WO2010066134A1

WO2010066134A1 - Uniformity compensating method for lcd which has an uneven backlight board and display thereof

Info

Publication number: WO2010066134A1
Application number: PCT/CN2009/073107
Authority: WO
Inventors: 王遵义
Original assignee: 光远科技股份有限公司
Priority date: 2008-12-09
Filing date: 2009-08-05
Publication date: 2010-06-17
Also published as: CN101751872B; CN101751872A

Abstract

A uniformity compensating method for LCD which has an uneven backlight board, by selecting the uniform standard that all the crystal cells can achieve as virtually primary color, calculating the relationship of tri-stimulus values between every crystal cell and virtually primary color, and recording the values as compensating data. When the display runs, according to the positions of the applied crystal cells, all the input image signals calculating and conversing based on the compensating data operator of crystal cells, and attaining the compensating image signals of the corresponding crystal cells.

Description

Method for compensating uniformity of liquid crystal display with non-uniform backlight and the display [Technical Field]

The invention relates to a display uniformity compensation method, in particular to a liquid crystal display uniformity compensation method with a non-uniform backlight and the display. 【Background technique】

The liquid crystal display mainly comprises a rear backlight panel and a front liquid crystal module. Since the image display of the liquid crystal display uses a backlight in the backlight panel to illuminate the front color filter (color-filter), corresponding to the front liquid crystal mode The primary color of red, green and blue is formed at each liquid crystal valve position; the electric signal is used to control the voltage between the electrodes on the front and rear sides of each liquid crystal valve. The light transmittance of the liquid crystal is for the sake of explanation. Here, each liquid crystal valve is referred to as a sub-cell, and the red, green, and blue light respectively passing through the three sub-cells are mixed into a so-called color. A pixel (color p _lxe i;), which combines the brightness and chromaticity that can be transmitted by each pixel position, constitutes the entire picture.

Since the color of the color filter (color-filter;) is made by the principle of dye translucency, the transmission spectrum of the three basic colors of red, green and blue is as shown in Fig. 1. It shows that it has good reproducibility, making the whole filter transparent. Where R is the red basic color transmission spectrum, and G is the green transmission spectrum, and B is the blue transmission spectrum. Because the LCD uses three basic colors of red, green, and blue color-filters to form various color pixels at each cell position, the backlight must use white light.

On the other hand, due to the development of the local color dimming control technology, in recent years, the three basic colors of the backlight panel may also have different brightness variations depending on the color of the screen. Since the LED's luminous efficiency is improved and the cost is reduced, and the LED is used as the backlight, the area brightness control can be used to improve the contrast ratio, and the RGB LED can be used to increase the color gamut range. The NTSC standard reduces the effects of Moving Blur, reduced power consumption and ultra-thin thickness design, and no environmental pollution. Therefore, the use of LED as a backlight for LCD displays has been widely recognized and accepted by the market.

The use of LEDs as a light source can be divided into two methods, one is to use a blue LED to excite the phosphor powder and emit a longer wavelength component to synthesize a white light white LED; the other method is to directly use the RGB three-color LED chip combination to form a white light. LED. However, regardless of the white light produced by the above, there is a problem of unevenness in chromaticity and brightness between the different LEDs. For example, when a blue LED die is used to excite fluorescent powder into white light, the wavelength of the blue light and the composition, ratio, and mixing state of the fluorescent powder affect the chromaticity and brightness of the white light, so that the same type of product White LEDs are more yellowish, and some are more bluish; if they are classified by their color coordinates, the range is about 0.26 0.36.

Similarly, when white light is synthesized by RGB three-color LED crystal grains, the color coordinates of the white light mixed by each unit cell differ depending on the color coordinates of the basic colors of the respective crystal grains. Although the applicant's Taiwan Patent No. 480879, "Method for Compensating Color Inconsistent Color Display Colors", has revealed that when using RGB tri-color LEDs as white light sources, individual RGB to different brightness distributions can be adjusted. The synthesized light is similar in chromaticity and brightness at each pixel. In view of the above, since the chromaticity and brightness of the respective light sources are still different, the backlight may not be able to provide uniform illumination of the entire screen even after passing through the diffuser. If the main backlight of the i-th unit cell in the liquid crystal module is LEDi, the main backlight of the i+1th unit cell is LEDi+1. When the LEDi illuminating component is more reddish, and LEDi+Ι is more blue, and for convenience of explanation, the image signal intensity is set to be between 0 and 1, where 0 means the light valve is fully closed and 1 is the light valve. Fully open. When the full white screen needs to be displayed, the image signals SS _g and 8 _{1 1} provided to each unit cell are all 1.0, 1.0, 1.0), indicating that the light valves of the three sub-cells of red, green and blue are all open. Since the LEDi is reddish, the pixel 1 displayed by the cell position will also be reddish and the LEDi+Ι will be bluish so the pixel 1+1 will also be bluish. Therefore, the chroma and brightness of the entire picture will be uneven.

