JPH11109916A - Color picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color picture display device superior in motion resolution characteristic, inconspicuous in color blotting in motion edge part and capable of displaying high quality dynamic picture. SOLUTION: In this device that displays a color picture by supplying color video signals of red, green and blue to each light emitting cell of these colors, assuming time response characteristic of each light emission of these cells to be TR, TG and TB, the difference between TR and TG is made sufficiently small compared with the difference between TR and TB as well as between TG and TB. In addition, as the luminous weight array of the subfield, the one with the largest weight is arranged near the center of one field, with a chevron shaped luminous distribution employed in which the luminous weight becomes successively smaller in the direction away from the center to the front/ rear. otherwise, as the luminous weight array of the subfield having two luminous peaks in one field, the time interval between the two peaks is set at one half field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image display device for displaying a color image by controlling light emission of three primary colors of red (R), green (G), and blue (B). The present invention relates to a color image display device which has excellent characteristics and can display a high-quality color moving image in which color bleeding at a moving edge portion is less noticeable.

[0002]

2. Description of the Related Art In recent years, a conventional cathode ray tube (CRT)
In place of the display device, a flat panel type display device which is thin and light, has little screen distortion, and is hardly affected by geomagnetism and which seals a liquid crystal or a plasma is becoming widespread. Among them, in particular, a plasma display device which has a wide viewing angle due to a self-luminous type and which is relatively easy to produce a large panel has attracted attention as a next-generation color image display device. In such a flat panel display device, one pixel is constituted by three light emitting cells of red (R), green (G), and blue (B), and the color of the light is controlled by controlling the light emission amount of each light emitting cell. Display is realized.

In a display device, such as a plasma display device, in which it is difficult to display an intermediate gradation between light emission and non-light emission, the amount of light emitted from each of the R, G, and B light emitting cells is controlled so as to reduce the intermediate gradation. As a display method, a so-called subfield method is employed. In the subfield method, 1
The field is divided into a plurality of sub-fields on the time axis, a unique light-emission weight is assigned to each sub-field, and the presence or absence of light emission in each sub-field is controlled to express a luminance gradation.

[0004] For example, one field is divided into six subfields SF0 to SF5, each of which is 1, 2, 4,.
By assigning the light emission weights in the ratio of 8, 16, and 32, from the gradation “0” in which none of the subfields SF0 to SF5 emits light, the gradation “63” (= 1 + 2 + 4 + 8 + 16 + 32) in which all six subfields emit light. Up to 64 gradations can be expressed.

As described above, in the color image display device in which the light emission amount of each of the R, G, and B light emitting cells is controlled by the subfield method, first, the image quality when displaying a moving image is as follows.
A time response characteristic (hereinafter, sometimes simply referred to as a light emission response characteristic) relating to light emission of each of the R, G, and B cells;
This is greatly affected by the arrangement of the emission weights assigned to each subfield in each field.

The light emission response characteristics of each of the R, G, and B cells include a rise time characteristic from when a light emission start instruction is given from the control circuit to when the cell actually reaches a desired light emission luminance, and
It shows the afterglow time characteristics after the emission end instruction.
In general, the longer the afterglow time, the longer the rise time, so that the afterglow time is usually used as a measure representing the time response characteristic of light emission. Therefore, even in the following, the light emission response characteristic is represented by “afterglow time” (time from the peak of light emission to 1/10 decay), and the “rise time characteristic” is represented by the “afterglow time”. Shall be inherent.

In such a color image display device, the shorter the light emission response characteristic, the more the ideal operation is possible. However, it is impossible to make it zero. In addition, the light emission response characteristic largely depends on the physical characteristics of a material such as a phosphor material used as a light emitting cell, and it is very difficult to make the response characteristics of R, G, and B cells having different emission wavelengths uniform. is there. For this reason, when a moving image is displayed, the R, G, and B light emission may be overlapped with a time shift due to a difference in time response between the light emitting cells, resulting in a color shift. This color shift is
At an edge portion where luminance changes sharply, such as from black to white or from white to black, a color that is not originally present in the original image appears as a phenomenon, resulting in remarkable image quality degradation when displaying a moving image.

Hereinafter, the process of occurrence of colored disturbance at the edge will be described with reference to FIGS. As shown in FIG.
Consider a case where a white rectangular pattern 32 is displayed on a screen of a display device on a black background 31 and the white rectangular pattern 32 is moved rightward. FIG. 4 shows colored interference generated at the boundary between white and black at this time.

FIG. 4A shows the intensity (amplitude) of each light emitting cell, and FIG. 4B shows the colors displayed on the screen. As shown in FIG. 7A, if the light emission response of R is slower than that of R and B, for example, among R, G, and B, the light emission response of G indicated by a broken line changes to the light emission response of R indicated by a solid line. , B, the edge regions A, B are colored.
More specifically, in the edge region A, magenta (R + B) is perceived due to the lack of the amplitude of G with respect to R and B as shown in FIG. Green (G) is perceived due to excessive amplitude of G. The edge region where coloring occurs increases as the moving image speed increases.

As described above, while the original video signal is only white and black, a color (magenta or green) which is not present in the original image is perceived due to the movement, and the image quality is largely deteriorated.
In particular, in a plasma display or the like, a material having an afterglow time of 12 ms or more is often used as a G light emitting cell, and the response is delayed as compared with R and B. Had become.

On the other hand, in a display device that expresses an intermediate gradation by the subfield method, the dynamic resolution is largely influenced by the light emission weight arrangement of each subfield in each field. In order not to degrade the dynamic resolution, it is desirable that the video signal arriving for each field be emitted in an impulse manner in a very short time within each field period. In a display device using a CRT, horizontal and vertical scanning processes require one field time, but when focusing on one pixel at a specific screen position, impulse light emission is performed for each field.

