JP2018040879A - Color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter that reduces influences of a build-up portion or a build-up step portion produced on an end of a black matrix and has excellent flatness and excellent display characteristics while preventing degradation in oblique visibility due to leakage of light from an adjoining pixel or abnormality in driving a liquid crystal.SOLUTION: The color filter includes a black matrix, a color pixel, and an overcoat layer on a glass substrate, and the color filter includes a transparent resin pattern on the glass substrate in an opening of the black matrix. The outer periphery of the transparent resin pattern forms a gap separated from the black matrix. The color filter has the color pixel on the black matrix, on the transparent resin pattern and in the gap, and has the overcoat layer on the color pixel.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a color filter used for a color display panel of a color liquid crystal display device.

  In a display device such as a liquid crystal display device, it is a useful means to use a color filter for purposes such as color display, reflectance reduction, contrast adjustment, and spectral characteristic control. In many cases, color filters used in display devices are formed and used as pixels. As a method for forming a pixel of a color filter used in a display device, a printing method, a photolithography method, and the like can be given as methods that have been put into practical use.

  FIG. 3 is a schematic cross-sectional view showing a part of pixels of a color filter used in the liquid crystal display device in an enlarged manner. As shown in FIG. 3, the color filter 50 used in the liquid crystal display device includes a black matrix 52 having an opening formed on a glass substrate 51, and red and green colors formed in the opening of the black matrix 52. , Blue colored pixels 53 (53 (R), 53 (G), 53 (B)) and an overcoat layer 54 formed on the entire surface of the colored pixels 53.

  As a method for manufacturing a color filter, first, a black matrix 52 having openings of a predetermined shape is formed on a glass substrate 51, and then a colored pixel 53 is formed by being aligned with the openings of the black matrix 52. Further, a method of sequentially forming the overcoat layer 54 is widely used.

  The black matrix 52 has a light-shielding property, and positions of the colored pixels 53 on the glass substrate 51 are determined at the openings so that the size of the colored pixels 53 is uniform. Further, when used in a display device, it has a function of shielding unwanted light and making an image of the display device a uniform image with no unevenness and an improved contrast.

  The black matrix 52 is usually formed by a photolithography method. A black resist (black photosensitive curable resin composition) coating film is provided on the glass substrate 51, and pattern exposure is performed on the coating film via a photomask. Then, unnecessary portions of the resist are removed by development, and the black matrix 52 is formed with the remaining resist. The film thickness of the black resist is, for example, about 1.0 to 1.5 μm so as to obtain a necessary optical density.

  The colored pixels 53 have, for example, red, green, and blue filter functions, and the colored pixels 53 are usually formed by a photolithography method on the glass substrate 51 on which the black matrix 52 is formed. A coating film of a negative coloring resist (colored photosensitive curable resin composition) in which a pigment such as a pigment is dispersed is provided, and the colored pixels 53 are formed by exposing and developing the coating film through a photomask.

  Further, a thermosetting transparent resin is used for the overcoat layer 54, which is formed by applying by spin coating or die coating, drying under reduced pressure, and baking.

  FIG. 4 is a schematic cross-sectional view illustrating the steps from the formation of the colored pixels 53 to the formation of the overcoat layer 54 by enlarging the vicinity of the black matrix 52.

In FIG. 4A, in order to form a green pixel after forming the red pixel 53 (R), the green resist 53 (G) a is applied and then exposed through a photomask 59. Here, the first colored pixel (here, the red pixel 53 (R)) has already run over the end of the black matrix 52, and the swell has occurred. This rise is referred to as a horn portion 56, and the difference in height between the upper portion of the horn portion 56 and the upper surface of the red pixel 53 (R) (ΔH _{1 in} FIG. 4A) is referred to as a horn step. Also, the second color is green resist 53 (G) a coating film of, generates a swelling at the edge of the black matrix, the ends of the black matrix horn step [Delta] H ₁ by the red pixel 53 (R) is present, Tsunoda A higher bulge is generated on the portion 56.

FIG. 4B shows a form after the formation of the second color green pixel 53 (G). As a result of the rising of the coating film of the green resist 53 (G) a, a horn step (ΔH ₂ ) similar to the horn step (ΔH ₁ ) of the red pixel is formed at the end of the black matrix where no red pixel exists. Further, a horn step (ΔH ₃ ) higher than the horn step (ΔH ₁ ) of the red pixel is formed at the end of the black matrix where the horn step ΔH ₁ due to the red pixel 53 (R) exists.

