JPH09179529A - Correcting circuit for color slurring in color image display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate color slurring of each pixel of a color image display device. SOLUTION: This correcting circuit is provided in a color image display device in which a specified number (1 to n) pixels each composed from three- red, green and blue- liquid crystal cells disposed stripelike are arranged to form a matrix. When red or blue is displayed with a specified luminance using a required number, 1 to n, of pixels in this circuit, the luminance of red (1R to nR) or blue (1B to nB) liquid crystal cells and the luminance of the liquid crystals of the color components corresponding to the above liquid crystal cells and belonging to other one or more pixels (1 to n) neighboring the above liquid crystal cells are controlled to shared between them so that an arbitrary point inside the pixel subjected to the above display gives the above specified luminance. In other words, the color slurring occurring in individual one of 1 to n pixels is designed not to be dissolved individually but evaded by the sharing between at least tow or more pixels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color shift correction circuit provided in a color image display device. As a color image display device, for example, a color LCD (Liquid Crystal D
isplay), a color PDP (Plasma Display Panel), a color LED (Light Emitting Diode), and the like.

[0002]

2. Description of the Related Art In general, a color image display device is one in which a required number of fine pixels having a function of changing the amount of light, the traveling direction, etc. are arranged in a matrix in accordance with a video signal from the outside. . Each pixel is, for example, a color LC
In the case of D, it is made of at least two liquid crystal cells in which the amount of transmitted or reflected light can be adjusted.

Several methods are known as the principle of the color image display device. Here, the principle of the color LCD shown in FIG. 6 will be described.

The color LCD shown in the figure has a large number of pixels (1 to n) arranged in a matrix, and each pixel (1 to n) emits light of the three primary colors of red, green and blue, respectively. A set of three liquid crystal cells (1R, 1G, 1B), (2R, 2G, 2B) that selectively transmit or reflect.
... (nR, nG, nB). The color of each pixel (1 to n) is three liquid crystal cells (1
R, 1G, 1B) to (nR, nG, nB) can be arbitrarily changed by controlling the amount of transmitted light or reflected light.

Three liquid crystal cells (1R, 1G, 1
B) to (nR, nG, nB) are arranged side by side in the row arrangement direction of the pixels (1 to n), which is a so-called stripe arrangement. That is, in each pixel (1 to n), a green liquid crystal cell (1G, 2G, ..., nG) is located at the center in the row arrangement direction, and a red liquid crystal cell (1R, 2R ,. ..NR)
On the right side of the row arrangement direction, the blue liquid crystal cells (1B, 2B,
... nB) are respectively arranged.

[0006]

By the way, in the above-mentioned color LCD, when the width of each pixel (1 to n) is W, the center of the red liquid crystal cell (1R, 2R, ... The centers of the blue liquid crystal cells (1B, 2B, ..., nB) are arranged on the left side and the right side, respectively, by W / 3 from the center of each pixel (1 to n).

Therefore, in the conventional color LCD, red appears to be shifted to the left and blue appears to be shifted to the right. For example,
As shown in FIG. 7, when the background portion A is black and the rectangular area B therein is displayed white, the left side of the rectangular area B is reddish and the right side is bluish. appear. It should be noted that such color misregistration causes similar symptoms regardless of the arrangement form of the liquid crystal cells (stripe arrangement, delta arrangement, etc.). The conventional color LCD has such a problem.

In order to solve such a problem, conventionally, for example, CR
In the case of T (Cathode Ray Tube) and video printers, one pixel is designed to be as small as possible so that color misregistration is not a concern, but especially in the case of a color LCD, there is a limit. Yes, other measures are needed.

[0009]

In the first color misregistration correction circuit of the present invention, the amount of light to be emitted, absorbed, transmitted or reflected, or the traveling direction of the light is controlled to be at least two or more, and A color image display device configured by combining required numbers of dots having different wavelengths or different color components to form one pixel and arranging the required number of pixels is provided. When displaying an arbitrary color component at a predetermined brightness, a pixel to be displayed and one or more other pixels different from that are used, and an arbitrary point in the pixel to be displayed becomes the predetermined brightness. Thus, the display operation of each of the pixels is controlled.