However, in the gradation display by the subfield method, the video signal arriving for each field is divided into a plurality of subfields within each field period to emit and display. Therefore, it is difficult to realize a dynamic resolution characteristic equivalent to that of a CRT.

The phenomenon in which the dynamic resolution is degraded according to the light emission weight arrangement in the subfield will be described below with reference to FIGS.
This will be described with reference to FIG. Consider a case where the white rectangular pattern 32 shown in FIG. 3 is displayed on a display device that expresses 64 gradations from zero to 63 using the subfield configuration of six divisions illustrated in FIG. Focusing on the pixel for displaying white (gradation 63), in this pixel, the subfields SF0, SF1, SF2, SF from the top of one field
3, SF4, and SF5 all emit light, and the ratios of the light emission intensities are 16, 4, 1, 2, 8, and 32, so that a substantially valley-shaped light emission weight array in which energy is concentrated before and after the field.

FIG. 6 shows the distribution of the amount of light emission when the video signals of field 1, field 2,... Which are sequentially input have a light emission weight array of valley-shaped subfields. In such a valley-shaped subfield arrangement, light emission is concentrated most near the boundary T1 of each field, and strong light emission appears at a field cycle. At this boundary T1, the light emission of the first field and the light emission of the second field are mixed, so that when a moving rectangular pattern is displayed, as shown by a solid line in FIG. Images in which the images overlap and the resolution is severely deteriorated are perceived.

That is, for example, when the light emission response time of the G cell is slow, the pattern shown by the broken line in FIG. 7 is detected. Thus, as in the case of FIG. As a result, magenta is perceived as colored disturbance, and in the edge regions B1 and B2, green is perceived due to excessive G amplitude.

When the amount of interference at this time is compared with FIG. 4, the range of the interference is widened, but the density of the generated false color (magenta, green) is reduced. This is due to the fact that the resolution is degraded due to the overlap of two images shifted in time, and there is no sudden change in luminance. As described above, the light-emission weight arrangement of the subfield is closely related to the response characteristics of the R, G, and B cells, and the color of the edge portion caused by the difference in the light-emission response characteristics of the R, G, and B cells. Since it is possible to reduce the interference by the arrangement of the light-emission weights of the subfields, it is necessary to optimize both of them in order to realize high-quality moving image reproduction.

The gradation expression method using the subfield method is described in, for example, Japanese Patent Publication No. Sho 51-32051, and the method for reducing pseudo contour noise inherent in the subfield method is described in, for example, It is described in Japanese Unexamined Patent Publication No. Hei 4-21294.

[0018]

In the above-described conventional color image display apparatus, the light emission response characteristics of the R, G, and B cells are focused on the image quality of a still image, and the chromaticity coordinates,
Only the phosphor material is selected in consideration of the white balance condition and the light emission efficiency, etc., and the light emission response characteristics focused on the image quality of the moving image are not taken into consideration. It has been all about reducing the afterglow by shortening the light emission response characteristic of the device as much as possible.

Further, the emission weight arrangement of the subfields is determined with an emphasis on the reduction of flicker or the reduction of pseudo contour disturbance which is a problem inherent to the subfield method, and does not consider the deterioration of dynamic resolution characteristics. Was.

Further, in the conventional color image display device,
No consideration has been given to the interaction between the light emission response characteristics of the R, G, and B cells and the effect of the light emission weight arrangement of the subfields on the image quality.

For this reason, in the above-described conventional color image display device, when a moving image is displayed, the light emission timing of R, G, and B is temporally changed due to the difference in the light emission response characteristics of the R, G, and B cells. There is a problem in that a shift occurs, and a color that is originally not present in the original image is perceived at the edge portion, resulting in remarkable image quality deterioration.

Even if the light emission response characteristics of the R, G, and B cells are set to be faster, the dynamic resolution characteristics cannot be improved if the arrangement of the light emission weights in the subfields is inappropriate. There was a problem.

An object of the present invention is to solve the above-mentioned problems of the prior art, to provide a color image display device which is excellent in dynamic resolution characteristics, in which color blur at a moving edge portion is not conspicuous, and which can display a high quality moving image. Is to provide. Another object of the present invention is to provide a display device with higher image quality by using a pseudo contour interference reduction technique together.

[0024]

Means for Solving the Problems In order to achieve the above object, the present invention takes the following measures. (1) The time response characteristics regarding the light emission of each of the red, green, and blue light emitting cells are set to values corresponding to each of the red, green, and blue colors.

According to the above-described structure, it is possible to provide a color image display device which can display a high-quality moving image, in which color bleeding at the moving edge portion is less noticeable. (2) When the time response characteristics of the light emission of the red, green, and blue light emitting cells are TR, TG, and TB, respectively, the difference between TR and TG is sufficiently larger than the difference between TR and TG and TB. To smaller.

According to the above arrangement, the moving edge portion includes
Since blue or yellow coloring, which is low in visibility and is hardly noticeable, occurs, deterioration in image quality due to coloring is reduced, and a high-quality moving image can be displayed. (3) The emission weight assigned to each subfield is increased from the front and back of the array toward the center.

According to the above arrangement, since light emission is substantially concentrated in a short period of time, deterioration in resolution when displaying a moving image is reduced, and a high-quality moving image can be displayed. (4) Among the plurality of subfields, [N], [2 · N], [3 · N],... Are assigned to 2 · K−1 upper subfields including the subfield having the largest emission weight.
[(K-1) · N], [K · N], [(K-1) ·
N], ... [2 · N], [N] (where K and N are natural numbers)
Are assigned.

According to the above-described structure, the "switching of light emission" when the gradation continuously changes is dispersed without being concentrated on a specific gradation, so that excellent dynamic resolution characteristics and pseudo contour interference are prevented. Reduction can be achieved at the same time. (5) A weight arrangement of two peak-shaped subfields having two peaks of the light emission amount in one field period, and the time interval between the peaks of the light emission amount is set to １ ／ field.

