JP3805189B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device capable of color display.
[0002]
[Prior art]
In recent years, liquid crystal display devices capable of color display have become widespread as display devices for personal computers, video cameras, car navigation systems, and the like.
[0003]
As a method for improving the brightness of the pixels of the liquid crystal panel of this liquid crystal display device, an RGBW liquid crystal display device (hereinafter referred to as “RGBW liquid crystal”) in which a transparent filter (W) is installed in addition to the conventional RGB RGB filter. A display device ”is proposed in Japanese Patent Laid-Open No. 10-10998.
[0004]
[Problems to be solved by the invention]
However, even if an attempt is made to improve the brightness of the liquid crystal panel simply by adding a transparent filter, if the brightness of the pixels in the transparent filter section is not properly controlled independently, white will be mixed in all display colors, so color purity (color For example, an image with an unintended display color different from the original image is displayed.
[0005]
Therefore, the present invention improves the brightness of the image output from the liquid crystal panel by appropriately controlling the brightness of the pixels of the transparent filter portion independently and under a predetermined calculation when determining the brightness of the liquid crystal panel. It is a first object of the present invention to provide an RGBW liquid crystal display device that can be used.
[0006]
In addition, the RGBW liquid crystal display device, like a TV with a CRT, does not only have a sparkling performance, that is, high brightness but also a sparkle white color. For example, the lamp light source itself in TV images, or the reflection of metallic reflections, the edges of clouds in the clear sky, the reflection of snow on mountains, etc. It reproduces the performance of “things”.
[0007]
Therefore, the present invention is based on the characteristics of the RGBW type liquid crystal display device, but it is not necessary to emphasize white in particular, for example, in the office while maintaining the same main structural part for realizing the above characteristics. A second object of the present invention is to provide a device that can be easily used as an RGB liquid crystal display device in document creation work in a work. Further, an RGBW type liquid crystal display for an image that requires white enhancement on a part of a screen using a PC window, and an image that does not require white enhancement on a part. The RGB type liquid crystal display can be easily used simultaneously.
[0008]
[Means for Solving the Problems]
According to the liquid crystal display device according to claim 1, the predetermined calculation processing by the data calculation unit sets the digital value of the luminance sub-pixel as Wo, the red input sub-pixel, and the green input sub-pixel. , And when the minimum value is Ymin and the maximum value is Ymax among the digital values for each of the blue input subpixels, the luminance subpixel is calculated by the function represented by the arithmetic expression Wo = f (Ymin, Ymax). Since the digital value for driving can be obtained, the first object can be achieved.
[0009]
According to the liquid crystal display device according to claim 2, the function represented by the arithmetic expression Wo = f (Ymin, Ymax) is a function that monotonously increases as the value of Ymin or the value of Ymax increases. Therefore, the first object can be achieved.
[0010]
According to the liquid crystal display device described in claim 3, the function represented by the arithmetic expression Wo = f (Ymin, Ymax) is a function in which the Ymin is a variable and the Ymax is a constant. Since the value of Wo is a function that monotonously increases as the value of Ymin increases, the first object can be achieved.
[0011]
According to the liquid crystal display device of claim 4, α, β, and n are arbitrary real values, and the digital value for each of the red input subpixel, the green input subpixel, and the blue input subpixel. When the maximum value that can be taken by Y is Ymax, the calculation formula Wo = f (Ymin, Ymax) is obtained by the function represented by Wo = Ymax * {(Ymin + α) / (Ymax + β)} ⁿ . Since the digital value for driving the sub-pixel can be obtained, the first object can be achieved.
[0012]
According to the liquid crystal display device described in claim 5, in the liquid crystal display device according to any one of claims 1 to 4, the red input subpixel, the green input subpixel, and the blue input subpixel. When one of the digital values for each pixel is 0 value, the value of W takes 0 value, so that the first object can be achieved.
