JPH05276404A - Side pin cushion correcting circuit - Google Patents

Abstract

PURPOSE:To smoothly move the change of a horizontal size and to correct trapezoidal distortion caused by the swing of a deflected yoke. CONSTITUTION:The waveforms of parabolic waves are shaped from a vertical circuit, and those waves are inputted to the noninverted input terminal of an operational amplifier(OA) 2 in the second step. The output step is inputted to the noninverted input terminal of an OA 1 in the first step. The output step of the OA in the first step is inputted to the base of a side pin cushion correcting drive Tr2. Sawteeth waves are inputted from the vertical circuit to the noninverted input terminal of the OA 2 in the second step, and vertical trapezoidal distortion is corrected. A DC bias for horizontal size control is inputted to the noninverted terminal of the OA 1 in the first step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side pincushion correction circuit, and more particularly to a side pincushion correction circuit of a diode modulation type in a television circuit using a cathode ray tube.

[0002]

2. Description of the Related Art Conventionally, the occurrence of trapezoidal distortion and pincushion distortion in a projection television receiver has been a problem. Trapezoidal distortion is a distortion caused by the angle between the projection optical axis and the screen. On the other hand, pincushion distortion (pincushion) is a distortion caused by the projection distance, that is, since the screen surface of the picture tube is not a spherical surface but a flat surface, the distance from the deflection center of the electron beam differs greatly between the center and the end. The raster on the screen surface is distorted vertically and horizontally like a pincushion.
Therefore, in actual use, it is necessary to correct the trapezoidal distortion and the pincushion distortion. Up and down (horizontal)
The pincushion distortion (side pincushion) of (1) is corrected by superimposing a parabolic current having a horizontal period proportional to the vertical deflection angle on the vertical deflection current. The left and right pincushion distortions are corrected by increasing the horizontal amplitude of the central portion by amplitude-modulating the envelope of the horizontal deflection current in a parabolic shape with a vertical deflection period.

For trapezoidal distortion, a trapezoidal distortion correction signal (vertical sawtooth wave voltage) may be applied to the horizontal deflection coil. As a device for correcting the trapezoidal distortion and the side pincushion, for example, Japanese Patent Publication No. 63-34673.
A "vertical line correction device" is proposed in the publication. According to this publication, a rectangular wave having a pulse width of one vertical blanking period is applied to a horizontal output circuit together with a vertical sawtooth wave voltage or the like to correct a vertical line without bending at the upper part of the screen.

FIG. 7 is a circuit diagram showing a conventional side pincushion correction circuit. Deflection yoke vertical coil DY
Waveform shaping parabolic wave emanating from V by a resistor 14 and 13 and the capacitor C8, C7, via a variable resistor R9 to adjust the transistor Tr ₃ and the side pincushion correction amount, and a resistor R8 and the DC cut capacitor C6 Input to the non-inverting input terminal of the first-stage operational amplifier OA1. Again 1
DC bias adjust horizontal size to the inverting input terminal of the stage of the operational amplifier OA1 is inputted in the voltage division ratio of the variable resistors R5 and R6 and R7, the output is input to the base of the side pincushion correction output transistor Tr _2, Connected to diode modulation circuit. By the way, when the DC bias is changed by the horizontal size adjusting resistor R5 or the frequency change, the positive feedback current i ₁ flows through R3 and i ₂ flows into the DC cut capacitor C6, but the time constant T becomes
T = (R3 + R8 + R9 + R10) × C6 [sec], and the delay of change appears on the screen.

[0005]

As described above, in the conventional side pincushion correction circuit, the variable resistor R is used.
When 5 is suddenly changed or when the horizontal frequency is changed, the DC bias is switched to adjust the horizontal size in order to adjust the horizontal size, but at that time, the horizontal size changes with a delay due to the influence of the time constant. Further, there is a problem in that it is impossible to correct the trapezoidal distortion due to the swing of the deflection yoke.