According to the above configuration, the repetition period of the light emission pattern becomes twice the approximate field frequency.
Flicker disturbance and false contour disturbance can be reduced. (6) In addition to the configuration described in (5), the afterglow time of the green and red light emitting cells is configured to be substantially equal to or longer than 1/2 field.

According to the above configuration, the light emission is smoothed by the response characteristic of the light emission of the light emitting cell, so that the false contour interference is further reduced and a high quality moving image can be displayed.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a color image display device according to an embodiment of the present invention. The A / D conversion circuits 101, 102, and 103 convert R, G, and B analog video signals into digital signals, respectively. The subfield conversion circuit 2 converts the A / D-converted digital signal into subfield data indicating the presence or absence of light emission in each subfield. The subfield sequential conversion circuit 3 converts subfield data expressed in pixel units into field sequential data in subfield units. The frame memory 301 is a storage area provided in the subfield sequential conversion circuit 3 for realizing frame sequential in bit units.

The drive circuit 4 additionally inserts a drive pulse into a signal converted into field-sequential data in subfield units,
A voltage (or current) for driving the matrix display panel 5 is output. The control circuit 6 generates a control signal necessary for each circuit based on the dot clock CK, the horizontal synchronization signal H, the vertical synchronization signal V, and the like, which are timing information of the input video signal.

In such a configuration, the input R,
The G and B video signals are respectively supplied to the A / D conversion circuit 10
The signals are converted into digital signals by 1, 102 and 103. This digital signal is based on general binary notation, and each bit has a power of two weight. Specifically, each video signal is represented by b0, b1... B6, b7.
When quantizing to an 8-bit signal of
0 has a weight of “1”, b1 is “2”, b2 is “4”
... b7 has a weight of "128".

Each digital signal is converted by the subfield conversion circuit 2 into subfield data indicating the presence or absence of light emission in each subfield. This subfield data is composed of information of the number of bits corresponding to the number of subfields, and when displaying by eight subfields, it is composed of eight bits S0, S1,... S7. Bit S0 indicates whether or not the pixel is to emit light during the light emission period of the first subfield SF0.
, S2,...
1, the presence or absence of light emission in SF2,...

The sub-field data is input to the sub-field sequential conversion circuit 3, and its frame memory 30
1 is written in pixel units. Reading from the frame memory 301 is performed on a subfield basis in a frame-sequential manner. That is, after the bit S0 indicating whether light is emitted during the subfield SF0 is read for one field, the bit S1 indicating whether light is emitted during the subfield SF1 is read for one field, and so on. To
The bits are read in the order of S2, S3,. The drive circuit 4 performs signal conversion, pulse insertion, and the like necessary for driving the display element, and drives the matrix display panel 5.

The matrix display panel 5
As shown in FIG. 2, a pixel 50 corresponding to the number of effective display pixels unique to the panel is arranged in a matrix. For example, a display panel having 640 horizontal pixels and 480 vertical pixels has a configuration in which 640 pixels 50 are arranged in the horizontal direction and 480 pixels are arranged in the vertical direction. Further, each pixel 5
The inside of 0 is constituted by light emitting cells 51, 52 and 53 of R (red), G (green) and B (blue).
By controlling the light emission of the three primary colors B, a color image can be displayed.

In the color image display device of the present invention, R
The light-emitting cells 51, 52, and 53 are formed using a light-emitting material in which the light-emission response characteristics of (red) and G (green) are substantially equal in comparison with the light-emission response characteristics of B (blue). As an example of a specific configuration, the afterglow time of the green (G) light emitting cell 52 is 12 to 17 ms, the afterglow time of the red (R) light emitting cell 51 is 8 to 13 ms, and the blue ( The afterglow time of the light emitting cell 53 of B) is 1 ms or less.

As described above, by making the afterglow time of R substantially equal to the afterglow time of G, even if the emission response characteristics of R, G, and B do not completely match, it is possible to prevent the occurrence of colored interference. The influence can be reduced. Hereinafter, this effect will be described with reference to FIG.

FIG. 8 shows a color image display device according to the present invention.
FIG. 4 shows a state of color disturbance at an edge portion generated when the same black and white rectangular pattern as shown in FIG. 3 is displayed.
Since the blue (B) light emitting cell has a fast light emitting response, a rectangular pattern shown by a solid line in FIG.
(Red) and G (Green), as indicated by the dashed line and the dashed line, respectively, have characteristics almost equally delayed.
As a result, each edge portion has blue (= white-red-green) coloring (leading edge of movement) due to the light emission response of R (red) and G (green) being almost equally delayed, and R (red). ) And G
Yellow (= red + green) coloring (the trailing edge of the motion) due to the (green) afterglow occurs.

The coloring of the blue color generated at the leading edge is hardly noticeable and hardly hindered because the visibility characteristic of the blue color is lower than that of red and green. Further, each coloring occurs in a thin area having a contour shape because it is concentrated on an edge portion. Here, as a human perceptual characteristic, the color resolution is the blue-yellow axis (B
It is known that the change of (−Y axis) has the weakest characteristic, and the blue and yellow coloring that occurs finely in the contour becomes high-resolution information, and is hardly detected due to the dull resolution characteristic.

As described above, by configuring the afterglow time of R to be substantially equal to that of G, even if the light emission response characteristics of R, G, and B do not completely match, the generated colored interference occurs. Can be made less noticeable, and high-quality display can be performed.

In the present embodiment, the afterglow time of R and G, whose emission response characteristics are set to be substantially equal, is longer than that of B, but may be shorter. For example, the afterglow time of R and G is set to 5 to 7 ms, and B
May be set to 10 to 15 ms. At this time, the same effect as described above can be obtained because the leading edge of the movement is yellow (= white-blue) and the trailing edge is blue.

