JP4298055B2 - Liquid crystal panel and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bright liquid crystal panel in relation to a liquid crystal panel used for a liquid crystal display device, a light shutter or the like, and to provide a method for manufacturing it. SOLUTION: In the liquid crystal panel comprising a liquid crystal held between at least a pair of substrates with attached electrodes and with a formed film, which vertically aligns the liquid crystal, a convex insulation layer 2 is formed on at least one of the substrates and an electrode is formed on the insulation layer 2. Thereby, white display is obtained because a sufficient electric field is applied to liquid crystal molecules 5. Also, the aperture ratio is widened because the electrode is formed on the insulation layer 2 and moreover, the brightness is improved. Also, by using the insulation layer 2 for improving the aperture ratio as the insulation layer 2 for tilting the liquid crystal molecules 5, the manufacturing steps are reduced.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal panel used for a liquid crystal display device, an optical shutter, and the like, and a method for manufacturing the same.
[0002]
[Prior art]
Liquid crystal panels are used for wristwatches, electronic desk calculators, personal computers, personal word processors, etc. due to their advantages of being thin, light and low voltage.
[0003]
Conventionally used TN (Twisted Nematic) type liquid crystal panel is a system in which electrodes are formed on upper and lower substrates and the liquid crystal is switched by a vertical electric field perpendicular to the substrate.
[0004]
On the other hand, as a method for widening the viewing angle of a liquid crystal panel, a horizontal electric field method (IPS (In−) in which liquid crystal molecules are operated by forming a pixel electrode and a counter electrode on the same substrate and applying a horizontal electric field. Plane-Swiching method or comb-shaped electrode method), or a method in which liquid crystal molecules are aligned vertically and liquid crystal molecules are horizontally aligned when voltage is applied (VA (Vertical Alignment) method or vertical alignment method) Has been proposed).
[0005]
[Problems to be solved by the invention]
FIG. 5 shows a configuration diagram of a conventional vertical alignment type liquid crystal panel. FIG. 5a) is a top view showing a configuration of a conventional liquid crystal panel. FIG. 5b) is a cross-sectional view taken along the line AA 'of FIG. 5a). FIG. 5c) is a cross-sectional view taken along the line BB 'of FIG. 5a).
[0006]
In a conventional liquid crystal panel, vertical alignment films 4a and 4b are formed on electrodes 3a and 3b, and liquid crystal 5 having a negative dielectric anisotropy is sealed in the panel. When a voltage is applied between the substrates, the liquid crystal molecules 5 are arranged horizontally on the substrate.
[0007]
In the conventional vertical alignment method, when a voltage is applied, liquid crystal molecules are tilted in one direction, so that a sufficient viewing angle cannot be obtained. On the other hand, as shown in FIG. 6, a method of tilting liquid crystal molecules in two directions by forming protrusions on the pixel electrode 3a (or the counter electrode 3b) in order to widen the viewing angle has been proposed (Japanese Patent Laid-Open No. Hei. 10-301114).
[0008]
However, in the conventional method as shown in FIG. 6, since the protrusion is formed on the pixel electrode, there is a drawback that an electric field is not easily applied to the protrusion and the drive voltage becomes high. That is, since it is difficult to apply a voltage to the liquid crystal molecules on the protrusions with a conventional voltage, it is difficult to sufficiently drive the liquid crystal molecules, and white display at the time of voltage application is insufficient.
[0009]
In addition, there is a drawback that the aperture ratio becomes small due to the protrusion.
[0010]
The present invention has been invented in view of the problems of conventional liquid crystal panels, and it is an object of the present invention to obtain a bright display by lowering the driving voltage and increasing the aperture ratio.
[0011]
[Means for Solving the Problems]
Liquid crystal panel according to the first aspect of the present invention in order to achieve the object of the film to align the liquid crystal vertically is formed, met LCD panel formed by sandwiching a liquid crystal between at least a pair of substrates with electrodes Thus, a convex color filter and a pixel electrode disposed on the convex color filter are formed on at least one of the substrates.