FIG. 4C shows a form after the blue pixel 53 (B) of the third color is formed and the overcoat layer 54 is further formed. Here, for the same reason as when forming the green pixel 53 (G), the same horn step as the horn step (ΔH ₃ ) of the green pixel is present at the end of the black matrix where the horn step ΔH ₂ due to the green pixel exists. (ΔH ₄ ) is formed. Further, the overcoat layer 54 has a large height difference due to the influence of the black matrix 52 and the above-described horn steps ΔH ₁ , ΔH ₂ , ΔH ₃ , and ΔH ₄ .

  If the color filter having the horn step formed at the end of the black matrix 52 is used in a liquid crystal display device, the visibility is deteriorated due to light leakage from an adjacent pixel and the contrast is lowered due to color mixing. Will be adversely affected.

  FIG. 3 also shows a liquid crystal layer 57 on the color filter 50, and shows that the viewer 58 visually recognizes the display object from an oblique direction on the glass substrate 51 side. Here, since only the liquid crystal on the blue pixel 53 (B) is driven (ON) by a liquid crystal driving element (not shown), only blue must be visually recognized, but in the direction of the line of sight L indicated by a dotted line. A state in which green color is visually recognized by light passing through the green pixel (light leakage) is shown.

  As can be easily seen from FIG. 3, light leakage is more likely to occur as the distance from the liquid crystal layer 57 to the black matrix 52 increases. However, in recent years, the thickness of the colored pixel 53 tends to increase in order to display a darker color. As the thickness of the colored pixel 53 increases, the surface unevenness due to the horn step increases, and there is a concern that liquid crystal drive abnormality such as liquid crystal tilt may occur. In order to flatten the unevenness of the surface, the overcoat layer 54 also needs to be thickened, and there is a problem that the distance between the black matrix 52 and the liquid crystal layer 57 becomes longer.

  As a method for reducing the horn step, for example, a) a method of polishing the surface of the color filter to reduce the height of the horn step before forming the overcoat layer (Patent Document 1), b) black A method of forming the matrix film thickness (a, see FIG. 4 (c)) low, and c) increasing the length of the tapered portion (P, see FIG. 4 (c)) on the side surface of the black matrix to increase the horn step. A method of lowering (Patent Document 2) has been proposed.

However, the above-mentioned a) the method of polishing the surface of the color filter causes a problem that the surface of the colored pixel is scratched, and b) the method of reducing the film thickness of the black matrix causes a problem that the optical density of the black matrix is insufficient. In the method c), although the horn step is lowered, there is a problem that the oblique visibility of the display image is deteriorated due to the taper angle (θ, see FIG. 4C) being reduced. In the next-generation high-definition display device, the taper angle (θ
) Must be maintained at 80 ° or more. As described above, there is a limit to the correspondence with the methods a) to c).

JP 2008-281678 A Japanese Patent Laid-Open No. 9-189899

  The present invention has been made in order to solve the above-described problem. In a color filter in which a black matrix, a colored pixel, and an overcoat layer are formed on a glass substrate, a horn portion generated at an end of the black matrix, When reducing the height of the horn step, the horn and horn step can be reduced without causing problems such as scratches on the surface of the colored pixels, insufficient optical density, and deterioration of oblique visibility due to a smaller taper angle. Reduced and improved flatness, reduced the overcoat layer thickness and shortened the distance from the liquid crystal layer to the black matrix, therefore worsening oblique visibility due to light leakage from adjacent pixels and abnormal liquid crystal drive An object of the present invention is to provide a color filter excellent in display characteristics that does not generate mist.

In order to solve the above-mentioned problem, the invention described in claim 1
A color filter comprising a black matrix, colored pixels and an overcoat layer on a glass substrate,
A transparent resin pattern is provided on the glass substrate at the opening of the black matrix,
The outer peripheral part of the transparent resin pattern is a gap part separated from the black matrix,
The colored pixels are provided on the black matrix, on the transparent resin pattern, and in the gap,
A color filter comprising the overcoat layer on the colored pixel.

  The invention according to claim 2 is characterized in that the width of the gap portion at a height of ½ of the film thickness of the black matrix in a cross-sectional view is 1.5 to 7.5 μm. This is the color filter described.

