JP2003076341A - Sequential color display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sequential color display device of less degradation in picture quality. SOLUTION: The display device divides one field into four periods for display of a red picture, a green picture, a blue picture, and a picture of another color to display the pictures, and the red picture, the green picture, the blue picture, and the picture of another color are subjected to gradation correction independently of one another in a gradation correction circuit 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sequential color display device.

[0002]

2. Description of the Related Art In this type of sequential color display device, as shown in FIG. 5, a display device for displaying an image by dividing one field into four periods for displaying red, green, blue and white is provided. It is known from Japanese Patent Laid-Open No. 09-90916.

In this conventional device, for example, as shown in FIG.
As shown in (b), the one having the minimum gradation from the RGB three-primary-color video signal (256 gradations) (G: 96 in FIG. 6).
Is subtracted, and this is made a white (W) video signal.

In a display device having a small number of gray levels that can be displayed, a circuit configuration as shown in FIG. 7 is used, and an input video signal is pseudo-expressed with a small number of gray levels by error diffusion processing or dither processing. . Reference numeral 600 is an RGB conversion circuit for converting an input signal into RGB3 primary color signals, 601 is a gradation limiting circuit for limiting the number of gradations of the RGB3 primary color video signals to be displayed, and 602 is a pseudo from the gradation limited video signal. A tone correction circuit for reproducing an input image, 603 generates a W signal from RGB3 primary color signals as described above, and RGBW
604 is a field memory for outputting a signal of the above, and 604 is a field memory. While writing in one, it reads from the other in the order of RGBW and inputs it to the source driver 606 of the field sequential display 605. The field sequential display 605 divides and displays one field into four periods of RGBW. The tone correction circuit 602 uses error diffusion processing or dither processing.

In the above circuit, the input video signal is R = 210, G = 90, B = 150 as shown in FIG.
When the gradation correction is R, as shown in FIG.
= 224, G = 96, B = 160. When a white signal is created from this, R = 128, G = 0, B = 64, W = 96, as shown in FIG. 8C, which is displayed on the display.

[0006]

However, the RGB
When the W video signal is generated after the gradation correction is performed on the three primary color video signals, the image deteriorates in the moving image due to the following reasons.

The error diffusion processing is a method of displaying a desired gradation in a pseudo manner by diffusing an error between an input video signal and a value actually displayed to surrounding pixels at a predetermined ratio.
The dither processing is a method in which a dither matrix having a predetermined number of rows and columns is added to the video signal, and then the one exceeding a predetermined threshold value is moved up.

The common point of these methods is that a desired gradation is obtained by spatially arranging a plurality of pixels having an optimum brightness according to a predetermined rule.

When gradation correction is performed on each of the RGB three-primary color video signals by error diffusion processing or dither processing, and then a W video signal is created, since RGBW does not express gradation by itself, RGBW The input image can be pseudo-expressed only when the four images completely overlap.
However, if the line-of-sight tracks the video and observes it, RG
Since the four BW images are observed spatially displaced, the input image signal is not represented correctly. In addition, the image quality deteriorates even when the displayable gradation levels are not evenly spaced as described above.

The input video signal has 256 gradations from 0 to 255, and the number of displayable gradations is 0, 1, 3, 7, 13,
23, 37, 56, 82, 115, 155, 202, 2
Consider the case of 13 gradations of 55.

As shown in FIG. 9A, the input video signal is R
= 210, G = 90, B = 150, it is considered that R = 202, G = 82, B = 155 after error diffusion (FIG. 9B). When a white signal is created from this, R = 120, G = 0, B = 73, W = 82 (FIG. 9C), but these are out of the displayable luminance level. Therefore, even if the closest value is selected for display, R = 115, G = 0, B = 82, W
= 82 (FIG. 9 (d)). When converted into RGB, R = 197, G = 82, B = 164, which deviates from the values determined by error diffusion. The value determined by error diffusion is the optimum value for pseudo-reproducing the input image with a small number of gradations, so if it deviates from this value, the input image will not be reproduced and the image quality will deteriorate. To do.

The present invention has been made in view of the above problems, and provides a sequential color display device with little deterioration in image quality.

