JP2000155548A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to uniformly keep an emitted wavelength of LEDs forming the whole screen of a mosaic display. SOLUTION: Light emitting data are fed to an RDATA latch 13R, a GDATA latch 13G, and a BDATA latch 13B, and latched as R, G, B data for each picture element. An arithmetic processing part 14 performs calculations by the latched R, G, B data and chromaticity correction factors Cij written in a chromaticity correction factor register 16. The calculation result of the arithmetic processing part 14 are fed to a data memory 15 as corrected luminescence data and stored. From a brightness correction data memory 20, a brightness correction data is fed to a constant-current driver 18 according to a control signal supplied. The constant-current driver 18 drives an LED display 19 according to the corrected luminescence data and the brightness correction data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention particularly relates to a case where a screen is formed by assembling luminous bodies, such as a mosaic display, because if there is a portion having a different emission wavelength, the uniformity of the screen is deteriorated. The present invention relates to a display device that can maintain the colors of the entire screen uniform by correcting each of the three primary colors of color light emission to have the same chromaticity point.

[0002]

2. Description of the Related Art For example, a trio of light emitting diodes (hereinafter, referred to as LEDs) of three primary colors of R, G, and B (hereinafter, referred to as RG).
Mosaic display (large video display)
It is necessary to select and use LEDs within a standard (hereinafter referred to as a rank) having a certain luminous intensity and emission wavelength. This is to avoid the problem of uneven color due to variations in LED characteristics.

The variations include: 1. variations in luminous intensity (luminance) and 2. variations in emission wavelength (chromaticity). When one pixel is constituted by the RGB trio, the variation in luminous intensity deteriorates the uniformity of luminance and the chromaticity of intermediate colors. Also, the variation in the emission wavelength deteriorates the uniformity of the chromaticity of the intermediate color and the three primary colors. If LEDs having such variations in characteristics are used randomly without being selected, color unevenness due to a difference in emission wavelength is conspicuous,
Image quality deteriorates.

[0004]

However, when using LEDs of the same rank on one screen, it is necessary to prepare LEDs for maintenance for each rank in advance when performing productivity for each screen and service maintenance. There is a problem that wasteful costs are generated when viewed from the viewpoint of management and the like.

Japanese Unexamined Patent Application Publication No. 10-26959 discloses a brightness unevenness of each of R, G, and B single colors due to a position on an LED array caused by a variation in luminous intensity (brightness) of each LED element, and an overlap of these. In order to correct the color unevenness due to the alignment, both the amplitude and the DC level of the video signal of at least one of R, G, and B are corrected with the brightness correction data stored according to the screen position. I have. As described above, an apparatus that corrects luminance unevenness due to variation in luminous intensity (luminance) and color unevenness due to the superposition of these luminances by aligning the luminance level of each single-color pixel is already known.

However, the method described in this document can solve the luminance unevenness due to the variation in the luminous intensity (luminance), but cannot correct the color unevenness caused by the variation in the emission wavelength (chromaticity).

Therefore, an object of the present invention is to express colors (hereinafter, referred to as pixels) of each pixel constituting the entire screen without selecting LEDs.
It is an object of the present invention to provide a display device capable of keeping the CIE tristimulus values uniform.

[0008]

According to a first aspect of the present invention, there is provided a display device for performing display based on a set of trios composed of light emitters of three primary colors based on an input signal.
When driving the light emitters of the three primary colors, one of the trios
A display device comprising chromaticity correction means for adding data obtained by multiplying data of one or two other colors of a trio to data of a color by a previously calculated chromaticity correction coefficient.

When driving a mosaic display in which one pixel is composed of three primary color luminous elements (RGB trio) and a plurality of pixels are aggregated, a chromaticity correction data memory previously determined for supplied luminescence data Is corrected with one or two other colors according to the variation in the characteristics of each light-emitting body (LED). As a result, the chromaticity points of the three primary colors can be aligned, so that there is no need to manage the rank of the emission wavelength of the light emitting body. In addition, wasteful costs such as improvement in product productivity, serviceability, and rank management of product stock can be reduced, and a product with uniform image display quality can be stably manufactured.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a mosaic display to which this embodiment is applied. In this example, four units 2 are arranged vertically and four horizontally in the main body 1. In the unit 2, four cells 3 each composed of light emitters of three primary colors are arranged vertically and four horizontally.
As shown in FIG. 2, the cell 3 includes three LEDs of green (G), red (R), and blue (B).
One pixel is constituted by one LED (hereinafter, referred to as an RGB trio). It is also possible to arrange a plurality of the main bodies 1 vertically and horizontally to form a larger mosaic display.

