JPH07212614A - Picture distortion correction device - Google Patents

Abstract

PURPOSE:To obtain the picture distortion correction circuit in which S-shaped distortion correction is realized with low power consumption by using a resonance circuit causing basically no power consumption so as to supply a correction current to a horizontal deflection auxiliary coil. CONSTITUTION:When a horizontal deflection pulse V1 is given to a monostable multivibrator 1, the monostable multivibrator 1 enerates a pulse V2 having a width of 174 horizontal period. The pulse V2 is applied to a monostable multivibrator 2, and the monostable multivibrator 2 generates a pulse V3 whose phase is shifted from that of the horizontal deflection pulse V1 by nearly or just a width of 1/4 horizontal period. The pulse V3 is boosted by a transformer F1 and the boosted pulse is applied to an LC resonance circuit comprising a C1, L1, L2 as a trigger pulse. The LC resonance circuit has a horizontal deflection frequency for its resonance frequency, the LC resonance circuit generates a sine wave current of a horizontal period and supplies the current to a horizontal deflection coil L3 as a correction current is. The horizontal deflection by the horizontal coil L3 is corrected by the correction current is and the S-shaped distortion correction is realized with low power consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention corrects the linear distortion (hereinafter referred to as S-shaped distortion) between the center and the periphery in the horizontal direction of an image generated in a CRT display, and realizes a good image without geometrical distortion. The present invention relates to an image distortion correction device for a display.

[0002]

2. Description of the Related Art S-shaped distortion is a phenomenon in which, when displaying crosshatch signals at evenly spaced time intervals as shown in FIG. The amount of this distortion mainly depends on the CRT deflection angle and CRT.
It is determined by the curvature of the face, and in the case of a projection television, the curvature of the screen surface and the difference in magnification around the center of the lens magnification.

A conventional S-shaped distortion correction is an S-shaped distortion correction as shown in FIG.
There are a method of connecting the character correction coil L11 to the horizontal deflection coil L12 in series and a method of setting the capacity of the S-shape correction capacitor C11. In FIG. 3, TR11 is a horizontal output transistor, D11 is a damper diode, C12 is a resonance capacitor, and i is a horizontal polarization current.

The method of FIG. 3 will be described with reference to the waveform chart of FIG. The S-shaped correction coil L11 in this system exhibits a supersaturation reactance characteristic as shown in FIG. 4B for a bipolar current, and the horizontal deflection current i is shown in FIG.
It is modulated like the dashed line. Therefore, the deflection amount at the peripheral portion is smaller than that at the central portion of the horizontal deflection, so that S as shown in FIG.
The character distortion is corrected so that it is evenly spaced.

The horizontal deflection amount is proportional to the voltage across the S-shaped correction capacitor C11, and the voltage VC11 across the S-shaped correction capacitor C11 has a horizontal parabolic component as shown in FIG. 4 (c). S-shaped correction capacitor C1
When the capacity of 1 is lowered, this horizontal parabolic component becomes larger. Therefore, the amount of deflection in the peripheral portion is smaller than that in the central portion of the horizontal deflection, so that the S-shaped distortion as shown in FIG.

[0006]

When the amount of S-shaped distortion is small, there is no problem even with such a conventional method. However, when the amount of distortion is large, the conventional method consumes too much power for correction and becomes a problem.

The present invention solves the above problems, and an object of the present invention is to provide an image distortion correction apparatus that can realize S-shaped distortion correction with low power consumption.

[0008]

In order to solve the above-mentioned problems, the image distortion correction apparatus of the present invention uses a resonance circuit which basically does not consume power to supply a correction current to a horizontal deflection auxiliary coil to form an S-shape. In order to realize distortion correction, a horizontal deflection auxiliary coil for correcting horizontal deflection by the horizontal deflection coil, a resonance circuit configured to include the horizontal deflection auxiliary coil and have a horizontal deflection frequency at a resonance frequency, and a horizontal Means for applying, as a trigger pulse to the resonance circuit, a pulse whose phase is delayed by a 1/4 cycle or a cycle close to the horizontal cycle of the deflection pulse, and a resonance current obtained from the resonance circuit is horizontally deflected. It is configured to flow in the auxiliary coil and correct the linearity in the horizontal direction of the image.