In the second color misregistration correction circuit of the present invention, the amount of light emitted, absorbed, transmitted or reflected, or the traveling direction of the light is controlled to be at least two or more, and the wavelength or color component of the light is different. This is provided in a color image display device configured by combining a required number of characteristic dots to form one pixel, and arranging the required number of the pixels to determine a desired color component of the required pixel. Brightness of the dot of the corresponding color component belonging to the pixel to be displayed, and the brightness of the dot of the color component corresponding to the dot belonging to one or more other pixels different from the pixel to be displayed. And are controlled so that an arbitrary point in the pixel to be displayed has the predetermined brightness.

A third color misregistration correction circuit of the present invention is a red,
A color image display device in which three dots having a function of controlling the amounts of green and blue light are arranged in a horizontal direction and combined in a required number of pixels arranged in a matrix,
When red or blue of a required pixel is displayed at a predetermined brightness, the brightness of a red or blue dot belonging to the pixel to be displayed and another 1 adjacent to the pixel to be displayed.
The brightness of dots of color components corresponding to the dots belonging to one or more pixels is distributed and controlled so that an arbitrary point in the pixel to be displayed has the predetermined brightness.

The above-described brightness distribution control of each dot is
It is preferable to change the drive signal level of each dot according to the distance from the center of each dot to an arbitrary point of the pixel to be displayed. In addition, the brightness distribution control of each dot described above is such that a dot belonging to a pixel to be displayed and a dot corresponding to the dot belonging to a pixel to be shared are repeatedly displayed and the display operation of each dot is performed. It is preferable to change the time.

In short, the present invention focuses on the fact that even if several spots in an arbitrary narrow region are illuminated, when the region is viewed from a distance, the entire region appears to shine like dots. Thus, the color shift occurring in each pixel is not solved by each pixel but is avoided by sharing at least two pixels. Specifically, in the pixel to be displayed, the brightness of the dots arranged offset from the center of the pixel and the brightness of the dot corresponding to the dot in the pixel to be shared are distributed at a required ratio to obtain the display target. The center of the pixel becomes to appear to shine with a predetermined brightness.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in FIGS.

FIG. 1 is a diagram showing a color misregistration correction circuit according to the first embodiment of the present invention. Here, as the color image display device using the color shift correction circuit, the same one as the color LCD shown in the conventional example is taken as an example.

The color LCD shown in the figure has a large number of pixels (1 to n) arranged in a matrix, and each pixel (1 to n) emits light of the three primary colors of red, green and blue, respectively. A set of three liquid crystal cells (1R, 1G, 1B), (2R, 2G, 2B) that selectively transmit or reflect.
... (nR, nG, nB). The color of each pixel (1 to n) is three liquid crystal cells (1
R, 1G, 1B) to (nR, nG, nB) can be arbitrarily changed by controlling the amount of transmitted light or reflected light.

Three liquid crystal cells (1R, 1G, 1
B) to (nR, nG, nB) correspond to the dots described in the claims, and are arranged so as to be adjacent to each other in the row arrangement direction of the pixels (1 to n), that is, a so-called stripe arrangement. . That is, each pixel (1-
n), green liquid crystal cells (1G, 2G, ... nG) are arranged in the center of the row arrangement direction, and red liquid crystal cells (1R, 2R, ... Blue liquid crystal cells (1B, 2B, ... nB) on the right side of the array direction
But they are arranged respectively.

Then, a set of three liquid crystal cells (1R, 1G, 1) of red, green, and blue for each of a large number of pixels (1 to n).
B) to (nR, nG, nB), individual signal lines (20R, 20G, 20B) to (nR, nG, n) respectively.
The video signals of red, green and blue are individually supplied via B).