[0013]
According to the liquid crystal display device described in claim 6, the liquid crystal display device according to any one of claims 1 to 5 includes a plurality of arithmetic expressions Wo = f (Ymin, Ymax). An arithmetic expression of any one of the functions represented by the storage means storing the function of the type and the plurality of kinds of arithmetic expressions Wo = f (Ymin, Ymax) stored in the storage means The first object can be achieved.
[0014]
According to the invention described in claim 7, the liquid crystal display device according to any one of claims 1 to 6 uses the luminance sub-pixel by using a predetermined control signal. Without being used as a liquid crystal display device capable of color display including a liquid crystal panel having the red output subpixel, the green output subpixel, and the blue output subpixel as one main pixel unit. The second objective can be achieved.
[0015]
According to the invention described in claim 8, the liquid crystal display device according to any one of claims 1 to 6 uses the luminance sub-pixel by using a predetermined control signal. Without displaying the red output subpixel, the green output subpixel, and the blue output subpixel as one main pixel unit,
Since the luminance subpixel can be used to simultaneously perform image display using the red output subpixel, the green output subpixel, and the blue output subpixel as one main pixel unit. The second objective can be achieved.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the liquid crystal display device according to the present invention will be described.
[0017]
FIG. 1 is a block diagram showing a configuration of a liquid crystal display device 100 according to an embodiment of the present invention. The liquid crystal display device 100 includes a liquid crystal panel 1.
[0018]
FIG. 2 is a plan view schematically showing a horizontal cross section of the liquid crystal panel 100. As shown in FIG. 2, this liquid crystal panel 1, line-shaped gate bus G1 through Gm: and (m natural number), rows of source bus S1 to Sn: are equipped with (n is a natural number) and. Then, gate buses G1 to Gm are sequentially connected to the gate driver 2, and source buses S1 to Sn are sequentially connected to the source driver 3.
[0019]
Further, R (red), G (green), B (blue), or in the mesh formed by the gate buses Gi and Gi + 1 (i = 1 to m) and the source buses Sj and Sj + 1 (j = 1 to n), or A W (white (for brightness enhancement)) sub-pixel Lij is arranged.
[0020]
A TFT (thin film transistor) Qij is arranged near the intersection of the gate bus Gi and the source bus Sj. Further, the gate bus Gi is connected to the gate of the TFT Qij, the source bus Sj is connected to the source of the TFT Qij, and the display electrode of each subpixel Lij is connected to the drain of the TFT Qij. Further, the display electrodes and the opposing electrodes of each subpixel Lij as a common electrodes, the common electrodes are connected to a common voltage supply circuit (not shown).
[0021]
When the sub-pixels are arranged in a vertical stripe shape as shown in FIG. 2, the RGBW color filter is arranged as follows for each sub-pixel Lij, and one pixel has four sub-pixels of RGBW. It consists of pixels.
[0022]
R: Lij (i = 1, 2, 3,..., M−1, j = 1, 5, 9,..., N−3)
[0023]
G: Lij (i = 1, 2, 3,..., M, j = 2, 6, 10,..., N−2)
[0024]
B: Lij (i = 1, 2, 3,..., M, j = 3, 7, 11,..., N−1)
[0025]
W: Lij (i = 1, 2, 3,..., M−1, j = 4, 8, 12,..., N)
[0026]
In the liquid crystal panel 1, these sub-pixels form a vertical stripe arrangement.
[0027]
In addition, in the direction perpendicular to the panel surface of the liquid crystal panel 1, although not shown, a TFT substrate on which subpixel electrodes are formed, a color filter substrate on which common electrodes are formed, a glass substrate, and the like are provided. Liquid crystal is sandwiched and filled between these substrates. In the color filter substrate, red, green, and blue translucent color filters are installed in the portions corresponding to the sub-pixels RGB, but color filters are installed in the portions corresponding to the sub-pixels W. Do not install or install a transparent filter.
