JPH06160833A - Production of liquid crystal display device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the electrode from breaking at the edge of the smoothing layer. A photomask in which a color filter 33 is provided on the upper electrode substrate 11, a photocurable resin is applied on the color filter 33, and a metal light-shielding film 72 is formed on a transparent substrate 71 having a frosted surface 71a on the exposure light source side. Exposure light through
3 is irradiated on the photo-curable resin to cure the photo-curable resin to form the smooth layer 23, and the non-cured portion 23b of the photo-curable resin is removed, and then the upper electrode 31 and the terminal 31 are formed.
a is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device capable of multicolor display.

[0002]

2. Description of the Related Art In a field effect type liquid crystal display device of a simple matrix system called super twist nematic, two transparent electrode substrates having transparent electrodes formed on them are opposed to each other with an interval of several μm. It has a structure filled with liquid crystal. When performing multicolor display in this liquid crystal display device, a color filter is formed on either electrode substrate, but the electrodes are often formed on the color filter. In this case, a smoothing layer is formed between the color filter and the electrode to protect and flatten the surface of the color filter.

A driving IC is connected to the terminal formed at the end of the electrode, but the smooth layer is often an organic substance, and the mechanical strength of the smooth layer is low. Therefore, when the terminals are formed on the smooth layer, there is a problem that the terminals are separated from the protective film when the driving IC is connected to the terminals or when the defective IC is removed. Therefore, terminals are formed on the electrode substrate.

A conventional method of manufacturing a liquid crystal display device will be described with reference to FIG. First, as shown in FIG. 11A, the color filter 33 is provided on the upper electrode substrate 11. Next, as shown in FIG. 11B, the photocurable resin 23 a is applied on the color filter 33. Next, as shown in FIG. 11C, the exposure light (ultraviolet ray) 93 is exposed to the photocurable resin 2 through a photomask in which a metal light shielding film 92 is formed on the transparent substrate 91.
The smoothing layer 23 is formed by irradiating 3a to cure the photocurable resin 23a. Next, as shown in FIG. 11D, the non-cured portion 23b of the photocurable resin 23a
Then, an ITO (In ₂ O ₃ ) film is provided on the smoothing layer 23, and the ITO film is selectively etched to form the upper electrode 31 and the terminal 31a.

A field effect type liquid crystal display device is known, for example, from Japanese Patent Publication No. 51-13666.

[0006]

In this method of manufacturing a liquid crystal display device, since a step corresponding to the thickness of the smoothing layer 23 is formed at the end of the smoothing layer 23, the above-mentioned process is performed at the time of etching when forming the upper electrode 31. Side etching occurs at the step,
In many cases, the upper electrode 31 is broken at the step.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a liquid crystal display device in which electrodes are not broken at the end of the smoothing layer.

[0008]

To achieve this object, in the present invention, a color filter is provided on an electrode substrate, a smooth layer is formed on the color filter, and an electrode is formed on the smooth layer. In the method of manufacturing a liquid crystal display device in which the terminal of the electrode is formed on the electrode substrate, a photocurable resin is applied on the color filter, and the light shielding film portion of the photomask is irradiated with scattered light.

[0009]

In this liquid crystal display device, since the gently sloping surface is formed at the end of the smooth layer, side etching does not occur at the end of the smooth layer during etching when forming the electrode.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a liquid crystal display device for carrying out the method according to the present invention will be described in detail with reference to the drawings.

FIG. 4 shows an arrangement direction of liquid crystal molecules on the electrode substrate (for example, a rubbing direction), a twisting direction of the liquid crystal molecules, a polarization axis (or an absorption axis) direction of a polarizing plate when the liquid crystal display device 62 is viewed from above. FIG. 5 shows the optical axis direction of the member that produces the birefringence effect, and FIG.

