JP2011118089A - Color filter and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color filter achieving high contrast and high color reproducibility, and a liquid crystal display device including the color filter. <P>SOLUTION: The color filter includes a plurality of color pixels including a yellow pixel, wherein the yellow pixel is formed by using yellow composition containing at least a yellow pigment, a red pigment, a pigment dispersing agent and a pigment carrier and has a film thickness of under 2 μm, and chromaticity coordinates (x, y) in an XYZ color specification system chromaticity diagram are located in a quadrangle surrounded by (0.550, 0.450), (0.400, 0.600), (0.350, 0.550) and (0.510, 0.430). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a color filter and a liquid crystal display device including the color filter.

  The color liquid crystal display device basically includes a first transparent substrate on which a color filter and a first transparent electrode layer are formed, and a second transparent substrate on which a second transparent electrode layer is formed. The second transparent electrode layer is disposed so as to face each other, and a liquid crystal layer is interposed therebetween. First and second polarizing plates are provided outside the first and second transparent substrates, respectively, and a backlight unit including a backlight light source is provided outside the first polarizing plate. .

  In the liquid crystal display device configured as described above, the voltage applied between the first and second transparent electrode layers is adjusted for each pixel, and the degree of polarization of light from the backlight unit that has passed through the first polarizing plate is controlled. The display is performed by controlling the amount of light passing through the second polarizing plate. Therefore, the color characteristics of the color filter and the polarizing plate are important factors that determine the color characteristics of the liquid crystal display device.

  A color filter has a black matrix, which is a light-shielding pattern, and red, green and blue fine band (stripe) pixels arranged in parallel or intersecting on the surface of a transparent substrate such as glass, or fine pixels. It consists of what is regularly arranged vertically and horizontally.

  In recent years, liquid crystal display devices have been evaluated for space saving, light weight, and power saving due to their thinness, and their applications are rapidly expanding to large televisions and monitors. There is an increasing demand for higher brightness, higher color reproducibility, and higher contrast for color filters that determine the color characteristics (see, for example, Patent Documents 1, 2, and 3).

  As a means for achieving high color reproduction, it is effective to add fourth, fifth, and sixth pixels to the color filter in addition to the red, green, and blue pixels. Patent Documents 4 and 5 add color pixels in yellow, cyan, and magenta in addition to red, green, and blue pixels, and Patent Document 6 reproduces colors by adding cyan pixels. It proposes expansion of the area. As the fourth pixel to be added to the red, green, and blue pixels, it is effective to use a yellow pixel that is advantageous in terms of increasing the luminance. By performing color reproduction with four color pixels, the color reproduction range can be expanded compared to a color filter composed of three colors, and by adding yellow having higher saturation than red, green and blue, Brightness of the liquid crystal display device can be increased.

  However, in yellow-colored compositions, there is a trade-off between saturation and contrast, that is, high-contrast pigments have low saturation, and high-saturation pigments have low contrast, achieving both high contrast and high saturation. It was difficult to do.

JP 2001-194658 A JP 2002-214436 A JP 2005-316439 A JP 09-251160 A Japanese Patent No. 4170899 JP 2001-306003 A

  The present invention has been made under the circumstances as described above. A color filter capable of achieving a high color reproducibility by adjusting and providing a yellow coloring composition capable of increasing contrast and having high saturation, and the color filter. An object is to provide a liquid crystal display device including a color filter.

  In order to solve the above problems, a first aspect of the present invention is a color filter including a plurality of color pixels including a yellow pixel, wherein the yellow pixel includes at least (a) a colorant and (b) a photopolymerization. (C) a photopolymerization initiator, (d) a transparent resin, (e) a pixel formed using a yellow composition containing a solvent, and (a) a yellow pigment CI Pigment Yellow in the colorant 138, 139, 150, and 185 and red pigment CI Pigment Red 242, and (a) the weight ratio of the red pigment in the colorant is 0.01 or more and less than 0.1. Is a color filter.

  In the second aspect of the present invention, the chromaticity coordinates (x, y) in the XYZ color system chromaticity diagram of the yellow pixel are (0.550, 0.450), (0.400, 0.600). , (0.350, 0.550), (0.510, 0.430). The color filter according to claim 1, wherein the color filter is located within a square.

