JP2000004375A - Distortion correction wave generation circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distortion correction wave generation circuit for correcting image distortions at four corners on CRT, through the use of a corner distortion correction wave generated by using a saw-tooth wave associating with a vertical picture position. SOLUTION: A vertical saw-tooth wave generation part 1 inputs a synchronizing signal and generates a prescribed vertical saw-tooth wave. A vertical output part 2 inputs the vertical saw-tooth wave which the vertical saw-tooth wave generation part 1 outputs and converts in into the vertical saw-tooth wave of vertically polarized current inletlocked with a vertical image portion. An upper triangular wave cut part 3 and a lower triangular cut part 4 input vertical saw-tooth waves which the vertical output part 2 outputs and cut the vertical saw-tooth waves into triangular forms at prescribed voltages V1 and V2. An adder 5 adds triangular waveforms, which the upper triangular wave cut part 3 and the lower triangular wave cut part 4 output and outputs a corner distortion correction wave. An adder 6 adds the corner distortion wave which the adder 5 outputs, and a vertical parabolic wave, generates right/left bobbin correction waves and outputs them to a horizontal polarizing circuit side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion correction wave generation circuit, and more particularly, to a circuit for correcting image distortion generated at four corners on a picture tube (hereinafter referred to as a CRT; Cathode Ray Tube) in a television receiver. The present invention relates to a distortion correction wave generation circuit that generates a correction wave for correction.

[0002]

2. Description of the Related Art As is well known, a television receiver using a CRT generates image distortion at four corners on the CRT due to its structure and characteristics. Therefore, conventionally, in a television receiver using a CRT, a corresponding correction wave is generated in a deflection circuit to correct image distortion. Less than,
Generation of a correction wave and correction of image distortion performed by a conventional deflection circuit will be briefly described with reference to FIGS.

FIG. 9 is a block diagram showing a configuration of a distortion correction wave generation circuit in a conventional deflection circuit. FIG. 10 is a diagram showing signal waveforms of respective portions in FIG. 9, and the symbols (A to G) in FIG. 9 correspond to the same symbols in FIG. In FIG. 9, the conventional distortion correction wave generation circuit includes a vertical sawtooth wave generation unit 11, an upper triangular wave cutout unit 13, a lower triangular wave cutout unit 14, and adders 15 and 16. In FIG. 9, the configuration of the vertical output unit 12 is also described in order to correspond to an embodiment of the present invention described later.

Referring to FIG. 9 and FIG. 10, a vertical sawtooth generator 11 receives a synchronization signal (A) and generates a predetermined vertical sawtooth (B). The upper triangular wave cutout unit 13 receives the vertical sawtooth wave (B) output from the vertical sawtooth wave generation unit 11 and inputs a predetermined slice voltage S
In step 1, the vertical sawtooth wave is cut into a triangular shape (C). Similarly, the lower triangular wave cutout unit 14 receives the vertical sawtooth wave (B) output from the vertical sawtooth wave generation unit 11 and cuts the vertical sawtooth wave into a triangular shape (D) at a predetermined slice voltage S2. . The adder 15 adds the triangular waveforms (C, D) output from the upper triangular wave cutout unit 13 and the lower triangular wave cutout unit 14, and outputs a corner distortion correction wave (E). The adder 16 adds the corner distortion correction wave (E) output by the adder 15 and the vertical parabola wave (F) to generate a left and right pincushion distortion correction wave (G), and outputs it to the horizontal deflection circuit side. Note that one or more multipliers may be inserted between the adder 15 and the adder 16 as necessary.

Then, on the horizontal deflection circuit side, the horizontal sawtooth wave is amplitude-modulated in accordance with the left and right pincushion distortion correction wave (G), and as a result, image distortion at four corners on the CRT is corrected.

