KR950003228Y1 - Abnormal votage protecting circuit - Google Patents

Abstract

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Description

Abnormal high voltage prevention circuit of TV

1 is a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

10: synchronization generating unit 20: horizontal driving unit

30: amplifier 40: high voltage stability circuit

Q1: Transistor C1-C3: Capacitor

R1-R8: resistor D1-D5: diode

ZD: Zener Diode

The present invention relates to a horizontal deflection circuit in a television, and more particularly to a circuit for preventing abnormal high voltage generation.

Generally, a television uses a cathode ray tube (CRT) to display a screen, and the cathode ray tube generates an electron beam to scan in the horizontal and vertical directions of the screen. At this time, the electron beam scanning point on the screen is changed by the horizontal deflection circuit and the vertical deflection circuit, and during deflection, the deflection voltage has a high voltage having a constant voltage level width. Therefore, the horizontal deflection circuit must generate a high voltage at a prescribed level, and for this purpose, an abnormal high voltage prevention circuit is provided. However, the conventional abnormal high voltage prevention circuit included in the horizontal deflection circuit has a problem in that its configuration is complicated and power consumption is high because the reference voltage for abnormal high voltage detection is high.

Accordingly, an object of the present invention is to provide an abnormal high voltage prevention circuit that can simplify the circuit configuration and reduce power consumption in a television.

Hereinafter will be described in detail with reference to the present invention.

1 is a circuit diagram of the present invention, in which a horizontal synchronizing signal is generated for a horizontal deflection by a synchronizing generator 10 generating a horizontal vertical synchronizing synchronizing signal and a horizontal vertical synchronizing synchronizing signal supplied from the synchronizing generating unit 10. Amplification consisting of a transistor (Q1), diode (D1) and a capacitor (C1) to amplify the horizontal drive unit 20 and the horizontal deflection sawtooth wave signal output from the horizontal drive unit 20 at a constant amplification rate. Flyback consisting of the primary and secondary coils (L1, L2) and auxiliary coils (L3) to boost the output of the amplification unit (30) and the amplification unit (30) to a horizontal deflection coil of the cathode ray tube. A high voltage stability circuit 40 for stably supplying a bias bias high voltage B + to one of the transformer FBT and the primary coil L1 of the flyback transformer FBT, and an operating voltage Vcc. In order to supply the synchronization generator 10 with a predetermined abnormal high pressure detection standard by dividing the pressure. A reference level setting means comprising a diode (D) resistor (R1) and a diode (D2) and a capacitor (C2) for rectifying and smoothing the sustain voltage induced on the auxiliary coil (L3) of the flyback transformer (FBT). The rectifier smoothing means and the output of the rectifying smoothing means are divided by a constant partial pressure ratio to the four resistors (R2-R5) and one capacitor (C3) for supplying to the synchronization generating unit 10 as a voltage state signal. It consists of a voltage dividing means.

With reference to FIG. 1, the present invention will be described in detail.

The synchronizing generator 10 generates a synthetic synchronizing signal obtained by synthesizing the horizontal and vertical synchronizing signals, and supplies the synchronizing signal to the horizontal driving unit 20. The horizontal driving unit 20 is the horizontal synchronizing signal supplied from the synchronizing unit 10. The synchronization signal is separated and supplied to the base of the transistor Q1. Transistor Q1 amplifies the horizontal synchronous signal drawn from the horizontal driver 20 and supplies it to one tap of the primary coil L1 of the flyback transformer FBT, wherein the diode D1 provides a damper function. The capacitor C1 serves as a resonant capacitor.

And the flyback transformer (FBT) is a cathode ray tube by inducing a bias voltage on the secondary side coil (L2) when the current path for the bias bias high voltage (B +) supplied to the primary coil (L1) is formed by the horizontal synchronizing signal. It is supplied to the deflection coil of, while the auxiliary coil (L3) is induced a voltage proportional to the deflection voltage induced in the secondary side coil.

If the abnormal high voltage state is a high voltage is induced on the auxiliary coil (L3). The diode D2 rectifies the voltage on the auxiliary coil L3 of the flyback transformer FBT, and the capacitor C2 smoothes the voltage on the auxiliary coil L3 rectified together with the diode D2.

In addition, the three resistors R2-R4 divide the voltage rectified and smoothed by the diode D2 and the capacitor C2 and supply them to the synchronization generator 10 through the resistor R5 as an abnormal high voltage detection signal. . At this time, resistor R5 is for current limiting and capacitor C3 is for noise elimination. The zener diode ZD limits the operating voltage Vcc supplied through the resistor R1 to its own operating voltage VZD and stably supplies the reference voltage for detecting the abnormal high voltage.

The diodes D3-D5 inserted in the secondary coil of the flyback transformer FBT are used to prevent current direction and counter electromotive force, and the resistors R6-R7 are used to limit current.

Then, the synchronization generating unit 10 normalizes the generation of the synthetic synchronous signal in the abnormal high voltage state when a voltage greater than the abnormal voltage detection reference voltage set by the zener diode ZD is drawn through the resistor R5. Suspend until voltage is restored.

As described above, the present invention has the advantage of preventing abnormal high voltage conditions and reducing the power consumption by performing abnormal high voltage detection at a low voltage level.

Claims (1)

In a television having a cathode ray tube, a horizontal synchronizing signal for horizontal deflection by a synchronizing generator 10 for generating a horizontal vertical synchronizing synchronizing signal and a horizontal vertical synchronizing synchronizing signal supplied from the synchronizing generator 10. Amplification consisting of a transistor (Q1), diode (D1) and a capacitor (C1) to amplify the horizontal drive unit 20 and the horizontal deflection sawtooth signal output from the horizontal drive unit 20 at a constant amplification factor. Flyback consisting of the primary and secondary coils (L1, L2) and auxiliary coils (L3) to boost the output of the amplification unit (30) and the amplification unit (30) to a horizontal deflection coil of the cathode ray tube. A high voltage stability circuit 40 for stably supplying a bias bias high voltage B + to one of the transformer FBT and the primary coil L1 of the flyback transformer FBT, and an operating voltage Vcc. Partial pressure is applied to the synchronization generating unit 10 to supply a constant abnormal pneumatic detection standard A reference level setting means composed of a zener diode (ZD) resistor (R1) and a diode (D2) and a capacitor (C2) for rectifying and smoothing the sustain voltage induced on the auxiliary coil (L3) of the flyback transformer (FBT). Four resistors (R2-R5) and one capacitor (C3) for dividing the output of the rectifying smoothing means at a constant partial pressure ratio and supplying them to the synchronization generating unit 10 as voltage state signals. Abnormal high voltage prevention circuit, characterized in that consisting of a voltage divider.