Next, an embodiment of the present invention will be described with reference to FIG. Light emission data of an image is supplied from an image processing device (not shown) to the chromaticity correction unit 12 via the input terminal 11. The chromaticity correction unit 12 includes a latch 13R for RDATA (red component data), a latch 13G for GDATA (green component data), and a BDATA (blue component data).
Latch 13B, arithmetic processing unit 14, data memory 15,
It comprises a chromaticity correction coefficient register 16 and a chromaticity correction data memory 21.

MPU (microprocessor unit) 1
7 supplies a control signal to a chromaticity correction data memory 21 in which chromaticity correction coefficients of each RGB trio are stored. The chromaticity correction data memory 21 reads chromaticity correction coefficients of the respective RGB trios according to the control signal. The read chromaticity correction coefficient is written to the chromaticity correction coefficient register 16.

The chromaticity correction coefficient is corrected by a chromaticity adjuster in advance so that each of the three primary colors of color light emission is corrected to a chromaticity point within a correction range as described later.
A coefficient for measuring the characteristics of the trio and multiplying data of another one or two colors constituting the same one pixel,
It is stored in the chromaticity correction data memory 21. In particular,
Green (G) having variation is corrected by red (R) and / or blue (B) constituting the same one pixel, so that the chromaticity is set to a chromaticity point within a correction range as described later. A correction coefficient is formed.

The input light emission data is stored in a latch 13R for RDATA, a latch 13G for GDATA, and a BDAT.
The data is supplied to the A latch 13B and is latched as R, G, and B data for each pixel. At this time, the light emission data is input as serial data. At the timing when the red light emission data is input from the light emission data, the red light emission data is latched by the RDATA latch 13R,
The green light emission data is latched by the GDATA latch 13G at the timing of inputting the green light emission data, and the blue light emission data is latched by the BDATA latch 13B at the timing of input of the blue light emission data. That is, the RDATA latch 13R, the GDATA latch 13G, and the BDATA latch 13B perform serial / parallel conversion.

The arithmetic processing section 14 calculates the latched R, G, B data and the chromaticity correction coefficient written in the chromaticity correction coefficient register 16 to generate corrected emission data. The generated corrected light emission data is supplied to the data memory 15. In the data memory 15, the supplied corrected light emission data is stored. This data memory 1
Reference numeral 5 denotes an MPU 17 which is composed of a memory for each frame, and in which writing and reading of the supplied corrected emission data are performed.
Is controlled by After receiving all the corrected light emission data assigned to the LED display device 19, the stored corrected light emission data is supplied to the constant current driver 18.

The MPU 17 has a brightness correction data memory 2 in which brightness correction data of the LED display device 19 is stored.
The control signal is supplied to 0. Brightness correction data memory 20
Then, the luminance correction data is supplied to the constant current driver 18 according to the supplied control signal. The luminance correction data is formed by measuring the characteristics of each of the three primary colors in advance by a luminance adjuster in order to adjust the luminosity variation of each pixel of the LED display device 19 with the drive current, and stores the data in the luminance correction data memory 20. Is done.

The constant current driver 18 includes the data memory 1
5 and the luminance correction data from the luminance correction data memory 20. At this time, an amount of current corresponding to the luminance correction data is supplied to the LED display device 19 for a time corresponding to the corrected light emission data. That is, the constant current driver 18 drives the LED display device 19 by PWM (pulse width modulation).

In this manner, the LED display device 19 that emits light can reproduce an image with good uniformity in which both luminous intensity (luminance) and luminous wavelength (chromaticity) are uniform. This L
As shown in FIG. 2 described above, the ED
One pixel is composed of the B trio, and a large number of pixels are arranged. A mosaic display (large image display device) provided on a street or a stadium is one example.

As described above, in this embodiment, first, the variation of the emission wavelength (chromaticity) is corrected, and then,
Variation in luminous intensity (luminance) is corrected. The correction of the emission wavelength will be described in more detail. The chromaticity correction unit 12 corrects the emission wavelength for each pixel. As a method of correcting the color unevenness caused by the variation of the emission wavelength,
A chromaticity conversion function is provided for each pixel.