On the other hand, the vertical sawtooth generator 11 outputs the generated vertical sawtooth (B) to the vertical output unit 12. The vertical output unit 12 converts a vertical sawtooth wave (B), which is a voltage waveform, into a vertical deflection current for driving the vertical deflection coil, and outputs the current to the vertical deflection coil. The vertical output unit 12 controls the screen display position on the CRT by increasing or decreasing the vertical deflection current.

[0007]

In recent years, a television receiver has been equipped with a special screen display (zoom display) in order to cope with various video media in addition to a normal screen display (a screen display in which no control is performed). Display, subtitle movie display, etc.).

However, in the case of the method of controlling the display screen position by the vertical deflection current as described above, the vertical sawtooth wave (B) used in the above-described conventional distortion correction wave generation circuit is a fixed sawtooth wave corresponding to a normal screen display. It is a sawtooth wave. Therefore, when the special screen display is performed, the content of the special screen display that is separately controlled is not reflected on the corner distortion correction wave (E) generated based on the vertical sawtooth wave (B), and the corner distortion correction wave is not reflected. The vertical position of (E) does not correspond to the vertical position of the distortion correction required for the image actually displayed on the screen.

For example, the following is the case. As shown in FIG. 11, in a wide television receiver,
Normally, a portion where distortion correction is applied to an image is a portion indicated by a black circle (marked by ●) (FIG. 11A). Here, consider a case where a letterbox signal (a signal having a portion with no image above and below) is received. Even in this case, if the special image display is not performed, the four corners are distortion-corrected as in the normal image display (FIG. 11).
(B)). However, the letterbox signal is a signal that enables a wide-screen television to perform a large-screen display even if the video is enlarged in the vertical direction without losing the circularity of the screen. For this reason, in general, in a wide television receiver, the vertical amplitude is changed to enlarge a letterbox signal image. However, when such control is performed, the position where distortion correction is performed also moves to the outside of the effective screen at the same time as the image is enlarged (FIG. 11C).

As described above, in the conventional distortion correction wave generation circuit that controls the display screen position by the vertical deflection current, the generated corner distortion correction wave (E) is not linked to the vertical image position.
For this reason, when the vertical image position is moved, there is a problem that distortion correction is not performed at a necessary position, or distortion correction is applied to an unnecessary position, thereby distorting the image.

Therefore, an object of the present invention is to generate a corner distortion correction wave using a sawtooth wave linked to a vertical image position, and to correct the image distortion at the four corners on a CRT using the corner distortion correction wave. It is to provide a generating circuit.

[0012]

Means for Solving the Problems and Effects of the Invention The first invention is a distortion correction wave generation circuit used for a television receiver for displaying an image on a CRT, and the vertical direction of an image scanned on the screen of the CRT is provided. Vertical output means for generating a vertical sawtooth wave interlocked with the amplitude and the vertical position; upper triangular wave cutting means for cutting an upper triangular wave from the vertical sawtooth wave based on a predetermined first voltage; The lower triangular wave cutting means for cutting the lower triangular wave from the vertical sawtooth wave based on the voltage of the vertical sawtooth wave, the upper triangular wave output by the upper triangular wave cutting means, and the lower triangular wave output by the lower triangular wave cutting means are added. And a second adding means for adding the waveform output from the first adding means to the vertical parabolic wave.

As described above, according to the first aspect, the CR
A distortion correction wave is generated using a vertical sawtooth wave interlocked with the screen display on T. Thereby, even in a television receiver of the type in which the vertical image position is controlled by the vertical deflection current,
It is possible to correct image distortion linked to the vertical amplitude and the vertical position.

According to a second aspect of the present invention, in the first aspect, one or two multiplication means for multiplying and outputting two input waveforms are provided between the first addition means and the second addition means. The above is further provided.

As described above, according to the second aspect, the first aspect
According to the invention, the distortion correction wave is further generated via the multiplication means. As a result, it is possible to generate a correction wave that matches the actual distortion appearing on the CRT of the television receiver.