  According to a third aspect of the present invention, in the color filter according to the first or second aspect, the film thickness of the transparent resin pattern is 0.8 to 1.2 times the film thickness of the black matrix. It is what.

  According to the color filter of the present invention, the transparent resin pattern is provided on the glass substrate in the opening portion of the black matrix, and the outer peripheral portion of the transparent resin pattern is a gap portion separated from the black matrix. Without causing problems such as scratches on the surface, insufficient optical density, and deterioration in oblique visibility due to a decrease in taper angle, it reduces horns and horn steps and has excellent flatness and suppresses the thickness of the overcoat layer. Therefore, the distance from the liquid crystal layer to the black matrix can be shortened, and therefore, a color filter having excellent display characteristics that does not cause deterioration of oblique visibility due to light leakage from adjacent pixels and liquid crystal drive abnormality can be obtained. it can.

It is (a) schematic plan view (b) schematic sectional drawing which shows embodiment which concerns on the color filter of this invention. It is a schematic cross section which shows a part of manufacturing process which concerns on the color filter of this invention. It is a schematic cross section for demonstrating the structure of the conventional color filter, and the problem of diagonal visual recognition. It is a schematic cross section which shows a part of manufacturing process of the conventional color filter.

  Hereinafter, embodiments of the color filter of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments without departing from the spirit of the present invention. In addition, the same code | symbol is attached | subjected about the same component unless there is a reason for convenience. Further, in the drawings used in the following description, in order to make the features easier to understand, the portions that become the features are enlarged and shown, and the dimensional ratios of the respective constituent elements are not the same as actual.

  FIG. 1 is a (a) schematic plan view (b) schematic sectional view showing an embodiment according to the color filter of the present invention. As shown in FIG. 1, a color filter 10 of the present invention includes a black matrix 2, a colored pixel 3, and an overcoat layer 4 on a glass substrate 1, and a transparent resin pattern on the glass substrate 1 in the opening of the black matrix 2. 5 is a color filter. Although not shown, since the black matrix 2 is usually a lattice or stripe pattern in plan view, the transparent resin pattern 5 has a quadrangular shape in plan view, and the outer periphery of the transparent resin pattern 5 is the black matrix 2. The gap S is separated. The colored pixels 3 are present on the transparent resin pattern 5, the black matrix 2, and the gap S. The overcoat layer 4 is present on the entire surface of the colored pixel 3.

  As described above, the color filter 10 of the present invention is provided with the transparent resin pattern 5 on the glass substrate 1 in the opening of the black matrix 2 unlike the color filter of the conventional structure, and the outer periphery of the transparent resin pattern 5 is the black matrix. 2, and the center position of the colored pixel 3 coincides with the center position of the transparent resin pattern 5 in plan view. Accordingly, the colored pixels 3 are formed on the transparent resin pattern 5 and the black matrix 2, and are also formed in the gap portion S (concave portion) at the outer peripheral portion of the transparent resin pattern 5. For this reason, even if adjacent colored pixels overlap on the black matrix 2 as in the prior art, they do not rise greatly, and the height of the horn portion or horn step can be kept low.

  Accordingly, since the flatness of the surface of the colored pixel 3 is improved, the overcoat layer 4 can be formed with a reduced thickness, and the distance from the liquid crystal layer to the black matrix can be shortened. Therefore, it is possible to obtain a color filter excellent in display characteristics that does not cause deterioration in oblique visibility due to light leakage from adjacent pixels and liquid crystal drive abnormality.

  FIG. 2 is a schematic cross-sectional view showing a part of the manufacturing process according to the color filter of the present invention. Hereinafter, an embodiment of the color filter of the present invention will be described in more detail with reference to FIG.

  First, a black matrix 2 pattern is formed on a glass substrate 1 by a known method (FIG. 2A). Next, a transparent resin pattern 5 patterned with a transparent resin is formed in the opening of the black matrix 2 (FIG. 2B). The transparent resin pattern 5 is formed by applying a transparent resist, which is a photosensitive curable resin composition, on the glass substrate 1 on which the black matrix 2 is formed by a known photolithography method by spin coating or the like, and after exposure through a photomask, It is formed by developing with a solvent or an aqueous alkali solution.

  It is unnecessary that the refractive index of the transparent resin forming the transparent resin pattern 5 is close to the refractive index of the green pixel 3 (G), the red pixel 3 (R), and the blue pixel 3 (B) that are in contact with each other on the upper and side surfaces. This is desirable because it does not generate reflected light.