In the color LCD having such a structure,
The signal lines (20R, 21R, ... nR) for the red liquid crystal cells (1R, 2R, ... nR) and the signal lines (2 for the blue liquid crystal cells (1B, 2B, ... nB).
0B, 21B, ..., nB) have color misregistration correction circuits 30, 30 inserted therein, respectively, and the green liquid crystal cell (1
Signal lines (20G, 21) for G, 2G, ...
G, ..., nG) does not include the color shift correction circuit 30 described above.

The color shift correction circuit 30 includes a linear conversion circuit 31.
And a non-linear conversion circuit 32, a first multiplication circuit 33, a second multiplication circuit 34, and an addition circuit 35. However, when the relationship between the level of the input video signal and the displayed luminance has a linear characteristic, the pair of conversion circuits 31 and 32 described above can be omitted.

The linear conversion circuit 31 in the front stage makes the video signal having the γ characteristic a linear characteristic, and the non-linear conversion circuit 32 in the rear stage γ-corrects the video signal having the linear characteristic to make the nonlinear characteristic. It is something to return.

The first multiplication circuit 33 applies a coefficient 2 / to the video signal.
The second multiplying circuit 34 multiplies the video signal by a coefficient ⅓. In the example shown in the figure, if the width of the pixel (1 to n) is W, the red liquid crystal cell (1
The center of R, 2R, ... nR is W / 3 on the left side, and the center of the blue liquid crystal cell (1B, 2B, ... nB) is W on the right side.
Since they are offset by / 3, the coefficients are set as described above. This coefficient is preferably set appropriately according to the arrangement of the liquid crystal cells, and can be set, for example, according to the distance from the center of the display target pixel to the center of each liquid crystal cell of the display target pixel and the sharing target pixel. .

The adder circuit 35 outputs the output of the first multiplication circuit 33 of the pixel in the front row in the row arrangement direction to be displayed and the second multiplication circuit 34 of the pixel in the rear row in the row arrangement direction to be shared.
And the output of.

Next, the operation of the color shift correction circuit 30 will be described. Here, an example is given in which only the second pixel 2 in the row arrangement direction in the drawing is illuminated with red light having a luminance L [cd / m ² ]. In this case, the third pixel 3 is selected to be shared by the second pixel 2. Note that the sharing target pixel is arranged before and after the liquid crystal cell corresponding to the display target pixel in the row arrangement direction, and has a relationship of sandwiching the central liquid crystal cell of the display target pixel with the corresponding liquid crystal cell of the display target pixel. Is selected.

That is, the color misregistration correction circuit 30 displays from the center of the red liquid crystal cell 2R of the second pixel 2 to be displayed and the red liquid crystal cell 3R of the third pixel 3 to be shared. The drive signal levels of both the liquid crystal cells 2R and 3R are distributed and controlled according to the distance to the center of the target pixel 2. That is, the luminance of the red liquid crystal cell 2R of the second pixel 2 is set to "2L / 3", and the luminance of the red liquid crystal cell 3R of the third pixel 3 is set to "L /
3 ″. As a result, the center of the second pixel 2 appears to shine in red with the brightness L.

Then, the second pixel 2 is set to the luminance L.
In the case where the third pixel 3 is illuminated in red with [cd / m ² ] and the third pixel 3 is illuminated in red, the luminance of the red liquid crystal cell 2R of the second pixel 2 is “2L /
3 ", the red liquid crystal cell 3R of the third pixel 3
Is "L / 3 + 2L '/ 3", and the red liquid crystal cell 4R of the fourth pixel 4 is "L' / 3".

The blue liquid crystal cells (1B, 2B, ...
The same applies to nB). When the second pixel 2 in the row arrangement direction in the drawing is made to emit blue light having the brightness L, the first pixel 1 is the second pixel 2
Will be shared. In this case, the brightness of the blue liquid crystal cell 2B of the second pixel 2 to be displayed is set to "2L /
3 ", the brightness of the blue liquid crystal cell 1B of the first pixel 1 to be shared may be set to" L / 3 ". As a result, the center of the second pixel 2 is blue with the brightness L. Will appear to shine.

