KR960007539B1 - Horizontal output circuit of monitor - Google Patents

Abstract

The horizontal output circuit of a monitor comprises: a horizontal oscillating section for generating pulses by an oscillator; a first field effect transistor connected to the output of the horizontal oscillating section with its gate, grounded at its source, and switched on/off based on the output waveform of the horizontal oscillating section; a photo coupler connected to the output of the horizontal oscillating section and for introducing the output waveform of the horizontal oscillating section to a secondary stage; and a second field effect transistor connected to the secondary stage of the photo coupler with its gate, connected to the drain of the first field effect transistor with its source, connected to a horizontal deflection yoke with its drain, and switched on/off by a voltage introduced to the secondary stage of the photo coupler and a synthesized voltage applied to the drain of the first field effect transistor, so as to supply a voltage to the deflection yoke.

Description

Horizontal output circuit of monitor

1 is a horizontal output circuit diagram of a conventional monitor.

2 is a horizontal output circuit diagram of a monitor according to the present invention.

FIG. 3 is a waveform diagram showing an operating state of each part of FIG.

* Explanation of symbols for main parts of the drawings

10: horizontal oscillation unit 30: optocoupler

20,40: Field effect transistor driving IC C1 ~ C5: Capacitor

R1; Resistance D1 ~ D4: Diode

L1: Horizontal deflection coil L2: Horizontal deflection yoke

L3: Horizontal linearity correction coil FET1, FET2: Field effect transistor

The present invention relates to a horizontal output circuit of a monitor. More specifically, the monitor horizontally uses two Field Effect Transistors (hereinafter referred to as FETs) in series so as to be suitable for a large current and voltage. Relates to an output circuit

In general, the horizontal frequency increases (120 kHz or more) as the resolution of the monitor increases (e.g. 2000 pixels X 2000 lines), so that devices in horizontal output circuits also require large currents, high voltages, and fast rise / fall times. have.

1 is a horizontal output circuit diagram of a conventional monitor.

In FIG. 1, the output waveform of the horizontal oscillator 10 is applied to the horizontal drive transistor FET1 and excited and then applied to the base of the horizontal output transistor Q1 through the horizontal output transistor T1.

In addition, voltage and current flow through the collector of the transistor Q1 by turning the horizontal output transistor Q1 on and off. The current and voltage at this time should be used within the specifications of transistor Q1.

Then, the voltage and current flowing through the collector are applied to the horizontal deflection yoke L2 to form scanning lines from left to right on the screen of the monitor.

At this time, since the CRT surface is curved and the distance from the electron gun to the screen is different, the linearity correction coil L3 and the S-correction capacitor C2 are used to correct the linearity of the screen.

R1, which is not mentioned in FIG. 1, is a load resistor, L1 is a horizontal deflection coil, C1 is a resonant capacitor, and D1 is a damping diode.

On the other hand, to design ultra-high resolution (e.g., 20A, 2000V) horizontal output circuits such as medical devices, devices with high voltage, high current, and high switching time are required.

Therefore, although the specification of the horizontal output transistor Q1 should be increased, the horizontal output transistor Q2 has a problem of failing to construct an output circuit of 20A, 2000V or more because 15A and 1500V are the best specifications.

In addition, since the transistor Q1 is controlled by a current, there is a difficulty in supplying a large current to the base of the transistor Q1. Also, since the transistor Q1 has a slow switching time, a fast rise / fall time is required. It was not appropriate in the circuit.

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and an object of the present invention is to form a horizontal output circuit by connecting several FETs in series, which are eliminated by voltage and have a fast switching time, so that a large amount of current and a high voltage and a rapid rise / The present invention provides a horizontal output circuit of a monitor that is suitable for an ultra high resolution monitor requiring a fall time.

The horizontal output circuit of the monitor according to the present invention for achieving the above object is a horizontal oscillator for generating and outputting a pulse wave by the oscillator, the gate end is connected to the output terminal of the horizontal oscillator and the source end is grounded A first FET which is turned on / off according to the output waveform of the horizontal oscillator, an optical coupler connected to an output terminal of the horizontal oscillator to maintain the output waveform of the horizontal oscillator on the secondary side, and a gate is connected to the secondary side of the optical coupler The source terminal is connected to the drain terminal of the first FET, and the drain terminal is connected to the horizontal deflection yoke to be turned on / off by the combined voltage of the voltage induced on the secondary side of the optocoupler and the voltage applied to the drain terminal of the first FET. It consists of a second FET which supplies a voltage to the deflection yoke.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, a preferred temporary example of a horizontal output circuit of a monitor according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a horizontal output circuit diagram of a monitor according to the present invention.