  In the formation of the transparent resin pattern 5, the center position of the transparent resin pattern 5 is made to coincide with the center position of the opening of the black matrix 2, and the outer peripheral portion of the transparent resin pattern 5 has a gap S separated from the black matrix 2. To have. Here, the width W of the gap S is preferably 1.5 to 7.5 μm at a height b that is ½ of the film thickness a of the black matrix 2 in a cross-sectional view. The film thickness T of the transparent resin pattern 5 may be 0.8 to 1.2 times the film thickness a of the black matrix 2, but is preferably equal to the film thickness a.

  In the numerical range, the thickness and line width of the black matrix 2 are 1.0 to 1.5 μm and 4.0 to 5.0 μm, respectively, and the thickness of the colored pixel 3 is about 2.0 to 3.0 μm. In consideration of this, when forming colored pixels 3 to be described later, a colored resist is caused to flow into the gap portion S, and the heights of the horn portions and horn steps are suppressed even when adjacent pixels rise on the black matrix 2. Therefore, it is a preferable numerical range.

  Next, after the black matrix 2 and the transparent resin pattern 5 are formed, red, green, and blue colored pixels 3 (R), 3 (G), and 3 (B) are sequentially formed by a known method (FIG. 2). (C)). As described above, due to the presence of the transparent resin pattern 5 and the gap portion S, the height of the horn portion and the horn step can be kept low even if the colored pixels overlap on the black matrix 2. 2 (c) (and correspondingly FIG. 1 (b)) shows a case where a colored resist having particularly high fluidity is used. In this case, due to the presence of the transparent resin pattern 5 and the gap portion S, FIG. No horn portion or horn step occurs, and a groove-like recess M is formed between adjacent colored pixels. On the other hand, if the fluidity is too high and the dent M is too large, the flatness of the overcoat layer 4 deteriorates. Therefore, the depth of the dent M is preferably 1.0 μm or less even when the groove is formed.

  Next, an overcoat layer 4 made of a transparent resin is formed on the entire surface of the colored pixels 3 by a known method (FIG. 2D). In the color filter of the present invention, as described above, it is low even if a horn portion or a horn step is generated, and is shallow even if a groove-like dent M is formed, so that the low portion can be easily filled with the overcoat layer 4. it can. Therefore, the thickness of the overcoat layer 4 is excellent in flatness even as a thin film of about 0.5 to 1.0 μm, and the distance from the liquid crystal layer to the black matrix can be shortened. Thereby, it is possible to obtain a color filter excellent in display characteristics that does not cause deterioration in oblique visibility due to light leakage from adjacent pixels and liquid crystal drive abnormality.

  The color filter of the present invention can be suitably used for a high-definition liquid crystal display device that requires high display quality, a color filter substrate that constitutes the same, and a liquid crystal display panel.

10, 50: Color filter 1, 51: Glass substrate 2, 52: Black matrix 3, 53: Colored pixels 3 (R), 53 (R): Red pixels 3 (G ), 53 (G)... Green pixel 53 (G) a... Green resist 3 (B), 53 (B)... Blue pixel 4, 54. Resin pattern S... Gaps T between black matrix and transparent resin pattern... Transparent resin pattern film thickness a... Black matrix film thickness b.
W ··· width M ···· groove-like indentations 56 ... horn section 57 ... liquid crystal layer 58 ... the viewer 59 ... photomask ΔH ₁ of the gap portion, ΔH _2, ΔH _3, ΔH ₄ ... Horn step L ... Line of sight P ... Length of taper part θ ... Taper angle

Claims (3)

A color filter comprising a black matrix, colored pixels and an overcoat layer on a glass substrate,
A transparent resin pattern is provided on the glass substrate at the opening of the black matrix,
The outer peripheral part of the transparent resin pattern is a gap part separated from the black matrix,
The colored pixels are provided on the black matrix, on the transparent resin pattern, and in the gap,
A color filter comprising the overcoat layer on the colored pixel.   2. The color filter according to claim 1, wherein the width of the gap at a height of ½ of the film thickness of the black matrix in a cross-sectional view is 1.5 to 7.5 μm.   3. The color filter according to claim 1, wherein the film thickness of the transparent resin pattern is 0.8 to 1.2 times the film thickness of the black matrix.