Twisting direction 10 of liquid crystal molecules and twist angle θ
Is the rubbing direction 6 of the alignment film 21 on the upper electrode substrate 11,
The rubbing direction 7 of the alignment film 22 on the lower electrode substrate 12 and the optical rotatory substance added to the nematic liquid crystal layer 50 having a positive dielectric anisotropy sandwiched between the upper electrode substrate 11 and the lower electrode substrate 12 Specified by type and quantity.

In FIG. 5, liquid crystal molecules are aligned between the upper electrode substrate 11 and the lower electrode substrate 12 sandwiching the liquid crystal layer 50 so as to form a twisted spiral structure. A method of rubbing the surfaces of the alignment films 21 and 22 in contact with the liquid crystal on the transparent upper electrode substrate 11 and the lower electrode substrate 12, which are made of, for example, an organic polymer resin made of polyimide in one direction, for example, with a cloth, so-called rubbing method. Is taken. The rubbing direction at this time, that is, the rubbing direction, the rubbing direction 6 in the upper electrode substrate 11, and the rubbing direction 7 in the lower electrode substrate 12 are the alignment directions of the liquid crystal molecules. Oriented in this way 2
The upper electrode substrate 11 and the lower electrode substrate 12 are opposed to each other with a gap d ₁ so that the rubbing directions 6 and 7 intersect each other at approximately 180 to 360 degrees. When a nematic liquid crystal having a positive dielectric anisotropy and having a predetermined amount of an optical rotatory substance is sealed by bonding with a frame-shaped sealant 52 having a cutout portion 51 for injecting liquid crystal, Liquid crystal molecule is its electrode substrate 1
The molecular arrangement of the helical structure having the twist angle θ in the figure is between 1 and 12. Reference numerals 31 and 32 are transparent upper and lower electrodes made of, for example, indium oxide or ITO (Indium Tin Oxide). A member that produces a birefringence effect on the upper electrode substrate 11 of the liquid crystal cell 60 thus configured (hereinafter referred to as a birefringence member. Fujimura et al. "STN-
"Retardation film for LCD", magazine electronic material 1991 2
40 of the monthly issue (pages 37-41), and the upper polarizing plate 1 with the birefringent member 40 and the liquid crystal cell 60 sandwiched therebetween.
5, the lower polarizing plate 16 is provided.

The twist angle θ of the liquid crystal molecules in the liquid crystal 50 can take a value in the range of 180 ° to 360 °, preferably 200 ° to 300 °, but the transmittance-applied voltage curve is turned on near the threshold value. From the practical viewpoint of avoiding the phenomenon that the state becomes an orientation that scatters light and maintaining excellent time division characteristics, the range of 230 to 270 degrees is more preferable. This condition basically makes the response of the liquid crystal molecules to the voltage more sensitive and acts to realize excellent time division characteristics. In order to obtain excellent display quality and the refractive index anisotropy [Delta] n ₁ of the liquid crystal layer 50 a product [Delta] n ₁ of the thickness d ₁
-D ₁ is preferably set in the range of 0.5 μm to 1.0 μm, more preferably 0.6 μm to 0.9 μm.

The birefringent member 40 acts so as to modulate the polarization state of the light passing through the liquid crystal cell 60, and converts what could be displayed only in the liquid crystal cell 60 alone into a black and white display. Thus the birefringent member 40 refractive index anisotropy [Delta] n ₂ and is extremely important product [Delta] n ₂ · d ₂ of a thickness d _2, preferably 0.8μm from 0.4 .mu.m, more preferably 0.5μm To 0.7 μm.

Further, the liquid crystal display device 62 according to the present invention.
Uses elliptically polarized light due to birefringence, so polarizing plate 1
When the uniaxial transparent birefringent plate is used as the birefringent member 40, the relationship between the axes of 5 and 16 and the liquid crystal alignment directions 6 and 7 of the electrode substrates 11 and 12 of the liquid crystal cell 60 is extremely important. Is.

The function and effect of the above relationship will be described with reference to FIG. FIG. 4 shows an axis of a polarizing plate, an optical axis of a uniaxial transparent birefringent member when the liquid crystal display device having the configuration of FIG. 5 is viewed from above,
3 shows the relationship between the alignment directions of liquid crystal molecule axes of an electrode substrate of a liquid crystal cell.