A third invention is characterized in that, in the first and second inventions, the first voltage and the second voltage are DC voltages having the same polarity but different DC voltages.

As described above, according to the third aspect, the first aspect
In the second and third aspects of the present invention, the first and second voltages can be set with the same polarity, so that a power supply circuit of another polarity is not required, and the circuit configuration is simplified.

According to a fourth aspect of the present invention, there is provided a television receiver provided with a distortion correction wave generation circuit for generating a correction wave for correcting image distortion on a CRT. Vertical output means for generating a vertical sawtooth wave interlocked with the vertical amplitude and vertical position of the image to be scanned, and an upper triangular wave cutting means for cutting an upper triangular wave from the vertical sawtooth wave based on a first predetermined voltage; Lower triangular wave cutting means for cutting a lower triangular wave from a vertical sawtooth wave based on a second predetermined voltage, an upper triangular wave output by an upper triangular wave cutting means, and a lower triangular wave output by a lower triangular wave cutting means. A first adding means for adding a triangular wave is provided, and a second adding means for adding a waveform output from the first adding means to a vertical parabola wave.

In a fifth aspect based on the fourth aspect, one or two multiplication means for multiplying and outputting two input waveforms are provided between the first addition means and the second addition means. The above is further provided.

According to a sixth aspect, in the fourth and fifth aspects, the first voltage and the second voltage are DC voltages having the same polarity but different from each other.

As described above, the fourth to sixth inventions correspond to the first invention.
A television receiver including the distortion correction wave generation circuit according to the third to third aspects of the present invention. Therefore, the television receivers of the fourth to sixth inventions can exhibit useful effects in the first to third inventions, respectively.

A seventh aspect of the present invention is a distortion correction method performed in a television receiver for displaying an image on a CRT, wherein a vertical sawtooth wave generated at a terminal of a vertical deflection current detection resistor and linked to a vertical amplitude and a vertical position is generated. A triangular wave corresponding to the position to be corrected is generated using the correction wave obtained by adding the triangular wave to the vertical parabolic wave, and image distortion correction at four corners on the CRT is performed.

As described above, according to the seventh aspect, the CR
A distortion correction wave is generated using a vertical sawtooth wave interlocked with the screen display on T. Thereby, even in the case of the method of controlling the vertical image position by the vertical deflection current, it is possible to correct the image distortion linked to the vertical amplitude and the vertical position.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a block diagram showing a configuration of a distortion correction wave generation circuit according to a first embodiment of the present invention. In FIG. 1, a distortion correction wave generation circuit according to the first embodiment includes a vertical sawtooth wave generation unit 1.
A vertical output unit 2, an upper triangular wave cutout unit 3, a lower triangular wave cutout unit 4, and adders 5 and 6. Note that the distortion correction wave generation circuit according to the first embodiment is basically configured as a deflection circuit of a television receiver.

FIG. 2 is a diagram showing a signal waveform of each part in FIG. 1. Symbols (A to G) in FIG. 1 correspond to the same symbols in FIG.

Referring to FIGS. 1 and 2, a vertical sawtooth wave generator 1 receives a synchronization signal (A) and generates a predetermined vertical sawtooth wave (B). The vertical output unit 2 outputs a vertical sawtooth wave (B) output by the vertical sawtooth wave generation unit 1.
And converts the vertical sawtooth wave, which is a voltage waveform, into a vertical sawtooth wave (B ′) of a vertical deflection current (similar to a vertical deflection current for driving a vertical deflection coil). The vertical output unit 2 is directly linked to the control of the screen display position on the CRT, and controls the vertical deflection current in accordance with the control of the screen display position.