For example, even if the same input signals R, G, and B are input, the CIE tristimulus values differ due to the different emission wavelengths of the pixels. As an example,
Equations (1) and (2) show the CIE tristimulus values when the same input signals R, G, and B are supplied to the pixel 1 and the pixel 2, respectively. At this time, when the color conversion coefficient of pixel 1 is Aij and the color conversion coefficient of pixel 2 is A'ij, the CIE tristimulus values of pixel 1 are X, Y, and Z, and the CIE tristimulus values of pixel 2 are X ', Y', Z '.

[0021]

(Equation 1)

Hereinafter, only the pixel 1 will be described for ease of description. The chromaticity of each LED of R, G, B of the pixel 1 is shown below. Further, the luminance ratio of each of the R, G, and B LEDs is given by LR: LG: LB = 0.9886: 0.7073: 0.
0941.

The chromaticity of the three primary colors that the pixel 1 should originally represent and the chromaticity of the reference white set by mixing the three primary colors are shown below. .

Here, input signals R, G, B are supplied to the pixel 1.
Is supplied, the CIE tristimulus value X of this pixel 1
Y and Z follow the following equation (3).

[0025]

(Equation 2)

The CIE tristimulus values X ₀ , Y when the same input signals R, G, B are supplied for the chromaticity of the three primary colors and the reference white, which the pixel 1 should originally represent.
₀ and Z ₀ follow the following equation (4).

[0027]

(Equation 3)

Here,

[0029]

(Equation 4)

In this embodiment, the input signal R supplied to the pixel 1 is calculated according to the following equation (5).
G and B are multiplied by a chromaticity correction coefficient Cij to obtain signals R ′, G ′,
Convert to B '.

[0031]

(Equation 5)

When the converted signals R ′, G ′, and B ′ are substituted into equation (3), the following equation (6) is obtained.

[0033]

(Equation 6)

Therefore, from equations (4) and (6), (Bij)
= (Aij) (Cij). From this, the chromaticity correction coefficient (Cij) = (Aij) ^-1 (Bij) of the signal is obtained. In this example,

[0035]

(Equation 7)

## EQU1 ## By performing this operation on all the pixels of the RGB trio, the obtained chromaticity correction coefficient Cij is obtained.
Are stored in the chromaticity correction data memory 21. As described above, a mosaic display in which chromaticity correction is performed by adding one or two other colors of a trio to one color of a trio of pixels using the chromaticity correction coefficient Cij has a uniform image quality. Is obtained.

Next, using the CIE chromaticity diagram shown in FIG.
The variation of the ED will be described. On the CIE chromaticity diagram shown in FIG. 4, the chromaticity variation of the LED, NTSC reproduction,
The emission chromaticity point after CRT phosphor correction is shown. CR
The T chromaticity points are the emission chromaticity points of the three primary colors after the CRT composed of the P-22 phosphor. NTSC reproduction is NT
These are emission chromaticity points of each of the three primary colors determined by the SC method. The color variation ranges Ar1, Ag1, Ab1 indicated by oblique lines are the variation ranges of the three primary colors depending on the emission wavelength when the LED is manufactured. The correction ranges Ar2, Ag2, Ab2 indicated by crosses
Is a range after the variation of the input signals R, G, and B is corrected, and it is difficult to distinguish the three primary colors.
cAdam) is the color discrimination range.

On the CIE chromaticity diagram, tangent lines La1, La2 and La3 connecting the outer edge of the red color variation range Ar1 and the outer edge of the green color variation range Ag1 are displayed, and the green color variation range Ag1 is displayed. And the blue color variation range A
Tangent lines Lb1, Lb2, Lb3 connecting the outer edge of b1 are displayed, and tangential lines Lc1, Lc2, Lc3 connecting the outer edge of the blue color variation range Ab1 and the outer edge of the red color variation range Ar1 are displayed. The intersections obtained by minimizing the angles extending toward the color variation ranges Ar1, Ag1, and Ab1 of the respective colors are indicated by Pr, Pg, and Pb. That is, the intersections Pr, Pg, Pb are tangents La1,
Generated by Lb1 and Lc1. Also, the intersection points Pr, Pg
, Pb are included in the correction ranges Ar2, Ag2, Ab2.

In this embodiment, by correcting the variation of each of the three primary colors, the color variation ranges Ar1, Ag1,.
The LED is illuminated so that the emission chromaticity of Ab1 becomes the emission chromaticity at the intersections Pr, Pg, and Pb. On the chromaticity diagram, the color reproduction range indicated by the triangle having the intersections Pr, Pg, and Pb as vertices is one light emission arbitrarily selected in each of the color variation ranges Ar1, Ag1, and Ab1 of the three primary colors. It is included in the color reproduction range indicated by the triangle having the chromaticity point as the vertex. Therefore, the intersection points Pr, P
Assuming that the g and Pb are the chromaticity points to be corrected, if the LEDs corresponding to the three primary colors are within the respective ranges having the color variation ranges Ar1, Ag1, and Ab1, the intersection P
It can be adjusted to the chromaticity indicated by r, Pg, and Pb.