In FIG. 4, 5 is the optical axis of the uniaxial transparent birefringent member 40, 6 is the alignment direction of the liquid crystal molecules of the birefringent member 40 and the upper electrode substrate 11 adjacent thereto, and 7 is the lower electrode substrate 12. The liquid crystal alignment direction, 8 is the absorption axis or polarization axis of the upper polarization plate 15, 9 is the absorption axis or polarization axis of the lower polarization plate 16, and the angle α is uniaxial birefringence with the liquid crystal alignment direction 6 of the upper electrode substrate 11. The angle β formed by the optical axis 5 of the member 40 is the angle formed by the absorption axis or polarization axis 8 of the upper polarizing plate 15 and the optical axis 5 of the uniaxial transparent birefringent member 40, and the angle γ is the lower polarizing plate 16. Is the angle between the absorption axis or polarization axis 9 of the liquid crystal and the liquid crystal alignment direction 7 of the lower electrode substrate 12.

Here, how to measure the angles α, β, and γ in this specification will be defined. In FIG. 6, the intersection angle between the optical axis 5 of the birefringent member 40 and the liquid crystal alignment direction 6 of the upper electrode substrate will be described as an example. The intersection angle between the optical axis 5 and the liquid crystal alignment direction 6 can be represented by φ ₁ and φ ₂ , as shown in FIG.
In this specification, the smaller corner of φ ₁ and φ ₂ is adopted. That is, since φ ₁ <φ ₂ in FIG. 6A, φ ₁ is defined as an intersection angle α between the optical axis 5 and the liquid crystal alignment direction 6,
Since φ ₁ > φ ₂ in FIG. 6B, φ ₂ is defined as an intersection angle α between the optical axis 5 and the liquid crystal alignment direction 6. Of course, either _one may be adopted when φ ₁ = φ ₂ .

In the liquid crystal display device according to the present invention, the angles α, β and γ are extremely important.

The angle α is preferably 50 ° to 90 °, more preferably 70 ° to 90 °, the angle β is preferably 20 ° to 70 °, more preferably 30 ° to 60 °, and the angle γ is preferably. It is desirable to set each to 0 to 70 degrees, and more preferably to 0 to 50 degrees.

If the twist angle θ of the liquid crystal layer 50 of the liquid crystal cell 60 is in the range of 180 ° to 360 °, the above angle is satisfied regardless of whether the twist direction 10 is clockwise or counterclockwise. α, β, and γ may be within the above range.

In FIG. 5, the birefringent member 40 is disposed between the upper polarizing plate 15 and the upper electrode substrate 11, but instead of this position, the lower electrode substrate 12 and the lower polarizing plate 16 are provided.
You may arrange | position between and. This case corresponds to the case where the entire configuration of FIG. 5 is inverted.

As shown in FIG. 7, a red color filter 33R, a green color filter 33G, and a blue color filter 33B are provided on the upper electrode substrate 11, and each color filter 33 is provided.
A light-shielding film 33D is provided between the R, 33G, and 33B to enable multicolor display.

In FIG. 7, a smoothing layer 2 made of an insulating material is formed on each of the color filters 33R, 33G, 33B and the light shielding film 33D in order to reduce the influence of these irregularities.
An upper electrode 31 and an alignment film 21 are formed on top of the layer 3.

FIG. 8 is an exploded perspective view of a liquid crystal display module 63 in which the liquid crystal display device 62, a drive circuit for driving the liquid crystal display device 62, and a light source are compactly integrated. IC3 for driving the liquid crystal display device 62
4 is mounted on a frame-shaped printed circuit board 35 having a window portion for fitting the liquid crystal display device 62 in the center. The printed circuit board 35 in which the liquid crystal display device 62 is fitted is fitted in the window portion of the frame-like body 42 formed by plastic molding,
The metal frame 41 is superposed on this, and the claw 43 is bent into the notch 44 formed in the frame-shaped body 42 to fix the frame 41 to the frame-shaped body 42.