[0013]

In order to solve the above problems, the sequential color display device of the present invention has four periods in which one field displays an image of red, green, blue, and another one color. It is a display device that divides and displays the image in a divided manner, and is a sequential color display device characterized by independently performing gradation correction on images of red, green, blue, and another one color.

[0014]

A sequential color display device according to claim 1 of the present invention divides one field into four periods for displaying images of red, green, blue, and another one color. A sequential color display device for displaying red generated from an input signal,
Since it is a sequential color display device characterized by independently performing gradation correction on green, blue, and other one-color images, each image of RGBW is also observed when a moving image is chased and observed. Since the required gradation is pseudo-expressed in the space, the deterioration of the image quality is less than that in the case where the gradation correction is performed and then the signal of another one color is generated. Even when the displayable gradations are not arranged at equal intervals, the gradation-corrected video signal, that is, the value to be displayed and the actually displayed video match.

Further, in the sequential color display device according to the second aspect of the present invention, one field is displayed by dividing an image of red, green, blue and other one color into four periods. A display device that performs gradation correction on the three primary colors of red, green, and blue, creates an image of the other one color, and independently creates an image signal of the red, green, blue, and the other one color. Since the sequential color display device is characterized by performing gradation correction processing, even if the arrangement of displayable gradations is not at equal intervals, the video signal after gradation correction, that is, the value to be displayed and The images that are actually displayed match.

According to a fifth aspect of the present invention, a sequential color display device includes a signal producing section for producing another one-color signal from an image signal corresponding to three primary colors, and gradation correction for the image signal. A sequential color display device, comprising: a gradation correction unit that performs a moving image portion; and a moving image processing unit that detects the moving image portion and changes the processing order of the signal generation unit and the gradation correction unit in the moving image portion and the still image portion. Is. When the error diffusion process or the dither process is performed, a feeling of noise appears in the image. Rather than performing tone correction on four images of RGBW, it is better to perform tone correction on three images of RGB and then generate a signal of another one color. Also has less noise. Therefore, a display image can be optimally obtained by distinguishing a moving image or a still image for processing.

According to a sixth aspect of the present invention, in the sequential color display device, in the still image portion, the image signal corresponding to the three primary colors is subjected to tone correction by the tone correction unit and then in the signal generation unit. Since the sequential color display device is characterized by producing another one-color signal, an image with less noise feeling due to gradation correction can be obtained in the still image portion.

A sequential color display device according to a seventh aspect of the present invention is 3 in the moving image portion.
From the image signal corresponding to the primary color, another
After creating the color signal, in the tone correction section, red, green,
Since the sequential color display device is characterized by performing gradation correction independently for each of the image signals of blue and other one color, the RGBW of each RGBW can be observed even when the moving image is chased and observed. Since the image expresses the required gradation in space in a pseudo manner, the image quality is less deteriorated as compared with the case where the signal of another one color is generated after the gradation correction.

According to the eighth aspect of the present invention, in the sequential color display device, the moving image detecting section is
The sequential color display device is characterized in that a portion in which motion is detected in any of red, green, and blue video signals is determined to be a moving image portion. This is because if motions are detected independently for each of RGB, for example, R is a moving image and G and B are still images in order to switch the processing order of signal generation and gradation correction between the moving image portion and the still image portion. This is because the W signal cannot be created if it is determined that

A sequential color display device according to an embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to the drawing of FIG.

(Embodiment 1) The input video signal is 0 to 25
There are 256 gradations up to 5, and the number of displayable gradations is 0,
1, 3, 7, 13, 23, 37, 56, 82, 115,
It is assumed that there are 13 gradations of 155, 202, and 255. Further, it is assumed that the other one color created from the RGB three primary color signals is white.

