JP3809043B2 - Manufacturing method of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device with a uniform cell gap and high display quality and its manufacturing method. SOLUTION: In the liquid crystal display device 23, a color filter substrate 25 with projecting parts 5 formed with black masks 4 and a TFT(thin film transistor) substrate 26 with recessing parts 18 formed with resin films 16 such as alignment layers are stuck together via scattered spacers 1 in between and a liquid crystal is enclosed between the substrates. The resin films 16 such as the alignment layers are pattern formed in parts other than those opposite to the projecting parts so as to form the recessing parts 18 on the TFT substrate 26. Owing to the formation of the recessing parts 18, even if scattered spacers 21 are arranged on the projecting parts 5, the scattered spacers 21 do not push up the cell gap. Thus, the cell gap is kept uniform even when the respective substrates 25, 26 are not flat.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display device.
[0002]
[Prior art]
The liquid crystal display device has a pair of substrates facing each other, a cell gap is held constant by spacers, and liquid crystal is sealed between the substrates. FIG. 3 is a cross-sectional view showing a configuration of a conventional liquid crystal display device 20. The liquid crystal display device 20 includes a color filter substrate 25 and a TFT (Thin Film Transistor) substrate 26.
[0003]
In the color filter substrate 25, the color filter 2, the black mask 4 and a counter electrode (not shown) are arranged on a transparent substrate 8 made of glass or the like, and the alignment film 15 is coated on the surface. In the TFT substrate 26, a liquid crystal driving element such as a TFT element, a wiring portion 3, an insulating film 7, a pixel electrode (not shown) and the like are disposed on a transparent substrate 9, and an alignment film 16 is coated on the surface.
[0004]
The liquid crystal display device 20 is, for example, a liquid crystal sealing in which a color filter substrate 25 and a TFT substrate 26 are mixed with a dispersion spacer 1 for holding a cell gap and a spacer 13 for holding a cell gap at the periphery of the liquid crystal display device 20. It is manufactured by forming an empty cell by laminating through the sealing material 14 and injecting liquid crystal 17 into the empty cell and sealing the injection port with a sealing agent such as resin.
[0005]
The cell gap is an interval G between the color filter substrate 25 and the TFT substrate 26 in a pixel region where the pixel electrode and the counter electrode face each other. The cell gap mainly includes the diameter of the spacer 13 in the scattering spacer 1 and the sealing material 14 and the liquid crystal. 17 injection and sealing conditions. In addition, the uniformity of the cell gap is closely related to the display quality of the liquid crystal display device 20. If the uniformity of the cell gap is low, display unevenness such as luminance unevenness and color unevenness occurs on the display screen. Occurs.
[0006]
[Problems to be solved by the invention]
In the rectangular display portion of the liquid crystal display device 20, a large number of pixels facing the counter electrode and the pixel electrode are arranged vertically and horizontally, and the color filter 2 is provided corresponding to each pixel. In the display unit, in order to prevent light leakage between adjacent pixels, a black mask 4 surrounding the color filter 2 of each pixel is formed in a lattice shape over the entire display unit as necessary, and is formed on the frame portion surrounding the display unit. A frame-shaped black mask 10 is formed.
[0007]
Since the black masks 4 and 10 are made of resin in the same manner as the color filter 2, it is necessary to increase the film thickness in order to obtain sufficient light shielding properties. For this reason, the film thickness of the black masks 4 and 10 is larger than the film thickness of the color filter 2, whereby the convex portions 5 and 12 are formed on the surface of the alignment film 15 of the color filter substrate 25.
[0008]
In the liquid crystal display device 20, the convex portions 5 and 12 are formed on the surface of the color filter substrate 25 facing the liquid crystal 17 by the black masks 4 and 10. A convex portion generated by a liquid crystal driving element or the like is formed, and irregularities may be formed on the surfaces of the substrates 25 and 26 facing the liquid crystal.