A cold cathode fluorescent lamp 36 arranged at the upper and lower ends of the liquid crystal display device 62, a light guide 37 made of an acrylic plate for uniformly irradiating the liquid crystal display cell 60 with light from the cold cathode fluorescent lamp 36, A reflecting plate 38 formed by applying white paint to a metal plate and a milky white diffusing plate 39 for diffusing light from the light guide 37 are fitted into the window portion from the back side of the frame-shaped body 42 in the order of FIG. Be done. An inverter power supply circuit (not shown) for turning on the cold cathode fluorescent lamp 36 is provided with a recess (not shown) provided on the right side rear portion of the frame-shaped body 42. The recess 45 of the reflector 38 is provided.
It is in a position facing. ). Diffusion plate 39,
The light guide 37, the cold cathode fluorescent lamp 36, and the reflector 38 are fixed by bending a tongue piece 46 provided on the reflector 38 into an edge 47 provided on the frame-shaped body 42.

FIG. 9 shows a block diagram of the liquid crystal display module 63 used in the display section of a laptop personal computer, and FIG. The result calculated by the microprocessor 49 is sent to the driving IC 34 via the control LSI 48.
The liquid crystal display module 63 is driven by.

Next, a method of manufacturing the liquid crystal display device according to the present invention will be described with reference to FIG. First, as shown in FIG. 1A, a color filter 33 is provided on the upper electrode substrate 11 by a pigment dispersion method, a dyeing method, a printing method, an electrodeposition method or the like, and a photocurable resin 23a is spun on the color filter 33. The metal light-shielding film 7 is applied to the transparent substrate 71 having a frosted surface 71a on the exposure light source side by applying it by a method such as coating or roll coating.
The photocurable resin 23a is irradiated with the exposure light 73 from the ultra-high pressure mercury lamp through the photomask on which the photocurable resin 2 is formed, and the photocurable resin 23a is cured to form the smooth layer 23. Next, as shown in FIG. 1B, the photocurable resin 23
After removing the non-cured part 23b of a, the smoothing layer 23
An ITO film having a thickness of 240 nm is provided on the upper side by sputtering, and the ITO film is selectively etched with a strong acid to form the upper electrode 31 and the terminal 31a.

In this method of manufacturing a liquid crystal display device,
Since the exposure light 73 is scattered on the frosted surface 71a, the metal light-shielding film 72 of the photomask is irradiated with the scattered light, so that the relationship between the position shown in FIG. 1A and the illuminance on the surface of the photocurable resin 23a. As can be seen from the graph in FIG.
The illuminance of the portion corresponding to the outside of 2 gradually decreases. Then, as is clear from FIG. 2 showing the relationship between the exposure amount and the post-development residual film thickness of the photocurable resin 23a, the post-development residual film thickness increases as the exposure amount increases. Therefore, the smoothing layer 23
Since a gently sloping surface is formed at the end of the
Since side etching does not occur at the end of the smoothing layer 23 during the etching for forming No. 1, the smoothing layer 23
There is no disconnection of the electrode 31 at the end of the.

Next, a method of manufacturing another liquid crystal display device according to the present invention will be described with reference to FIG. First, the color filter 33 is provided on the upper electrode substrate 11, and the photocurable resin 23 a is applied onto the color filter 33. Next, the exposure light 83 from the extra-high pressure mercury lamp 81 is reflected by a reflecting mirror 82 having a frosted surface, and the exposure light 83 scattered by the reflecting mirror 82 is passed through a photomask in which a metal light shielding film 85 is formed on a transparent substrate 84. The photocurable resin 23a is irradiated with the photocurable resin 2a.
The smoothing layer 23 is formed by hardening 3a. Next, after removing the non-cured portion 23b of the photocurable resin 23a, an ITO film is provided on the smoothing layer 23, and the ITO film is selectively etched to form the upper electrode 31 and the terminal 31a.