[0028]
Returning to FIG. 1, the description of the liquid crystal display device 100 will be continued. Around the liquid crystal panel 1, a gate driver 2 and eight source drivers 3 are arranged. Each source driver 3 includes an amplifier, a DAC (DA converter), and a latch (not shown). In addition, the liquid crystal display device 100 includes a signal control unit 4. The signal control unit 4 supplies a power supply voltage to the gate driver 2, the source driver 3, the image data holding unit 5, and the decoder 6, and also supplies a control signal. A decoder 6 is connected to each source driver 3. The decoder 6 is connected to an image data holding unit 5 that holds 8-bit red, green, and blue subpixel input data Ri, Gi, and Bi of a digitally acquired image. .
[0029]
In addition, the liquid crystal display device 100 includes a reference potential generation circuit (not shown) that supplies each source driver 3 with a reference potential based on a predetermined clock frequency.
[0030]
Hereinafter, the operation of the liquid crystal display device 100 shown in FIG. 1 will be described.
[0031]
A control signal is supplied from the signal control unit 4 to the gate driver 2 and each source driver 3. Based on the control signal, the gate driver 2 transmits a signal for turning on the TFT Qij to each gate bus (see FIG. 2).
[0032]
Further, when a control signal is supplied to each source driver 3, 8-bit sub-pixel output luminance data Ro, Go, Bo, and the like are output from a latch unit (not shown) of each source driver 3 based on the control signal. And Wo are latched.
[0033]
The 8-bit sub-pixel output luminance data Ro, Go, Bo, and Wo are decoders for the sub-pixel input data Ri, Gi, and Bi constituting the digital image held in the image data holding unit 5. 6 is obtained as a result of performing a predetermined calculation (described later).
[0034]
The subpixel output luminance data Ro, Go, Bo, and Wo latched by the latch unit are sequentially output and input to a DAC unit (not shown). The control power supply 4 is a polarity control signal for controlling whether the DAC unit selects a potential from the positive reference potential or a negative reference potential generated from the reference potential generation circuit. The polarity control signal is input to the DAC unit. Based on the input polarity control signal and subpixel output luminance data Ro, Go, Bo, and Wo, the DAC unit generates the W subpixel output luminance data Ro, A potential corresponding to Go, Bo, and Wo is selected.
[0035]
When the potential is selected by the DAC unit, the DAC unit appropriately divides the voltage at the selected potential by resistance division into several stages so that a desired gradation can be obtained. Thereafter, the divided voltage is current-amplified by an amplifier and transmitted to one of the corresponding source buses S1 to Sn (see FIG. 2). A signal representing the potential transmitted to the source bus is transmitted to each subpixel electrode via the TFT when the TFT is turned on by the signal transmitted to any of the gate buses G1 to Gm.
[0036]
Thereby, a potential corresponding to the luminance data for subpixel output is applied to each subpixel electrode. Accordingly, a voltage is applied to the liquid crystal layer sandwiched between the common electrode and each subpixel electrode, the liquid crystal layer is driven according to the potential applied to each subpixel electrode, and an image is displayed on the liquid crystal panel 1 by the principle of additive color mixing. Is displayed.
[0037]
In more detail, a preferred embodiment relating to the arithmetic processing of the decoder 6 described above will be described below with reference to FIG.
[0038]
As shown in FIG. 3, the decoder 6 acquires 8-bit red, green, and blue input subpixel digital data Ri, Gi, and Bi from the image data holding unit 5, and these Ri, RGBW sub-pixel output luminance data Ro, Go, Bo, Wo are output from Gi and Bi to the source driver 3.
[0039]
On the other hand, in order to obtain W subpixel output luminance data Wo, the following processing is performed.
[0040]
The decoder 6 includes a comparator 7 and a lookup table 8.
The comparator 7 compares the values of the acquired input sub-pixel data Ri, Gi, and Bi, selects the minimum value Ymin among these Ri, Gi, and Bi values, and then calculates this value. Convert to luminance data dimensions.
[0041]
Next, the look-up table 8 converts the Ymin value selected and converted by the comparator 7 into W subpixel output luminance data Wo.
[0042]
The conversion of the Ymin value into W subpixel output luminance data Wo is performed by using the calculation result of Formula 1 described later as the Ymin address for each value of Ymin that changes from 0 to 255 (in the case of 256 gradations). This can be easily realized by using a stored PROM. Furthermore, with such a circuit configuration, a control signal from the signal control unit 4 to the decoder 6 and a memory for storing data are unnecessary.