Next, in order to compare the effects of the present invention,
The light emitting cells 51, 52, and 53 were configured so that the light emission response characteristics of R (red) and B (blue) were approximately equal to that of G (green) among the three light emission response characteristics of R, G, and B. The operation in this case will be described with reference to FIG. Specifically, the afterglow time of the green (G) light emitting cell 52 is set to 12 to 17.
However, the afterglow time of the red (R) light emitting cell 51 was 3 to 5 ms, and the afterglow time of the blue (B) light emitting cell 53 was 1 ms or less.

As can be seen from the response characteristics shown in FIG.
Magenta (= white-green) coloring (leading edge of motion) due to green (G) rising with a large delay and green coloring (trailing edge of motion) due to afterglow of green (G) occur. . Compared with the response characteristics in FIG. 8, the visibility characteristics of green are higher than those of blue and red, so that the coloring of green tends to be conspicuous and hindered. Further, the coloring of green and magenta is also close to the red-cyan axis (RY axis), which is the most sensitive and sensitive color resolution characteristic, and compared to the blue-yellow axis (BY axis). Interference is likely to be detected due to high resolution characteristics.

As described above, by configuring the light emission response characteristics of R and G to be substantially equal to each other, it is possible to greatly reduce interference as compared with the case where the light emission response characteristics of R and B are equalized. become.

It is also possible to configure the light emission response characteristics of B and G to be substantially equal. In this case, the color of cyan (= blue + green) or red (= white-blue-green) Sticking occurs, and the interference is more noticeable than the yellow-blue coloring shown in FIG.

Ideally, the time response characteristics of the three light-emitting cells R, G, and B are ideally uniform, so that a colorless image at the edge of a moving image can be displayed. However, even when the light emission response characteristics of R, G, and B do not completely match, by at least aligning the light emission time response characteristics of G and R,
The generated disturbance can be made less noticeable, and a high-quality moving image can be displayed.

In practice, it is difficult to completely match the light emission time response characteristics of G and R, but the difference between the light emission response times of G and R is smaller than that of G and B, and
If the light emission response time of R and B can be set smaller,
The color of the edge portion can be almost blue or yellow, and the effect of reducing interference according to the present invention can be obtained. Expressing using the afterglow time as a characteristic value representative of the time response characteristic of the light emitting cell is as follows.

That is, the afterglow time of the red (R) cell is T
Let R be the afterglow time of the green (G) color cell and TG be the afterglow time of the blue (B) cell, and let the difference between TR and TG be the difference between TB and TR and TG. What is necessary is just to make it small enough. In other words, each afterglow time TR, TG, TB
Satisfies the following expression, an effect of interference reduction can be obtained.

| TR-TG | <| TR-TB | AND
| TR-TG | <| TG-TB | The materials constituting the light emitting cell (phosphor, etc.) are, as basic conditions, various conditions such as chromaticity coordinates of RGB three primary colors, white balance conditions, light emission efficiency, and the like. Needs to be satisfied. For moving image display,
Further, it is required that the three light emitting cells of R, G, and B have uniform time response characteristics. However, in the display device of the present invention, only the light emission time response characteristics of G (green) and R (red) are provided. Can be considered, and the range of selection of the light emitting cell constituent material can be expanded. Accordingly, a light emitting cell constituent material having higher luminance or higher color purity can be used as compared with a conventional display device, and a display device with higher image quality can be provided.

Further, a CRT which is a conventional display device
In the case of plasma displays and the like having different light emission principles, it is necessary to develop new phosphor materials and the like. Economic benefits from shortening can also be expected.

Next, a description will be given of an embodiment in which the degradation of the resolution when displaying a moving image is reduced by devising the emission weight arrangement of the subfields. The light-emission weight array of the sub-field is determined by the sub-field conversion circuit 2 that controls light emission / non-light emission of each sub-field.

In this embodiment, in order to prevent the dynamic resolution characteristic from deteriorating, as shown in FIG. 10, the sub-field having the largest light-emitting weight (light-emitting amount) is arranged near the center of one field as shown in FIG. SF4 was arranged, and a mountain-shaped light emission distribution was employed in which the light emission weight gradually decreased as the distance from the center increased.

More specifically, in this embodiment,
Eight subfields SF0 from the beginning of one field,
SF1, SF2,.
Light emission weights of 6, 64, 128, 32, 8, and 2 are assigned. Since all the light-emitting weights are powers of 2, A /
By changing the order of the bits of the D-converted binary data,
It can correspond to subfield data for controlling light emission / non-light emission of a subfield.

FIG. 11 shows a temporal change of the light emission amount in each field when a video signal is displayed by the subfield data of the light emission weight array shown in FIG. Each field has the mountain-shaped emission weight array shown in FIG.
Light emission concentrates at a substantially central portion (T0 in FIG. 11) of one field. In the halftone display method based on the subfield method, it is basically not possible to concentrate the light emission amount according to the video signal in a short period of time and emit light in an impulse manner. Thus, the light emission can be concentrated substantially in a short time without dispersing the light emission in the field.

The emission weight array of the subfield is as follows.
Not limited to the configuration shown in FIG. 10, any light-emission weight array may be used as long as the light-emission weight increases as approaching the center from the front and back of each field. For example, the light-emission weight arrangement of FIG. 10 is reversed on the time axis to form a light-emission weight array in which the light-emission weights of the subfields SF0 to SF7 are 2, 8, 32, 64, 16, 4, 1, respectively. Is also good.

Next, FIG. 12 shows an example of an embodiment in which a subfield having a large emission weight is further divided into a plurality of sub-fields in order to reduce a false contour which is a problem when displaying a moving image using the sub-field method. .

