JP2014021320A - Color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter for liquid crystal display devices, which comprises a black matrix layer 1 having openings 4, for partitioning colored pixels 2, and the colored pixels 21, 22, 23 provided on a substrate 5 and is capable of enhancing resolution of liquid crystal display devices through miniaturization of pixels without inviting troubles with the black matrix 1.SOLUTION: Openings 4 are circular and colored pixels 21, 22, 23 are circular in planar view and concave shaped in (vertical) cross-sectional view. The colored pixels 2 and a black matrix layer 1 are covered with a transparent conductive film 3.

Description

  The present invention relates to a color filter used in a liquid crystal display device.

  In recent years, liquid crystal display devices are increasingly required to have a larger screen and higher resolution as consumer and industrial display devices.

FIG. 4 is an explanatory view schematically showing an example of a color filter used in a liquid crystal display device, and FIG. 4 (a) is an explanatory view seen in a plane. FIG. 4B is an explanatory view of the color filter shown in FIG.
As shown in FIGS. 4A and 4B, the color filter used in the liquid crystal display device includes a black matrix 10, a colored pixel 12, and a colored pixel 12 that partition the colored pixels 12 with openings 14 on the glass substrate 15. The transparent conductive film 13 is sequentially formed.
4A and 4B schematically show a color filter, and 12 colored pixels 12 are shown. In an actual color filter, for example, a diagonal 17 type (diagonal, A large number of colored pixels of about 100 μm are arranged on a screen of about 43 cm). In addition, although the shape of the colored pixel is rectangular in the figure, a stripe shape is also employed, and the shape is changed as necessary.

As a method of manufacturing a color filter having the above structure, which is used in many liquid crystal display devices, first, a black matrix is formed on a glass substrate, and then a colored pixel is aligned with this black matrix pattern. A method of forming a transparent conductive film and aligning a transparent conductive film is widely used.
The black matrix 10 is a matrix having a light shielding property, and the colored pixels 12 have, for example, red, green, and blue filter functions and are provided adjacent to each other. Reference numeral 13 is provided as a transparent electrode. On top of this, in order to improve the visibility of the final product (liquid crystal display device), a device such as providing an MVA (liquid crystal alignment protrusion) is devised.

  The black matrix 10 includes a matrix portion 10a between the colored pixels 12 and a frame portion 10b that surrounds a peripheral portion of a region (display portion) where the colored pixels 12 are formed. In the black matrix, the colored pixels of the color filter are defined by the openings 14, the positions thereof are determined, and the size is uniform. Further, the black matrix 10 has a function of shielding unwanted light when used in a display device, and making an image of the display device a uniform image with no unevenness and an improved contrast.

  The black matrix is formed on the glass substrate by, for example, forming a metal thin film on the glass substrate 15 and photoetching the metal thin film. Alternatively, a method is employed in which the black matrix 10 is formed on the glass substrate 15 by a photolithography method using a black photoresist for forming a black matrix.

  In addition, the colored pixels 12 are formed by providing a coating film on a glass substrate on which the black matrix is formed using, for example, a negative coloring photoresist in which a pigment such as a pigment is dispersed. A method is employed in which colored pixels are sequentially formed for each color by exposure and development. The transparent conductive film 13 is formed on a glass substrate on which a black matrix and colored pixels are formed by, for example, forming a transparent conductive film by sputtering using ITO (Indium Tin Oxide). .

  When forming the black matrix, the colored pixels, and the associated layers as a pattern by photolithography, for example, first, a glass substrate is subjected to a cleaning treatment as necessary, and then a photoresist is applied by a coating apparatus. Then, a preliminary drying process with a reduced pressure drying apparatus, a pre-baking process with a pre-baking apparatus, a pattern exposure with an exposure apparatus, a developing process with a developing unit, and a post-baking process with a heating unit are sequentially performed to form a predetermined pattern on the glass substrate.

