is induced from the primary coil L1 to the secondary coil L1 of the flyback transformer 20. Pulses induced in the secondary coil L2 of the flyback transformer 20 are rectified by the high-pressure rectifier diodes D1-DN. An anode voltage VA of about 30 KV rectified by the high voltage rectifying diode is provided to the anode of the water pipe, and the voltage from the middle tap MT of the secondary coil L2 is included in the double focus unit. It is divided by voltage division resistor circuits R11, R12, R21, R22, VR11, and VR21 (R3, VR3) and provided to the focus voltages VF1 and VF2 and the screen voltage VS of the CRT.

The AC component included in the focus voltage is piped to the ground by the bypass capacitor C2 to provide a more stable focus voltage, and the coupling capacitor C1 of the focus voltage output terminal converts the AC component of the focus voltage into a parabola circuit. To provide.

On the other hand, when the anode voltage discharges in the tube, the discharge voltage is a pulsed AC component whose magnitude rises and falls momentarily rapidly. As described above, the discharge voltage is conventionally used as the focus voltage (VF1, VF2). The output stage, bypass capacitor (C2), and condenser (C3) in the set are sequentially passed through the ABL stage to the rectifying diode (DN), and the rectifying diode (DN) is destroyed, causing the flyback transformer to lose its function. It became.

However, in the present invention, the resistor R4 is coupled between the bypass capacitor C2 and the ground, and the size of the resistor R4 is set to such an extent that the discharge voltage can be sufficiently reduced, thereby providing the focus voltage VF1. The magnitude of the discharged voltage through the output terminal and the bypass capacitor C2 and then at the discharge voltage blocking resistor R4 is significantly reduced.

Thus, the discharge voltage of which the magnitude is reduced is different from the pulsed voltage before the reduction, so that the DC component is strong, so that the inflow into the ABL stage is suppressed through the condenser in the set, and the discharge voltage having the reduced magnitude flows into the ABL stage. Even though the size is significantly reduced, the rectifier diode is not destroyed by the discharge voltage.

According to the present invention as described above, the rectifying diode is prevented from being destroyed by the instantaneous discharge of the anode voltage, so that the flyback transformer is more stable against the discharge in the tube.

The above description is only a description of one embodiment of the present invention, the present invention is capable of various changes and modifications within the scope of the configuration. In addition, one of ordinary skill in the art will readily recognize that the flyback transformer having a capacitor protection function during discharge in a tube is not limited to the above-described embodiment.

Claims (1)

After voltage conversion from the primary coil L1 to the secondary coil L2, the anode voltage VA is supplied through the high voltage rectification diodes D1 to DN, and rectified from the intermediate tap MT of the secondary coil. The divided voltage is divided into a predetermined size in a double focus unit to supply the focus voltages VF1 and VF2 and the screen voltage VS, and a bypass capacitor C2 for bypassing the AC component of the focus voltage to ground. In flyback transformer, Through the focus voltage (VF) output terminal and the bypass capacitor (C2), through the condenser (C3) between the ground and the ABL terminal in the set, and after the ABL terminal to cut off the high voltage discharge voltage flowing into the rectifying diode (DN). And a discharge voltage blocking resistor (R4) provided between the bypass capacitor (C2) and the ground.