[0009]
FIG. 3 shows a state in which the cell gap is uniformly formed without the scattering spacer 1 being disposed on the convex portions 5 and 12 formed by the black masks 4 and 10. However, since the distribution spacer 1 is randomly distributed on the color filter substrate 25 or the TFT substrate 26, the arrangement position is unspecified.
[0010]
FIG. 4 is a cross-sectional view schematically showing a state where the scattering spacer 6 is disposed on the convex portion 5 of the display unit. Since the scattering spacer 6 is arranged on the convex portion 5 formed by the black mask 4 of the color filter substrate 25, the cell gap defined by the scattering spacer 6 arranged on the convex portion 5 is arranged in a flat portion. It is larger than the cell gap defined by the other scattering spacers 1 by the height of the convex portion 5, and the cell gap is uneven due to the difference in the substrate spacing, and display unevenness such as uneven brightness and uneven color on the display screen. Will occur.
[0011]
FIG. 5 is a cross-sectional view schematically showing a state where the scattering spacer 11 is arranged on the convex portion 12 of the frame portion. Whereas most of the display unit except for the liquid crystal driving element and the wiring unit 3 is formed of a transparent thin film capable of transmitting pixel electrode light, light does not leak from the peripheral portion of the display unit. Therefore, since the frame-like black mask 10 is formed, the display portion and the frame portion have different film structures.
[0012]
The film thickness of the black mask 10 is thicker than the film thickness of the color filter 2, thereby causing a step between the display portion and the frame portion, and the convex portion 12 is formed on the surface of the alignment film 15 of the color filter substrate 25 in the frame portion. It is formed. For this reason, the cell gap prescribed | regulated by the spreading | diffusion spacer 11 arrange | positioned at the convex part 12 of a frame part is larger than the cell gap prescribed | regulated by the spacer 13 in the sealing material 14, and the spreading | diffusion spacer 11 is a cell around a display part. The gap is pushed up to cause unevenness in the cell gap, and display unevenness such as luminance unevenness and color unevenness occurs on the display screen near the scattering spacer 11.
[0013]
In the related art for the spacer of the liquid crystal display device, there is one in which the cell gap in the peripheral portion is adjusted by changing the diameter of the spacer 13 in the sealing material 14. However, as shown in FIG. 5, when the scattering spacer 11 is disposed on the convex portion 12 such as the black mask 10 at the frame portion, the scattering spacer 11 is more cell gap than the spacer 13 in the sealing material 14. Therefore, even if the diameter of the spacer 13 in the sealing material 14 is changed, it is impossible to prevent the unevenness of the cell gap due to the scattering spacers 11 arranged in the frame portion.
[0014]
On the other hand, other prior arts attempt to improve the cell gap non-uniformity by reducing the film thickness of the film forming the convex portion such as a black mask. There is a problem that the film thickness of the film forming the convex portion cannot often be reduced due to technical reasons or display quality reasons such that sufficient light shielding properties cannot be obtained if the film thickness is reduced.
[0015]
In another conventional technique, an acrylic liquid resin or the like is applied to a substrate by a spin coat method, and the applied thin film is baked to overcoat convex portions, thereby improving the flatness of the substrate. . However, this prior art method has the problem that the overcoat process increases.
[0016]
In another prior art disclosed in Japanese Patent Laid-Open No. 7-92477, a cell gap between a portion where a transparent electrode ITO (Indium-Tin Oxide) film is formed and a portion where a cell gap is not formed is formed. The difference is corrected by forming a dummy ITO film. However, in this method, the position where the ITO film can be formed and the film thickness of the ITO film are limited, and thus the unevenness of the cell gap due to the fine protrusions formed by a black mask or the like cannot be improved.
[0017]
An object of the present invention is to provide a method for manufacturing a liquid crystal display device having a uniform cell gap and high display quality.
[0018]
[Means for Solving the Problems]
The present invention relates to a method of manufacturing a liquid crystal display device in which a spacer is interposed between a pair of substrates facing each other with a predetermined interval, and liquid crystal is sealed between the substrates.