  A third aspect of the present invention is the color filter according to claim 1 or 2, wherein a contrast ratio of the yellow pixel is 10,000 or more.

  A fourth aspect of the present invention is the color filter according to any one of claims 1 to 3, wherein the yellow pixel has a film thickness of less than 2 μm.

  According to a fifth aspect of the present invention, there is provided a liquid crystal display device comprising the color filter according to any one of the first to fourth aspects.

  A sixth aspect of the present invention is a liquid crystal display device comprising the color filter according to any one of claims 1 to 4 and using a three-wavelength LED as a light source. is there.

  According to the present invention, a color filter capable of realizing high contrast and high color reproducibility by forming a yellow pixel using a yellow composition having both high contrast and high saturation, and this color A liquid crystal display device including a filter can be obtained.

The figure which shows the range of the chromaticity coordinate (x, y) in the XYZ color system chromaticity diagram of the yellow pixel used for the color filter which concerns on one Embodiment of this invention. 1 is a diagram illustrating a configuration of a liquid crystal display device including a color filter according to an embodiment of the present invention. The figure for demonstrating the measuring method of contrast. The characteristic view which shows the emission spectrum of a backlight.

  Hereinafter, the present invention will be described based on embodiments.

  The color filter which concerns on one Embodiment of this invention comprises the colored pixel of multiple colors including a yellow pixel. Examples of pixels other than yellow pixels include red pixels, green pixels, and blue pixels. These pixels are formed using a coloring composition containing a pigment, a pigment dispersant, a pigment carrier, and the like.

  As a pigment contained in a coloring composition, an organic or inorganic pigment can be used individually or in mixture of 2 or more types. Among the pigments, pigments having high heat resistance, particularly pigments having high heat decomposition resistance are preferable, but organic pigments are usually used because of high color developability.

  The yellow pixel is a pixel formed using a yellow composition containing at least (a) a colorant, (b) a photopolymerizable monomer, (c) a photopolymerization initiator, (d) a transparent resin, and (e) a solvent. And (a) the colorant contains at least one or more of yellow pigments CI Pigment Yellow 138, 139, 150, and 185 and a red pigment CI Pigment Red 242; (a) the red pigment in the colorant; The weight ratio is 0.01 or more and less than 0.1.

  The yellow pixel included in the color filter of the present invention is a pixel having a film thickness of less than 2 μm formed using a yellow composition containing a red pigment together with a yellow pigment, and is a color in an XYZ color system chromaticity diagram. The degree coordinates (x, y) are (0.550, 0.450), (0.400, 0.600), (0.350, 0.550), (0.510, as shown in FIG. , 0.430). In particular, the chromaticity coordinates (x, y) in the XYZ color system chromaticity diagram are (0.465, 0.535), (0.428, 0.493), (0.510, 0.430). , (0.550, 0.450). This range is an area where the color expression of yellow pixels is rich.

  The spectral transmittance of such a yellow pixel has a region with a transmittance of 20% or less within a wavelength range of 470 nm to 570 nm and a width of 20 nm or more, and a region with a transmittance of 60% or more has a width of 40 nm or more.

  As described above, the yellow pixel is formed using a yellow composition containing both a yellow pigment and a red pigment, and the yellow pixel exhibiting the chromaticity or spectral transmittance as described above has high contrast and saturation, For example, a color filter in which such yellow pixels are added to red, green, and blue pixels can achieve high contrast and high color reproducibility.

  In other words, it is not possible to achieve both contrast and saturation with a yellow pigment alone, but by using a yellow composition in which a red pigment is mixed with a yellow pigment with low saturation but high contrast, both contrast and saturation are high. A yellow pixel can be obtained.

CI Pigment Yellow 138, 139, 150, 185 is used as a yellow pigment for the yellow coloring composition forming a yellow pixel. Furthermore CI Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 12, 13, 14, 15, 16, 17, 18, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 83, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123, 126, 127, 128, 129, 147, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 179, 180, 181, 182, 187, 188, 1 Or the like can be used 3,194,198,199,213,214.
Two or more of the above yellow pigments can be mixed and used.