In FIG. 2, a first FET driving IC 20 for turning on / off a first FET 1 is connected to an output terminal of the horizontal oscillator 10 and at the same time, a second FET 2 is connected through an optocoupler 30. The second FET driving IC 40 to turn on / off is connected.

In this case, the optocoupler 30 is divided into a light emitting unit 31 and a light receiving unit 32. The light emitting unit 31 compares an output signal of the horizontal oscillator 10 with a reference voltage to amplify and output the first amplification. It consists of a part OP1 and a light emitting diode LED1. In addition, the light receiving unit 32 may include a second amplifier OP2 that amplifies a voltage applied according to an operation of the light receiving diode LED2 and the light receiving diode LED2 that are turned on / off according to the light emission of the light emitting diode LED1. And a third FET and a fourth FET connected to the second amplifier OP2.

At this time, the source terminal of the third FET and the drain terminal of the fourth FET are connected to each other, and an output signal is transmitted to the second FET driving IC 40 through the connection point.

In this case, the first and second FET driving ICs 20 and 40 serve as amplification and buffers to the applied power.

In addition, a resistor R1, a zener diode D1, and a diode D2 are connected between the light receiving unit of the optocoupler 30 and the power supply 12V to maintain the voltage of the light receiving unit 30 at a predetermined voltage. do

At this time, the diode D2 is turned off when a high voltage is applied to the source side of the second FET2 so as not to affect the power supply 12V, thereby preventing damage to a component using the power supply 12V.

In addition, a horizontal deflection coil L1 is connected between the drain side of the second FET2 and the power supply B + terminal.

Resonant capacitors C3 and C4 and damping diodes D3 and D4 are connected to the first and second FETs FET1 and FET2 in parallel, and a horizontal deflection yoke L2 and a horizontal linear correction coil ( L3) and the S-correction capacitor C3 are connected.

3 is an operation waveform diagram of each part of FIG. 2, and FIG. 4 (a) is an output waveform diagram of the horizontal oscillator 10, and FIG. 3 (b) is an output waveform diagram of the FET driver IC 20. FIG. 3C is a voltage waveform diagram showing the drain side of the first FET FET1, and FIG. 3D is a voltage waveform diagram showing the drain side of the second FET FET2.

The present invention configured as described above has a first FET whose output waveform from the horizontal oscillator 10 as shown in FIG. 3 (b) is a horizontal output FET as shown in FIG. 3 (b) directly through the first FET driver IC 20 ( It is applied to the gate of FET1, and the waveform shown in FIG. 3 (C) appears on the drain side of the first FET.

Since the drain side of the first FET 1 and the source side of the second FET 2 are connected, the high voltage appearing at the drain side of the first FET 1 is again received by the light-receiving side and the second ET of the optocoupler 30. It is fed back to the driving IC 40.

The output waveform from the horizontal oscillator 10 as shown in FIG. 3A is transmitted to the light emitting part of the optocoupler 30, amplified at the light receiving part, and applied to the second FET driving IC 40.

Therefore, the voltage applied to the gate of the second FET (FET2) through the second FET driving IC 40 is a voltage obtained by combining the voltage waveform of FIG. 3 (C) with the voltage waveform of FIG.

In addition, for the FET to operate, the gate side voltage must be at least 10V to 20V higher than the source side voltage. At this time, since the drain side of the first FET FET1 and the source side of the second FET FET2 are connected, the second FET FET2 must operate higher than the high voltage shown on the drain side of the first FET FET1.

Therefore, on the drain side of the second FET FET2, a very high voltage waveform as shown in FIG. That is, if the voltage on the drain side of the first FET FET1 is about 900V, the voltage on the drain side of the second FET FET2 is about 1800V.

For example, if the specifications of the first and second FETs FET1 and FET2 are 20A and 1000V, output voltages of 20A and 2000V can be obtained by the direct connection of the first and second FETs FET1 and FET2.