In this embodiment, the circuit configuration as shown in FIG. 1 is used. Reference numeral 100 is an RGB conversion circuit for converting an input signal into RGB3 primary color signals, 101 is a gradation limiting circuit for limiting the number of gradations of RGB3 primary color video signals to be displayed, 102
Is a gradation correction circuit for reproducing an input image in a pseudo manner from a gradation-limited image signal, and 103 is RGB as described above.
A signal generation circuit for generating a W signal from the three primary color signals and outputting an RGBW signal, 104 is a field memory,
While writing to one, RGBW is read in order from the other and input to the source driver 106 of the field sequential display 105. The field sequential display 105 divides one field into four RGBW periods for display. The circuit configuration is the same as the circuit configuration of FIG. 7 described in the related art except that the order of the signal generation circuit 103, the gradation limiting circuit 101, and the gradation correction circuit 102 is reversed.

As shown in FIG. 2A, R = 210, G
When an image signal of 90 = 90 and B = 150 is output from the RGB conversion circuit, a white signal is first created in this circuit configuration (FIG. 2B). At this time, G = 90, which is the minimum gradation level of RGB, is set as the value of the white signal,
The gradation level is obtained by subtracting 0. Therefore, R = 120, G = 0, B = 60, W = 90. Since this value is still a value for 256 gradations, the value (R
= 115, G = 0, B = 56, W = 82) (FIG. 2 (c)), which is displayed on the field sequential color display.

In the present embodiment, R = 210, G = 90, B = 150 input as shown in FIG. 2A is finally converted into R = 115, G = 0, B = 56, W. It has been described that it is converted to = 82 and displayed.

As described above, R = 210, G = 90, B = 150 input as shown in FIG. 9A is finally R = 115, G = 0, B = 82, W = It has been described that it is converted into 82 and displayed.

In both cases, the values finally displayed on the display are almost equal. However, the image quality does not deteriorate in the present embodiment, and the image quality deteriorates in the related art. In this embodiment, the value (gradation-corrected value) optimized to represent the input signal in a pseudo manner is expressed as it is, whereas in the conventional example, the input signal is simulated. This is because the value that is different from the value that is optimized to be expressed is displayed. Tone correction is simulated by arranging pixels with the optimum brightness spatially, so if each pixel displays a different value from the specified value, the input image will be simulated. I can't express it.

Therefore, as described in this embodiment, the white signal is first created from the input signal, and then the RGB signal is generated.
By independently performing gradation limitation and gradation correction with four signals of W, it is possible to represent the input image in a pseudo manner without deteriorating the image quality as compared with the related art.

(Second Embodiment) FIG. 3 shows a circuit configuration according to the present embodiment. The input video signal is converted into an RGB three-primary color video signal (256 gradations) in the RGB conversion circuit 300. Next, the motion detecting circuit 301 detects a moving part of the video signal. Motion detection circuit 3
In 01, when motion is detected in any of the RGB primary color video signals, the video portion is determined to be a moving image portion. This is because when motion is detected independently for each of RGB, the processing is switched between the moving image portion and the still image portion. For example, when it is determined that R is a moving image and G and B are still images, W This is because the signal cannot be created.

Next, the selector 302 causes the still image portion to pass the flow shown in (a), and the moving image portion to pass the flow shown in (b). The still image portion is limited to the number of gray scales that can be displayed on the display by the gray scale limiting circuit 304, and after the pseudo input video signal is reproduced by the gray scale correcting circuit 305, the W signal is created by the signal creating circuit 303. In the moving image portion, first, the signal creating circuit 306 creates a W signal and then RG
Each of the BWs is independently processed in the gradation limiting circuit 307 and the gradation correcting circuit 308. A portion 309 surrounded by a dotted line from the selector to the front of the field memory is a moving image processing unit.

These signals are once written in the field memory 310 and then read out in the order of RGBW,
Written in source driver. In the field sequential color display 311, one field period is divided into four periods and RGBW video signals are sequentially displayed.

The error diffusion processing is a method of modulating the display error when the gradation is limited to a high spatial frequency for display, and the dither processing is basically a method of adding noise to the image. When the key adjustment is performed, the image may have graininess or noise. When gradation correction is performed on the four RGBW images after the white signal is generated, the roughness for four times is added, and the white signal is generated after the gradation correction is performed on the three RGB images. In this case, the roughness for three times will be added.

Therefore, it is more perceptible to generate a white signal after performing gradation correction on three RGB images than to generate a white signal and then perform gradation correction on four RGBW images. Less is.