The method for manufacturing a liquid crystal display panel according to the second aspect of the present invention includes a step of forming a scanning signal line (gate line), a video signal line (source line) and a semiconductor layer on one substrate; Forming a partially convex color filter on the scanning signal line, video signal line and semiconductor layer; forming a pixel electrode on the convex color filter; and A step of forming an alignment film for vertically aligning the liquid crystal, and a step of enclosing the liquid crystal between the substrate and the other substrate.
[0012]
According to the present invention, by forming an electrode on the insulating film, a liquid crystal molecule is sufficiently driven because an electric field is sufficiently applied to the liquid crystal molecule, so that a bright display can be obtained. In addition, since the electrode is formed on the insulating film, the aperture ratio can be increased and the luminance can be further improved.
[0013]
Further, by combining the insulating film for improving the aperture ratio and the insulating film for tilting the liquid crystal molecules, the number of processes can be reduced.
[0014]
Further, by forming a convex color filter and forming an electrode thereon, the insulating film and the color filter can be used together, so that the number of processes can be reduced, and at the same time, the array substrate and the counter substrate This eliminates the need for a margin for alignment, and can further increase the aperture ratio.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiments.
[0016]
(Embodiment 1)
FIG. 1a) is a top view showing a configuration of a liquid crystal panel according to the present invention. FIG. 1b) is a cross-sectional view taken along the line AA 'of FIG. 1a). FIG. 1c) is a sectional view taken along the line BB ′ of FIG. 1a).
[0017]
Examples of the liquid crystal panel shown in FIGS. 1a), b) and c) will be described below.
[0018]
A scanning signal line (gate) and a video signal line (source) are formed in a matrix form on the glass substrate 1 as metal wiring, and a semiconductor layer (TFT: Thin Film) is formed as an active element (switching element) at the intersection. Transistor).
[0019]
First, a scanning signal line (gate) 20 is formed of a metal such as Al on the glass substrate 1a.
[0020]
Thereafter, an insulating film 2 such as SiNx is formed to protect the wiring, and a TFT is formed as a semiconductor layer 21 thereon. On top of that, SiNx is formed as a protective film 24.
[0021]
Next, a metal such as Al / Ti is formed as the video signal line (source) 22 and the drain 23.
[0022]
A convex insulating film 30 was formed thereon using a photosensitive acrylic resin (PC302: manufactured by JSR) by the following method.
[0023]
PC302 was applied onto the array substrate by spin coating, and pre-baked at 80 ° C. for 1 minute.
[0024]
Thereafter, exposure was performed at 300 mJ / cm ² from the glass substrate 1a side while pressing with a mold whose surface was processed into a predetermined shape. Thereafter, development is performed with a developer CD702AD at 25 ° C. for 1 minute, washed with running water, post-baked at 220 ° C. for 1 hour (temperature rise from room temperature), and a convex insulating film having a thickness of 1.5 μm. 30 was formed.
[0025]
In order to obtain sufficient insulation and to form the pixel electrode on a substantially flat surface, the film thickness of the insulating film is preferably 1 μm or more.
[0026]
Moreover, when irradiating light from the glass substrate 1a side, it is desirable to enter diffused light (either light is incident from the lateral direction or light is irradiated through the diffusion plate). Further, if a mold that transmits light is prepared, light can be incident from the insulating film surface 30.
[0027]
The pixel electrode 3a connected to the drain 23 is formed of a transparent conductive film (ITO: indium oxide-tin oxide). A contact hole 31 is formed in the insulating film 30, and the drain 23 and the pixel electrode 3a are in contact with each other.
[0028]
As the counter substrate, the black matrix 11 is formed on the glass 1b, and then the color filter 10 is formed. As a method for forming a color filter, a photosensitive resist in which a pigment is dispersed is applied onto a substrate, exposed, and developed (in order to produce a color filter in accordance with each color of red, blue, and green, the above step 3). Repeat).
