JP3134592B2 - Corner pincushion distortion correction wave generation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical / horizontal deflection circuit for a television receiver (hereinafter referred to as TV), and more particularly to a corner pin cushion correction circuit of an improved horizontal deflection pincushion distortion correction circuit. is there.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional horizontal deflection pincushion distortion (hereinafter referred to as pincushion distortion) correction circuit.
In FIG. 4, reference numeral 21 denotes a vertical sawtooth voltage signal produced by taking charge / discharge timing of an external capacitor using a video vertical synchronization signal, and reference numeral 22 denotes a lower corner of the screen when the vertical sawtooth signal 21 is used for vertical deflection. 23 is a differential comparison circuit for extracting a portion corresponding to the upper corner of the screen when the vertical sawtooth wave 21 is used for vertical deflection, and 24 is a multiplier for multiplying the waveform extracted by the differential comparison circuit 22. 25, a multiplier for multiplying the waveform extracted by the differential comparison circuit 23, 26, an amplitude adjustment circuit for the secondary waveform output from the multiplier 24, and 27, an adjustment of the amplitude adjustment circuit 26. A control voltage input terminal for adjusting the amplitude of the secondary waveform output from the multiplying circuit 25; A control voltage input terminal 30 is an addition for forming a corner distortion correction wave by adding the lower screen corner correction wave signal output from the amplitude adjustment circuit 26 and the upper screen corner correction wave signal output from the amplitude adjustment circuit 28. A voltage / current converter 31 for converting the vertical sawtooth voltage signal 21 into a current; and a voltage / current converter 32 for changing the distribution ratio of the current signal output from the voltage / current converter 31 to change the phase of the pincushion distortion corrected parabolic wave signal. A control voltage input terminal 33 for changing the voltage, a multiplier circuit for forming a pincushion distortion-corrected parabolic wave by squaring the vertical sawtooth current output from the voltage / current converter 31, and a output 34 from the multiplier circuit 33. A control voltage input terminal for controlling the amplitude of the parabolic wave signal; Amplifier circuit for the corner distortion correction wave signal output emission correction wave signal from the adder circuit 30 and the input 36 is a pincushion correction wave signal hazy corner distortion correction. 27.2
The control voltage input terminals 9, 32, and 34 receive data signals from a microcomputer or the like. In the block diagram of this embodiment configured as described above, the operation will be described below with reference to FIG.

When a signal as shown in FIG. 5A is inputted to 21, a portion corresponding to a lower corner of a vertical sawtooth signal is extracted by a differential comparison circuit 22 as shown in FIG.
The result is multiplied by the multiplication circuit 24 as shown in FIG. 5C, and the amplitude of the signal is adjusted by the gain control circuit 26.
By adding the signal to the amplifying circuit 35, the corner distortion at the lower portion of the screen is corrected, and a portion corresponding to the upper corner of the vertical sawtooth signal is extracted by the differential comparing circuit 23 as shown in FIG. As shown in FIG. 5E, the amplitude of the signal is adjusted by the gain control circuit 28 and added to the amplifier circuit 35 to correct the corner distortion at the upper part of the screen, and the corrected waveform as shown in FIG. Get.

Conventionally, a quartic wave signal obtained by multiplying a corner distortion correction wave signal by a pincushion correction parabola wave signal twice is used, so that the correction of the upper corner and the lower corner of the screen may become imbalanced. However, by adding the circuit within the broken line and using the above method, the upper corner and the lower corner can be independently corrected, and better pincushion distortion correction can be performed. With the pincushion correction circuit configured as described above, not only the normal pincushion distortion but also the distortion of the screen corner caused by the variation of the deflection yoke or the CRT can be independently corrected vertically.

[0005]

The circuit having the above-mentioned structure can correct the distortion of the upper corner and the distortion of the lower corner independently, so that more accurate image distortion can be corrected. Start point remains at a fixed bias. The point at which corner distortion starts varies depending on the combination and type of each CRT and deflection yoke, and cannot be fixed unconditionally. Here, the upper corner refers to the left and right corners of the upper portion of the CRT, and the lower corner refers to the left and right corners of the lower portion of the CRT.

In view of the above, the present invention makes it possible to perform the distortion correction of the upper corner and the distortion correction of the lower corner independently, and furthermore, it is also possible to arbitrarily change the start point of the corner distortion correction, thereby achieving a more accurate correction. It is intended to correct image distortion.

[0007]

In order to solve the above problems, a corner pincushion distortion correction wave generating circuit according to the present invention comprises a circuit for extracting a portion of a vertical sawtooth voltage signal corresponding to an upper side of a screen shown in FIG. A multiplication circuit for multiplying the added portion, a circuit for adjusting the amplitude of the multiplied waveform,
A circuit for extracting a portion of the vertical sawtooth voltage wave signal corresponding to the lower side of the screen, a multiplication circuit for multiplying the extracted portion,
A circuit for adjusting the amplitude of the multiplied waveform, a bias circuit for changing the upper and lower extraction points on the screen, and an output of the amplitude adjustment circuit for the upper correction wave and an output of the amplitude adjustment circuit for the lower correction wave. It is equipped with an addition circuit for adding and a circuit for adjusting the amplitude of the output of the addition circuit, and performs distortion correction of a corner separately on an upper part and a lower part of a screen,
In addition, the correction start point can be arbitrarily changed.