The upper triangular wave cutting section 3 receives the vertical sawtooth wave (B ') output from the vertical output section 2 and cuts the vertical sawtooth wave into a triangular shape (C) at a predetermined slice voltage V1. Similarly, the lower triangular wave cutout unit 4 receives the vertical sawtooth wave (B ′) output from the vertical output unit 2 and cuts the vertical sawtooth wave into a triangular shape (D) at a predetermined slice voltage V2. At this time, one triangular wave is inverted and output so that the triangular wave cut out by the upper triangular wave cutout unit 3 and the triangular wave cut out by the lower triangular wave cutout unit 4 have the same GND potential and polarity. In the first embodiment, the triangular wave cut by the lower triangular wave cutout unit 4 is inverted and output). The adder 5 adds the triangular waveforms (C, D) output from the upper triangular wave cutout unit 3 and the lower triangular wave cutout unit 4, and adds a corner distortion correction wave (E).
Is output. The adder 6 adds the corner distortion correction wave (E) output from the adder 5 and the vertical parabola wave (F) to generate a left and right pincushion distortion correction wave (G), and outputs it to the horizontal deflection circuit side.

Then, on the horizontal deflection circuit side, the horizontal sawtooth wave is amplitude-modulated in accordance with the left and right pincushion distortion correction waves, and as a result, image distortion at four corners on the CRT is corrected.

Here, the difference between the distortion correction wave generation circuit according to the first embodiment of the present invention and the above-described conventional distortion correction wave generation circuit is that the distortion correction wave generation circuit is a vertical sawtooth wave for generating a corner distortion correction wave. A vertical sawtooth wave (B ') interlocked with the screen display output from the output terminal (terminal on the side not connected to GND) of the vertical deflection current detection resistor R3. Therefore, the slice voltage V for cutting the triangular wave by the upper triangular wave cutting unit 3 and the lower triangular wave cutting unit 4 is set.
The levels of 1, V2 correspond to the actual positions on the display screen in an absolute relationship (in the related art, there is only a relative positional relationship).

As a result, the distortion correction wave generation circuit according to the first embodiment of the present invention has a useful effect that has not been achieved in the past. Hereinafter, this useful effect will be specifically described with reference to FIGS.

As described in the above prior art, when a letter box signal image is enlarged in the vertical direction by a wide television receiver, the distortion correction wave generating circuit according to the first embodiment uses the vertical deflection current detection. The amplitude of the vertical sawtooth wave (B ′) output from the output terminal of the resistor R3 is extended in conjunction with the screen display (FIG. 3 (B ′)). Here, since the slice voltages V1 and V2 are fixed at predetermined values, the triangular waves (C and D) cut by the upper triangular wave cutout unit 3 and the lower triangular wave cutout unit 4 respectively have the vertical sawtooth wave (B). ') Changes with amplitude extension (Fig. 3 (C),
(D)).

Therefore, even when an image is enlarged, a portion to which distortion correction is applied by the enlargement follows and is enlarged. Therefore, even if the corner portion of the original video moves out of the effective screen range due to the enlargement, it is possible to apply appropriate distortion correction to the corner portion after the enlargement.

Conversely, when the image is reduced in the vertical direction, the distortion correction wave generating circuit according to the first embodiment uses the vertical sawtooth wave (B ') output from the output terminal of the vertical deflection current detection resistor R3. ) Is compressed in conjunction with the screen display (FIG. 4 (B ′)). Here, the slice voltages V1, V2
Is fixed at a predetermined value, so that the triangular waves (C, D) cut by the upper triangular wave cutout unit 3 and the lower triangular wave cutout unit 4, respectively, are accompanied by the amplitude compression of this vertical sawtooth wave (B '). (FIGS. 4C and 4D).

Therefore, even when the image is reduced, the portion to which the distortion correction is applied by the reduced amount is also followed and reduced. Therefore, even if the corner portion of the original video moves to a position where distortion correction is unnecessary due to the reduction, distortion correction is not applied to the corner portion after the reduction.