In FIG. 12, the upper two sub-field bits SF4 (emission weight 12
8), the light emission amount of SF3 (light emission weight 64) is added and divided into four equal parts, and the light emission weight is 48 (= (128 + 64) /
By dispersing the light into the four subfields of 4), the emission weight arrangement of the subfields is trapezoidal.

Even in such a trapezoidal light emission weight array, the subfields (SF3, SF
4, SF5, SF6) are arranged at the center, and the subfields having a smaller light emission amount are sequentially arranged as the distance from the center increases, thereby achieving the same effect as described above.

By the way, if the light emission weight of each subfield is a power of 2 as described above, when the gradation is continuously changed, light emission of a subfield bordering on a specific gradation stops. It is known that “light emission switching” in which light emission starts in other subfields is concentrated at a specific change point, thereby causing a disturbance in periodicity of light emission and causing false contour interference.

For example, in the light emission weight array shown in FIG. 10, when the display gradation is the 127th gradation, the subfield SF4
All the sub-fields emit light except for the sub-field SF4 in the 128th gradation, so when the display gradation is switched from the 127th gradation to the 128th gradation, the light emission switching is concentrated at this change point. Occurs.

Therefore, in the embodiment of the present invention described below, the emission weight of each subfield is set to a value that does not depend on the power of 2 in order to effectively reduce the above-described pseudo contour disturbance. These light emission weight arrays have the following three conditions. (1) The upper subfield group having a large light emission weight does not take a value of a power of two. (2) Assuming that N and K are both natural numbers, 2 · K−1 upper subfields are N, 2 · N, 3 · N,.
1) · N, K · N, (K−1) · N,... (3) The upper subfield is the maximum light emission amount (K-1)
The arrangement is symmetrical with respect to the N subfields.

In the light emission weight arrangement shown in FIG. 13, five subfields SF2, SF3, SF4, SF5, SF
6 is the upper subfield, N = 6, K = 3, and the emission weight of each upper subfield is 6
(= N), 12 (= 2 · N), 18 (= K · N), 12
(= 2 · N) and 6 (= N).

Similarly, in the emission weight arrangement shown in FIG. 14, seven subfields SF1 to SF7 are the upper subfields, and N = 3 and K = 4. Similarly, FIG.
In the light emission weight array shown in FIG.
F1 to SF9 are upper subfields, and N = 2, K
= 5.

Here, the gradation expression method in the case where the light-emission weight arrangement adopts a light-emission weight array that does not depend on the power of 2 and the effect on pseudo contour interference will be described with reference to FIG. FIG. 16 shows a light emission control pattern when each gradation is expressed by the subfield configuration having the light emission weight arrangement of FIG.

As shown in FIG. 16, it is possible to express a five-gradation sentence (= 1 + 2 + 2) by combining the light-emission weights 1, 2, and 2 of the lower subfields SF0, SF1, and SF7. Also, upper subfields SF2, SF6, S
In F3, SF5, and SF4, a gradation of a multiple of 6 can be expressed, so that continuous gradation can be expressed in combination with the lower subfield.

Focusing only on the upper subfield, even if the gray level changes from the sixth gray level to the twelfth gray level, the twelfth gray level to the eighteenth gray level, the eighteenth gray level to the twenty-fourth gray scale, etc.
At least one upper sub-field is controlled so as to continue to emit light over two or more gray levels. This allows
Even when the gradation is continuously changed, the above-described “light emission switching” can be dispersed without being concentrated on a specific gradation.

As described above, by adopting the subfield structure shown in FIGS. 13, 14, and 15, excellent dynamic resolution characteristics due to a mountain-shaped light emission distribution and reduction of false contour interference can be achieved at the same time. A display device can be realized.

The configuration of the upper subfield described with reference to FIGS. 13, 14, and 15 is symmetrically arranged within one field with the subfield having the largest light emission amount as the center. For example, in the subfield configuration illustrated in FIG. 13, the subfields SF3 and SF5 of the emission weight 12 and the subfields SF2 and SF6 of the emission weight 6 are symmetric about the subfield SF4 having the largest emission weight of 18. Are located.

As described above, the subfields (SF3 and SF5 and SF2 and SF5) having the same emission weight
By disposing 6), exactly the same gradation can be expressed even if the control of light emission / non-light emission is switched. By switching this light-emission weight array in a cycle of a field, a line, a pixel, or the like, the periodicity of light emission can be further randomized, and pseudo contour interference can be reduced.

Specifically, as shown in FIG. 17, the first light emission control pattern shown in FIG. 16 and the second light emission in which the light emission order of subfields SF3 and SF5 and SF2 and SF6 are interchanged. What is necessary is just to prepare a control pattern and configure the subfield conversion circuit 2 so that each light emission control pattern can be switched on a field, line or pixel basis.

The switching timing of such a light emission control pattern is not limited to the above, and each light emission control pattern may be switched in accordance with the arrangement position of each pixel. For example, when the pixels arranged in a matrix are regarded as a checkered pattern (checker flag pattern), the light emission control pattern may be switched between the pixels arranged at the white position and the pixels arranged at the black position. Further, one light emission control pattern that causes the pixels at the white position to emit light and the other light emission control pattern that causes the pixels at the black position to emit light may be switched for each field.

The subfield structure of the present invention described above has a mountain-shaped light emission distribution in which the subfield having the largest light emission amount is arranged substantially at the center of one field period as shown in FIG. In this case, a group of light emission is performed by a mountain-shaped light emission distribution once per field. When the total number of subfields in one field period can be set to be large, a configuration may be employed in which light emission is performed twice according to a mountain-shaped light emission distribution in one field period as shown in FIG.

In the configuration having two peaks in one field as shown in FIG. 18, the amount of light emission is set to be small near the boundary between the fields. In addition, mixing with adjacent field data, which is a problem in the valley-shaped subfield arrangement, is unlikely to occur, and resolution degradation in moving image display can be reduced.