In particular, in accordance with current practice, in order to reduce the cost and structural cost of the LED driving circuit, a common circuit is shown in FIG. 2, and the driving voltage V _DD greater than the total forward bias of all the series LEDs is simultaneously driven in series. Fluorescent white LED or RGB LED :). In this example, the driving current Is is a constant current source, and a set of control circuits regulates the duty cycle ratio of the constant current source between 0 and 1 to output different magnitudes of PWM. (pulse-width modulation) signal, which enables the entire string of LEDs to emit light, and thereby adjust the brightness of the string of LEDs.

However, in this driving mode, the effective luminous current of the entire string of LEDs can only be a single value between 0 and ls. Although the cost can be reduced, the chromaticity and brightness of the string of LEDs cannot be individually adjusted. Therefore, when the chromaticity and brightness of the individual LEDs in the string of LEDs are not uniform, the above-mentioned techniques possessed by the applicant cannot be used for compensation, resulting in uneven chromaticity and brightness of each pixel on the LCD display screen.

To improve the above unevenness, the only way to do this is to screen the chromaticity and brightness of all the LED dies one by one. In particular, the human eye has a good ability to distinguish between brightness and chromaticity. Clearly distinguish the level of brightness and chromaticity unevenness, the classification must be quite detailed: If the LED used as the backlight is a blue light-excited fluorescent powder structure, its chromaticity classification (bm) needs to be more than 20 kinds, and the brightness classification is more than 5 kinds. Multiplying the two conditions, the total number of classifications may reach 100; if the red, green, and blue LED crystals are combined to form a white light structure, the chromaticity and brightness classification of each basic color must be distinguished as About 30 kinds, the total number of classifications of the three colors is also about 100.

When there are so many classifications of backlight crystals or unit cells, whether it is stock material or purchase management, it will cause significant troubles to the inventory. In contrast, such procurement and management troubles will also greatly increase manufacturing costs and increase the working hours. The price of the product is soaring. The more serious problem is: the brightness and chromaticity of each LCD display are even, but when displayed in a store, even if two monitors of the same brand are juxtaposed, it may be selected. Backlight LEDs are classified differently, making each other's chromaticity And the difference in brightness not only causes a big problem on the finished tube, but also makes consumers doubt the quality of the product.

Therefore, the industry does not expect to have a proper solution, not only to ensure the brightness and chromaticity of the product itself, but also to ensure that each display has the same brightness and chromaticity; in particular, LED dies of different brightness and chromaticity can be used as the backlight source, without Close classification can increase manufacturing flexibility and reduce selection costs.

[Summary of the Invention]

One of the objects of the present invention is to provide a uniformity compensation method for a liquid crystal display having a non-uniform backlight panel which can ensure brightness and chromaticity uniformity of the liquid crystal display itself.

Another object of the present invention is to provide a non-uniform backlight liquid crystal display uniformity compensation method which can ensure that the brightness and chromaticity of each liquid crystal display product are maintained at the same level and that all product qualities are neatly drawn.

Still another object of the present invention is to provide a uniformity compensation method for a non-uniform backlight liquid crystal display which can greatly reduce the number of classifications of LED dies as a backlight source, and does not even need to be classified, thereby increasing the elasticity of material selection.

Still another object of the present invention is to provide a liquid crystal display which can ensure uniform brightness and chromaticity of a rendered picture even if the brightness and chromaticity of the backlight used are not uniform.

Still another object of the present invention is to provide a liquid crystal display which can adopt a backlight having uneven brightness and chromaticity, and can still maintain uniform brightness and chromaticity of a product image, thereby increasing material selection flexibility and reducing production cost.

Therefore, the present invention discloses a method for uniformity compensation of a liquid crystal display having a non-uniform backlight, wherein the liquid crystal display comprises a set of non-uniform backlights, and one set is located on the light exit side of the backlight, and includes a plurality of unit cells whose light transmittance can be changed, Displaying a picture composed of a plurality of pixels, and the unit cell is divided into many a liquid crystal module of the adjustment area, a set of control devices for controlling the individual light transmittance of each of the cells, and a set of brightness and chromaticity distributions for storing a plurality of adjustment regions according to the backlight illumination, and correspondingly a memory device for compensating data of uniform brightness and chromaticity distribution of each of the adjustment regions, and the method comprises the following steps: a) receiving from an image source, including a plurality of instructions for instructing all of the above-mentioned unit cell individual light channels The image data of the image signal of the transmittance; b) the image signal in the image data is respectively subjected to the corresponding adjustment area, and the compensation image including the plurality of compensation image signals respectively corresponding to each of the unit cells is obtained according to the weighting operation of the compensation data. The data and the cM clothing compensation image signal determine the individual light transmittance of the above unit cell in the liquid crystal module.