[0029]
Thereafter, SiO2 was formed as an overcoat 12, and then a counter electrode 3b made of a transparent conductive film (ITO: indium oxide-tin oxide) was formed.
[0030]
Thereafter, a vertical alignment film (0.3% isopropyl alcohol solution of n-octadecyltriethoxysilane) is formed on the layers 1a and 1b as alignment films 4a and 4b, and is thermally dried at 100 ° C. for 1 hour.
[0031]
Next, a seal resin (Struct Bond: manufactured by Mitsui Toatsu) is printed on the edge of the glass substrate 1b.
[0032]
In the seal resin, 5.0 μm glass fiber (manufactured by Nippon Electric Glass) is mixed as a spacer.
[0033]
Thereafter, resin balls (Eposta GP-HC: manufactured by Nippon Shokubai Co., Ltd.) having a diameter of 4.5 μm are sprayed as a spacer in the display area in order to maintain the substrate interval.
[0034]
In order to establish electrical connection between the array substrate 1 and the counter substrate 2, a conductive paste is applied to the substrate end.
[0035]
Thereafter, the substrate 1a and the counter substrate 2a are bonded together, and the seal resin is cured by heating at 150 ° C. for 2 hours.
[0036]
Liquid crystal 5 (ZLI4788: manufactured by Merck & Co., Inc.) was vacuum-injected into the empty panel produced as described above (installed in a tank in which the empty panel was decompressed, the inside of the panel was evacuated, and then the inlet was brought into contact with the liquid crystal. The liquid crystal is injected by a method of injecting liquid crystal into the panel by returning the inside of the tank to normal pressure.
[0037]
Thereafter, a photocurable resin (Loctite 352A: manufactured by Nippon Loctite) was applied as a sealing resin to the injection port of the liquid crystal panel, and light was irradiated at 10 mW / cm ² for 5 minutes to cure the sealing resin.
[0038]
Polarizing plates (NPF-HEG1425DU: manufactured by Nitto Denko) were attached to the upper and lower sides of these substrates 1 and 2 (outside of the glass substrate).
[0039]
As a comparative example, a liquid crystal panel having protrusions 25 formed on the pixel electrodes 3a was also manufactured (FIG. 6).
[0040]
When a voltage was applied to these liquid crystal panels and they were observed using a microscope, the liquid crystal panel in which the protrusions were formed on the pixel electrodes (the above comparative example) did not apply a sufficient transverse electric field to the liquid crystal molecules around the protrusions. In contrast, the liquid crystal molecules did not move sufficiently and a sufficient white display could not be obtained. On the other hand, in the liquid crystal panel in which the electrode is formed on the insulating film according to the present embodiment, an electric field is sufficiently applied to the liquid crystal molecules. Therefore, a sufficient white display could be obtained.
[0041]
Further, since the electrode is formed on the insulating film, the aperture ratio can be increased as shown in FIG. 1a), and a brighter display can be obtained (the conventional example is FIG. 5a)).
[0042]
In a conventional TN panel, a method of forming an insulating film (also referred to as a planarizing film) to improve the aperture ratio and forming an electrode on the insulating film has been devised. The present invention is the first method for forming liquid crystal and thereby tilting liquid crystal molecules.
[0043]
Thus, the process can be reduced by combining the insulating film for improving the aperture ratio and the insulating film for inclining liquid crystal molecules.
[0044]
In this embodiment, a convex insulating film having a mountain shape (semispherical or semi-elliptical spherical shape) is used, but it is not a mountain shape but a semi-cylindrical shape (semi-elliptical column shape) (FIGS. 2a), b), and c). ), Triangular shape (triangular prism shape), polygonal shape, conical shape, or the like.
[0045]
Although FIG. 1 shows the case where the alignment direction of the liquid crystal is divided into multiple parts, it may be divided into two parts as shown in FIG.