As described above, the distortion correction wave generation circuit according to the first embodiment of the present invention uses the vertical sawtooth wave generated at the output terminal of the vertical deflection current detection resistor R3 in conjunction with the screen display to correct the corner distortion. Generate waves. Thereby, even in the case of the method of controlling the vertical image position by the vertical deflection current, it is possible to correct the image distortion linked to the vertical amplitude and the vertical position.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration of a distortion correction wave generation circuit according to the embodiment. In FIG. 5, a distortion correction wave generation circuit according to the second embodiment includes a vertical sawtooth wave generation unit 1, a vertical output unit 2, an upper triangular wave cutout unit 3, a lower triangular wave cutout unit 4, an adder 5 and 6 and a multiplier 7.

As shown in FIG. 5, the distortion correction wave generation circuit according to the second embodiment is provided between the adder 5 and the adder 6 of the distortion correction wave generation circuit according to the first embodiment. , Multiplier 7
Is further added. The other configuration of the distortion correction wave generation circuit according to the second embodiment is the same as the configuration of the distortion correction wave generation circuit according to the first embodiment, and the same reference is used for the other configuration. Numbers are assigned and explanations are omitted.

The multiplier 7 receives the corner distortion correction wave (E) output from the adder 5 and multiplies it, that is, squares the corner distortion correction wave (E). The multiplied corner distortion correction wave has a spire shape as shown in FIG.

As described above, the multiplication of the corner distortion correction wave (E) output from the adder 5 via the multiplier 7 is performed by the final corner distortion correction wave (H) added to the vertical parabolic wave (F). ) Is adjusted to a correction wave that matches the actual corner distortion on the CRT. Therefore, in the distortion correction wave generation circuit according to the second embodiment, the configuration via one multiplier 7 is shown, but two or more multipliers are connected in series according to the corner distortion to be corrected. To output a final corner distortion correction wave.

As described above, the distortion correction wave generation circuit according to the second embodiment of the present invention generates a final corner distortion correction wave via the multiplier 7. Thereby, the actual CRT
Image distortion can be corrected using a correction wave that matches the above corner distortion.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration of a distortion correction wave generation circuit according to the embodiment. 7, a distortion correction wave generation circuit according to the third embodiment includes a vertical sawtooth wave generation unit 1, a vertical output unit 2, an upper triangular wave cutout unit 3, a lower triangular wave cutout unit 4, an adder 5 and 6, and resistors R4 and R5.

As shown in FIG. 7, the distortion correction wave generation circuit according to the third embodiment has a configuration in which resistors R4 and R5 are further added to the distortion correction wave generation circuit according to the first embodiment. . The other configuration of the distortion correction wave generation circuit according to the third embodiment is the same as the configuration of the distortion correction wave generation circuit according to the first embodiment, and the same reference is used for the other configuration. Numbers are assigned and explanations are omitted.

One terminal of the resistor R4 has an arbitrary voltage VD.
, And the other terminal is connected to one terminal of the resistor R5. The other terminal of the resistor R5, which is not connected to the resistor R4, is an output terminal of the vertical deflection current detection resistor R3 of the vertical output unit 2 (a terminal on the side not connected to GND).
It is connected to the. The connection point between the resistors R4 and R5 is connected to the inputs of the upper triangular wave cutout unit 3 and the lower triangular wave cutout unit 4.

With the above configuration, the vertical deflection current detection resistor R
The vertical sawtooth wave appearing at the output terminal of No. 3 is level-shifted by the voltage VD and the voltage drop determined by the resistors R4 and R5 (by the resistor R5), and appears at the connection point between the resistors R4 and R5. Therefore, the voltage VD and the resistances R4, R
By appropriately setting the value of 5, the potential of all the vertical sawtooth waves can be level-shifted to the positive polarity side as shown in FIG.

As described above, the distortion correction wave generation circuit according to the third embodiment of the present invention includes the voltage VD and the resistors R4 and R4.
5, the potential of all the vertical sawtooth waves can be level-shifted to the positive polarity side. As a result, the slice voltage V2 in the lower triangular wave cutting unit 4 can be set at a positive potential, so that a power supply circuit for generating a negative voltage is not required, and the circuit configuration is simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a distortion correction wave generation circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing signal waveforms of respective parts in FIG.