As shown in FIG. 3 (d), when a very large voltage shown on the grain side of the second FET 2 is applied to the horizontal deflection yoke L2, a large current flows to the horizontal deflection yoke L2, and thus the screen of the monitor is horizontal. Scan lines are formed from left to right.

On the other hand, the optocoupler 30 is used to maintain insulation so that the horizontal oscillator 10 does not have a high voltage fed back from the drain side of the first FET1.

In addition, the output waveform of the horizontal oscillation unit 10 provided to the light emitting unit 31 side of the optocoupler 30 is induced on the light receiving unit 32 side and applied to the second FET driving IC 40. In this case, the voltage of the light emitting unit 31 side of the optocoupler 30 may be 5 V directly, and the voltage of the light receiving unit 32 side may be 5.1 V due to the zener diode D1, the diode D2, and the resistor R1. Approved to be authorized.

Here, the zener diode D1 is a voltage control element for maintaining a constant voltage and has a breakdown voltage of 5.1B.

The power supply of the first FET driving IC 20 is directly applied at 12V, and the power supply of the second FET driving IC 30 is applied with 12V through the diode D2.

Therefore, when power is supplied, since the diode D2 is in the forward direction, the second FET driving IC 40 is provided with 12V through the diode D2. However, when the high voltage applied to the source side of the second FET2 is fed back to the diode D2, the diode D2 is turned off to prevent breakage of components using the 12V. That is, without the diode D2, since high voltage is applied instead of 12V to the parts using 12V, most of the parts are damaged.

In addition, the first and second FET driving ICs 20 and 30 are connected to a large-capacity FET front end. In the present invention, the first and second FETs FET1 and FET2 do not affect the horizontal oscillator 10. Used to not. In addition, the first and second FET driving ICs 20 and 40 serve as amplification and buffers according to power applied to the first and second FET driving ICs 20 and 40.

On the other hand, since the CRT surface is curved and the distance from the electron gun to the screen is different, the linearity preservation coil L3 and the S-correction capacitor C5 are used to correct the linearity of the screen.

As described above, according to the horizontal output circuit of the monitor according to the present invention, instead of a horizontal drive bipolar transistor controlled by current, a FET controlled by voltage is connected in series, and an optocoupler is used to insulate the horizontal oscillator and the FET. By using it, it is possible to implement a horizontal output circuit of an ultra-high resolution monitor requiring high current, high voltage, and high switching time. In addition, since the horizontal drive transistor and the drive transformer can be omitted, the difficulty of the drive transformer design can be eliminated and the cost can be reduced.

Claims (6)

A first field effect transistor having a horizontal oscillation part and a gate end connected to an output end of the horizontal oscillation part and a source end being grounded on / off in accordance with the output waveform of the horizontal oscillation part, the horizontal oscillation part generating and outputting a pulse wave by an oscillator; An optical coupler connected to an output terminal of the optical oscillator for inducing an output waveform of the horizontal oscillation unit to a secondary side, a gate terminal connected to a secondary side of the optical coupler, and a source terminal connected to a drain terminal of the first field effect transistor, and a drain terminal Is a second electric field connected to a horizontal deflection yoke and turned on / off by a combined voltage of a voltage induced on the secondary side of the optocoupler and a voltage applied to a drain terminal of the first field effect transistor to supply a voltage to the deflection yoke. Horizontal output circuit of the monitor consisting of effect transistors, The horizontal output circuit of a monitor according to claim 1, wherein the first and second field effect transistors are configured in series connection. The horizontal output circuit of a monitor according to claim 1, wherein a driving IC of a first field effect transistor is connected to a front end of the first field effect transistor to satisfy and buffer an output of a horizontal oscillator. The horizontal output circuit of a monitor according to claim 1, wherein a second field effect transistor driving IC for amplifying and buffering the secondary voltage of the optocoupler is connected to the front end of the second field effect transistor. 5. The method of claim 1 or 4, wherein a diode is connected between the second field effect transistor driving IC and a power supply terminal to prevent a high voltage applied to the source side of the second field effect transistor from being fed back to the power supply terminal. Horizontal output circuit of the monitor. The horizontal thrust circuit of claim 1, wherein the optocoupler maintains insulation so that a high voltage fed back from the drain terminal of the first field effect transistor does not affect horizontal footing.