Thus, the red liquid crystal cell (1R, 2
R, ... nR and blue liquid crystal cells (1B, 2B, ...
··· NB), not only the pixel to be displayed but also at least one pixel adjacent to it in the row arrangement direction is shared. However, the sharing target is different between the red liquid crystal cells (1R, 2R, ... nR) and the blue liquid crystal cells (1B, 2B, ... nB).

FIG. 2 is a diagram showing a color shift correction circuit according to the second embodiment of the present invention. The difference between this embodiment and the first embodiment is the configuration of the color misregistration correction circuit 40.

The color misregistration correction circuit 40 here is a red liquid crystal cell (1R, 2R, ... N) of each pixel (1 to n).
R) and blue liquid crystal cells (1B, 2B, ... nB) are alternately supplied with two types of video signals at a required cycle, whereby red liquid crystal cells (1R, 2R ,.
nR) and blue liquid crystal cells (1B, 2B, ..., nB) are made to blink, and are composed of switching elements whose contacts a and b are controlled to be switched by control pulses P1 and P2 having a required duty ratio. ing.

Specifically, the high level period ta of the control pulses P1 and P2 is connected to the a contact, and the low level period tb is connected to the b contact. When the contact a is connected, the corresponding signal lines (20R, 20B) are connected to the red liquid crystal cells (1R, 2R, ... nR) and the blue liquid crystal cells (1B, 2B ,. , 21R, 21B ... n
When the contact point b is connected while the video signal is supplied from R, nB), the red liquid crystal cells (1R, 2R, ...
R) and the blue liquid crystal cells (1B, 2B, ... nB), the red liquid crystal cells (1R,
2R, ... nR and blue liquid crystal cells (1B, 2B, ...
..NB corresponding signal lines (20R, 21R, ...
The video signal is supplied from the branch lines of (nR), (20B, 21B, ..., nB).

By switching between the contacts a and b, a red liquid crystal cell (1R, 2R, ... nR) or a blue liquid crystal cell (1R
B, 2B, ... nB) will be blinked, but if the blinking cycle is made sufficiently short, it does not appear to be blinking to the human eye, and it is as if there were two types of video signals. It seems to be shining at the middle brightness of each brightness. Because
This is because the human eye has the characteristic of LPF (Low Pass Filter) and cannot follow the blinking of a very short period. By the way, the brightness of the liquid crystal cell is controlled by the control pulses P1, P
It is determined by the duty ratio of 2. If the switching operation of applying the video signal La for the time ta and then applying the video signal Lb for the time tb is repeated at high speed to the liquid crystal cell to be displayed, the liquid crystal cell becomes (Lata + Lbtb).
It looks like it is shining with a brightness of / (ta + tb). Therefore, as the above-mentioned duty ratio, for example, ta:
It suffices to determine ta and tb so that tb = 2: 1.

The control pulses P1 and P2 described above are
In the case of a raster scan type color image display device,
It can be made with a relatively simple circuit using a vertical synchronizing signal or the like. In this embodiment, the conversion circuit 3 such as γ correction is used.
The presence or absence of 1, 32 is arbitrary. This embodiment is mainly used for displaying a still image or a moving image,
Especially effective. If the vertical frequency is set high enough, the problem of flicker does not occur. It can also be applied when the driver controlling the liquid crystal cell can display only two gradations (8 colors). Furthermore, the color shift correction circuit 40 and the liquid crystal cells (1R, 1G, 1B), (2R, 2G, 2B), ...
A low pass filter (LPF) may be inserted between (nR, nG, nB). By inserting a low-pass filter, flicker can be prevented even when the vertical frequency is not very high.

3 and 4 relate to the third embodiment of the present invention. FIG. 3 is a diagram showing a color misregistration correction circuit, and FIG. 4 is a table used for explaining the operation. Here, three signal lines (20
R, 20G, 20B) and video signals serially input from each of a plurality of pixels (1 to n) of red, green, and blue liquid crystal cells (1R, 1G, 1).
B), (2R, 2G, 2B), ... (nR, nG, n
B) to serial / parallel conversion circuits 50R, 50
The case where the present invention is applied to a color image display device having a configuration of supplying in parallel via G and 50B is given as an example. The serial / parallel conversion circuit 50R, 5 described above
0G and 50B are for sequentially outputting the video signals sequentially applied to each liquid crystal cell of a required pixel with one clock of the sampling clock supplied from the control circuit 100. The sampling clock by the control circuit 100 can be relatively easily created based on the horizontal and vertical synchronizing signals of the video signal.