[0046]
Further, these shapes can be formed by etching, and a convex portion may be formed after a flat insulating film is formed. The convex portion in that case can also be achieved by rapidly increasing the post-bake temperature of the insulating film.
[0047]
1 can be used as a reflective liquid crystal by using a reflective electrode such as Al.
[0048]
(Embodiment 2)
FIG. 3 is a cross-sectional view showing the configuration of the liquid crystal panel according to the present invention.
[0049]
In the first embodiment, the electrode is formed on the top of the convex insulating film 30, but instead, the electrode is formed on the convex color filter 10.
[0050]
The color filter layer 10 was formed by forming a colored resist, in which a pigment was dispersed in an acrylic photosensitive resin, on a substrate using an ink jet method, and prebaked at 80 ° C. for 1 minute.
[0051]
The coloring resist was formed at the positions corresponding to the respective primary colors of R, G, and B.
[0052]
Thereafter, exposure was performed at 500 mJ / cm ² from the glass substrate 1 side while pressing with a mold whose surface was processed into a predetermined shape. Thereafter, development was performed with a developer at 25 ° C. for 2 minutes, washed with running water, and post-baked at 200 ° C. for 1 hour to form an uneven color filter layer 10 having a thickness of 1.0 μm.
[0053]
In this embodiment, each color (R, G, B) is formed simultaneously using the ink jet method, but it may be formed one color at a time using a spin coating method or a printing method.
[0054]
Although a photosensitive colored resist is used, after forming a non-photosensitive polymer material in which a pigment is dispersed on a substrate, a photosensitive resist layer may be separately formed, and exposure and development may be performed. It is also possible to use other methods such as a staining method.
[0055]
In addition, when irradiating light from the glass substrate 1 side, it is preferable to enter diffused light, and if a mold that transmits light is prepared, light can be incident from the color filter surface 10. This is the same as the first embodiment.
[0056]
The subsequent electrode forming method and panel forming method are the same as those in the first embodiment.
[0057]
With the configuration of the present invention, the driving voltage can be lowered because a sufficient electric field is applied to the liquid crystal molecules. Further, since the electrode 3a is formed on the color filter 10, the aperture ratio can be widened, and an object is to obtain a bright display.
[0058]
Compared to the first embodiment, since the insulating film and the color filter can be used together, the number of processes and members can be reduced, and at the same time, a margin for aligning the array substrate 1a and the counter substrate 1b is provided. Since it becomes unnecessary, the aperture ratio can be further increased.
[0059]
In this embodiment, a convex color filter having a mountain shape (semispherical or semi-elliptical spherical shape) is used. A shape, a cone shape, etc. may be sufficient.
[0060]
In this embodiment, the alignment direction of the liquid crystal is divided into multiple parts. However, the liquid crystal may be divided into two parts, such as a triangular prism, or a quadrangular pyramid.
[0061]
These shapes can be formed by etching, or a convex portion may be formed after a flat color filter is formed.
[0062]
(Embodiment 3)
FIG. 4a) is a top view showing the configuration of the liquid crystal panel according to the present invention. FIG. 4b) is a cross-sectional view taken along the line AA 'of FIG. 4a). FIG. 4c) is a cross-sectional view taken along the line BB 'of FIG. 4a).
[0063]
Examples of the liquid crystal panel shown in FIGS. 4a), b) and c) will be described below.
[0064]
In the first embodiment, the projections made of the insulating film are provided in a mountain shape in the pixel as shown in FIG. 1, but a large number of irregular projections are formed in the pixel as shown in FIG. With this configuration, as shown in FIGS. 4b) and 4c), the liquid crystal molecules are divided into fine regions and tilted in multiple directions, so that a panel with a wide viewing angle can be obtained.
[0065]
4 can be used as a reflective liquid crystal by using a reflective electrode such as Al.
[0066]
In this embodiment, a three-terminal element TFT is used as the active element, but a two-terminal element MIM (Metal-Insulator-Metal), ZnO varistor, SiNx diode, a-Si diode, or the like may be used.