Further, by configuring the time interval between two subfields, which are the emission peaks in one field, to be approximately 時間 field time, the emission peak in the latter half of the field is shifted to the first half in the next field. , The time interval up to the emission peak can be adjusted to フ ィ ー ル ド field. As a result, the light emission distribution is substantially equivalent to the display performed at twice the field frequency (in a single mountain-shaped subfield arrangement). Thereby, generation of flicker can be suppressed.

By dividing a plurality of upper subfields having a large amount of light emission into two peaks, gradations that can be represented by the divided subfields (only rough gradations with rough steps can be represented) Will be displayed at twice the field frequency. Further, since the two peaks before and after are substantially the same in configuration, the gray scale can be roughly expressed (the maximum luminance is １ ／) only by the subfields constituting one of the peaks. This is equivalent to the fact that the sub-fields that have been emitting light in one field period are substantially concentrated in the period of 1/2 field, and the pseudo contour disturbance can be reduced.

Further, the afterglow time of the phosphor is approximately こ の of this.
If the afterglow time is longer than the field (8.3 ms) or the afterglow time is longer, the light emission of each subfield is made uniform by the afterglow characteristic, and the effect of reducing the pseudo contour can be further enhanced. The afterglow time of this phosphor is RGB
It is desirable that all the light-emitting elements have a half field or more. However, G (green) and R (red) having high luminosity characteristics are high.
If the color has an afterglow time of approximately 8.3 ms or longer, a significant improvement can be obtained.

Next, a subfield structure for realizing the two-peak light emission distribution shown in FIG. 18 will be described with reference to FIGS.
This will be described with reference to FIGS.

FIG. 19 shows a subfield configuration for displaying 64 gradations using 9 subfields from SF0 to SF8. A configuration in which the upper three subfields 32, 16, and 8 are each divided into two with respect to 32, 16, 8, 4, 2, and 1, which are light-emitting weights having natural binary weights of 6 bits (64 gradations). It has become. That is, SF2 and SF7 are subfields of 16 light emission weights obtained by dividing the light emission weight of 32 into two, SF3 and SF8 are subfields of 8 light emission weights obtained by dividing the light emission weight of 16 by two, and SF1 and SF6 are divided by two light emission weights of 8 This is a subfield of the light emission weight 4 that has been set. Further, SF2 and SF, which are emission peaks
The time interval between the light emission centers of No. 7 is configured to be approximately 1/2 field.

FIG. 20 shows a subfield configuration for displaying 80 gradations using 10 subfields from SF0 to SF9. Basically, N = 16 and K = 2 based on the subfield configuration shown in FIG. 13 to FIG. 15 and having a light emission weight of 32, 16, 16, 8, 4, 2, 1 It is. On the basis of this, the upper three subfields 32, 16, and 16 having a large light emission amount are
It has a split configuration. That is, SF2 and SF7 are subfields of 16 light emission weights obtained by dividing the light emission weight of 32 into two, SF1 and SF6 are subfields of light emission weight 8 obtained by dividing the light emission weight of 16 by two, and SF3 and SF8 are divided by two light emission weights of 16 This is a subfield of the light emission weight 8 that has been set. As in the case of FIG.
The time interval of the light emission center of F7 is configured to be approximately 1/2 field. In the subfield configuration of FIG. 20, in addition to the effect of dispersing the light emission switching at the time of gradation change shown in FIGS. A display device having excellent image display quality can be realized.

FIG. 21 shows a subfield configuration for displaying 64 gradations using eight subfields SF0 to SF7. The upper two sub-fields 32 and 16 are added to 32, 16, 8, 4, 2, and 1, which are light-emitting weights having 6-bit (64-gradation) natural binary number weights.
It has a divided configuration ((32 + 16) / 4 = 12), and SF1, SF2, SF5, and SF6 are the subfields having the largest light emission amount. Unlike the configuration examples shown in FIG. 19 and FIG. 20, there are four subfields having the largest light emission amount. However, two subfields are adjacent to each other to form a “double mountain type” as shown in FIG. The interval between the two peaks is a time interval from the center of light emission combining SF1 and SF2 to the center of light emission combining SF5 and SF6, and is configured to be フ ィ ー ル ド field.

FIG. 22 shows a subfield configuration for displaying 64 gradations using 10 subfields from SF0 to SF9. 32, 16, 8, 4, 2, 1 which are light emission weights having natural binary weights of 6 bits (64 gradations)
, The highest emission weight 32 is divided into three,
Is divided into two. That is, S
F2 (weight 14), SF5 (weight 4) and SF7 (weight 1
Three of 4) are subfields (14 + 4 + 14 = 32) obtained by dividing 32 emission weights. SF1 and SF6 are 1
A light-emitting weight of 8 is obtained by dividing the light-emitting weight of 6 into two, and a light-emitting weight of 4 is obtained by dividing the light-emitting weight of 8 into two by SF3 and SF8. Further, the time interval between the emission centers of SF2 and SF7 at which the emission peaks is approximately 1
/ 2 fields. As described above, a subfield having a non-power-of-two light emission weight can be formed by dividing into three parts, whereby pseudo contour interference caused by light-emission switching of the sub-field, which occurs near the power-of-two power gradation, is distributed to other tones. Has the effect of causing

The subfield structure shown in FIGS. 19 to 22 is obtained by dividing a large upper subfield of the light emission amount of the subfield constituting the central portion of the two mountain-shaped arrangements in one field period. For example, in the configuration of FIG. 19, SF1, SF2, and SF3 forming the first half and SF6, SF7, and SF8 forming the second half divide the upper 3 bits (32, 16, 8) of the natural binary number weight into two. It was done. As a result, rough gradation expression every eight gradations is displayed at twice the field frequency,
This is effective for reducing flicker and false contours.