At this time, by correcting the variation of each of the three primary colors, the LED is made to emit light so that the emission chromaticity of the color variation range Ar1, Ag1, Ab1 becomes the emission chromaticity of the correction range Ar2, Ag2, Ab2. You may do it. Correction range A
r2, Ag2, and Ab2 are ranges in which it is difficult to distinguish colors as described above. For example, the emission chromaticity included in the green correction range Ag2 appears to be the emission chromaticity at the position of the intersection Pg. In other words, the emission chromaticity (color variation range Ar1, Ag1, Ab1) of the LED having the variation is corrected as if the LEDs are emitting light in the range (correction range) Ar2, Ag2, Ab2 where the color is difficult to distinguish. Intersection points Pr, Pg
, Pb, so as to appear to shine at the emission chromaticity, thereby suppressing the influence of variations in the emission wavelength of the LED.

At this time, for example, green perception 520 occurs.
Correction is performed to increase the purity of the emission wavelength of the green LED within the correction range Ag2 so that nm and the emission wavelength of the green LED are the same. Similarly, the emission wavelengths of the red and blue LEDs within the correction ranges Ar2 and Ab2 are also corrected so as to increase the purity. as a result,
A triangle larger than the triangle formed by the intersection points Pr, Pg, Pb can be realized. That is, a larger color reproduction range can be realized.

Specifically, a green LED of an RGB trio
Are included in the color variation range Ag1 to the correction range Ag2, the red LED and / or the blue LED constituting the same one pixel are corrected by the chromaticity correction coefficient Cij to emit light.

As shown in FIG. 4, the corrected color reproduction range is the range inside the triangle formed by the intersections Pr, Pg, and Pb. If the number of light emitting points is completely one, the color reproduction range becomes narrower, but the color discrimination range (correction range Ar2,
Ag2, Ab2) can extend the color reproduction range.

In this embodiment, the correction is performed for the three primary colors of red, green and blue. However, as shown in FIG. The same effect can be obtained even if the chromaticity correction is performed only for the chromaticity correction.

In this embodiment, an LED is used as an example of a light-emitting body. However, the present invention can be similarly applied using a discharge tube, a CRT, a liquid crystal, or the like.

In this embodiment, this correction circuit is used for each pixel composed of RGB trios. However, the screen of the mosaic display is divided into a plurality of units, and this correction circuit is used for each unit. May be.
For example, by randomly arranging LEDs having a variation in characteristics in a unit, uniformity in the unit can be ensured from a distance. However, since the emission wavelength (chromaticity) differs between the units, by providing this correction circuit for each unit, the uniformity of the emission wavelength of the entire screen can be improved, and the difference in the expression color between the units can be improved. Can also be corrected.

[0047]

According to the first aspect of the present invention, when driving a display device of three primary colors, data of one color of a trio is previously converted to data of another one or two colors of the trio. By adding data multiplied by the calculated chromaticity correction coefficient, it is possible to make display devices with different emission wavelengths appear as if they glow at the same emission wavelength, eliminating the need to manage the rank of the emission wavelength of the display device. It is possible to reduce wasteful costs such as productivity improvement, serviceability, and product inventory rank management, and to stably produce products with uniform image display quality.

According to the second aspect of the present invention, after performing chromaticity correction on the input signal, the display device is driven based on the luminance correction data. Therefore, not only the variation in the color of the display device but also the variation in the luminance can be corrected, so that an image having excellent color and luminance uniformity can be displayed on the entire screen.

According to the third aspect of the present invention, the chromaticity correction coefficient stored in the memory corresponding to the input signal and the input signal are calculated, and the display device is driven according to the calculation result. Therefore, display control according to the light emission characteristics of each display device can be realized.

According to the fourth aspect of the present invention, the emission wavelength of one color in the trio of a plurality of three primary colors can be adjusted even if individual display devices corresponding to each of the three primary colors have a predetermined variation.
The effect of correcting to the same chromaticity indicated by the intersection of the present invention can be obtained.

According to the fifth aspect of the present invention, even if the individual display devices corresponding to each of the three primary colors have a predetermined variation in the emission wavelength of each color in the plurality of three primary color trios, the present invention is applicable. Can be corrected to the same chromaticity indicated by the intersection of.