When the W signal is generated after the gradation correction is performed on the three RGB images, the four RGBW signals are observed spatially displaced when the moving image is observed by the line of sight. Therefore, the input video signal is not visually reproduced, and the image quality is greatly deteriorated. However, when the W signal is first generated and then the gradation correction is independently performed for each of RGBW, pixels of spatially optimum brightness are arranged in each image of RGBW, and the image is independently formed. Therefore, even if the four RGBW signals are observed spatially displaced, the image quality is not significantly deteriorated.

In consideration of these matters, in the present embodiment,
For the still image portion, gradation correction is performed on the RGB video signal so as to reduce noise, and then a white signal is generated. For the moving image portion, a white signal is generated so that image quality is less deteriorated and then RGBW is generated. Gradation correction is applied to the video signal.

(Third Embodiment) Input video signal is 0 to 25
There are 256 gradations up to 5, and the number of displayable gradations is 0,
1, 3, 7, 13, 23, 37, 56, 82, 115,
It is assumed that there are 13 gradations of 155, 202, and 255. Further, it is assumed that the other one color created from the RGB three primary color signals is white.

In this embodiment, the circuit configuration as shown in FIG. 4 is used. Reference numeral 400 is an RGB conversion circuit for converting an input signal into RGB3 primary color signals, 401 is a gradation limiting circuit for limiting the number of gradations of the RGB3 primary color video signals to be displayed, 402
Is a gradation correction circuit for artificially reproducing the input image from the gradation-limited video signal, and 403 is RGB as described above.
A signal generation circuit for generating a W signal from the three primary color signals and outputting an RGBW signal, 404 is a field memory,
While writing to one, RGBW is read in order from the other and input to the source driver 406 of the field sequential display 405. The field sequential display 405 displays one field by dividing it into four periods of RGBW.

In this example, the circuit configuration is the same as that shown in FIG. 7 described in the prior art except that the gradation correction circuit 402 is provided again after the signal generation circuit 403.

As shown in FIG. 9A, the input video signal is R
= 210, G = 90, B = 150, R = 202, G = 82, B = 155 after the first gradation correction circuit.
It can be considered that (Fig. 9 (b)). When a white signal is created from here, R = 120, G = 0, B = 73,
Although W = 82 (FIG. 9C), these are out of the displayable luminance level. Therefore, even if the closest value is selected for display, R = 115, G = 0,
B = 82 and W = 82 (FIG. 9 (d)). This is RG
When converted into B, R = 197, G = 82, B = 164, which deviates from the values determined when the gradation correction was first performed.

In the present embodiment, it is possible to display an image close to the input video by performing gradation correction again here.

[0040]

As described above, the sequential
Color display devices have one field for red, green,
A sequential color display device for displaying a blue image and another one-color image divided into four periods and displaying the red, green, blue and other one-color images generated from an input signal. Since it is a sequential color display device characterized by performing gradation correction independently of each other, even when observing a moving image while observing it, each image of RGBW has a pseudo gradation required in space. Therefore, the deterioration of the image quality is less than that in the case where the signal of another one color is generated after the gradation correction. Even when the displayable gradations are not arranged at equal intervals, the gradation-corrected video signal, that is, the value to be displayed and the actually displayed video match.

A display device for displaying an image of one field of red, green, blue, and other one color by dividing it into four periods for displaying one field, and performs gradation correction on three primary colors of red, green and blue. After that, create another one color image, red, green,
By independently performing the gradation correction processing on the image signals of blue and the other one color, even when the displayable gradations are not arranged at equal intervals, the gradation-corrected video signal, that is, the displayed image signal is displayed. The power value and the image actually displayed match.

Further, a signal producing section for producing a signal of another one color from an image signal corresponding to the three primary colors, a tone correcting section for performing tone correction on the image signal, and a moving image portion by detecting a moving image portion. By providing the moving image processing unit that changes the processing order of the signal creation unit and the gradation correction unit in the still image portion, when an error diffusion process or a dither process is performed, a noise appears in the image. RGB
It is better to generate the signal of the other one color after performing the gradation correction on the three images of
There is less noise than performing gradation correction on the four images. Therefore, a display image can be optimally obtained by distinguishing a moving image or a still image for processing.