  Examples of the red pigment added to the yellow pigment include CI Pigment Red 7, 9, 14, 41, 48: 1, 48: 2, 48: 3, 48: 4, 81: 1, 81: 2, 81: 3, 122, 123, 146, 149, 168, 177, 178, 179, 184, 185, 187, 192, 200, 202, 208, 210, 216, 220, 223, 224, 228, 240, 242, 254, 255, One or more of red pigments such as H.264 and 272 can be used. Among these, C.I. Pigment Red 177, 242, and 254 can be preferably used.

  The weight ratio of the red pigment in the yellow coloring composition is desirably 0.01 or more and less than 0.1. If it exceeds 0.1, the chromaticity does not fall within the square shown in FIG.

  Specific examples of organic pigments that can be used in the coloring composition for forming pixels other than yellow pixels, for example, red pixels, green pixels, and blue pixels are shown below.

  The red pigment mentioned above can be used for the red coloring composition for forming a red pixel. In addition, the above-mentioned yellow pigment, orange pigments such as C.I. Pigment Orange 36, 38, 43, 51, 55, 59, 61, 64, 71, 73 can be added to these red pigments.

  Green pigments such as C.I. Pigment Green 7, 10, 36, 37, 58 can be used for the green coloring composition for forming a green pixel. The above-mentioned yellow pigment can be added to the green coloring composition.

  Blue coloring compositions for forming blue pixels include, for example, CI Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 60, 64, 80, etc. A pigment, preferably CI Pigment Blue 15: 6, can be used. Purple pigments such as C.I. Pigment Violet 1, 19, 23, 27, 29, 30, 32, 37, 40, 42, 50, preferably C.I. Pigment Violet 23 can be used in combination with the blue coloring composition.

  The coloring composition can be produced by finely dispersing the pigment in a transparent resin and an organic solvent together with a photopolymerization initiator as necessary using various dispersing means. When the pigment is dispersed in the transparent resin and the organic solvent, a dispersion aid such as a resin-type pigment dispersant, a surfactant, and a pigment derivative can be appropriately contained.

  The coloring composition can contain a storage stabilizer in order to stabilize the viscosity with time of the composition, and also contains an adhesion improver such as a silane coupling agent in order to improve the adhesion to the transparent substrate. It can also be made.

  In addition, it is preferable that the contrast ratio of the yellow pixel is 10,000 or more because the display of the liquid crystal display device equipped with this color filter becomes clear. Furthermore, when the film thickness of the yellow pixel is less than 2 μm, there is an advantage that the edge of the pixel is unlikely to be in an overhang state and the image line accuracy is improved.

  In the color filter according to the present embodiment, after forming a black matrix on a transparent substrate, each color-colored composition layer is provided in a region divided into the black matrix by a printing method or a photolithography method. It can be obtained by forming a pixel. As the transparent substrate, glass plates such as soda lime glass, low alkali borosilicate glass and non-alkali alumino borosilicate glass, and resin plates such as polycarbonate, polymethyl methacrylate, and polyethylene terephthalate are used. Further, a transparent electrode made of indium oxide, tin oxide, or the like may be formed on the surface of the glass plate or the resin plate for driving the liquid crystal after the liquid crystal panel is formed.

  FIG. 2 shows a liquid crystal display device including a color filter according to an embodiment of the present invention. In FIG. 2, a liquid crystal display device 10 is a typical example of a TFT drive type liquid crystal display device for a notebook personal computer, and includes a pair of transparent substrates 11 and 21 arranged to be spaced apart from each other. Liquid crystal (LC) is enclosed.

  A TFT (thin film transistor) array 12 is formed on the inner surface of the first transparent substrate 11, and a transparent electrode layer 13 made of, for example, ITO is formed thereon. An alignment layer 14 is provided on the transparent electrode layer 13. A polarizing plate 15 is formed on the outer surface of the transparent substrate 11. On the other hand, the color filter 22 according to the present embodiment is formed on the inner surface of the second transparent substrate 21.