On the other hand, when a convex portion is formed on the surface of the substrate facing the liquid crystal, the convex portion is formed by the resin black mask itself, and on the other side of the surface of the substrate facing the liquid crystal on the portion facing the convex portion of the black mask. Forming a recess,
The substrate interval in the recess is formed so that it is equal to or greater than the substrate interval in the area where the convex portion of the black mask does not exist, and the substrate interval of the portion where the protrusion and the recess are formed is arranged in the suburbs other than the spacer entering the recess The liquid crystal display device manufacturing method is characterized in that the cell gap is made uniform by being defined by another spacer.
[0019]
According to the present invention, when a convex portion is formed on one substrate, the convex portion is formed by a black mask made of resin itself, and the black mask is formed thicker than the color filter in order to obtain light shielding properties. By using the convex portion and forming a concave portion in the portion of the other substrate facing the convex portion, it is possible to prevent the cell gap from being pushed up by the spacer disposed in the convex portion, and the substrate interval in the concave portion. However, it is formed so that it is equal to or larger than the substrate interval in the region where the convex portion does not exist, and the substrate interval in the portion where the convex portion and the concave portion are formed is defined by other spacers disposed in the suburbs other than the spacer entering the concave portion Thus, the cell gap can be made uniform even if each substrate is not flat. For this reason, it is possible to prevent the display quality of the liquid crystal display device from being deteriorated due to the unevenness of the cell gap, and the display quality is improved.
[0020]
Further, if the concave portion is formed by the thin film constituting the other substrate, it is not necessary to add a process such as an overcoat process for forming a new film on the substrate surface, and the cost of the product is not increased.
[0026]
According to the present invention, the liquid crystal display device includes at least a display portion and a frame portion surrounding the display portion, and the black mask is formed so as to surround the color filter of each pixel in the display portion. Is provided as a convex portion, and a concave portion is formed on the other substrate corresponding to the convex portion of the black mask.
[0027]
According to the present invention, the black mask is also provided in the frame portion, and the spacer is accommodated by the corresponding concave portion, so that the cell gap can be made uniform.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
The liquid crystal display device has a pair of substrates facing each other, a cell gap is held constant by spacers, and liquid crystal is sealed between the substrates.
[0030]
On the other hand, the substrate is a color filter substrate in which a color filter, a black mask, a counter electrode, and the like are arranged on a transparent substrate made of glass and the like, and an alignment film is coated on the surface. The other substrate is a TFT on the transparent substrate. A TFT substrate in which a liquid crystal driving element such as an element, a wiring portion, an insulating film, a pixel electrode, and the like are arranged and an alignment film is coated on the surface.
[0031]
In many liquid crystal display devices, a color filter substrate and a TFT substrate are bonded to each other through a liquid crystal sealing seal material in which a spacer that holds the cell gap and a spacer that defines the cell gap around the display portion are mixed. It is manufactured by forming an empty cell, injecting liquid crystal into the empty cell, and sealing the injection port with a sealing agent such as resin.
[0032]
The cell gap is the distance between the color filter substrate and the TFT substrate in the pixel region where the pixel electrode and the counter electrode face each other. The cell gap mainly includes the diameter of the spacer in the scattering spacer and the sealing material, and the injection and sealing conditions of the liquid crystal. And determined by. In addition, the uniformity of the cell gap is closely related to the display quality of the liquid crystal display device. If the uniformity of the cell gap of the display portion is low, display unevenness such as luminance unevenness and color unevenness occurs on the display screen.
[0033]
FIG. 1 is a schematic cross-sectional view showing a configuration of a display unit of a liquid crystal display device 23 according to an embodiment of the present invention. The liquid crystal display device 23 includes a color filter substrate 25 and a TFT substrate 26.