[0043]
However, the number of clocks after the input subpixel data Ri, Gi, and Bi are input to the decoder 6 and before the comparator and the lookup table output the W subpixel output luminance data Wo to the source driver 3. This may cause delay and take time. In this case, it is necessary to delay the output of RGB subpixel output luminance data Ro, Go, and Bo within the decoder 6 in accordance with the output of W subpixel output luminance data Wo.
[0044]
In this way, the decoder 6 obtains W subpixel output luminance data Wo from the input subpixel data Ri, Gi, and Bi obtained from the input original image.
[0045]
Further, the formula Wo = f (Ymin, Ymax) (hereinafter referred to as “Formula 1”) will be described. In this equation 1, the luminance data for W subpixel output is Wo, and the minimum value is Ymin and the maximum value is Ymax among the digital data for each of the red input subpixel, the green input subpixel, and the blue input subpixel. Is an arbitrary function represented by As a function represented by this equation, a function that monotonously increases as the value of Ymin or the value of Ymax increases can be employed. For example, it is Wo = (Ymax * Ymin) / Ymax 2 becomes function. Here, Ymax is the maximum value that the values of the input luminance data of Ri, Gi, and Bi can take.
[0046]
Furthermore, as another suitable example of Formula 1,
[0047]
Wo = Ymax * {(Ymin + α) / (Ymax + β)} ⁿ
(Hereinafter, this formula is referred to as “Formula 2”).
[0048]
Formula 2 will be described in detail below. Equation 2 is a function for obtaining the luminance data Wo for the W sub-pixel using the minimum value of the input luminance data for the RGB sub-pixel output to the decoder 6 as a variable. In Equation 2, Wo is output luminance data for the W sub-pixel, Ymax is the maximum value that can be taken among the input luminance data values of Ri, Gi, and Bi in the same manner as described above, and Ymin is Ri, This is the minimum value that can be taken from the values of the input luminance data of Gi and Bi. Α, β, and n are arbitrary real values. The values of α, β, and n are determined by optical characteristics such as target luminance of the liquid crystal display device 100 used.
[0049]
For example, the condition that β = 0 is that the condition that Wo becomes MAX when the minimum value Ymin of the input luminance data of Ri, Gi, and Bi is MAX (maximum value), that is, the liquid crystal panel 1 of the liquid crystal display 100 Derived from conditions that give maximum brightness.
[0050]
Also, the condition for α = 0 and β = 0 is that, under this condition, when the minimum value Ymin of the input luminance data of Ri, Gi, and Bi is 0, Wo becomes 0, and Ri, Gi, and Bi Since Wo = MAX when the minimum value Ymin of the input luminance data is MAX, it is derived from the condition that the contrast inherent in the liquid crystal display 100 is not lowered.
[0051]
Note that the value of MAX is MAX = 255 when the color to be displayed on the liquid crystal display device 100 is 256 gradations.
[0052]
The calculation according to Equation 2 can also be realized by using a lookup table (LUT) provided in the decoder 6 as described above. Such a look-up table can be easily incorporated in the ASIC of the decoder 6, and can be easily realized by a PROM or EEPROM having a storage capacity of 256 bytes if each RGBW input and luminance data are 8 bits. Is possible. The values of α, β and n are set in advance in the look-up table according to the desired optical characteristics (brightness) of the liquid crystal display device.
[0053]
Here, the theory that is the basis for obtaining Formula 2 will be supplementarily described below with reference to the chromaticity diagram of FIG.
[0054]
Now, when Ri, Gi, and Bi and the points R, G, B, and W on the chromaticity diagram of FIG. 4 have the following relationship, that is, Ri = MAX and G = B = When 0, point R, when G = MAX and R = B = 0, point G, when B = MAX and R = G = 0, point B, and R = G When = B, the following conclusion is obtained based on a general chromaticity diagram satisfying the relationship of the point W.