According to the sixth aspect of the present invention, it is possible to increase the purity of one luminescent color in a plurality of three primary color trios within a predetermined range where the corrected color identification level is predetermined. As a result, it is possible to obtain an effect of expanding a color reproduction range displayed by a plurality of trio of three primary colors.

According to the seventh aspect of the present invention, there are three primary colors of red, blue and green, and particularly for green having a large variation in light emission characteristics, the same as the above-described fourth or sixth aspect of the present invention. The effect can be obtained.

According to the eighth aspect of the present invention, it is possible to increase the purity of one emission color in a plurality of three primary color trios within the color discrimination range of Macadam where it is difficult to identify the color after correction. As a result, the color reproduction range displayed by the trios of the three primary colors can be expanded.

According to the ninth aspect of the present invention, LEDs having different emission wavelengths can be made to appear as if they have the same emission color.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example of a mosaic display to which the present invention is applied.

FIG. 2 is a schematic diagram illustrating a pixel to which the present invention is applied;

FIG. 3 is a block diagram of one embodiment of a light emitting unit to which the present invention is applied.

FIG. 4 is an example of a chromaticity diagram for explaining colors according to the present invention.

[Description of Signs] 12: chromaticity correction unit, 13R: latch for RDATA, 13G: latch for GDATA, 13B: B
Latch for DATA, 14 ... arithmetic processing unit, 15 ...
Data memory, 16: chromaticity correction coefficient register, 17
... MPU, 18 ... Constant current driver, 19 ...
LED display device, 20: brightness correction data memory, 2
1: Chromaticity correction data memory

Claims (9)

[Claims] 1. A display device which performs display by a set of trios composed of light emitters of three primary colors based on an input signal, wherein when driving the light emitters of the three primary colors, data of one color of the trio is driven. A display device comprising chromaticity correction means for adding data obtained by multiplying data of another one or two colors of the trio by a chromaticity correction coefficient obtained in advance. 2. The method according to claim 1, further comprising the step of driving the light emitters of the three primary colors based on brightness correction data obtained in advance to correct the luminance of the light emitters of the three primary colors. 2. The display device according to 1. 3. The chromaticity correction means includes: a memory for storing the chromaticity correction coefficient; and arithmetic means for calculating the input signal and the chromaticity correction coefficient. The display device according to claim 1, wherein the trio is driven in accordance with a result of the calculation means. 4. The chromaticity correcting means, wherein: a first range formed by a variation of a luminescent color of a first color of the luminous body of the three primary colors represented on a chromaticity diagram; A second range formed by the variation of the emission color of the second color of the illuminant; a third range formed by the variation of the emission color of the third color of the illuminant of the three primary colors; A first tangent connecting the outer edge of the first range and the outer edge of the second range intersects a second tangent connecting the outer edge of the first range and the outer edge of the third range The first color is corrected to a chromaticity indicated by an intersection obtained by minimizing an angle extending toward the first range from the generated angles. The display device according to claim 1. 5. The method according to claim 1, wherein the first tangent intersects a third tangent connecting an outer edge of the second area and an outer edge of the third area. The second color is corrected to a chromaticity indicated by an intersection obtained by minimizing an angle extending toward the second range, and the second tangent and the third tangent are corrected. The third color is corrected to the chromaticity indicated by the intersection obtained by minimizing the angle extending toward the third range from the angles generated by crossing. The display device according to claim 4, wherein: 6. The chromaticity correction means, wherein: a first range formed by a variation in a luminescent color of a first color of the luminous body of the three primary colors represented on a chromaticity diagram; A second range formed by the variation of the emission color of the second color of the illuminant; a third range formed by the variation of the emission color of the third color of the illuminant of the three primary colors; A first tangent connecting the outer edge of the first range, the outer edge of the second range, and a second tangent connecting the outer edge of the first range and the outer edge of the third range intersect. And an intersection obtained by minimizing an angle extending toward the first range from the angles generated by the above, and a color indicated by the intersection from a reference white obtained by combining the three primary colors. The first color is corrected in a fourth range that is farther away from the first color. The features of claim 1
The display device according to claim 1. 7. The display device according to claim 4, wherein the three primary colors are red, blue, and green, and the first color is green. 8. The display device according to claim 6, wherein the fourth range is a color discrimination range of Macadam. 9. The display device according to claim 1, wherein the light emitter of the three primary colors is a light emitting diode.