  The red, green and blue pixels constituting the color filter 22 are separated by a black matrix (not shown). A transparent protective film (not shown) is formed so as to cover the color filter 22 and further, a transparent electrode layer 23 made of, for example, ITO is formed thereon, and the alignment layer 24 covers the transparent electrode layer 23. Is provided. A polarizing plate 25 is formed on the outer surface of the transparent substrate 21. Note that a backlight unit 30 including a three-wavelength lamp 31 is provided below the polarizing plate 15.

  In addition to the LED backlight, a cold cathode fluorescent lamp (CCFL) backlight can be used as the backlight included in the liquid crystal display device including the color filter of the present invention.

[Pigment adjustment]
The pigments used in Examples and Comparative Examples are shown in Table 1. Table 2 shows the dispersants used in Examples and Comparative Examples.

[Preparation of acrylic resin solution]
The preparation of the acrylic resin solution used in Examples and Comparative Examples will be described. The molecular weight of the resin is a weight average molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography).

First, 370 parts of cyclohexanone is placed in a reaction vessel, heated to 80 ° C. while injecting nitrogen gas into the vessel, and a mixture of the following monomers and a thermal polymerization initiator is added dropwise at the same temperature over 1 hour to conduct a polymerization reaction. It was.
Methacrylic acid 20.0 parts Methyl methacrylate 10.0 parts n-Butyl methacrylate 35.0 parts 2-Hydroxyethyl methacrylate 15.0 parts 2,2'-azobisisobutyronitrile 4.0 parts paracumylphenol ethylene oxide modification Acrylate 20.0 parts
("Aronix M110" manufactured by Toa Gosei Co., Ltd.)

After completion of the dropwise addition, the mixture was further reacted at 80 ° C. for 3 hours, and then 1.0 part of azobisisobutyronitrile dissolved in 50 parts of cyclohexanone was added, and the reaction was further continued at 80 ° C. for 1 hour. A resin solution was obtained. The weight average molecular weight of the acrylic resin was about 40,000.

  After cooling to room temperature, about 2 g of the resin solution was sampled, heated and dried at 180 ° C. for 20 minutes to measure the nonvolatile content, and cyclohexanone was added to the previously synthesized resin solution so that the nonvolatile content was 20% by weight. To prepare an acrylic resin solution.

[Preparation of pigment dispersion]
A mixture having the composition (weight ratio) shown in Table 3 was uniformly stirred and mixed, then dispersed with an Eiger mill for 2 hours using zirconia beads having a diameter of 0.5 mm, and then filtered through a 5 μm filter to prepare a pigment dispersion. .

[Adjustment of colored composition (hereinafter referred to as resist)]
Next, the pigment dispersion prepared above and the following composition were stirred and mixed so as to be uniform at the composition (weight ratio) shown in Table 4, and then filtered through a 1 μm filter to obtain each color resist.

In the table above,
Monomer: Trimethylolpropane triacrylate (“NK ESTER ATMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.)
Photopolymerization initiator: 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (“Irgacure 907” manufactured by Ciba Specialty Chemicals)
Sensitizer: 4,4′-bis (diethylamino) benzophenone (“EAB-F” manufactured by Hodogaya Chemical Co., Ltd.)
Organic solvent: cyclohexanone.

[Preparation of dry paint film for measuring the contrast ratio of yellow pixels]
The obtained yellow resists (Table 4 YPR1 to YPR3, YPR4-1 to YPR4-6) were applied to a glass substrate by spin coating, and then prebaked at 70 ° C. for 20 minutes in a clean oven. Next, the substrate was cooled to room temperature and then subjected to ultraviolet exposure using an ultrahigh pressure mercury lamp. Thereafter, post-baking was performed at 230 ° C. for 40 minutes in a clean oven to prepare 27 kinds of dry coating films for measuring the contrast ratio of yellow pixels (Examples 1 to 8, Comparative Examples 1 to 20).

  These coating film samples were evaluated as follows.

[Measurement of chromaticity of parallel transmitted light]
The chromaticity coordinates of the obtained sample were measured using a microspectrophotometer OSP-2000 (manufactured by Olympus Optical Co., Ltd.) using an LED under the condition of 2 ° visual field. The results are shown in Tables 5 and 6.