The liquid crystal display disclosed by the present invention comprises: a set of non-uniform backlights; a set of cells on the light exit side of the backlight, including a plurality of cells having different light transmittances and having a plurality of sub cells, respectively, to display a picture formed by pixels, and the unit cells are liquid crystal modules that are divided into a plurality of adjustment areas; one set stores a plurality of brightness and chromaticity distributions according to the illumination area of the backlight, and correspondingly makes each of the above adjustments a memory device for compensating data of uniform light transmittance and chromaticity distribution; and a group for controlling individual light transmittance of each of the above cells, and for supplying all of the above crystals from one image source The image signal in the image data of the individual light transmittance image signal is respectively determined according to the corresponding adjustment area, and the weighting operation of the compensation data is used to determine the individual light transmittance control device of the unit cell in the liquid crystal module; When one of the command signals in the image signal corresponds to any one of the unit cells in the image signal, at least one of the remaining cells in the unit cell is supplemented. Instruction video signal light.

The present invention records a virtual basic color and separately measures the difference between the three-color stimuli value of the three-color stimuli and the virtual basic color after all the adjustment regions are affected by the rear uneven backlight, and records as compensation data. . Then, when receiving the image data from the image source, the original image signal is converted into a compensated image signal according to the compensation data of each unit cell, which not only ensures the uniformity of brightness and chromaticity of the liquid crystal display itself; One to ensure that each LCD product, This brightness and chromaticity are maintained at the same level, and all product quality is neatly drawn; in particular, the number of classifications of LED dies as backlight sources can be greatly reduced, even without classification, thereby increasing material flexibility and reducing cost.

Therefore, through the technology disclosed by the invention, the liquid crystal display can ensure the uniformity of brightness and chromaticity of the presented picture even under the condition of uneven brightness and chromaticity of the used backlight board; Reduce production costs and provide a more profitable LCD monitor.

[Description of the Drawings]

Figure 1 is a schematic diagram showing changes in transmittance versus wavelength of common filters;

2 is a schematic diagram of a common light-emitting diode die driving circuit;

Figure 3 is a flow chart of a first preferred embodiment of the present invention;

4 is a perspective exploded view of a liquid crystal display according to a first preferred embodiment of the present invention; FIG. 5 is a schematic diagram showing the coloring coordinates of a light beam transmitted by each unit cell of the embodiment of FIG. 4, illustrating a selection rule of a virtual basic color. ;

Figure 6 is a side elevational view showing the structure of the embodiment of Figure 4;

7 is a perspective exploded view of a liquid crystal display according to a second preferred embodiment of the present invention; FIG. 8 is a side elevational view showing the structure of a third preferred embodiment of the present invention;

9 is a schematic diagram showing the coloring of a light beam transmitted through a unit cell of the embodiment of FIG. 8 in a color spectrum, illustrating the weighting effect of two different light sources on the same unit cell;

10 is a schematic diagram showing the color coordinates of a light beam transmitted by a unit cell of the embodiment of FIG. 8 in a color spectrum, illustrating a case when a plurality of light sources simultaneously act on a unit cell;

11 is a perspective exploded view of a liquid crystal display according to a fourth preferred embodiment of the present invention; and FIG. 12 is a perspective exploded view of a liquid crystal display according to a fifth preferred embodiment of the present invention.

[Main component symbol description] 4, 4"...substrate 4", 1⁄2""...cold cathode tube

5, 5', 5", 5, "...filters 6, 6', 6", 6," ... LCD module

31~37...歩 43"' ...light guide

41, 42, 40, 4, 42, 41, 42", 4", 42", ... LED

41 _r , , 41 _g , 41 _b , , 42 _r ,, 42 _g \ 42 _b , 41r", 42r", 43r", 44r", 45r", A, B, C...

61, 62, 61", 62,,... unit cell

【detailed description】

The foregoing and other technical aspects, features and advantages of the present invention will be apparent from In the present invention, the backlight can be formed not only by the backlight of LED1, LED2, ..., LEDn or the like but also by a combination of a cold cathode tube (CCFL) and an LED. Moreover, the above LEDs can be formed by using an LED module composed of R, G, and B crystal grains, or a white light LED such as a blue LED plus a fluorescent powder mixed light, or a white LED and a RGB LED.

Since the three basic colors of each unit cell position are respectively controlled by the image signals (^, S _g , Sb), the light transmittance of each unit cell is controlled by the brightness of each color of each unit cell. A point source consisting of three basic colors. As mentioned above, even if the filter can be regarded as uniform, due to the chromaticity and brightness of the backlight, the chromaticity and brightness of the three basic colors of red, green and blue appearing at the position of each unit cell are inevitable. not exactly. In addition, the light beams passed by the three sub-cells are not substantially pure colors. Therefore, the main basis of the present invention is to treat the red, green, and blue sub-cells of each unit cell as sub-cells, respectively. Three independent three primary color illumination sources.