[0008]

According to the present invention, it is possible to independently correct the corner distortion of the upper portion and the lower portion of the screen and change the start point of the correction arbitrarily. By doing so, the deflection distortion of the screen can be corrected more accurately.

[0009]

FIG. 1 is a block diagram of a corner pincushion distortion correction wave generating circuit according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a vertical sawtooth voltage signal generated by taking charge / discharge timing of an external capacitor using a video vertical synchronization signal, and 2 denotes a lower portion of the screen when the above-mentioned vertical sawtooth signal is used for vertical deflection. The differential comparison circuit 3 extracts the portion corresponding to the upper portion of the screen when the vertical sawtooth wave is used for vertical deflection, and the differential comparison circuit 4 extracts the comparison bias voltage of the differential comparison circuits 2 and 3. The bias circuit 10 determines the start point of the corner distortion correction by deciding, and 10 is a control voltage input terminal for changing the start point, and 5 is the differential comparison circuit 2
A multiplication circuit for multiplying the waveform extracted by the differential comparison circuit 3, a multiplication circuit for multiplying the waveform extracted by the differential comparison circuit 3, an amplitude adjustment circuit for the secondary waveform output from the multiplication circuit 5,
11 is a control voltage input terminal for adjustment of the amplitude adjustment circuit 7, 8 is an amplitude adjustment circuit for the secondary waveform output from the multiplication circuit 6, 12 is a control voltage input terminal for adjustment of the amplitude adjustment circuit 8, Reference numeral 9 denotes an addition circuit that forms a corner distortion correction wave by adding the lower-corner correction wave signal output from the amplitude adjustment circuit 7 and the upper-corner correction wave signal output from the amplitude adjustment circuit 8. A circuit for adjusting the amplitude of the entire corner correction wave output from the adder circuit 9, a control voltage input terminal 14 for varying the amplitude, and a corner distortion correction waveform 15. The above 11
Data signals are sent to the 12 control voltage input terminals from a microcomputer or external pins. In the block diagram of this embodiment configured as described above, the operation will be described below with reference to FIGS.

The corner distortion of the screen is shown in FIG.
Some start points are deep and some are shallow, as in 1).
Therefore, in the waveform of FIG. 2C, even though the distortion of FIG. 2A1 can be accurately corrected as shown in FIG. 2A, the distortion of FIG. ) May be distorted. Therefore, the bias circuit of 4 above
By changing the comparison points of the differential comparison circuits of FIG.
The waveform shown in FIG. 2D is obtained, and the distortion shown in FIG.
Can be corrected accurately as in

Further, since the amplitude of the extracted sawtooth wave is changed by changing the correction start point from FIGS. 3 (a1) and 3 (b1), the gain after multiplication of the corner correction wave is reduced as shown in FIG. 3 (a2).
It is different as in (b2). Therefore, the amplitude adjustment circuit 13
By re-adjusting the gain of the entire wave, accurate and wider corner pincushion distortion correction can be performed.

[0012]

As described above, according to the present invention, by providing the pincushion distortion correction circuit having the upper corner and lower corner independent control systems as shown in FIG. 1, it is possible to perform better pincushion distortion correction. , Its practical effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram of a corner pincushion distortion correction wave generation circuit according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of screen distortion correction using the corner distortion correction wave of FIG.

FIG. 3 is a conceptual diagram of a change in gain of a corner distortion correction wave in FIG. 1;

FIG. 4 is a block diagram of a conventional pincushion distortion correction circuit.

FIG. 5 is a conceptual diagram of conventional corner distortion correction wave signal formation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sawtooth signal of one vertical cycle 2, 3 differential comparison circuit 4 reference bias variable circuit of differential comparison circuit 5, 6 multiplication circuit 7, 8 amplitude adjustment circuit 11, 12 control voltage input terminal 9 addition circuit 10 corner slice point Variable input terminal 13 Corner pincushion distortion correction wave amplifier circuit 14 Corner gain variable input terminal 15 Corner pincushion distortion correction wave signal

Claims (2)

(57) [Claims] An input of a sawtooth voltage signal having a period of one vertical period of a video signal is input to a C of a television receiver.
A differential comparator circuit a for taking out a portion corresponding to RT lower corners, and the differential comparator circuit b for taking out the upper corner portion corresponding to the CRT, a bias circuit for determining a slice potential of the upper corner and lower corner, the differential ratio
Multiplication circuit a for squaring the output signal extracted from the comparison circuit a
And the output signal extracted from the differential comparison circuit b is squared.
Multiplication circuit b, an amplitude adjustment circuit a for adjusting the amplitude of the output signal from the multiplication circuit a, an amplitude adjustment circuit b for adjusting the amplitude of the output signal from the multiplication circuit b, and the amplitude adjustment circuit a A corner which comprises an adder circuit for adding an output from the amplitude adjusting circuit b as an input, independently controlling distortion of an upper corner and a lower corner of the CRT, and allowing a correction start point to be arbitrarily variable. Pincushion distortion correction wave generation circuit. 2. A comprising an amplitude adjustment circuit c for adjusting the amplitude of the correction wave output as input from the corner pincushion distortion correction wave generating circuit according to claim 1, corner
Even after arbitrarily changing the correction start point, the gain of the entire correction wave is
Corner pincushion distortion correction wave amplitude adjustment circuit characterized by readjusting the Inn