JP3344806B2 - Image distortion correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention corrects linear distortion (hereinafter referred to as "S-shaped distortion") at the center and periphery in the horizontal direction of an image generated on a CRT display, and realizes a good image without geometric distortion. And an image distortion correcting device for a display.

[0002]

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

In the conventional S-shaped distortion correction, an S-shaped distortion as shown in FIG.
There is a method of connecting the character correction coil L11 to the horizontal deflection coil L12 in series, and a method of setting the capacitance using the capacitance of the S-character 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.

[0004] The method of FIG. 3 will be described with reference to the waveform diagram of FIG. The S-shaped correction coil L11 in this method has a supersaturated reactance characteristic as shown in FIG. 4B with respect to the bipolar current, and the horizontal deflection current i is shown in FIG.
Are modulated as indicated by the broken line. Therefore, the amount of deflection in the peripheral portion is smaller than that in the central portion of the horizontal deflection.
The character distortion is corrected to be at equal intervals.

The amount of horizontal deflection is proportional to the voltage across the S-shaped correction capacitor C11. The voltage VC11 across the S-shaped correction capacitor C11 has a horizontal parabolic component as shown in FIG. S-shaped correction capacitor C1
When the capacity of 1 is reduced, the horizontal parabolic component increases. Therefore, since the amount of deflection in the peripheral portion is smaller than that in the central portion of the horizontal deflection, the S-shaped distortion as shown in FIG.

[0006]

In the case where 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 power consumption required for correction becomes excessive in the conventional method, causing a problem.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide an image distortion correcting apparatus which can realize S-shaped distortion correction with low power consumption.

[0008]

In order to solve the above-mentioned problems, an image distortion correction apparatus according to the present invention basically uses a resonance circuit which does not consume power to supply a correction current to a horizontal deflection auxiliary coil, thereby forming an S-shape. A horizontal deflection auxiliary coil for correcting horizontal deflection by a horizontal deflection coil, a resonance circuit including the horizontal deflection auxiliary coil and configured to have a horizontal deflection frequency at a resonance frequency, and a horizontal circuit. Means for applying, as a trigger pulse, a pulse obtained by delaying the phase of the deflection pulse by a quarter cycle or a cycle close to the horizontal cycle to the resonance circuit, and applying a resonance current obtained from the resonance circuit to the horizontal deflection. It is configured to flow through the auxiliary coil to correct the linearity in the horizontal direction of the image.

[0009]

With the above arrangement, a horizontal deflection pulse is applied as a trigger pulse to a resonance circuit having a horizontal deflection frequency as a resonance frequency, and a resonance current generated as a sine wave current is caused to flow 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 center of the horizontal period. That is, the phase of the horizontal deflection pulse is delayed by approximately 1/4 cycle with respect to the horizontal cycle, and this is applied to the resonance circuit as a trigger pulse.
Since the thus obtained sine wave resonance current is used for correcting horizontal deflection, S-shaped distortion correction can be realized with low power consumption.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an image distortion correcting apparatus according to one embodiment of the present invention, and FIG. In FIG.
Reference numeral 2 denotes a mono-multi for shifting the phase of the horizontal deflection pulse by 1/4 horizontal period, and is connected in cascade. T ₁ is a transformer connected to the multivibrator 2. L ₁ and L ₂ are a variable coil and a horizontal deflection auxiliary coil connected in series to the output end of the transformer T ₁ , and the horizontal deflection auxiliary coil L ₂ is arranged close to the horizontal deflection coil L ₃ for CRT deflection. ing. C
₁ is connected to the resonant capacitor to the connection point of the variable coil L ₁ and the horizontal deflection auxiliary coil L _2, a variable coil L _1,
An LC resonant circuit with the horizontal deflection auxiliary coil L _2, each of the constant horizontal deflection frequency _{f H = (L 1 + L} 2) / 2π · L 1 · L
Is set to be ₂ · C _1. R ₁ is a damping resistor interposed at both ends of the horizontal deflection auxiliary coil L ₂ , R ₂ , R ₃
Is a resistor for a mono-multi time constant, C ₂ and C ₃ are capacitors for a mono-multi time constant, and C ₄ is a DC cut capacitor.

In such a configuration, the operation is shown in FIG.
This will be described with reference to the waveform diagram of FIG. Horizontal deflection pulse V₁But
When input to No Multi 1, Mono Multi 1 is 1/4 horizontal
A pulse V having a period width as shown in FIG._TwoOccurs.
This pulse V_TwoIs input to mono multi 2
2 is a horizontal deflection pulse V₁1/4 horizontal period or
Pulse V shifted in phase by approximately 1/4 horizontal cycle_ThreeDepart
Live. This pulse V _ThreeIs a transformer T₁Is boosted by C
₁, L₁, L_TwoTrigger pulse in LC resonance circuit composed of
Applied as This LC resonance circuit is
Since the horizontal deflection frequency is also linked to the resonance frequency,
Generates a horizontal period sinusoidal current with the phase shown
And horizontal deflection auxiliary coil L_TwoAs a correction current. This
The horizontal deflection coil L_ThreeDue to horizontal deviation
Direction is corrected, and S-shaped distortion correction can be realized with low power consumption.
You.

[0012]

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

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image distortion correction apparatus according to an embodiment of the present invention.

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

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

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

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

[Explanation of symbols]

 1, 2 mono-multi L1 variable coil L2 horizontal deflection auxiliary coil L3 horizontal deflection coil C1 resonance capacitor C2, C3 mono-multi time constant capacitor C4 DC cut capacitor R1 damping resistor R2, R3 mono-multi time constant resistor V1 horizontal deflection pulse V2 Mono multi 1 output V3 Mono multi 2 output is S-shaped distortion correction current

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 3/23

Claims (1)

(57) [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 configured to have a horizontal deflection frequency at a resonance frequency, and a horizontal cycle of a horizontal deflection pulse. 1/4 for
Means for applying, as a trigger pulse, a pulse whose phase is delayed by a cycle or a cycle close to the cycle as a trigger pulse, and flowing a resonance current obtained from the resonance circuit to the horizontal deflection auxiliary coil to correct the image linearity in the horizontal direction Image distortion correction device configured to perform