KR100194082B1 - Vertical Pin Cushion Correction Circuit of Cathode Ray Tube - Google Patents

Abstract

The present invention relates to a vertical pin-cushion correction circuit of a cathode ray tube that is capable of correcting the distortion phenomena at the top and bottom of the screen in a balanced manner throughout the screen, the image output device having a horizontal deflection and vertical deflection circuit of the electron beam To; Integrating means for integrating a vertical deflection voltage signal to generate a vertical parabola waveform; comparing means for outputting a switching control signal of a first or second level according to a potential polarity of the vertical deflection voltage signal; Phase inverting means for inverting the phase of the horizontal parabolic waveform, and switching the parabolic output waveform of the horizontal deflection circuit and the output signal of the phase inverting means in accordance with the switching control signal output from the comparing means. Switching means for alternately outputting a horizontal parabolic waveform having phases that are in phase with each other, and an amplifying means for adjusting a waveform amplification level with respect to an output signal of the switching circuit based on a vertical parabolic waveform output from the integrating means; And the output signal of the amplifying means is superimposed on the vertical deflection signal.

Description

Vertical Pin Cushion Correction Circuit of Cathode Ray Tube

The present invention relates to a vertical pin cushion correction circuit of a cathode ray tube, and more particularly, to a vertical pin cushion correction circuit of a cathode ray tube that is capable of correcting a distortion phenomenon that is prominent at the upper and lower ends of a screen in a balanced manner.

In general, a deflection circuit of an image output apparatus using a cathode ray tube (CRT) is used to deflect an electron beam emitted from an electron gun using a high voltage so that the emitted electron beam is formed on a fluorescent surface of a cathode ray tube (hereinafter referred to as a CRT). Fig. 1 shows a horizontal / vertical deflection circuit of a conventional general television receiver as a representative example using a cathode ray tube, for example.

In FIG. 1, reference numeral 1 denotes a CRT, 2 denotes a flyback transformer (FBT) for applying a high voltage to the anode electrode P of the CRT 1, 2a denotes a heater coil that generates a heater pulse, and reference numeral H _DY Is a horizontal deflection coil for horizontal deflection of the electron beam, and C2 is a charge / discharge capacitor.

Further, reference numeral 3 denotes a chroma IC for outputting predetermined oscillation pulses for horizontal and vertical outputs of the CRT 1 based on the synchronization signal separately detected from the broadcast signal, and adjusting the output of the oscillation pulses therein. An X-ray protection unit 3a and a horizontal oscillation circuit 3b and a vertical oscillation circuit 3c for outputting a horizontal oscillation frequency of the same phase as the synchronous signal input thereto are provided.

Reference numeral I is a horizontal driving unit for generating a horizontal driving voltage of a predetermined level based on the horizontal oscillation frequency; The horizontal driver I is a horizontal drive transistor Q1 driven on / off in accordance with a horizontal drive oscillation pulse output from the chroma IC 3, and the horizontal drive transistor Q1 is driven in accordance with the on / off drive of the horizontal drive transistor Q1. It consists of a horizontal drive transformer 4 which drives on / off the horizontal output transistor Q2 to be described later through a current induced in the secondary coil while the current flowing in the secondary coil is interrupted.

On the other hand, reference numeral II is a horizontal output unit for outputting a deflection signal for the horizontal scanning of the electron beam based on the driving pulse output from the horizontal driving unit (I); The horizontal output section (II) is driven on / off by a counter voltage induced by the secondary coil of the horizontal drive transformer (4) to interrupt the current flowing in the primary coil of the FBT (2) and the capacitor In addition to the horizontal output transistor Q2, which forms a current path during discharge of C2, and an LC resonance circuit together with the horizontal deflection coil H _DY , a negative half cycle of the sawtooth horizontal deflection current waveform is formed. A capacitor C2 to be generated and a damper diode D2 for bypassing the negative potential applied to the collector terminal of the horizontal output transistor Q2 by LC resonance to ground.

Also, ZD sets a predetermined zener voltage with respect to the voltage level signal applied from the heater coil 2a so that a predetermined detection signal is applied to the X-ray protection unit 3a when a voltage higher than this zener voltage is applied. Zener diode.