[0055]
“If all of the R, G, and B values are greater than 0, the chromaticity is inside the triangle RGB of FIG. 4, that is, approaching the point W, the color has a white (gray) color component.”
[0056]
Furthermore, the following conclusion about W can be obtained from the above conclusion.
[0057]
(1) “When R = G = B, only luminance can be increased without changing chromaticity even if W is added.”
[0058]
(2) “Triangle RG B is a color range that can be expressed by the liquid crystal display device. Therefore, in order not to narrow this range, if any one of R, G, and B is 0, W = 0. "
[0059]
(3) “The chromaticity when all of R, G, and B are greater than 0 approaches the point W as the minimum value of R, G, and B is larger. That is, R, G, and The minimum value of B represents how white the color is, so if W is given as a function of the minimum value of R, G, and B, one pixel is the three subpixels of RGB. The brightness can be increased without changing much the chromaticity when configured with. "
[0060]
Therefore, in view of the conclusions of (1), (2), and (3), Formula 2 is derived that can give Wo as a function of the minimum value of R, G, and B.
[0061]
Next, some embodiments (Examples 1 to 3) in which the decoder 6 obtains Wo using the equation 2 will be described below with reference to the graph of the equation 2 in FIG.
[0062]
FIG. 5 shows Wo obtained by substituting the Ymin value obtained by the decoder 6 into an X-axis variable and substituting the Ymin value into Equation 2 when the maximum number of gradations of each pixel of the display image is 256 gradations. It is a graph of Numerical formula 2 which made the value the variable of the Y-axis.
[0063]
As an example 1, a case where any one of the brightness data values of Ri, Gi, and Bi is 0 will be described.
[0064]
In this case, since Ymin = 0, Wo = 0 is obtained from the calculation of Formula 2 (on the x-axis of the graph of FIG. 5). That is, in this case, Wo = 0 can always be set, and there is no decrease in color purity (saturation).
[0065]
As an example 2, the case where α = β = 0 and n = 1 are set in Equation 2 will be described. In this case, since Formula 2 is transformed as Wo = Ymin, a result represented by a straight line in the graph of (Example 2) in FIG. 5 is obtained.
[0066]
Therefore, in this case, the gamma characteristic of the original image before being input to the image data holding unit 5 is held. The configuration of the circuit to be added is simple, and the scale for configuring the circuit can be small.
[0067]
As an example 3, the case where the value of n is set to be larger than 1 in Formula 2 will be described. In this example 3, n = 2 and α = β = 0 are set. Further, Ymax = 255. From this setting, Equation 2 can be expressed as Wo = 255 * (Ymin / 255) ⁿ
(Hereinafter, this equation is simply referred to as “Equation 3”), and this Equation 3 is represented by the graph of (Example 3) in FIG. As can be seen from the graph of (Example 3), the value of Wo increases rapidly as the value of Ymin increases.
[0068]
In other words, according to the calculation processing according to Equation 2, the luminance (Wo) for the W sub-pixel rapidly increases as the Ymin value approaches the maximum number of gradations, so that white display close to 100% with respect to the other display colors. Can stand out. As a result, it is possible to display an image such as the brightness of a white cloud illuminated on a day that can only be realized with a conventional CRT, or the glittering gloss of a metallic surface.
[0069]
Further, as can be seen from the graph of (Example 3), in the intermediate range of values that the Ymin value can take, the Wo graph has a pronounced downward convex curve shape (monotonic increase). As a result, for example, in the halftone such as Ymin = 64 to 192, the luminance Wo for the W subpixel can be suppressed, and the original chromaticity (saturation) in the halftone can be maintained in the display image.
[0070]
As described above, various image displays can be performed by appropriately determining the constant of Formula 2. A plurality of functions such as the above-described Examples 1 to 3 for obtaining Wo and other functions based on Equation 1 are stored in advance in the lookup table 8 provided in the decoder 6, and the user intends from the outside. You may make it selectable so that an image may be obtained.