The subfield configurations shown in FIGS. 19 to 22 mainly show the arrangement of the light emission weights, and actually include address processing, processing for initializing the light emitting elements, and the like. In consideration of these additional signals, the time interval (from the center of light emission to the center of light emission) of the two subfields where the amount of light emission peaks is configured to be approximately 1/2 field. In a system that requires more time for address processing, processing for initializing the light emitting element, and the like than for the period of the number of light emission sustaining pulses for determining the light emission weight, the total number of subfields is between two subfields having the maximum light emission amount. The number of subfields obtained by subtracting one from half the number may be arranged. Specifically, four sub-fields in ten sub-fields and three sub-fields in eight sub-fields may be arranged between two sub-fields having the maximum light emission amount. If the total number of subfields is odd, a blanking period equivalent to one subfield may be added, one subfield having a light emission weight of 0 may be added, and the total number of subfields may be processed as an even number. Alternatively, without adding blanking, 1 is added to the total number of odd subfields, and the number of subfields obtained by subtracting 1 from 1/2 is arranged between the subfields having the maximum light emission amount. At this time, by selecting a subfield having a small amount of light emission between the subfields having the maximum light emission amount, it is possible to make the light emission interval between the two subfields having the maximum light emission amount close to フ ィ ー ル ド field. . Further, by adjusting these methods and a blanking period in which no light is emitted, the light emission interval of the subfield having the maximum light emission amount may be set to フ ィ ー ル ド field. The blanking is inserted at the boundary with the next field (at the end or the beginning of one field), so that the light emission can be concentrated, and the degradation of the resolution of the moving image and the false contour disturbance can be reduced. it can.

The arrangement of these subfields is shown in FIG.
As shown in (1), the light emission distribution has two peaks in one field period and the time interval between the peaks is １ ／ field, and the arrangement is not limited to the subfield arrangement in the figure. For example, in the configuration of FIG. 19, SF0 to SF8 are arranged in a temporally inverted manner, or
The same effect can be obtained even if F1 and SF3 and SF6 and SF8 are exchanged.

As described above, by adopting the double-crest subfield arrangement, the characteristics of the crest-shaped subfield arrangement shown in FIG. 11 can be utilized to further reduce flicker disturbance and pseudo contour disturbance. In addition, the same time response characteristics of the R (red) light emitting element and the G (green) light emitting element as in the above-described double mountain type subfield arrangement make it possible to achieve high image quality with little disturbance such as coloring at the moving edge portion. Video display can be realized.

In the two-mountain subfield arrangement shown in FIGS. 19 to 22, two ridges are formed by dividing an upper subfield having a large light emission amount. Therefore, the number of subfields is required to be larger than the minimum number of subfields required for gradation expression (for example, 6 subfields for 64 gradations). Therefore, when the resolution is high and the total number of subfields cannot be obtained, a mountain-shaped subfield arrangement may be employed.

[0088]

As described above, according to the present invention, the following effects can be achieved. (1) Since the light emission response characteristics of the R and G light emitting cells are made uniform, it is possible to reduce a deterioration in image quality such as coloring at a moving edge portion and to realize a color image display device capable of displaying a high quality moving image. Can be.

(2) The emission weight arrangement of the subfield is
Since the light is concentrated at the center of the field, the resolution is reduced when displaying a moving image, and a color image display device capable of displaying a high-quality moving image can be realized.

(3) The light emission response characteristics of the R and G light emitting cells are made uniform, and the light emission weight arrangement of the subfields is formed into a mountain shape in which light emission is concentrated at the center of the field. Thus, a high-quality color image display device with few dynamic resolution characteristics and excellent image quality can be realized.

(4) The emission weight arrangement of the subfield is
Excellent kinetic resolution characteristics because the light emission is concentrated at the center of the field and the "light emission switching" when gradation changes continuously is dispersed without concentrating on a specific gradation. And a high-quality color image display device that can simultaneously achieve the reduction of false contour disturbance can be realized.

(5) A two-mountain subfield weight arrangement having two peaks of the light emission amount in one field period is provided.
By configuring the time interval of the peak of the light emission amount to be １ ／ field, flicker disturbance and pseudo contour disturbance can be reduced.

(6) The light emission response characteristics of the R and G light emitting cells are made uniform, and the light emission weight arrangement of the subfield is set to 1
Since a two-peak shape having two peaks of the light emission amount in the field period is used, it is possible to realize a high-quality color image display device with less disturbance of coloring at the moving edge portion and excellent dynamic resolution characteristics.

[Brief description of the drawings]

FIG. 1 is a block diagram of a color image display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a matrix display panel 5 shown in FIG.

FIG. 3 is a diagram (part 1) for describing colored disturbance at a moving image edge portion;

FIG. 4 is a diagram (part 2) for explaining colored disturbance at a moving image edge portion;

FIG. 5 is a diagram for explaining a conventional valley-type subfield configuration.

FIG. 6 is a diagram for explaining an emission weight arrangement in a valley-shaped subfield configuration.

FIG. 7 is a diagram for explaining dynamic resolution degradation due to a valley-shaped subfield configuration.

FIG. 8 is a diagram for explaining color disturbance at a moving image edge portion according to the present invention.

FIG. 9 is a diagram for explaining color disturbance at a moving image edge portion of the conventional device.

FIG. 10 is a diagram showing a subfield configuration according to an embodiment of the present invention.

FIG. 11 is a diagram showing an emission weight array in a mountain-shaped subfield configuration according to an embodiment of the present invention.

FIG. 12 is a diagram showing another subfield configuration according to the present invention.

FIG. 13 is a diagram showing still another subfield configuration according to the present invention.

FIG. 14 is a diagram showing still another subfield configuration according to the present invention.