In order to make the chromaticity and brightness of each unit cell uniform, the present invention first selects a "virtual basic color" as a standard according to the chromaticity and brightness that each unit cell can exhibit in the display (virtually Primary color); and in units of unit cells, respectively change the input of the original image signal (Sp S _g , S _b to (s , s _g ', s _b ', so that each unit cell is illuminated by the backlight, The light fluxes through the red, green, and blue sub-cells after the weighting is added, and the three sub-cells of the red (R; I, green (G:), and blue B) at the unit cell position are transparent. The tri-stimulus value after the color can match the three-color excitation value of the "virtual basic color" on the color spectrum, so that the entire display screen can be evenly distributed, and even the entire product line can be produced. The displays are all uniform and uniform in color and brightness.

Selecting a suitable "virtual basic color" step is shown in Figure 3. First, in step 31, the individual three-color stimuli of the three sub-cells of each unit cell in the fully open state of the light valve are measured one by one ( Tri-stimulus value), Here, the three-color 剌 excitability of the red sub-cell that defines the i-th unit cell is PQ, Υ _{τ τ} , and the green sub-cell is transparent. For the X _g , Y _g , Z _g , the blue color of the blue subcell is transparent (X _b , Y _b , Z _b ) _i; and corresponding to the color coordinates on the color spectrum ( , y _r ) (x _g y _g ) (x _b y _b . In this example, the liquid crystal display structure is as shown in FIGS. 4 and 5 , and is a plurality of direct-illuminated LEDs 41 , 42 . . . disposed on the substrate 4 . As the backlight, after passing through the filter 5, respectively, the cells are irradiated to the liquid crystal module 6. Since the thickness of the backlight of the LCD TV is as thin as in the example, the cells 61, 62 are mainly only Irradiated by a single LED 41, 42 and considering the angle of illumination of each cell relative to the LED in the backlight, its uniformity will be inversely proportional to the thickness ratio, which may have a very large difference in chromaticity and brightness.

At time 32, the color coordinates of the subcells at all unit cell positions are respectively plotted in the color coordinates specified by CIE1931, as shown in Fig. 6, where the R region is the red subcrystal of each unit cell. The color coordinate area of the cell pass light transmission, the G area is the color coordinate area of all the green sub cells, and the B area is the collection area of all the blue sub cells. Of course, as will be readily understood by those skilled in the art, the present principles are mainly designed to facilitate understanding of the techniques of the present invention. In actual sampling and calculation, the operation of the processor does not need to actually plot any coordinates into the color spectrum. .

Then, in step 33, in all the three color stimuli values PQ, Y _{r of the} red subcell, Wherein the minimum value is equal to, or even less than the minimum value as a virtual primary colors red stimulation value, i.e. X "≤PQ _mm; equal to or greater and selecting the maximum value as a straight virtual Basic Red The color stimulus value Y value, that is, Q _max , is equal to or greater than a certain value of the maximum value as the stimuli value Z value, that is, Zr (Zr) _max .

X

Thereby, the color coordinates of the red virtual basic color are set

X„, + Y„, + Z,

Y„

-, the coordinates are as shown in Figure 6, the color is all red times

Χ„, + Υ„, + ζ. Among the chromaticities exhibited by the unit cell, the farthest from the red solid color in the color spectrum, all red subcells can achieve the standard of the color coordinate. Similarly, in all the green subcell tristimulus values (X _gl , Y _gl , Z _gl :), the Y _g value with the smallest green stimuli value or a smaller value is used as the green virtual basic color. The Y value, that is, Y _gv ≤ 3⁄4 _mm , and the X value and the Z value which are equal to or greater than the maximum x _g value and the largest z _g value; that is, X _g (X _g :> _max , Z _Gv ≥(Z _g ) _max ; Obtain the "green virtual basic color" color coordinates as shown in the figure B, the blue virtual basic color

Zbv<(Zb)mm

Color coordinates are

Its color coordinates are marked as point C shown in the figure.

Of course, this virtual basic color is not the only solution. Other choices according to the above rules can constitute different virtual basic colors. Only the color coordinates of the three virtual basic colors are larger around the triangle area, and the color that can be rendered will be more rich. The "virtual basic color" is the chromaticity that all the cells can exhibit under the condition that the display is matched with the backlight behind the liquid crystal module. That is, when moderately adjusted The light transmittance of each unit cell allows each cell of the display to exhibit the same chromaticity for any of the same original image signals (Sp s _g , s _b ), resulting in uniform color throughout the display.