[0071]
As described above, according to the embodiment, the decoder 6 performs the arithmetic processing based on the mathematical formula 1, so that appropriate luminance data for the W sub-pixel can be obtained according to the image to be displayed. Further, by setting various functions in the lookup table 8 provided in the decoder 6 in advance, it is possible to provide optical characteristics of various desired luminances of the liquid crystal display device 100.
[0072]
Next, as described above, as a further embodiment, a configuration in which the liquid crystal display device 100 can be used as an RGBW type liquid crystal display or an RGB type liquid crystal display has the configuration shown in the block diagram of FIG. 3 as a main part. This will be described with reference to the written block diagram of FIG.
[0073]
In order to achieve this further embodiment, as shown in FIG. 6, in addition to the input signals Ri, Gi and Bi, a control signal Ci which functions as a switching control signal of one bit is added. This Ci signal is synchronized with the clock frequency of the input signals Ri, Gi and Bi. When this Ci signal is High, all the circuits in FIG. 6 which perform the function for displaying RGBW are enabled. . On the other hand, when the Ci signal is Low, then skip all CMP7 and LUT 8, and Wo = 0, the input signals Ri, Gi, and Bi is intact, the output signal Ro, Go, and to the source driver 3 as Bo Entered.
[0074]
As a result, by switching between High and Low of the Ci signal, either RGB display or RGBW display can be arbitrarily displayed. When RGB display is desired, the LUT 8 may be set to simply set Wo = 0.
[0075]
The Ci signal may be switched by software using a PC provided with the liquid crystal display device 100, or may be switched by pushing a shortcut key or the like on the keyboard of the PC.
[0076]
As a result, when creating office work documents, it is not necessary to shine white, so it can be used as an RG B- type liquid crystal display device. On the other hand, snowy scenery, the brightness of cars well polished with wax, When a cloud or white text is to be emphasized for promotion, it can be used as an RGBW liquid crystal display device.
[0077]
Furthermore, by using a window on the PC screen, a part of the RGBW screen and a part of the RGB screen can be displayed. In this case, as described above, the pixels based on the Ci signal assign the character to the pixels based on the input signals Ri, Gi, and Bi in units of one pixel. For example, RGBW display is performed on the pixels of the window screen where the Ci signal is High. The RGB signals can be displayed on the pixels of the window screen where the Ci signal is Low. Thus, for example, by providing the liquid crystal display device of the present invention on a PC for the promotion of vehicles at car sales offices and exhibitions, the right half window screen emphasizes the gloss obtained from the metallic of the car. The screen is displayed, and the left half of the window screen can display a text sentence describing the profile of the car. While taking advantage of the advantages of the RGBW screen, it is possible to display a piece of text so that the white color (luminance) is not emphasized so much that the white color is rather weakened to make it easier for the observer to read.
[0078]
In addition, RGBW liquid crystal displays have a clear difference in white brightness when viewed from a distance, compared to RGB liquid crystal displays. RGBW of the present invention when observing white characters such as telops on a liquid crystal display device of the type, or when the observer must observe the RGBW display from a distance provided on the wall of the building. The liquid crystal display device of the type exhibits a remarkable effect.
[0079]
In addition, the invention described in each claim is not limited to each embodiment described above, and various modifications can be adopted as described below within the scope described in each claim. It is.
[0080]
Hereinafter, some modified examples will be described.
[0081]
(1) Modification 1:
In the preferred embodiment, the arrangement of the sub-pixels RGBW is a vertical stripe arrangement as shown in FIG. 2, but it may be a square-shaped arrangement as shown in FIG. In this case, the individual shape of the sub-pixel is substantially square.
[0082]
(2) Modification 2:
In the first modification, as shown in FIG. 7, the source bus and the gate bus form a mesh, and each subpixel is arranged one by one in the mesh. As shown in FIG. 8, one gate bus may be wired for every two stages of subpixels, and two source buses may be wired between the subpixels. According to such a configuration, the number of gate buses is the same as in the conventional RGB system, and the writing characteristics of the TFTs can be kept as they are. In addition, according to this configuration, the color of the sub-pixel connected to one source bus is one kind, so that it is not necessary to rearrange the source signals for each row in the source driver 3.