Also in this method of manufacturing a liquid crystal display device,
Since the metal light-shielding film 85 of the photomask is irradiated with the scattered light, the illuminance of the portion corresponding to the outside of the metal light-shielding film 85 gradually decreases, so that a smooth inclined surface is formed at the end of the smoothing layer 23. It For this reason, side etching does not occur at the end of the smoothing layer 23 during etching when forming the upper electrode 31, so that the electrode 31 does not end at the end of the smoothing layer 23.
Does not break.

In the above embodiment, the frosted surface 71a is provided on the exposure light source side of the transparent substrate 71 of the photomask in order to irradiate the metal light shielding films 72 and 85 of the photomask with scattered light, and the exposure light is also used. Although 83 is reflected by the reflecting mirror 82 having a frosted surface, other light scattering means such as a plate having a frosted surface may be provided between the exposure light source and the light shielding film portion of the photomask.

[0034]

As described above, in the method of manufacturing a liquid crystal display device according to the present invention, since side etching does not occur at the end of the smoothing layer during etching when forming electrodes, the smoothing layer is not formed. The electrode does not break at the end of the. As described above, the effect of the present invention is remarkable.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for manufacturing a liquid crystal display device according to the present invention.

FIG. 2 is a graph showing a relationship between an exposure amount and a residual film thickness of a photocurable resin after development.

FIG. 3 is an explanatory view of a method of manufacturing another liquid crystal display device according to the present invention.

FIG. 4 is an explanatory diagram showing the relationship among the alignment direction of liquid crystal molecules, the twist direction of the liquid crystal molecules, the direction of the axis of the polarizing plate, and the optical axis of the birefringent member of the liquid crystal display device to which the method of the present invention is applied. .

FIG. 5 is an exploded perspective view of a main part of a liquid crystal display device.

FIG. 6 is a diagram for explaining how to measure intersection angles α, β, and γ.

FIG. 7 is a partially cutaway perspective view of an upper electrode substrate portion of a liquid crystal display device.

FIG. 8 is an exploded perspective view of a liquid crystal display module.

FIG. 9 is a block diagram of an example of a laptop personal computer.

FIG. 10 is a perspective view of an example of a laptop computer.

FIG. 11 is an explanatory diagram of a conventional method for manufacturing a liquid crystal display device.

[Explanation of symbols]

 11 ... Upper electrode substrate 12 ... Lower electrode substrate 15 ... Upper polarizing plate 16 ... Lower polarizing plate 23 ... Smoothing layer 23a ... Photocurable resin 31 ... Upper electrode 31a ... Terminal 33R ... Red color filter 33G ... Green color filter 33B ... Blue Color filter 34 ... Driving IC 40 ... Birefringent member 60 ... Liquid crystal cell 62 ... Liquid crystal display device 63 ... Laptop computer 71 ... Transparent substrate 71a ... Frost surface 72 ... Metal light-shielding film 73 ... Exposure light 81 ... Ultra-high pressure mercury lamp 82 ... Reflecting mirror 83 ... Exposure light 84 ... Transparent substrate 85 ... Metal light-shielding film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takumi Kuji 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Device Division (72) Inventor Kazumi Kanesaka 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. ( 72) Inventor Yoshihisa Watanabe 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd.

Claims (3)

[Claims] 1. A color filter is provided on an electrode substrate,
In the method of manufacturing a liquid crystal display device, wherein a smooth layer is formed on the color filter, an electrode is formed on the smooth layer, and terminals of the electrode are formed on the electrode substrate. A method for manufacturing a liquid crystal display device, which comprises applying a photosensitive resin and irradiating the light shielding film portion of the photomask with scattered light. 2. A method of manufacturing a liquid crystal display device according to claim 1, wherein a light source that generates scattered light is used. 3. The method for manufacturing a liquid crystal display device according to claim 1, wherein a photomask that scatters light is used as the photomask.