When the three-color stimuli of the three sub-cells of any unit cell 1 (measured in the state where the light valve is fully open:) are adjusted to conform to the above-described virtual basic colors, respectively, PQ _V , Y _rv Z _Rv ), (X _gv , Y _gv , Z _gv ), (X _bv , Y _bv , Z _bv ), then the original image signal (Sp S _g , S _b ; ^, the cell position i actually displayed pixels The tristimulus values ( , Y ) are:

However, when the light valve signal is fully open, the three primary colors of the three basic colors are measured as ρς, Υ _{τ τ} , (X _g , Y _g , Z _g , (X _b , Y _b , Z _b Therefore, when the unit cell i moves under the compensated image signal (S, S _g ', S _b '), the three-color 剌 excited value (ΧΛ ΥΛ ') is:

In other words, the original image signal (Sp S _g , 8^ is converted into a compensated video signal (S, S _g ', S _b ' by the compensation data, and the compensated video signal (S , S _g ', S _b ' is received). The three-color stimuli (ΧΛ Y ':) of the pixel displayed by the cell position i can conform to the original image signal (S _r , S _g , S _b ) of the liquid crystal display with the "virtual basic color" as the three primary colors. , the three-color stimuli that should be presented (Xp

Y).

Therefore, at time 34, the three color stimuli of each unit cell of each cell of the measured display are compared with the virtual basic color when the light valve is fully opened, and the weight is calculated. It is consistent with the weight of the virtual basic color, that is, the (ΧΛ Υ ') chromaticity and brightness of the three-color stimuli of the color image presented when the image signal is actually applied to each unit cell. Virtual basic When the color is the three primary colors, the stimuli value Pd that is driven by the original image signal is the same. therefore:

Simplified to MJS ^ MJSh (6)

Therefore, [S'

[S] ₁ (7)

When the image signal is within the virtual basic color range in the color spectrum, the compensated image signal after the (7) conversion (S, S _g ', S must have a solution greater than zero. and any original input to the position of the unit cell 1 Image signal Sp s _g , s _b , with ( ; ) for image signal conversion compensation, output pixel chromaticity and brightness at the unit cell position, under the ideal condition, the virtual basic color is the three primary colors and accept the original image When the signal is displayed, the pixel output is exactly the same. The entire picture has only one virtual basic color as the reference, and the whole picture will show the same and uniform chromaticity and brightness. Similarly, if all products of the entire product line select the same virtual basic color. Each LCD of the product line has the same color and brightness.

Therefore, it can be seen from the equation (7;) that the actual operation of the above step 34 is to perform a matrix operation of M " ¹ * M _V for each unit cell 1 after the LCD panel is manufactured. The inverse matrix ΜΓ ¹ of the three-color stimulus matrix of the three basic colors measured at the position of the light valve in the fully open state is applied to a three-color 适合 selected as the virtual basic color selected in the above step 33. The matrix of the excitatory value M _v , Wo U uses a computer to calculate the matrix operation of ^ " ^ Μ _ν , to obtain a 3x3 transformation matrix ( Μ _τ , and store the conversion matrix ( Μ _τ into an example of non-volatile memory (E2PR0M) in the memory device.

In the case of an HDTV LCD TV, the total resolution is about 2 million pixels, that is, 2 million cells are formed in the structure, and each cell needs to store 9 bytes of matrix data. The E2PR0M requires approximately 18M bytes of storage space. Therefore, when the display is shipped from the factory, as shown in step 35, the display receives image data input by one image source and containing multiple original image signals. Each image signal is used to instruct the individual light transmittance of the corresponding unit cell.

Then, in step 36, the image signal in the image data is respectively according to the corresponding adjustment region, and the ASIC special application IC of the fast logic parallel operation of the hardware is used to calculate the real time operation. (7-1) a conversion matrix ([mu] _[tau] is the compensation data is applied to each of the original image signal weighted calculation, comprising obtaining a plurality of image data respectively corresponding compensation compensating the image signal for each unit cell. Finally, the liquid crystal module to a ho in accordance with step 37 to the calculated compensated image signal _{(S, S g ', S} b'), determines the rate of permeation of each individual light may thus be any cell of the original image signal _{_{(Sp s g, s b;}} .> for The corresponding image processing is obtained and displayed corresponding to the compensated image signal.

Since the compensated image signal is originally based on the chromaticity of each unit cell under the backlight corresponding to the back of the unit cell, the chromaticity can be considered, and the same chromaticity and brightness can be exhibited by each unit cell. The unified standard is used as the "virtual basic color". Therefore, after applying the compensation data, the original chromaticity unevenness of the liquid crystal display hardware is solved by the mutual compensation between the sub-cells. Therefore, after the correction data of the present invention is corrected, even if the original image signal is a solid color such as pure red, c, s _g , s _b ) Ki, o, o), but the adjusted compensated image data, s _n 'will be less than 1, and at least one of S _gl ' and S _bl ' is greater than 0, to compensate for the difference between the red color of the virtual basic color and the red sub-cell of the cell position 1 in the full opening of the light valve. The special result of the actual implementation of the invention.