Reference numeral V _DY denotes a vertical deflection coil for vertical deflection of the electron beam, and III denotes a vertical drive voltage having a predetermined level based on an oscillation pulse output from the vertical oscillation circuit 3c of the chroma IC 3. The vertical drive section IV is a vertical output section that outputs a vertical deflection signal based on the output signal of the vertical drive section III.

That is, according to the device having the above-described configuration, in the case of the horizontal deflection circuit, the horizontal driving transistor Q1 is driven on / off in accordance with the oscillation pulse output from the chroma IC 3, so that 1 of the horizontal driving transformer 4 is used. As the current flows to the secondary coil, the reverse output voltage is induced in the secondary coil, thereby driving the horizontal output transistor Q2 to ON. As a result, the current flows in the primary coil of the FBT 2. At this time, the high voltage induced in the secondary coil is supplied to the anode terminal P of the CRT 1.

Meanwhile, due to the high inductance of the horizontal deflection coil H _DY , the collector current i _c does not increase rapidly and the collector current i _c gradually increases linearly in the collector terminal of the horizontal output transistor Q2. When the horizontal output transistor Q2 is turned off, a large negative voltage is applied to the collector terminal of the horizontal output transistor Q2 by LC resonance while discharging the electric charges charged in the capacitor C2. The negative voltage causes the damper diode D2 to conduct, so that the negative half-cycle of the sawtooth wave is generated.

As a result, the FBT 2 and the horizontal deflection coil H _DY are driven by the on / off driving of the horizontal output transistor Q2, thereby performing horizontal deflection with respect to the electron beam irradiated from the electron gun of the CRT 1. Will be.

On the other hand, the vertical deflection is also similar to the horizontal deflection process described above, based on the pulse output from the vertical oscillation circuit 3c of the chroma IC 3, the vertical deflection coil (III) through the vertical drive unit (III) and the vertical output unit (IV) V _DY ), which is implemented by controlling the current flowing in V _DY ), the conventional horizontal / vertical deflection circuit described above is suitable for the vertical pincushion phenomenon that is prominent at the top and bottom of the CRT screen as shown in FIG. 2. Since there was no solution, when the screen length in the horizontal direction was extended as in a widescreen TV having a 16: 9 aspect ratio, the upper and lower screens were severely distorted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a vertical pin cushion correction circuit of a cathode ray tube that is capable of correcting a distortion phenomenon that is prominent at the top and bottom of a screen in a balanced manner throughout the screen.

1 is a circuit configuration diagram showing a horizontal / vertical deflection circuit of a typical television receiver.

Figure 2 is a circuit diagram showing a vertical pin cushion correction circuit of a television cathode ray tube according to an embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation of the apparatus in the configuration of FIG. 2; FIG.

****** Explanation of symbols for main parts of the drawings ******

Ⅰ: Horizontal drive part Ⅱ: Horizontal output part

Ⅲ: vertical driving part Ⅳ: vertical output part

1: CRT 2: FBT (flyback transformer)

2a: heater coil 3: chroma IC

3a: X-ray protection unit 3b: horizontal oscillation circuit

3c: vertical oscillation circuit 4: horizontal drive transformer

5: integrating circuit 6: inverting circuit

7: switching circuit 8: amplifying circuit

T: Comparator ZD: Zener Diode

Q1: horizontal drive transistor Q2: horizontal output transistor

Q3: amplifying transistor P: anode electrode

C1 to C4: Capacitor D1, D2: Diode

H _DY : Horizontal deflection coil V _DY : Vertical deflection coil

R1 to R9: Resistor L1: Inductor

The vertical pin cushion correction circuit of the cathode ray tube according to the present invention for realizing the above object is in the image output device provided with a horizontal deflection and vertical deflection circuit of the electron beam; Integrating means for integrating a vertical deflection voltage signal to generate a vertical parabola waveform; comparing means for outputting a switching control signal of a first or second level according to a potential polarity of the vertical deflection voltage signal; Phase inverting means for inverting the phase of the horizontal parabolic waveform, and switching the parabolic output waveform of the horizontal deflection circuit and the output signal of the phase inverting means in accordance with the switching control signal output from the comparing means. Switching means for alternately outputting a horizontal parabolic waveform having phases that are in phase with each other, and an amplifying means for adjusting a waveform amplification level with respect to an output signal of the switching circuit based on a vertical parabolic waveform output from the integrating means; And the output signal of the amplifying means is superimposed on the vertical deflection signal.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention.