[0034]
In the color filter substrate 25, a color filter 2, a black mask 4, a counter electrode (not shown), and the like are disposed on a transparent substrate made of glass or the like, and an alignment film (not shown) is coated on the surface. The TFT substrate 26 includes a liquid crystal driving element such as a TFT element (not shown), a wiring portion, an insulating film, a pixel electrode, and the like disposed on a transparent substrate, and a resin film (hereinafter referred to as an alignment film) 16 such as an alignment film is coated on the surface. ing.
[0035]
The area where the counter electrode and the pixel electrode of the liquid crystal display device 23 face each other is a pixel area directly related to display. A large number of pixels are arranged vertically and horizontally in a rectangular display portion, and a color filter 2 is provided for each pixel. Provided. In the display unit, a black mask 4 surrounding the color filter 2 of each pixel is formed in a grid pattern over the entire display unit of the color filter substrate 25 as necessary in order to prevent light leakage between adjacent pixels.
[0036]
Since the black mask 4 is made of resin in the same manner as the color filter 2, it is necessary to increase the film thickness in order to obtain sufficient light shielding properties. For this reason, the film thickness of the black mask 4 is thicker than the film thickness of the adjacent color filter 2, whereby the convex portion 5 is formed on the surface of the color filter substrate 25 facing the liquid crystal 17.
[0037]
In the liquid crystal display device 23, the convex portion 5 generated by the black mask 4 is formed on the surface of the color filter substrate 25. In addition to this, the convex portion generated by the wiring portion and the liquid crystal driving element is formed on the surface of the TFT substrate 26. There are cases.
[0038]
In the liquid crystal display device 23, the alignment film 16 of the TFT substrate 26 is formed except for the portion facing the convex portion 5 of the color filter substrate 25, whereby the concave portion 18 is formed on the surface of the TFT substrate 26 facing the liquid crystal 17. It is formed. The interval between the substrate 25 and the substrate 26 in the recess 18 is formed to be equal to or greater than the substrate interval G, which is a cell gap in a region where the protrusion 5 does not exist.
[0039]
The distribution spacer 1 is randomly distributed on the surface of the alignment film of the color filter substrate 25 or the alignment film 16 of the TFT substrate 26. Therefore, as shown in FIG. 4, in the conventional liquid crystal display device 20, when the scattering spacers 6 are arranged on the convex portions 5 when the substrates 25 and 26 are bonded to form a cell, the convex portions 5 are arranged. The spreading spacer 6 is supported, and the surrounding cell gap becomes large, causing display unevenness.
[0040]
However, in the liquid crystal display device 23, the concave portion 18 is formed in the portion of the TFT substrate 26 that faces the convex portion 5, and therefore the scattering spacer 21 disposed on the convex portion 5 is formed in the concave portion formed in the TFT substrate 26. 18 and the cell gap can be prevented from being pushed up by the scattering spacer 21. For this reason, since the cell gap of the part in which the convex part 5 and the recessed part 18 are formed is prescribed | regulated by the other spreading | diffusion spacer 1 arrange | positioned in the suburbs, the cell gap of the liquid crystal display device 23 becomes uniform. In the liquid crystal display device 23, since the cell gap is made uniform even if the substrates 25 and 26 are not flat as described above, the substrate surface on which the convex portions are formed is planarized by an overcoat film. It is not necessary to add an overcoat process, and the cost of the product can be prevented.
[0041]
Next, an example of a method for forming the alignment film 16 will be described. First, a polyimide thin film is formed by applying and drying a liquid material to be the alignment film 16 on the surface of a substrate on which a wiring portion, a liquid crystal driving element, an insulating film, a pixel electrode, and the like are arranged on a transparent substrate by spin coating or the like. Then, a resist resin, which is an ultraviolet curable resin, is applied to the surface to form a resist film.
[0042]
Thereafter, a mask plate on which a predetermined mask pattern is formed is arranged above the resist film so that the portion where the concave portion 18 is formed is shielded from light. Next, exposure is performed by irradiating the resist film with ultraviolet rays from above the mask plate. The resist film in which the portion covering the surface of the polyimide film that becomes the alignment film 16 by exposure is developed, and the resist in the portion where the recess 18 is formed is removed.