Of course, as is well understood by those skilled in the art, according to the current technology, when a blue LED illuminating phosphor powder is used to generate white light as a backlight, the biggest disadvantage is the red component in the white LED spectrum. It is obviously low, causing the color of the object to be irradiated to be blue and white, that is, the so-called pale feeling. The current solution is mainly to reduce the penetration ratio of the green and blue components, for example, so that the emitted light beam can reddicate the color spectrum again. However, this method undoubtedly reduces the overall brightness of the illuminating beam, causing the problem of insufficient brightness; further solving the lack of brightness, and increasing the overall brightness of the backlight panel, not only the technical limit, but also the increase Electricity flow and The cost and manufacturing difficulty of the heat dissipation structure.

As shown in FIG. 7, the second embodiment of the present invention is an example of a 42-inch LCD TV. If a white LED 41', 42' of 5 1 m is used in the backlight, a total of about 2,000 white LEDs are required. The coordinates are (0.28, 0.3) blueish white. If 200 red LEDs 40' of 2 lm are added, the composition of red light is relatively increased. Since the spectrum is just in the R region of the color filter transmission spectrum T), as shown in FIG. 1, the highest light transmittance will increase the overall color coordinate Δχ of the backlight panel to about 0.38, thus displaying The picture will increase the flesh color.

However, only 200 red LEDs 40' are added. Compared with the huge area of the 42-inch display panel, the reinforcing red light must not be evenly distributed. Therefore, according to the above technique of the present invention, the unevenness caused by the red LED 40' is caused. , on the one hand, can be compensated by changing the input image signal; and can be selected

In the "virtual basic color", the reddish virtual three primary colors are selected, and the chromaticity exhibited by the overall picture can be shifted to the reddish direction in the color spectrum to compensate for the white picture originally lacking the red component. With this method, the display will not have to sacrifice overall brightness by reducing the green and blue light transmittance of the filter 5' or by reducing the green and blue sub-cell light transmittance of the liquid crystal module 6'.

Furthermore, in the third embodiment of the present invention, as shown in FIG. 8, when the distance between the backlight substrate 4" and the filter 5" and the liquid crystal module 6" is large, the LEDs of the plurality of LEDs will spread to each other. The unit cells 61", 62" may be simultaneously illuminated by a plurality of LEDs 41", 42". For the sake of explanation, the R, G, and B subcells in the cell 61" are defined by the illumination factor of the LED 41". LED 42" illumination factor ₂ . If only LED 41" is illuminated (g卩4=1, λ ₂ =0), the color coordinates of the R, G, and B cells on the color spectrum are respectively recorded as (x _kl , y _k i) (k= r, g, b), that is, points 41, 41 _g ', 41 _b ' shown in Fig. 9 _; and only LED 42" when irradiated (g卩4 = 0, λ ₂ = 1), R, G, B sub-crystal The color _{coordinates of the} cells are labeled ( _Xk2 , _yk2 ) (k = r, g, b), ie, points 42 _r ', 42 _g ', 42 _b ' of Fig. 9. When the LED 41" is irradiated with the illumination coefficient ( ₂ ≤ 1 ₂ ≤ 1:) with the illumination coefficient (0 ≤ ≤ 1), the color seat of the R, G, B sub-cells is mixed. Standard (Xkm, y _k „ according to the principle of color mixing, will be Oh,

Xkm— ■Xki+ - ■Xk2

It can be seen from equation (8) that the color coordinates after the light mixing are inevitably between the points 41, 41 _g ', 41 _b ' and the points 42 , 42 _g ', 42 _b ' between the respective illuminations. At a certain point, the ratio is weighted according to the spatial relationship between each of the LEDs 41", 42" and the unit cell 61".

When the above description is indicated by a numeral, only the LED 41" is irradiated (gP / l fl , A 2 = 0), and the subcells 1, G, B of the unit cell 1 are compensated for the image signals S, S _g ', When S _b ' is input, the three-color 剌剌 \ \ \ 透光

.(7-1)

And only in! ^^? , when the irradiation ^ ^ corpse. , λ ₂ =\), when the unit cells 1, G, B are input to compensate the image signals S, S _g ', S _b ', the three-color 剌剌₂ ', Υ ₂ ' Ζ ₂ ' is

.(7-2)

Therefore, if the LED 41" and the LED 42" are simultaneously illuminated by the illumination coefficients ^ and ₂ , respectively, the secondary cells R, G, B are compensated for the three colors of the synthesized light when the image signals S, S _g ', S _b ' are input. The excitation values Χ _τ ', Υ _τ , and Ζ _τ are

And if the mixed light is required, the three-color excitation value must be equal to the selected "virtual basic color". : the primary color, and the three-color stimuli value presented when the original image signal, s _g , s _{b is} input, then;

therefore

It can be seen from equation (10) that the compensated image signals (S , S _g ', S _b ') can be calculated by matrix operations of M _V - ¹ M ₁ and M _V - ¹ M ₂ , and then weighting the illumination coefficient A 1 and The linear operation is known by the inverse matrix operation. The operations of M _v — and M _v — ^ ₂ can be stored in the memory device by external computing into a 3 x 3 matrix. If the entire backlight panel is composed of 1000 LEDs of different brightness and chromaticity, a total of 1000 M ₁ matrices and an M _V matrix of the selected "virtual basic color" are used.