[0009]

With the above structure, the horizontal deflection pulse is applied as a trigger pulse to the resonance circuit having the horizontal deflection frequency as the resonance frequency, and the resonance current generated as the sine wave current is passed through the horizontal deflection auxiliary coil. At this time, the phase of the horizontal deflection pulse is corrected in advance so that the phase of the sine wave current crosses zero at the horizontal period center. That is, the phase of the horizontal deflection pulse is delayed by about 1/4 cycle with respect to the horizontal cycle, and this is applied as a trigger pulse to the resonance circuit.
Since the sinusoidal resonance current thus obtained is used for correction of horizontal deflection, S-shaped distortion correction can be realized with low power consumption.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an image distortion correction device according to an embodiment of the present invention, and FIG. 2 is a waveform explanatory diagram thereof. In FIG. 1, 1,
Reference numeral 2 is a mono-multi for shifting the horizontal deflection pulse by 1/4 horizontal cycle phase, which are connected in cascade. T ₁ is a transformer connected to the monomulti 2. L ₁ and L ₂ are a variable coil and a horizontal deflection auxiliary coil which are connected in series to the output terminal of the transformer T ₁ , and the horizontal deflection auxiliary coil L ₂ is arranged in the vicinity of the horizontal deflection coil L ₃ for CRT deflection. ing. C
Reference numeral ₁ denotes a resonance capacitor connected to a connection point between the variable coil L ₁ and the horizontal deflection auxiliary coil L ₂ , and the variable coil L ₁ ,
An LC resonance circuit is configured with the horizontal deflection auxiliary coil L ₂ and each constant has a horizontal deflection frequency f _H = (L ₁ + L ₂ ) / 2π · L ₁ · L.
It is set to be ₂ · C ₁ . R ₁ is a damping resistor provided at both ends of the horizontal deflection auxiliary coil L ₂ , R ₂ and R ₃
Is a resistor for mono-multi time constant, C ₂ and C ₃ are capacitors for mono-multi time constant, and C ₄ is a DC cut capacitor.

In such a structure, the operation is shown in FIG.
This will be described with reference to the waveform diagram of FIG. Horizontal deflection pulse V₁Is
When input to Nomultil 1, Monomulti 1 is 1/4 horizontal
A pulse V with a period width as shown in Fig. 2₂To occur.
This pulse V₂Is input to monomulti 2 and monomulti
2 is a horizontal deflection pulse V₁1/4 horizontal cycle or
Pulse V whose phase is shifted by approximately 1/4 horizontal period₃From
To live. This pulse V ₃Is a transformer T₁Boosted by C
₁, L₁, L₂In the LC resonance circuit composed of
Applied as a pulse. This LC resonant circuit is as described above
Since the horizontal deflection frequency depends on the resonance frequency,
Generates a horizontal cycle sinusoidal current with the phase shown
Horizontal deflection auxiliary coil L₂As a correction current. This
Horizontal deflection coil L by the correction current is of₃Horizontal deviation due to
Direction is corrected and S-shaped distortion correction can be realized with low power consumption.
It

[0012]

As described above, according to the present invention, a sine wave current, which is a correction current required for S-shaped distortion correction, can be generated with low power consumption, and power consumption required for correction becomes excessive. Can be avoided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image distortion correction device showing an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of an image distortion correction device showing an embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional image distortion correction device.

FIG. 4 is an operation waveform diagram of a conventional image distortion correction device.

FIG. 5 is a diagram for explaining the phenomenon of S-shaped distortion.

[Explanation of symbols]

 1, 2 Monomulti L1 Variable coil L2 Horizontal deflection auxiliary coil L3 Horizontal deflection coil C1 Resonance capacitor C2, C3 Monomulti time constant capacitor C4 DC cut capacitor R1 Damping resistor R2, R3 Monomulti time constant resistor V1 Horizontal deflection pulse V2 Mono-multi 1 output V3 Mono-multi 2 output is S-shaped distortion correction current

Claims (1)

[Claims] 1. A horizontal deflection auxiliary coil for correcting horizontal deflection by a horizontal deflection coil, a resonance circuit including the horizontal deflection auxiliary coil and having a horizontal deflection frequency at a resonance frequency, and a horizontal deflection pulse horizontal period. Against 1/4
A means for applying a pulse whose phase is delayed by a period or a period close thereto to the resonance circuit as a trigger pulse is provided, and a resonance current obtained from the resonance circuit is passed through the horizontal deflection auxiliary coil to correct the linearity in the horizontal direction of the image. An image distortion correction device configured to perform.