  The color filter shown in FIGS. 4A and 4B has a basic function as a color filter used in a liquid crystal display device. In recent years, with the refinement of pixels of a liquid crystal display device, the width of the formed black matrix is becoming narrower.

  In order to further improve the resolution of the liquid crystal display device, it is necessary to reduce the size of the colored pixels. As the size of the colored pixel becomes smaller, the width of the black matrix that plays a role of partitioning the colored layer by the opening needs to be reduced. This is because even if the size of the colored layer is reduced, if the width of the black matrix remains large, the area ratio (opening ratio) of the colored layer with respect to the black matrix portion cannot be secured.

  In order to solve this problem, it is necessary to make the size of the black matrix thinner, but when making it thinner, the line shape (matrix part) of the black matrix is constricted at the boundary between the thin line part and the thick line part (frame part) of the black matrix. There are problems such as.

  As the resolution limit is approached, the matrix portion 10a between the colored pixels 12 becomes constricted. FIG. 5 is a diagram showing a result of simulating the resolution in the vicinity of the intersection between the matrix portion 100a between the colored pixels of the black matrix and the frame portion 100b. In the figure, the pattern 102 is formed by changing the width of the matrix portion from 3.0 μm to 8 μm in 1 μm steps. The pattern 103 of the simulation result is not resolved at 4.0 μm or less and is resolved at 6.0 μm or more, but at 5.0 μm, the resolution pattern is between the vicinity of the frame portion and the matrix portion. Are enclosed and separated.

JP-A-8-201797

  The present invention has been made to solve the above problems, and it is an object of the present invention to provide a color filter capable of improving resolution by refinement of pixels of a liquid crystal display device without causing a defect of a black matrix. To do.

The present invention has been made in view of such problems, and the invention of claim 1 of the present invention provides
In a color filter for liquid crystal display provided with a black matrix layer for partitioning colored pixels at openings and colored pixels on a substrate,
The color filter is characterized in that the opening has a circular shape.

The invention of claim 2 of the present invention
2. The color filter according to claim 1, wherein the colored pixels are circular in a plan view.

The invention of claim 3 of the present invention
3. The color filter according to claim 1, wherein the colored pixel has a convex cross-sectional shape at the opening.

  Since the color filter of the present invention has the above-described configuration, it can be a color filter that can improve the resolution by refinement of pixels of the liquid crystal display device without causing a black matrix defect.

In the embodiment of the color filter of the present invention, FIG. (A) is a partial explanatory view seen in a plane, and FIG. It is explanatory drawing which looked at a part of black matrix layer of the example of embodiment of this invention in the plane. FIG. 2 is a partial explanatory diagram of a color filter according to an embodiment of the present invention, in which FIG. (A) is an explanatory diagram viewed from a plane, and FIG. (B) is an explanatory diagram viewed from a cross section of one pixel. Explanatory drawing which showed typically an example of the color filter used for the conventional liquid crystal display device It is a figure of the result of having simulated the vicinity of the intersection of the matrix part between the coloring pixels of a black matrix, and a frame part.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is an embodiment of a color filter according to the present invention, in which FIG. 1 (a) is a partial explanatory diagram viewed from a plane, and FIG. 1 (b) is an explanatory diagram viewed from a cross section of one pixel.
The color filter for liquid crystal display according to the present embodiment is provided with a black matrix layer 1 for partitioning pixels by openings 4 and colored pixels 2 on a substrate 5, and the openings 4 have a circular shape. The colored pixels 2 and the black matrix layer 1 are covered with a transparent conductive film 3.

  FIG. 2 is an explanatory view of a part of the black matrix layer of the present embodiment as seen in a plan view. Since the opening 4 has a circular shape, the boundary between the thin line portion (matrix portion between the colored pixels) and the thick line portion (frame portion) of the black matrix layer 1 is not a right angle, and the black matrix shape is not constricted. In addition, by forming the pixels partitioned by the openings in a circular shape, the aperture ratio is higher in the circular shape in the case of the same area than in the rectangular shape. In the case of the rectangular shape, the radiation of light at the four corners is affected by diffraction and the like, and the efficiency of radiation is deteriorated.