FIG. 2 is a circuit diagram showing a vertical pin cushion correction circuit of a cathode ray tube according to an embodiment of the present invention, in which components which perform the same functions as those shown in FIG. Is omitted.

In FIG. 2, reference numeral 5 denotes an integral for integrating an inductor L1 and a capacitor C4 to integrate a voltage waveform obtained from an A node, which is a contact between the vertical deflection coil V _DY and a resistor R5. Circuit, wherein reference symbol C3 is a coupling capacitor for removing direct current from the voltage signal of the node A, and T is high or low depending on the polarity of the signal passing through the coupling capacitor C3. A comparator for outputting a predetermined switching control signal of the level.

In addition, reference numeral 6 inverts the horizontal parabolic waveform (c) output from the node B which is the contact point between the horizontal deflection coil (H _DY ) and the capacitor (C2) as shown in (d) of FIG. 7 is an inverting circuit for converting the output signal S1 of the node B and the output signal S2 of the inverting circuit 6 in accordance with the switching control signal output from the comparator T. ) Is a switching circuit that alternately outputs horizontal parabolic waveforms having phases opposite to each other as shown in (e) of FIG.

On the other hand, reference numeral 8 denotes the switching circuit 7 as shown in FIG. 3 (f) by using the vertical parabola waveform output from the integrating circuit 5 as an emitter input of a transistor Q3 provided therein. The amplification circuit performs equal gain of gain '1' so that the maximum attenuation occurs at the center of the output signal.

Next, the operation of the apparatus having the above configuration will be described with reference to the waveform diagram of FIG.

The comparator T outputs a high level switching signal with a positive polarity with respect to the vertical deflection voltage signal a obtained from the node A based on the zero potential level, and a low level with the negative polarity. A level signal is output, and the integrating circuit 5 integrates the vertical deflection voltage signal a to output a vertical parabola waveform as shown in FIG.

On the other hand, the switching circuit 7 is a normal horizontal parabola waveform applied through the S1 terminal for every half period of the vertical parabola waveform based on a high or low level switching control signal output from the comparator T. And alternately output an inverted horizontal parabolic waveform applied through the S2 and S2 terminals, and the transistor Q3 in the amplifying circuit 8 is applied to the emitter input (vertical parabola waveform) applied from the integrating circuit 5. As a result, the amplification degree of the output signal is controlled, and as a result, the output waveform of the amplifying circuit 8 exhibits a characteristic of being attenuated toward the center of the screen as shown in FIG.

Therefore, when the output waveform obtained by the above-described process is applied to the node A and superimposed on the vertical deflection voltage signal, as shown in Fig. 3G, the differential waveform is supplied in accordance with the upper and lower scanning points of the screen. The vertical deflection voltage signal can be obtained.

That is, according to the above embodiment, in performing vertical deflection of the electron beam, the degree of deflection at the top and bottom of the screen can be increased, and in particular, even the uneven distortion deviation of each part is considered every horizontal scan based on the horizontal parabolic waveform. This enables accurate vertical pin cushion correction to match the scanning point of each part of the screen.

Meanwhile, the present invention is not limited to the above embodiments and can be variously modified within the scope not departing from the technical gist of the present invention.

As described above, according to the present invention, it is possible to realize the vertical pin cushion correction circuit of the cathode ray tube, which is capable of correcting the distortion phenomenon that is prominent at the upper and lower ends of the screen in a balanced manner throughout the screen.

Claims (1)

An image output apparatus comprising a horizontal deflection and a vertical deflection circuit of an electron beam; An integrating means for integrating the vertical deflection voltage signal to generate a vertical parabola waveform; Comparison means for outputting a switching control signal of a first or second level in accordance with the potential polarity of the vertical deflection voltage signal; Phase inverting means for inverting the phase of the horizontal parabola waveform output from the horizontal deflection circuit; According to the switching control signal output from the comparing means, the parabolic output waveform of the horizontal deflection circuit and the output signal of the phase shifting means are switched to half the vertical parabola waveform ( Switching means for alternately outputting a horizontal parabolic waveform having a phase in phase with each other per cycle, and And amplifying means for adjusting a waveform amplification level with respect to an output signal of the switching circuit based on the vertical parabola waveform output from the integrating means, And the output signal of the amplifying means is superimposed on the vertical deflection signal.