FIG. 15 is a diagram showing still another subfield configuration according to the present invention.

FIG. 16 is a diagram showing a first light emission control pattern.

FIG. 17 is a diagram showing a second light emission control pattern.

FIG. 18 is an explanatory diagram illustrating a light emission pattern having a (two-mountain) subfield configuration according to the present invention.

FIG. 19 is an explanatory diagram illustrating still another subfield configuration of the display device according to the present invention.

FIG. 20 is an explanatory diagram illustrating still another subfield configuration of the display device according to the present invention.

FIG. 21 is an explanatory diagram illustrating still another subfield configuration of the display device according to the present invention.

FIG. 22 is an explanatory diagram illustrating still another subfield configuration of the display device according to the present invention.

[Explanation of symbols]

101, 102, 103... A / D conversion circuit, 2... Subfield conversion circuit, 3.
301: frame memory, 4: drive circuit, 5: matrix display panel, 6: control circuit, 50: pixel,
51: red (R) light emitting cell, 52: green (G) light emitting cell, 5
3. Blue (B) light emitting cell.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akihiko Kogami 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref.Hitachi, Ltd.Household Electronics and Information Media Business Unit (72) Inventor Hiroshi Otaka Totsuka-ku, Yokohama-shi, Kanagawa 292 Yoshida-cho Hitachi, Ltd. Home Appliance and Information Media Business Division

Claims (19)

[Claims] 1. A color image display device for supplying a red, green, and blue color video signal to each of red, green, and blue light emitting cells to display a color image, wherein each of the red, green, and blue light emitting cells is provided. A color image display device, characterized in that the time response characteristic of the light emission of each of the above is set to a value corresponding to each color of red, green, and blue. 2. A color image display device for supplying a red, green, and blue color video signal to each of red, green, and blue light emitting cells to display a color image, wherein each of the red, green, and blue light emitting cells is provided. When the time response characteristics of the light emission of the light emitting device are TR, TG, and TB, respectively, TR and TG
A difference between TR and TB or a difference between TG and TB. 3. A color image signal of red, green, and blue is divided into a plurality of sub-fields to which light-emission weights are assigned on a field-by-field basis. In a color image display device, when time response characteristics of light emission of red, green, and blue light emitting cells are TR, TG, and TB, respectively, TR and TG
A difference between TR and TB or a difference between TG and TB. 4. The color image display device according to claim 1, wherein said TR, TG, and TB satisfy the following equations. | TR-TG | <| TR-TB |
And | TR-TG | <| TG-TB | 5. The color image display device according to claim 1, wherein a light emission weight assigned to each of the subfields increases from the front and rear of the arrangement toward the center. 6. The configuration of the emission weights assigned to each of the subfields is such that there are two subfields having the largest emission weights, and the time interval between the emission of these two subfields is approximately 1/2 field. 5. The color image display device according to claim 1, wherein: 7. The configuration of the emission weights assigned to each of the subfields is such that one or more sets of subfields having the same emission weight are present in other subfields except for the two subfields having the maximum emission weight. 6. The color image display device according to claim 5, wherein subfields are arranged separately in a first half and a second half in the field. 8. A time response characteristic of light emission of each light emitting cell, wherein at least the afterglow time of red and green light is approximately equal to or longer than half a field time. The color image display device according to claim 6 or 7. 9. A color image signal of red, green, and blue is divided into a plurality of sub-fields to which light-emission weights are assigned, on a field-by-field basis, and the presence or absence of light emission in each sub-field is controlled to express a gradation. In the color image display apparatus, the configuration of the emission weight assigned to each of the subfields includes two subfields having the largest emission weight, and the time interval between the emission of these two subfields is approximately １ ／ field. A color image display device characterized by being arranged. 10. The structure of light emission weights assigned to each of the subfields is such that one or more sets of subfields having the same light emission weight are included in other subfields except for the two subfields having the maximum light emission weight. 10. The color image display device according to claim 9, wherein subfields are arranged separately in a first half and a second half in the field. 11. The time response characteristic of light emission of each of the red, green, and blue light emitting cells includes at least the afterglow time of red and green light:
11. The color image display device according to claim 9, wherein the time is approximately equal to or longer than a half field time. 12. A color image signal of red, green, and blue is divided into a plurality of subfields to which respective light emission weights are assigned on a field basis, and the presence or absence of light emission in each subfield is controlled to express gradation. In the color image display device to perform, among the plurality of subfields, [N], [2 · N], and [3] are assigned to 2 · K−1 upper subfields including the subfield having the largest emission weight.・ N]…
[(K-1) · N], [K · N], [(K-1) ·
N], ... [2 · N], [N] (where K and N are natural numbers)
A color image display device, wherein the light emission weights are assigned. 13. The color according to claim 12, wherein the upper subfields are arranged so that the emission weight becomes larger toward the center before and after the subfield whose emission weight is [N]. Image display device. 14. A first light-emitting means for causing each of the sub-fields to emit light in a first order for each field; and
14. The color image according to claim 12, further comprising: a second light emitting unit that emits light in a second order different from the order described above, and a switching unit that switches each of the light emitting units at a predetermined cycle. Display device. 15. The color image display device according to claim 14, wherein the predetermined period is one of a field unit, a line unit, and a pixel unit. 16. A color image display device according to claim 14, wherein said switching means selects a light emitting means for each pixel in accordance with its arrangement position. 17. The method according to claim 16, wherein said switching means switches the light emitting means between a pixel at a white position and a pixel at a black position when the pixels arranged in a matrix are regarded as a checkered pattern. The color image display device as described in the above. 18. The apparatus according to claim 17, wherein said switching means switches, for each field, one light emitting means for emitting a pixel at a white position and the other light emitting means for emitting a pixel at a black position. Color image display device. 19. The color image display device according to claim 1, wherein said color image display device is a plasma display.