And the operation of M _v — is stored in the E2PROM (the memory requires a memory space of 1001 x 9 words), and for each unit i, it is necessary to memorize several pixels that have a large influence on the pixel (the illumination coefficient is large). The Ik value, for example, may have four adjacent LEDs of up, down, left, and right, so that if there are 2M cells in the panel, a total of 2Mx l6=32M word is stored. Memory space. Using the above principle, the desired conversion signal (S, S _g ', Sb') of any unit cell 1 can be expanded to:

Among them, LEDj, LED _i+1 , ..., LED _i+m , represent m+1 water which has a great influence on the unit cell i Therefore, if there are five LEDs that can affect a certain unit cell 1, the red color that can be presented by the cell lj is also formed by the common light of five LEDs. The red light that the cell can present is mixed. The color coordinates after the light will be as shown in Fig. 10, and it is also necessary to have five sides formed by the lines connecting the original color coordinates 41r", 42r", 43r", 44r", 45r" of the unit cell 1 respectively. A point in the shape. That is, no matter how many LEDs the backlight board is composed of, and diffusely illuminate each other, any water in the entire panel 曰

For the cells, the basic color coordinates must fall within the basic color area of the individual LEDs, for example, in the R, G, and B regions of Figure 5. This also means that even if each unit cell is affected by the mixed light of multiple LEDs in the backlight panel, a simple "virtual basic color" can be selected.

In a word, if the backlight board adopts local dimming control, the LED _{k of} each area can be adjusted to its brightness level _k (0 ≤ _k ≤ l> Therefore, the tri-color stimulus matrix M _{1 of} the LED of the area can be written as _k M _k , and when each LED _{k is} selected, the original image signal applied to each unit cell i must be converted into an otherwise compensated image signal to maintain the desired image. In accordance with the above, formula ll) must be Rewritten as:

With the formula (12), it is possible to obtain the compensated image signals (S, S _g ', S _b ') o of the "area brightness control" with uniform chromaticity and brightness at the same time. The present invention can also simultaneously solve the "area brightness control" interval. The problem of mutual diffusion and unevenness of chromaticity and brightness, as can be seen from the above description, the present invention can indeed select a less saturated "virtual basic color" as a common target standard color, and then use the change image signal to drive LCD. When the original image signal (Sp S _g , S _b M has one of the color components (ie, only one of S _g and S _b has a value greater than zero, the other is zero:), then the equation (7-1) After converting to a new image signal (s , s _g ', s _b ';>, the three values of S, S _g ', S _b ' may be greater than The value of zero. That is, if the original image signal has only a red primary color, but it must be compensated for a less saturated "virtual basic color" of red, the green sub-pixel and the blue sub-pixel may also be lightly bright to form a less saturated Red basic color. However, because the color saturation of the LED is very high, the color range of the "less saturated""virtual basic color" selected is still quite large enough to constitute a high-quality color LCD panel.

Although the direct-illuminated LED is used as the backlight in the above embodiments, it can be easily understood by those skilled in the art that the disclosed technology is not limited to the backlight constructed by the direct-illuminated LED, as shown in FIG. 11 . As shown in the fourth embodiment, even if the backlight includes the light bars formed by the side-emitting LEDs 41"', 42"', and the LEDs 41"', 42"' by the light guide 43' The illuminating beam turns to the filter 5"' and enters the liquid crystal module 6"', and the above manner can still be applied to solve the problem of brightness and chromaticity unevenness of the pixels appearing in the position of each unit cell of the display.

Even, as shown in the fifth embodiment of FIG. 12, even if the cold cathode tube 4L"" and "1"" are used as the backlight, the chromaticity and brightness of the cold cathode tubes on both sides are limited, or the same cold cathode. The unevenness of the tube itself in the longitudinal direction can still be solved by implementing the technique of the present invention and adjusting the image signal of the actual input driving liquid crystal module.

The above description is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are still covered by the present invention. In the range.