[Measurement of contrast ratio]
First, as shown in FIG. 3A, the polarizing plates 2 and 3 were arranged before and after the sample 4 with their polarization axes parallel to each other. A backlight 6 is irradiated from the side of one polarizing plate 3, and the luminance Lp (luminance of parallel transmitted light) of the light 7 transmitted through the other polarizing plate 2 is measured with a color luminance meter BM-5A (manufactured by Topcon Corporation) 1. Used and measured under the condition of a visual field of 2 ° (CIE 1931 color system).

Next, as shown in FIG. 3B, the polarizing axes of the polarizing plates 2 and 3 are orthogonal to each other, the backlight 6 is irradiated from the side of the one polarizing plate 3, and transmitted through the other polarizing plate 2. The luminance Lc of the light 8 (the luminance of the orthogonal transmitted light) was measured with the color luminance meter 1. The contrast ratio Lp / Lc was calculated using the measured values obtained by the above method. The luminance meter used was “Color luminance meter BM-5A” manufactured by Topcon Corporation, and the polarizing plate used was “polarizing film NFF-SEG1224DU” manufactured by Nitto Denko Corporation. In the measurement, a black mask with a 1 cm square hole was applied to the measurement portion in order to block unnecessary light.

  These results are shown in Tables 5 and 6.

  From Tables 5 to 6, the following can be understood. That is, the yellow pixels obtained by using the yellow composition YPR-1 containing only Y-1 (Comparative Examples 1 to 3) have good contrasts of 10,000 or more, but the chromaticity is shown in FIG. As such, it is outside the scope of the present invention. Moreover, as for the yellow pixel obtained by using the yellow composition YPR-2 containing only Y-2 (Comparative Examples 4 to 6), the chromaticity is within the scope of the present invention as shown in FIG. The contrast is as low as 10,000 or less. Furthermore, the yellow pixels (Comparative Examples 7 to 9) obtained by using the yellow composition YPR-3 obtained by adding Y-2 (20 parts by weight) to Y-1 (80 parts by weight) all have a contrast of 10,000 or less. And low.

  In contrast, the yellow pixels (Examples 1 to 8) obtained using the yellow composition YPR-4 to which Y-1, Y-2, and R-2 were added had chromaticity as shown in FIG. Within the scope of the present invention, the saturation is good, and the contrast is as high as 10,000 or more.

  Among the yellow compositions to which Y-1, Y-2, and R-2 are added, a film capable of producing a contrast of 10,000 or more within the scope of the present invention due to the weight of Y-1 and R-2. The thickness will change. As shown in Comparative Example 10 and Comparative Examples 11 and 12, when the amount of Y-1 and R-2 in the yellow composition is 89: 2 (Comparative Example 10), the chromaticity of the present invention up to a film thickness of 2.0 μm. When the range is satisfied and the contrast is 10000 or more, if 90: 1 (Comparative Examples 11 and 12), the chromaticity deviates from the range of the present invention at a film thickness of 1.5 μm. Further, when the amount of Y-1 and R-2 in the yellow composition is 79: 2 (Comparative Example 13), the chromaticity range of the present invention and the contrast of 10,000 or more are satisfied up to a film thickness of 2.0 μm. When the amounts of Y-1 and R-2 are 80: 1 (Comparative Examples 14 and 15), a contrast of 10000 or more cannot be achieved at a film thickness of 1.0 μm. Further, when Y-1, Y-2, and R-2 are 70: 25: 5, the film thickness of 1.0 μm is outside the chromaticity range of the present invention. This is within the scope of the invention, but the saturation is low. When the amount of R-2 added is increased to 10 parts by weight (Comparative Example 16), when the film thickness is 1.0 μm, the chromaticity range of the present invention is exceeded, and as the film thickness increases, the saturation decreases. .

(Examples 10 to 14 and Comparative Examples 19 to 22)
A color filter was produced by the following method using combinations of color resists shown in Table 7.

[Production of color filter]
First, a red resist was applied to a glass substrate on which a black matrix had been formed in advance by spin coating, and then prebaked at 70 ° C. for 20 minutes in a clean oven. Next, after cooling the substrate to room temperature, ultraviolet rays were exposed through a photomask using an ultrahigh pressure mercury lamp. Thereafter, the substrate was spray-developed using a sodium carbonate aqueous solution at 23 ° C., washed with ion-exchanged water, and air-dried.