[0083]
(3) Modification 3:
In the preferred embodiment, the decoder 6 and the source driver 3 are configured as separate units as shown in FIG. 3, but the decoder is arranged at the entrance of the source driver as shown in FIG. Therefore, the decoder and the source driver may be installed as an integrated structure. With such a configuration, it is possible to avoid an increase in luminance data for the W sub-pixel of the number of data wirings in the printed circuit board.
[0084]
【The invention's effect】
As described above, according to the liquid crystal display device of the present invention, it is possible to appropriately improve the luminance of the image displayed on the RGBW liquid crystal display panel. Further, although it is an RGBW liquid crystal display device, it can also be used as an RGB liquid crystal display device.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a liquid crystal display device 100 according to a preferred embodiment of the present invention.
2 is a plan view for explaining the arrangement of subpixels, gate buses, and source buses of the liquid crystal panel 1 shown in FIG. 1; FIG.
3 is a block diagram conceptually showing a source driver 3 and a decoder 6 shown in FIG.
4 is a chromaticity diagram used to explain Formula 2. FIG.
FIG. 5 is a graph of calculation results obtained using Equation 3.
FIG. 6 is a block diagram showing a configuration for enabling at least one of RGB display and RGBW display while using the configuration of the liquid crystal display device 100 of the preferred embodiment of the present invention as a main part.
FIG. 7 is a plan view showing a modification of the embodiment shown in FIG.
FIG. 8 is a plan view showing a modification of the embodiment shown in FIG.
FIG. 9 is a block diagram showing a modification of the embodiment shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Gate driver 3 Source driver 4 Signal control part 5 Image data holding part 6 Decoder 7 Comparator 8 Look-up table 100 Liquid crystal display device

Claims (4)

A liquid crystal display capable of color display, including a liquid crystal panel in which each of the red output sub-pixel, the green output sub-pixel, the blue output sub-pixel, and the luminance sub-pixel capable of gradation driving can be set as one main pixel unit A device,
Digital for driving the luminance subpixel by performing predetermined arithmetic processing using the digital values for the red input subpixel, the green input subpixel and the blue input subpixel obtained from the input image signal. Having data calculation means for obtaining a value;
Using the digital value for driving the luminance subpixel determined by the data calculation means and the digital value of the red input subpixel, the green input subpixel, and the blue input subpixel, the luminance subpixel is used. Driving pixel, red output subpixel, green output subpixel and blue output subpixel,
The predetermined calculation process by the data calculation means sets the digital value of the luminance subpixel as Wo, and sets the minimum value among the digital values of the red input subpixel, the green input subpixel, and the blue input subpixel. If Ymin and the maximum value is Ymax,
Formula Wo = f (Ymin, Ymax)
A digital value Wo for driving the luminance subpixel is obtained by a function represented by:
The luminance subpixel, the red output subpixel, the green output subpixel, and the blue output subpixel are set as one main pixel unit, and the luminance subpixel is used to improve the luminance in the one main pixel unit. RGBW display for displaying as an RGBW screen image, and an RGB image with the red output subpixel, the green output subpixel, and the blue output subpixel as one main pixel unit without using the luminance subpixel. It was possible to switch between RGB display to be displayed as an image of
Liquid crystal display device. A liquid crystal display device according to claim 1, performed switching between the RGBW display and the RGB display in each main pixel, on the screen, the simultaneous use of the image by the image and the RGB display by the RGB W display A liquid crystal display device that enables The liquid crystal display device according to claim 1 or 2,
The arithmetic expression Wo = f (Ymin, Ymax) function represented by a liquid crystal display device wherein Ymin or which is a function that monotonically increases as the value of the Ymax increases. The liquid crystal display device according to claim 1, 2 or 3,
Function represented by the mathematical expression Wo = f (Ymin, Ymax) is the Ymin as a variable, the Ymax a function of a constant, the value of Re One of the value of the Ymin increases W monotonously A liquid crystal display device characterized by increasing.

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