FIG. 3 is a diagram showing a signal waveform that changes as the vertical screen position moves.

FIG. 4 is a diagram illustrating a signal waveform that changes as the vertical screen position moves.

FIG. 5 is a block diagram illustrating a configuration of a distortion correction wave generation circuit according to a second embodiment of the present invention.

FIG. 6 is a diagram showing signal waveforms of respective parts in FIG.

FIG. 7 is a block diagram illustrating a configuration of a distortion correction wave generation circuit according to a third embodiment of the present invention.

FIG. 8 is a diagram showing signal waveforms of respective parts in FIG. 7;

FIG. 9 is a block diagram showing a configuration of a conventional distortion correction wave generation circuit.

FIG. 10 is a diagram showing signal waveforms of respective parts in FIG. 9;

FIG. 11 is a diagram showing a conventional distortion correction state when a special screen is displayed.

[Explanation of symbols]

 1,11 vertical sawtooth wave generator 2,12 vertical output unit 3,13 upper triangular wave cutout unit 4,14 lower triangular wave cutout unit 5,6,15,16 adder 7 multipliers R1 to R5 …resistance

Claims (7)

[Claims] 1. A distortion correction wave generation circuit used in a television receiver for displaying an image on a CRT, wherein the distortion correction wave generation circuit generates a vertical sawtooth wave linked to a vertical amplitude and a vertical position of an image scanned on a screen of the CRT. Vertical output means; upper triangular wave cutting means for cutting an upper triangular wave from the vertical sawtooth wave based on a predetermined first voltage; and lowering means from the vertical sawtooth wave based on a second predetermined voltage. A lower triangular wave cutting means for cutting the triangular wave on the side; an upper triangular wave output by the upper triangular wave cutting means; a first adding means for adding a lower triangular wave output by the lower triangular wave cutting means; A distortion correction wave generation circuit, comprising: a second addition unit that adds a waveform output from the first addition unit to the parabola wave. 2. The apparatus according to claim 1, further comprising one or two or more multiplication means for multiplying and outputting two input waveforms between said first addition means and said second addition means. The distortion correction wave generation circuit according to the above description. 3. The first voltage and the second voltage,
3. The distortion correction wave generation circuit according to claim 1, wherein the DC voltages have the same polarity but different DC voltages. 4. A television receiver comprising a distortion correction wave generation circuit for generating a correction wave for correcting image distortion on a CRT, wherein the distortion correction wave generation circuit scans a screen of the CRT. Vertical output means for generating a vertical sawtooth wave interlocked with the vertical amplitude and vertical position of an image; upper triangular wave cutting means for cutting an upper triangular wave from the vertical sawtooth wave based on a predetermined first voltage; Lower triangular wave cutting means for cutting a lower triangular wave from the vertical sawtooth wave based on the determined second voltage, upper triangular wave output by the upper triangular wave cutting means, and output by the lower triangular wave cutting means. A television receiver, comprising: first adding means for adding a lower triangular wave; and second adding means for adding a waveform output from the first adding means to a vertical parabolic wave. . 5. The apparatus according to claim 4, further comprising one or two or more multiplication means for multiplying and outputting two input waveforms between said first addition means and said second addition means. The television receiver as described. 6. The first voltage and the second voltage,
The television receiver according to claim 4, wherein the DC voltages have the same polarity but different DC voltages. 7. A distortion correction method performed in a television receiver for displaying an image on a CRT, wherein the correction is performed using a vertical amplitude generated at a terminal of a vertical deflection current detection resistor and a vertical sawtooth wave linked to a vertical position. A distortion correction method, comprising: generating a triangular wave corresponding to a position to be performed; and performing image distortion correction at four corners on the CRT using a correction wave obtained by adding the triangular wave to a vertical parabola wave.