  Furthermore, in this embodiment, the colored pixels 2 are circular in plan view. Further, the colored pixel 2 has a convex cross-sectional shape at the opening 4. By configuring the colored pixels 2 in this way, the pixel arrangement can be made high density and the aperture ratio can be further increased. Further, the colored layer can be a liquid crystal alignment protrusion that plays a role of alignment control. Therefore, it is possible to provide a color filter with improved visibility without adding a new process.

  In order to make the opening convex, it can be formed by using a conventional lithography technique using a light / dark mask and exposing / developing to make the cross-sectional shape of the resist convex.

  The following color filter was produced.

FIG. 3 is a partial explanatory view of the color filter of the present embodiment, FIG. 3A is an explanatory view seen from a plane, and FIG. 3B is an explanatory view seen from a cross section of one pixel. . The pixel shapes (RED, GREEN, BLUE) 21, 22, and 23 of the present embodiment are as shown in FIG.

Colored layer: 3 colors of RED21, GREEN22, BLUE23 Colored layer shape: circular, convex shape (diameter 40 μm, maximum film thickness difference from BM layer 1 2.5 μm)
・ Minimum dimension of BM line width: 3.0μm
Structure of color filter: BM layer 1 (film thickness 1.0 μm) + colored layer (R21, G22, B23 layer) + ITO layer 3 (conductive film layer (film thickness 1000 mm)).
(1) BM layer Material: Negative photosensitive resin in which black pigment is dispersed Production method:
-The BM layer was produced on the raw glass by the photolithographic method.

    -Although resin BM material was used this time, metal materials, such as CrBM, may be used.

      In addition to the photolithography method, the ink jet method may be used.

-The film thickness of BM layer was 1.0 micrometer. The film thickness of the BM layer is preferably between 0.5 μm and 2.5 μm.
(2) Colored layer (RGB layer)
Material: Negative photosensitive resin in which red, green and blue pigments are dispersed respectively.
-RGB layer 2 was laminated | stacked on the board | substrate 5 which laminated | stacked BM layer 1 with the photolithographic method.

      In addition to the photolithography method, the ink jet method may be used.

-The film thickness difference with the BM layer 1 was 2.5 μm at the maximum. The difference in film thickness is preferably about 1.0 to 3.5 μm.
(3) Transparent conductive film layer (ITO layer)
Material: ITO target Production method:
-ITO3 was vapor-deposited on the color filter using the sputtering device.

    ・ This time, the ITO3 film thickness was set to 1000 [Å]. The ITO3 film thickness is preferably between 500 [Å] and 2000 [Å].

  Through the above steps, a color filter having a circular pixel shape of the colored layer could be produced. The resolution of the color filter according to the present embodiment is improved by 3 to 5% compared with the conventional color filter.

DESCRIPTION OF SYMBOLS 1 ... Black matrix 2 ... Colored pixel 21 ... RED colored pixel 22 ... GREEN colored pixel 23 ... BLUE colored pixel 3 ... Transparent conductive film 4 ... Opening 5 ... Substrate 10 ... Black matrix 10a ... Matrix part 10b ... Frame part 12 ... Colored pixel 13 ... Transparent conductive film 14 ... Opening part 15 ... Glass substrate 100a ... -Matrix part 100b ... Frame part 102 ... Matrix part pattern 103 ... Simulation result pattern

Claims (3)

In a color filter for liquid crystal display provided with a black matrix layer for partitioning colored pixels at openings and colored pixels on a substrate,
A color filter, wherein the opening has a circular shape.   The color filter according to claim 1, wherein the colored pixels are circular in a plan view.   The color filter according to claim 1, wherein the colored pixel has a convex cross-sectional shape at the opening.

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