Claims

Claim

A method for compensating for uniformity of a liquid crystal display having a non-uniform backlight, wherein the liquid crystal display comprises a set of non-uniform backlights, and a set of cells on the light-emitting side of the backlight comprises a plurality of cells with a changeable light transmittance, a display unit composed of a plurality of pixels, wherein the unit cells are divided into a plurality of adjustment regions, a set of control means for controlling the individual light transmittance of each of the cells, and a set of Storing a plurality of memory devices for accommodating the brightness and chromaticity distribution of the adjustment regions according to the backlight, and corresponding to the compensation data for uniformizing the light transmission luminance and chromaticity distribution of each of the adjustment regions, and the method includes the following Step:

a) receiving image data from an image source comprising a plurality of image signals for instructing the individual light transmittances of all of the cells;

b) the image signals in the image data are respectively weighted according to the compensation data according to the corresponding adjustment regions, and the compensated image data including the plurality of compensated image signals respectively corresponding to each of the unit cells is obtained;

c) determining, according to the compensated image signals, that the individual cells of the liquid crystal module are transparent

2. The uniformity compensation method according to claim 1, further comprising: obtaining, before the steps, obtaining illuminance chromaticities of the adjustment regions, respectively adjusting to a virtual basic color, so that the adjustments are made. Step (1:) of compensation data for uniformity of regional light transmittance and chromaticity distribution.

3. The uniformity compensation method according to claim 2, wherein the three color stimuli values of the red, green, and blue basic colors defining the virtual basic color are (X _rv , Y _rv Z _rv ), respectively. (X _gv , Y _gb ,

Z _gv ), (X _bv , Y _bv , Z _bv ), and measure one of the unit cells i in the unit cell when the light transmittance of the liquid crystal valve is maximum, three basic colors of red, green, blue The color excitation values are (X _r , Y _r Z _r ) (x _g , Y _g , Z _g ) (X _b , Y _b , Z _b ) _1; then the compensated image signal of the unit cell (s' _{_{r, s 'g, s'}} b) the compensation data with _a relation to the image signal (Sp S _g, 8 ₁₃₎ as: -

4. The uniformity compensation method according to claim 1, wherein a uniform chromaticity standard common to the adjustment regions is defined as a virtual basic color, and the virtual basic colors are red, green, and blue. The color three-color stimuli are (X _rv , Y _rv , Z _rv ), (X _gv , Y _gb , Z _gv ), (X _bv , Y _bv , Z _bv ), and the cells are measured. One of the unit cells i, when the light transmittance of the liquid crystal valve is the largest, the three primary colors of red, green, and blue are respectively (X _r , Y _r , Z _r ) (X _g , Y _g , Z _g ) (X _b , Y _b , Z _b ) _1; the compensated image signal (S' _r , S' _g , S' _b ) of the unit cell i in the step _b ),

The inverse matrix YY _u of the tristimulus matrix of the unit cell 1 and the virtual base color

Excitation matrix

The conversion matrix (Μ _τ , obtained by the rv gv operation is applied to the original image signal ζ „, τ ζ. (S _r , S _g , 8 ₁₃ ) ₁ .

5. The uniformity compensation method according to claim 1, wherein a brightness adjustment value of one of the adjustment areas k of the adjustment area of the backlight is _k , to be applied to one of the unit cells The original image signal of the unit cell 1 is (Sp S _g , S _b , and the tristimulus matrix of each of the adjustment regions is M _k , and the illumination coefficient of the adjustment region region for the unit cell 1 is 4, respectively, and is defined. A uniform chromaticity standard jointly achievable by the adjustment regions is used as a virtual basic color, and the three-color stimuli value M _v of the red, green, and blue basic colors of the virtual basic color, the compensated image signal of the unit cell 1 S'g . S'b is

Wherein the adjustment regions j, j+l, ....., j+m are those having a predetermined influence on the unit cell i.

6. A liquid crystal display having a non-uniform backlight, comprising:

a set of non-uniform backlights;

a group of cells located on the light exiting side of the backlight, including a plurality of cells having different light transmittances and having a plurality of sub cells, respectively, to display a picture composed of a plurality of pixels, and the cell lines are divided into a plurality of cells a liquid crystal module of the adjustment area;

a memory device having a plurality of compensation data corresponding to the brightness and chromaticity distribution of the adjustment regions according to the backlight, and corresponding to uniformizing the light transmittance and chromaticity distribution of each of the adjustment regions; and

a group of image signals for controlling the individual light transmittance of each of the cells and for image signals from an image source including a plurality of image signals for instructing the individual light transmittances of all of the cells Determining, according to the weighting operation of the compensation data, the control device for the individual light transmittance of the cell in the liquid crystal module according to the corresponding adjustment region; causing a series of commands in the image signals to correspond to the image signal When any one of the unit cells transmits light, at least one of the remaining unit cells in the unit cell is transmitted by the compensated image signal.

7. The liquid crystal display according to claim 6, wherein each of the adjustment regions corresponds to a single unit cell.

8. The liquid crystal display of claim 6, wherein the backlight comprises a plurality of light emitting diodes.

9. The liquid crystal display according to claim 8, wherein the backlight comprises: a light guide plate; and

The light emitting diode systems are mounted on at least one side-lit light bar disposed on the light incident side of the light guide plate.

10. The liquid crystal display according to claim 8, wherein the light emitting diodes are disposed on the backlight in such a manner that the light is directly directed toward the liquid crystal module.

11. The liquid crystal display of claim 6, wherein the backlight comprises at least one cold cathode tube.