The present invention has been made in view of the above circumstances, and an impedance of the input side of the operational amplifier is increased by placing another operational amplifier before the operational amplifier for side pincushion correction and horizontal size adjustment. By preventing the flow of the feedback current to prevent the delay of the operation on the screen due to the change of the horizontal size, and by inputting the sawtooth wave to the inverting input terminal of the second stage operational amplifier, the deflection yoke swings up and down. It is an object of the present invention to provide a side pincushion correction circuit that also corrects trapezoidal distortion.

[0007]

In order to achieve the above object, the present invention provides a side pincushion correction circuit by a diode modulation method of a television circuit using a cathode ray tube, in which a parabola wave waveform-shaped from a vertical circuit is used. A second input terminal having a non-inverting input terminal and an inverting input terminal for inputting a sawtooth wave from the vertical circuit;
A first stage having an operational amplifier of a second stage, a non-inverting input terminal for inputting an output of the operational amplifier of the second stage, and an inverting input terminal for inputting a DC bias for changing a horizontal size;
It is composed of an operational amplifier in the second stage, and prevents the delay of the operation on the screen due to the change of the horizontal size and corrects the trapezoidal distortion.

[0008]

[Function] The parabolic wave is shaped by the vertical circuit, input to the second stage operational amplifier non-inverting input terminal, and its output stage is 1
It is input to the non-inverting input terminal of the operational amplifier of the first stage, and the output stage of the operational amplifier of the first stage is input to the base of the side pincushion correction drive Tr ₂ . On the other hand, the inverting input terminal of the second stage operational amplifier inputs the sawtooth wave from the vertical circuit,
The vertical trapezoidal distortion is corrected, and the horizontal size adjustment DC bias is input to the inverting input terminal of the first operational amplifier.

[0009]

Embodiments will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a side pincushion correction circuit according to the present invention, in which 1 is an operational amplifier of the first stage,
2 is a second stage operational amplifier, Tr ₁ is a horizontal output transistor, D1 is a damper diode, C1 is a resonance capacitor, DY / H is a deflection coil horizontal part, L1 is a linearity coil, C3 and C4 are S-shaped capacitors, and D2 is distortion. correction diode, L2 modulation coil, C2 modulation resonance capacitor, C5 modulation scanning capacitor, Tr ₂ are distortion correction drive transistor, C6 DC cutting capacitor, R5
The variable resistor for adjusting the horizontal size, R9 is a variable resistor for the strain amount adjustment, Tr ₃ is the current amplification transistor, DY · V deflection coil vertical section, C10 vertical coupling capacitor, R1
Reference numeral 9 is a vertical feedback resistor.

The parabolic wave from the vertical circuit deflection yoke DY.V is shown in FIG. 2 (A in FIG. 1). Further, as shown in FIG. 3 (B of FIG. 1), a sawtooth wave is input to the inverting input terminal of the second operational amplifier OA2 from between the coupling capacitor C10 and the feedback resistor R19, and as shown in FIG. Corrects vertical trapezoidal distortion due to swinging of the deflection yoke. The parabolic wave of FIG. 2 (A in FIG. 1) is shaped by the capacitors C8 and C7, and the current is amplified through Tr ₃ (FIG. 4).
Parabola wave like C) of the second operational amplifier OA2
Input to the non-inverting input terminal of. From the output terminal of the operational amplifier OA2, a composite wave of the positive feedback amplified non-inverted input wave and inverted input wave is output, and the first stage via the side pincushion amount correction resistors R9 and R8 and the DC cut capacitor C6. Input to the non-inverting input terminal of the operational amplifier OA1. Further, the inverting input terminal of the second-stage operational amplifier OA2 has a variable resistor R5 and a resistor R5 for horizontal size adjustment from + B.
6, the voltage division of R7 is applied, the output is input to the base of the side pincushion correction drive transistor Tr ₂ via the resistor R4, and the parabolic wave of FIG. 5 (D of FIG. 1) is input from the collector to the diode modulation circuit. Is entered.