[0043]
A portion of the polyimide film on which the resist pattern is formed where the concave portion 18 is formed is removed by etching, and the resist film is further removed. The patterned alignment film 16 is formed by rubbing the surface of the polyimide film thus patterned using a cloth or the like.
[0044]
As the film for forming the recess 18, in addition to the alignment film 16, a film that does not adversely affect the liquid crystal display, such as a coating film made of an acrylic resin constituting the TFT substrate 26, an inorganic insulating coat film made of water glass, and the like. select. If the film forming the recess 18 is patterned by, for example, a photo process that performs exposure and development, the recess 18 can be formed by changing the shape of the mask pattern of the mask plate. Further, as a method for forming these films, there is a printing method in addition to the above-described photolithography method.
[0045]
FIG. 2 is a schematic cross-sectional view showing the configuration of the frame portion of the liquid crystal display device 23 according to the embodiment of the present invention. A frame-shaped black mask 10 having a thickness greater than that of the color filter 2 is formed on the frame portion surrounding the display portion of the liquid crystal display device 23 in order to prevent light leakage therefrom. Therefore, the convex portion 12 is formed on the surface of the color filter substrate 25 facing the liquid crystal 17 at the frame portion. A recess 19 is formed by the alignment film 16 on the surface of the TFT substrate 26 facing the liquid crystal 17. The interval between the substrate 25 and the substrate 26 in the recess 19 is formed to be equal to or greater than the substrate interval G, which is a cell gap in a region where the protrusion 5 does not exist.
[0046]
As shown in FIG. 5, in the conventional liquid crystal display device 20, when the scattering spacer 11 is arranged on the black mask 10 in the frame portion, the spreading spacer 6 is arranged in the black mask 4 of the display portion shown in FIG. 4. Since the film thickness of the black mask 10 is thick, the cell gap is pushed up by the scattering spacers 11.
[0047]
The peripheral cell gap of the liquid crystal display device is optimized mainly by the spacer in the sealing material. However, when the scattering spacer 11 is disposed on the convex portion 12 as shown in FIG. Since the spreading spacer 11 is more dominant than the cell gap than 13, the cell gap in the frame portion is pushed up by the spreading spacer 11, and the cell gap in the vicinity of the frame portion is increased. For this reason, in the conventional liquid crystal display device 20, the scattering spacer 11 affects the display part in the vicinity of the frame part, and display unevenness occurs around the display part.
[0048]
However, when the concave portion 19 is formed in a portion facing the convex portion 12 of the TFT substrate 26 as in the liquid crystal display device 23 shown in FIG. 2, even if the scattering spacer 22 is disposed on the convex portion 12, the scattering spacer 22. Enters the recess 19, so that the cell gap is not pushed up by the scattering spacer 22. Therefore, the peripheral cell gap is defined by the diameter of the spacer 13 in the sealing material 14, and the cell gap can be made uniform by optimizing the diameter of the spacer 13.
[0049]
The recess 19 is formed by the patterned alignment film 16, and the alignment film 16 is patterned by the photolithography method described above.
[0050]
As the film for forming the recess 19, in addition to the alignment film 16, a film that does not adversely affect the liquid crystal display, such as a coating film made of an acrylic resin constituting the TFT substrate 26, an inorganic insulating coating film made of water glass, and the like. select. If the film for forming the recess 19 is patterned by, for example, a photo process that performs exposure and development, the recess 19 can be formed by changing the shape of the mask pattern of the mask plate. As a method for forming these films, there is a printing method in addition to the photolithography method.