[0067]
In this embodiment, the bottom gate structure a-Si is used as the transistor structure, but a top gate structure or p-Si may be used. A drive circuit may be formed around the substrate.
[0068]
In this embodiment, both substrates are formed of glass substrates, but one or both of the substrates may be formed of a film or plastic.
[0069]
Also, a polyimide-based or polyamic acid-based alignment film may be used as the vertical alignment film, and a method of aligning with light may be used as the alignment method.
[0070]
Further, a uniform cell thickness can be formed by using a cell thickness forming method that is not a spacer spraying method (for example, a method of forming columns with resin).
[0071]
【The invention's effect】
As described above, according to the present invention, in a liquid crystal panel in which a liquid crystal is sandwiched between at least a pair of substrates with electrodes formed with a film for vertically aligning liquid crystals, a convex insulation is formed on at least one substrate. By forming a film and forming an electrode on the insulating film, a sufficient white display can be obtained because an electric field is sufficiently applied to the liquid crystal molecules.
[0072]
In addition, since the electrode is formed on the insulating film, the aperture ratio can be increased and the luminance can be further improved. Further, by combining the insulating film for improving the aperture ratio and the insulating film for tilting the liquid crystal molecules, the number of processes can be reduced.
[Brief description of the drawings]
1A is a top view schematically showing the structure of a liquid crystal panel according to the first embodiment; FIG. 1B is a cross-sectional view schematically showing the structure of a liquid crystal panel according to the first embodiment; and FIG. 2 is a cross-sectional view schematically showing the structure of the liquid crystal panel in Embodiment 1. FIG. 2A is a top view schematically showing the structure of the liquid crystal panel in Embodiment 1. FIG. 2B is a cross-sectional view of the liquid crystal panel in Embodiment 1. Cross-sectional view schematically showing the structure (c) Cross-sectional view schematically showing the structure of the liquid crystal panel according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing the structure of the liquid crystal panel according to the second embodiment. 4A is a top view schematically showing the structure of the liquid crystal panel according to the third embodiment. FIG. 4B is a cross-sectional view schematically showing the structure of the liquid crystal panel according to the third embodiment. FIG. Sectional drawing which shows the structure of the liquid crystal panel in 3 typically 5A is a top view schematically showing the structure of a conventional liquid crystal panel. FIG. 5B is a cross-sectional view schematically showing the structure of a conventional liquid crystal panel. FIG. 5C is a cross section schematically showing the structure of a conventional liquid crystal panel. FIG. 6 is a cross-sectional view schematically showing the structure of a conventional liquid crystal panel.
1a Glass substrate 1b Glass substrate 2 Insulating film (SiNx)
3a pixel electrode 3b counter electrode 4a alignment film 4b alignment film 5 liquid crystal molecule 10 color filter
11 Black matrix 12 Insulating film (SiOx)
20 Gate 21 Semiconductor layer 22 Source 23 Drain 24 Insulating film (SiNx)
25 Protrusion 30 Insulating film

Claims (3)

A liquid crystal panel in which a liquid crystal is sandwiched between at least a pair of substrates with electrodes on which a film for vertically aligning liquid crystals is formed,
A liquid crystal panel in which a convex color filter and a pixel electrode disposed on the convex color filter are formed on at least one substrate.   Forming a scanning signal line (gate line), a video signal line (source line) and a semiconductor layer on one substrate;
  Forming a partially convex color filter on the scanning signal line, the video signal line, and the semiconductor layer;
  Forming a pixel electrode on the convex color filter;
  Forming an alignment film for vertically aligning liquid crystal on the pixel electrode;
  A method of manufacturing a liquid crystal panel, comprising: enclosing a liquid crystal between the substrate and the other substrate. The method for manufacturing a liquid crystal panel or a liquid crystal display panel according to claim 1, wherein the color filter has a thickness of 1 μm or more.

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