Further, in the still image portion, after the image signal corresponding to the three primary colors is subjected to the tone correction in the tone correcting section, the signal producing section prepares the signal of another one color to obtain the still image portion. In this way, gradation correction can provide an image with less noise. Further, in the moving image part, after the signal of the other one color is created in the signal creation part from the image signals corresponding to the three primary colors, the image signals of red, green, blue, and the other one color are created in the gradation correction part. By performing tone correction independently for R, even when observing a moving image
Since each of the GBW images pseudo-represents the required gradation in the space, the image quality is less deteriorated as compared with the case where the other color signal is generated after gradation correction is performed.

[Brief description of drawings]

FIG. 1 is a sequential diagram according to a first embodiment of the present invention.
Circuit diagram of color display device

FIG. 2 is an explanatory diagram of gradation correction in the same device.

FIG. 3 is a sequential diagram according to a second embodiment of the present invention.
Circuit diagram of color display device

FIG. 4 is a sequential diagram according to a third embodiment of the present invention.
Circuit diagram of color display device

FIG. 5 is an explanatory diagram for explaining a sequential color display display method.

FIG. 6 is an explanatory diagram of a white signal generation method in a sequential color display device.

FIG. 7 is a circuit configuration diagram of a conventional sequential color display device.

FIG. 8 is an explanatory diagram of gradation correction in a conventional sequential color display device.

FIG. 9 is an explanatory diagram of gradation correction when displayable gradations in a conventional sequential color display are not at regular intervals.

[Explanation of symbols]

100, 300, 400 RGB conversion circuits 101, 304, 307, 401 Gradation limiting circuits 102, 305, 308, 402 Gradation correction circuits 103, 303, 306, 403 Signal generation circuits 104, 310, 404 Field memories 105, 311 , 405 Sequential color display 301 Motion detection circuit 302 Selector 309 Video processing unit

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 660 G09G 3/20 660U 660W H04N 9/12 H04N 9/12 BF term (reference) 5C006 AA01 AA02 AA12 AA13 AA14 AA22 AF19 AF44 AF46 AF51 AF53 AF61 BB11 BC16 BF02 FA56 5C060 BC01 DB13 HB26 JA00 JA21 5C080 BB05 CC03 DD03 EE29 EE30 JJ02 JJ05

Claims (8)

[Claims] 1. A display device for displaying an image of one field of red, green, blue, and other one color divided into four periods for displaying one field, wherein an image signal corresponding to three primary colors of red, green and blue is used. Create another one color image, then red,
A sequential color display device characterized in that gradation correction processing is independently performed for green, blue, and other one-color images. 2. A display device for displaying an image of one field of red, green, blue, and other one color divided into four periods for displaying one field, and performing gradation correction on three primary colors of red, green and blue. After that, an image of the other one color is created, and gradation correction processing is independently performed on the image signals of the red, green, blue, and the other one color, respectively. . 3. The sequential color display device according to claim 1, wherein the gradation correction process is an error diffusion process. 4. The sequential color display device according to claim 1, wherein the gradation correction process is a dither process. 5. A signal creating section for creating another one-color signal from image signals corresponding to the three primary colors of red, green and blue, a gradation correcting section for carrying out gradation correction for the image signal, and a moving image for detecting a moving image portion. A sequential color display device comprising: a detection unit; and a moving image processing unit that changes the processing order of the signal generation unit and the gradation correction unit for a moving image portion and a still image portion. 6. In the still image portion, after the image signal corresponding to the three primary colors is subjected to gradation correction by the gradation correction unit, the signal preparation unit prepares the signal of the other one color. The sequential color display device according to claim 5. 7. In the moving image portion, after the signal of the other one color is created in the signal creating unit from the image signals corresponding to the three primary colors, the red, green, blue and other The sequential color display device according to claim 5, wherein gradation correction is independently performed for each video signal of one color. 8. The sequential unit according to claim 5, wherein the moving image detecting unit determines that a portion of the red, green, and blue video signals in which motion is detected is a moving image portion. -Color display device.