In this embodiment, a red liquid crystal cell (1R,
Color shift correction circuits 60 and 70 are inserted in the signal line 20R for 2R, ..., nR) and the signal line 20B for the blue liquid crystal cells (1B, 2B, ... The color shift correction circuits 60 and 70 described above are not inserted in the signal line 20G for the cells (1G, 2G, ..., nG), but the delay element 80 is inserted. That is, since it is only necessary to provide two color shift correction circuits, the configuration becomes simpler than in the first and second embodiments.

Then, the color misregistration correction circuit 60 for red is
A linear conversion circuit 61 and a non-linear conversion circuit 62, a first multiplication circuit 63, a second multiplication circuit 64, an addition circuit 65,
The blue color shift correction circuit 70 including the first and second delay elements 66 and 67 includes a linear conversion circuit 71 and a non-linear conversion circuit 72, a first multiplication circuit 73, and a second multiplication circuit 74.
And an adder circuit 75 and a delay element 76, all of which have the same structure as an FIR (Finite Impulse Response) filter. The color misregistration correction circuits 60 and 70
Since the other components (61 to 65, 71 to 75) other than the delay elements 66, 67 and 76 are the same as those described in the first embodiment, the description thereof will be omitted. Also in this case, if the relationship between the level of the input video signal and the displayed luminance has a linear characteristic, the pair of conversion circuits 61, 62, 71, 72 described above can be omitted. .

The delay element 80, the first and second delay elements 66 and 67, and the delay element 76 described above are connected to the signal line (20
The video signals serially input from R, 20G, and 20B) are each delayed by one clock, and may be, for example, a flip-flop or a sampling and holding circuit.

In operation, red, green, and blue video signals are serially applied through signal lines 20R, 20G, and 20B, of which the blue video signal is a blue liquid crystal cell (1B, 2B, ... nB), but the video signals for red and green are delayed by the delay elements 80, 66, 67.
Is delayed by the red liquid crystal cells (1R, 2R, ...
nR) and green liquid crystal cells (1G, 2G, ... NG). The operation of each unit is shown in the table of FIG. Also in this case, as in the first embodiment, when the brightness of the corresponding liquid crystal cell of the display target pixel is "L", the brightness of the liquid crystal cell of the display target pixel is "2L / 3", and Distributing the brightness of the liquid crystal cell as "L / 3" remains unchanged.

When the input video signal is a digital signal in the third embodiment, color shift correction circuits 60 'and 70' as shown in FIG. 5 can be used.

FIG. 5 is a diagram showing a color misregistration correction circuit according to the fourth embodiment of the present invention. The color misregistration correction circuit 60 ′ for red here includes delay elements 66 and 67, a control unit 68,
A color misregistration correction circuit 70 'for blue, which includes a storage unit 69.
Includes a delay element 76, a control unit 77, and a storage unit 78.

The storage units 69 and 78 are so-called look-up tables for preliminarily calculating multiplications and additions in the third embodiment and storing the results. In addition, this storage unit 6
The contents of 9, 78 may be γ-corrected if necessary.

The control units 68 and 77 appropriately create address information for the storage units 69 and 78 based on the supplied video signals, and based on the address information, the storage units 69 and 7 are generated.
8 is read and supplied to the serial / parallel conversion circuits 50R, 50G, 50B.

The present invention is not limited to the above embodiment, and various applications and modifications are possible.

(1) In the above embodiment, the color shift is avoided by sharing one pixel with the pixel to be displayed. However, two or more pixels are shared. Good.