Here, the diode modulation circuit will be briefly described. The parabolic wave of FIG. 5 (D of FIG. 1) is output from the side pincushion correction drive transistor Tr _2, but due to the parabolic wave of the vertical cycle,
The side pincushion correction is performed by manipulating the energy stored in the S-shaped capacitors C3 and C4 to change the deflection current of the deflection yokes DY and H. Further, the horizontal size is adjusted by the DC component which is the voltage V ₁ in FIG. By the way, when the DC bias of the inverting input terminal of the first-stage operational amplifier OA1 is changed in order to adjust the horizontal size when the horizontal frequency is switched, the feedback current from the collector of the transistor Tr ₂ through the resistor R3 is changed by one stage. Although it returns to the non-inverting input terminal of the operational amplifier OA1 of the eye, since it is a positive feedback circuit, a DC component flows into the capacitor C6. In the conventional side pincushion correction circuit, as shown in FIG. 7, resistors R8, R9, and R10 are provided on the negative electrode side of the capacitor C6.
The feedback current i has flowed in because it is grounded via. Therefore, by providing the second-stage operational amplifier OA2, the impedance can be increased, the discharge of the capacitor C6 can be reduced, the reverse current i ₂ in FIG. 7 can be reduced, and the horizontal size can be changed quickly. Become.

[0012]

Since the present invention is constructed as described above, it has the following effects. (1) Side pincushion correction and another stage operational amplifier is installed in front of the operational amplifier for horizontal size adjustment, the input side impedance of the operational amplifier is increased, the flow of feedback current is prevented, and it is variable to change the horizontal size. When the resistance or the DC device is rapidly changed, the movement having a time constant can be improved. (2) By inputting a sawtooth wave from the vertical circuit to the inverting input terminal of the second-stage operational amplifier, trapezoidal distortion due to swing adjustment of the deflection yoke can be corrected.

[Brief description of drawings]

FIG. 1 is a circuit diagram for explaining an embodiment of a side pincushion correction circuit according to the present invention.

FIG. 2 is a diagram showing a waveform at point A in FIG.

FIG. 3 is a diagram showing a waveform at point B in FIG.

FIG. 4 is a diagram showing a waveform at point C in FIG.

5 is a diagram showing a waveform at point D in FIG.

FIG. 6 is a diagram showing trapezoidal distortion.

FIG. 7 is a circuit diagram showing a conventional side pincushion correction circuit.

[Explanation of symbols]

1 ... 1st stage operational amplifier, 2 ... 2nd stage operational amplifier, T
r ₁ ... Horizontal output transistor, D1 ... Damper diode, C1 ... Resonance capacitor, DY.H ... Deflection coil horizontal part, L1 ... Linearity coil, C3, C4 ... S-shaped capacitor, D2 ... Distortion correction diode, L2 ... Modulation coil , C2 ... modulation resonance capacitor, C5 ... modulating scanning capacitor, Tr ₂ ... distortion correction drive transistor, C6 ... DC cut capacitor, R5 ... horizontal size adjusting variable resistor, R9 ... strain amount adjusting variable resistor, Tr ₃ ... current Amplifying transistor, DY · V ... Vertical portion of deflection coil, C10 ... Vertical coupling capacitor, R19 ... Vertical feedback resistor.

Claims (1)

[Claims] 1. A side pincushion correction circuit using a diode modulation method for a television circuit using a cathode ray tube, wherein a non-inverting input terminal for inputting a shaped parabolic wave from a vertical circuit and a sawtooth wave from the vertical circuit are input. Second having an inverting input terminal
A first stage having an operational amplifier of a second stage, a non-inverting input terminal for inputting an output of the operational amplifier of the second stage, and an inverting input terminal for inputting a DC bias for changing a horizontal size;
A side pincushion correction circuit comprising an operational amplifier in the second stage.