  Further, post-baking was performed at 230 ° C. for 30 minutes in a clean oven to form a striped red filter segment on the substrate. Next, using a green resist, form a green filter segment in the same way, then use a blue resist to form a blue filter segment, and then use a yellow resist to form a yellow filter segment to obtain a color filter. It was.

[Production of liquid crystal display devices]
A transparent ITO electrode layer was formed on the obtained color filter, and a polyimide alignment layer was formed thereon. A polarizing plate was formed on the other surface of this glass substrate. On the other hand, a TFT array and a pixel electrode were formed on one surface of another (second) glass substrate, and a polarizing plate was formed on the other surface.
The two glass substrates thus prepared face each other so that the electrode layers face each other, and are aligned using spacer beads while keeping the distance between both substrates constant, and the periphery is left so as to leave an opening for injecting the liquid crystal composition. Sealed with a sealant. A liquid crystal composition was injected from the opening to seal the opening. The liquid crystal display device thus produced was combined with a backlight unit to obtain a liquid crystal panel.

[Backlight]
As the backlight, a B-LED + R · G phosphor backlight that exhibits a white color by combining a blue LED, a red light emitting phosphor, and a green light emitting phosphor, and that exhibits an emission spectrum as shown in FIG. 4 was used. .

  The following evaluation was performed about the color filter obtained by the Example and the comparative example.

(Evaluation of color reproduction area)
NTSC ratio of the color filter when irradiated with the B-LED + R / G phosphor backlight using the produced color filter (standard primary colors defined by the US National Television System Committee (NTSC)) The area of a rectangle relative to the standard value area, where 100 is the area of a triangle of RGB3 colors defined by red, 0.67, 0.33, green (0.21, 0.71) and blue (0.14, 0.08). The ratio of was measured. Table 7 shows the evaluation results.

  From the results shown in Table 7, when the yellow composition component of the color filter contains 1 to 5% by weight of the red composition R-1 (Examples 10 to 14), the NTSC ratio is improved, and the brightness and contrast are increased. I understood. In contrast, when a color filter using a yellow composition component not containing the red composition R-1 (Comparative Example 21) and using YPR-1 as the color filter (Comparative Example 22), white As a result, the chromaticity of the display deviated from the target chromaticity, and the brightness and contrast were lowered. Furthermore, the color filter using the yellow composition component with 10% by weight of the red composition (Comparative Example 25) shows a high contrast but low brightness and NTSC ratio.

DESCRIPTION OF SYMBOLS 1 ... Color luminance meter 2, 3, 15 ... Polarizing plate 6 ... Backlight 7, 8 ... Light 10 ... Liquid crystal display device 11, 21 ... Transparent substrate 12 ... TFT (thin film transistor) array 13, 23 ... Transparent electrode layers 14, 24 ... Alignment layer 15 ... Polarizing plate 22 ... Color filter 30 ... Backlight unit 31 ... Three-wavelength lamp

Claims (6)

  A color filter comprising a plurality of color pixels including a yellow pixel, wherein the yellow pixel comprises at least (a) a colorant, (b) a photopolymerizable monomer, (c) a photopolymerization initiator, and (d) a transparent resin. (E) a pixel formed using a yellow composition containing a solvent, and (a) at least one or more of yellow pigments CI Pigment Yellow 138, 139, 150, and 185 in a colorant, and red A color filter comprising a pigment CI Pigment Red 242, wherein (a) the weight ratio of the red pigment in the colorant is 0.01 or more and less than 0.1.   The chromaticity coordinates (x, y) in the XYZ color system chromaticity diagram of the yellow pixel are (0.550, 0.450), (0.400, 0.600), (0.350, 0.550). ), (0.510, 0.430). The color filter according to claim 1, wherein the color filter is located within a square.   The color filter according to claim 1 or 2, wherein a contrast ratio of the yellow pixel is 10,000 or more.   4. The color filter according to claim 1, wherein a film thickness of the yellow pixel is less than 2 μm.   A liquid crystal display device comprising the color filter according to claim 1.   5. A liquid crystal display device comprising the color filter according to claim 1 and using a three-wavelength LED as a light source.

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