(2) In the above embodiment, one pixel is composed of three liquid crystal cells of red, green and blue. However, for example, two pixels of red and cyan or, for example, red and green, are provided.
The present invention can be applied even when the liquid crystal cell is composed of four or more blue and green liquid crystal cells. Further, the arrangement form of the liquid crystal cells is not limited to the stripe arrangement, and other various arrangement forms can be adopted.

(3) The coloring method is the addition method (red, green,
It is not limited to only the method of combining from blue), but the color reduction method (yellow,
A method of combining from magenta and cyan) can be used.

(4) The present invention can be applied not only to color LCDs but also to color PDPs, color LED displays and the like. Further, the color misregistration correction circuit is not limited to the one provided in the display driver, and in the case of a notebook personal computer, even if it is built in the video signal output buffer or the video controller, M
A PU (Micro Processing Unit) may be substituted for the function.

[0048]

According to the present invention, it is possible to effectively eliminate the color misregistration for each pixel which has occurred in the color image display device, and display a clear and faithful image.

[Brief description of the drawings]

FIG. 1 is a diagram showing a color misregistration correction circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a color misregistration correction circuit according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a color shift correction circuit according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a color misregistration correction circuit according to a fourth embodiment of the present invention.

FIG. 5 is a table used for explaining the operation in the fourth embodiment.

FIG. 6 is a plan view schematically showing a conventional color LCD.

FIG. 7 is an explanatory diagram showing a display example on a conventional color LCD.

[Explanation of symbols]

 1-n pixel 1R-nR red liquid crystal cell 1G-nG green liquid crystal cell 1B-nB blue liquid crystal cell 20R-nR signal line for red liquid crystal cell 20G-nG signal line for green liquid crystal cell 20B-nB blue liquid crystal Cell signal line 30 Color shift correction circuit

Claims (5)

[Claims] 1. The amount of light emitted or absorbed or transmitted or reflected or the traveling direction of the light is at least 2.
Provided in a color image display device in which one pixel is formed by combining a required number of dots having characteristics that are controlled as described above and different in wavelength or color component of light, and the required number of pixels is arranged. When a desired color component of a desired pixel is displayed at a predetermined brightness, the pixel to be displayed and another 1 different from that pixel are displayed.
A color shift of the color image display device, wherein one or more pixels are used to control the display operation of each of the pixels so that an arbitrary point in the pixel to be displayed has the predetermined brightness. Correction circuit. 2. The amount of light emitted or absorbed or transmitted or reflected or the traveling direction of the light is at least 2.
Provided in a color image display device in which one pixel is formed by combining a required number of dots having characteristics that are controlled as described above and different in wavelength or color component of light, and the required number of pixels is arranged. Therefore, when displaying an arbitrary color component of a required pixel at a predetermined brightness, the brightness of the dot of the corresponding color component belonging to the pixel to be displayed and another 1 different from the pixel to be displayed.
A color image, wherein the brightness of dots of color components corresponding to the dots belonging to one or more pixels is distributed and controlled so that any point in the pixel to be displayed has the predetermined brightness. Color shift correction circuit for display device. 3. A color misregistration correction circuit for a color image display device in which a required number of pixels, each of which is a combination of three dots arranged in a horizontal direction and having a function of controlling the amount of red, green, and blue light, are arranged in a matrix. Therefore, when displaying red or blue of a required pixel at a predetermined brightness, the brightness of the red or blue dot belonging to the pixel to be displayed and the other 1 adjacent to the pixel to be displayed.
A color image, wherein the brightness of dots of color components corresponding to the dots belonging to one or more pixels is distributed and controlled so that any point in the pixel to be displayed has the predetermined brightness. Color shift correction circuit for display device. 4. The brightness distribution control of each dot changes the drive signal level of each dot according to the distance from the center of each dot to an arbitrary point of the pixel to be displayed. 2. A color shift correction circuit of the color image display device described in 2 or 3. 5. The brightness distribution control of each dot causes a dot belonging to a pixel to be displayed and a dot corresponding to the dot belonging to a pixel to be shared to be repeatedly displayed, and The color misregistration correction circuit for a color image display device according to claim 2, wherein the display operation time is changed.