[0051]
As described above, in the liquid crystal display device 23, even when the film thickness of the black masks 4 and 10 cannot be reduced due to display quality reasons, the concave portions 18 and 18 are formed on the surface facing the liquid crystal 17 of the opposing TFT substrate 26. By forming 19, the cell gap can be made uniform even if the substrates 25 and 26 are not flat. Thus, in the liquid crystal display device 23, technical reasons such as a method of forming a film for forming the convex portions 5 and 12, or display quality reasons such that sufficient light shielding properties cannot be obtained if the above-described film thickness is reduced. Therefore, even when the film thickness cannot be reduced, the cell gap can be made uniform by adjusting the surface of the substrate 26 facing the liquid crystal 17 facing the convex portions 5 and 12.
[0052]
Note that each substrate of the liquid crystal display device may have not only the above-described convex portions but also concave portions. Due to the concave portions formed on the substrate, a part of the cell gap becomes small, and the cell gap becomes uneven. There is a case.
[0057]
【The invention's effect】
As described above, according to the present invention, when a convex portion is formed on one substrate, the convex portion is formed by the black mask made of resin itself, and the black mask is formed thicker than the color filter in order to obtain light shielding properties. Therefore, the convex portion is used, and a concave portion is formed in the portion of the other substrate facing the convex portion, and the concave portion is formed so that the substrate interval in the concave portion is equal to or larger than the substrate interval in the region where the convex portion does not exist. The distance between the substrate where the portion and the concave portion are formed is regulated by other spacers disposed in the suburbs other than the spacer entering the concave portion, thereby preventing the cell gap from being pushed up by the spacer disposed in the convex portion. The cell gap can be made uniform even if each substrate is not flat. For this reason, display unevenness such as color unevenness and brightness unevenness of the liquid crystal display device due to unevenness of the cell gap can be prevented, and the display quality is improved.
[0058]
Further, if the concave portion is formed by the thin film constituting the other substrate, it is not necessary to add a process such as an overcoat process for forming a new film on the substrate surface, and the cost of the product is not increased.
[0062]
Further, according to the present invention, the black filter surrounds the color filter of the display portion and forms the frame portion, and the corresponding substrate has the recess, so that the spacer can be accommodated here and the cell gap can be made uniform. .
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a configuration of a display unit of a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing a configuration of a frame portion of a liquid crystal display device 23 according to an embodiment of the present invention.
3 is a cross-sectional view showing a configuration of a conventional liquid crystal display device 20. FIG.
FIG. 4 is a cross-sectional view schematically showing a state in which the scattering spacer 6 is disposed on the convex portion 5 of the display unit.
FIG. 5 is a cross-sectional view schematically showing a state in which the scattering spacers 11 are arranged on the convex portion 12 of the frame portion.
[Explanation of symbols]
1, 2, 22 Spreading spacer 2 Color filter 4, 10 Black mask 5, 12 Protrusion 13 Spacer 14 in sealing material Sealing material 16 Resin film 17 such as alignment film Liquid crystal 18, 19 Recess 23 Liquid crystal display device 25 Color filter substrate 26 TFT substrate

Claims (2)

In a method of manufacturing a liquid crystal display device in which a spacer is interposed between a pair of substrates facing each other with a predetermined interval, and liquid crystal is sealed between the substrates.
On the other hand, when a convex portion is formed on the surface of the substrate facing the liquid crystal, the convex portion is formed by the resin black mask itself, and on the other side of the surface of the substrate facing the liquid crystal on the portion facing the convex portion of the black mask. Forming a recess,
The substrate interval in the recess is formed so that it is equal to or greater than the substrate interval in the area where the convex portion of the black mask does not exist, and the substrate interval of the portion where the protrusion and the recess are formed is arranged in the suburbs other than the spacer entering the recess A method of manufacturing a liquid crystal display device, characterized in that the cell gap is made uniform by being defined by another spacer.   The liquid crystal display device includes at least a display portion and a frame portion surrounding the display portion, and the black mask is formed so as to surround the color filter of each pixel in the display portion, and the frame portion also has a convex portion. 2. The method for manufacturing a liquid crystal display device according to claim 1, wherein a recess is formed on the other substrate provided and corresponding to the protrusion of the black mask.

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