JP3511218B2 - Liquid crystal display panel manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to is a method of manufacturing a liquid crystal display panel, in particular, liquid crystal display <br/> panel with improved viewing angle characteristics by varying the dielectric constant of the alignment layer to partially The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have come to be widely used in various electronic devices by taking advantage of their features such as thinness, light weight, low voltage driving, and low power consumption.
Since an active matrix type liquid crystal display panel using (thin film transistor) as an active element can obtain a display characteristic similar to that of a CRT, it has been widely used mainly for a display in an OA device or the like.

The basic structure of such a liquid crystal display panel is shown in FIG.
4-7Will be described with reference to. FigureFourIs the alignment mechanism of liquid crystal molecules
FIG.Four(A) is a rubbing direction and an alignment direction
And FIG.Four(B) is a liquid crystal molecule
It is a schematic cross-sectional view showing the state of the twist,Four
(C) is a schematic top view showing a twisting state of liquid crystal molecules.
It

[0006] FIG. 4 (a) and (b) refer to the general liquid crystal display panel, two glass substrates 11 and 13
The glass substrate 1 has a structure in which the liquid crystal 15 is sandwiched between and the outside thereof is sandwiched by a polarizing plate (not shown) or the like.
Active elements such as TFTs, data bus lines, gate bus lines, pixel electrodes, and
A color filter or the like (none of which is shown) is provided, and alignment films 12 and 14 made of polyimide or the like are further formed thereon.

Then, the alignment films 12 and 14 are subjected to an alignment treatment by a so-called rubbing treatment in which they are rubbed in a certain direction by a cloth such as rayon, so that the liquid crystal molecules 28 constituting the liquid crystal 15 in contact with the alignment films 12 and 14 are also formed. They will be arranged along the rubbing direction.

In this case, the liquid crystal molecules 28 are aligned in a state of having a predetermined angle θ called a so-called pretilt angle. The pretilt angle θ is the kind of alignment film to be used, the kind of liquid crystal, and the rubbing treatment. Changes according to the conditions of
It is usually in the range of 1 ° to 10 °.

[0007] FIGS. 4 (b) and 4 (c) refer to and, in the active matrix liquid crystal display panel arranged an active element such as TFT for every one single pixel, the rubbing direction of the two glass substrates 11 and 13 90 ° to each other
A so-called TN (Twisted Nematic) mode for shifting is mainstream, and liquid crystal molecules 28 sandwiched between two glass substrates 11 and 13 are arranged while being continuously twisted from one glass substrate 11 to the other glass substrate 13. (In the case of the figure, it is clockwise when viewed from the substrate 11 side).

In this case, since it is uncertain in which direction the liquid crystal molecules 28 are twisted, a chiral agent (chiral agent) having a property of twisting the liquid crystal molecules 28 clockwise or counterclockwise. The direction of the twist is controlled by adding a substance called) to the nematic liquid crystal.

See FIG. 5 (a). When a voltage is applied between the two glass substrates 11 and 13, when the applied voltage is gradually increased from 0 V, a certain voltage value (threshold value) is obtained. At the boundary, the liquid crystal molecules 28 start to face in the direction of the electric field, and at a sufficiently large voltage value, the liquid crystal molecules 28 are almost perpendicular to the glass substrates 11 and 13.

5 (b) and 5 (c) In this case, if the pretilt angle is 0 °, the movement when the liquid crystal molecules 28 start to tilt with respect to the electric field is as shown in FIGS. 5 (b) and 5 (c). There are two possibilities shown, and it was uncertain which one to actually lean.

[0011] refer to FIG. 6 (a) and (b) However, if that has been given a pre-tilt angle θ of the liquid crystal molecules 28 rubbed alignment film 12, 14, movement of the liquid crystal molecules 28 with respect to the electric field Since it follows the direction of the inclination of the pretilt angle, it is defined in one way.

In FIG. 6 , for simplification of description, the rubbing direction 29 of the alignment film 12 and the rubbing direction 29 of the alignment film 14 are shifted by 180 °, so that the liquid crystal molecules 28 are not twisted. As explained, alignment film 1
2 rubbing direction 29 and rubbing direction 29 of alignment film 14
The same phenomenon occurs in the case of the TN mode where and are shifted by 90 °.

[0013]

[Problems to be Solved by the Invention] However, such TN
Type liquid crystal display panels have a drawback in that the viewing angle characteristics are poor and display inversion occurs when viewed from an oblique direction. This situation will be described with reference to FIG. Note that FIG. 7 (a)
The three directions A shown in FIG. 7 (b), B, the transmittance when viewed from the C - is indicative of the voltage characteristic, this case, the polarization axis of the outer two glass substrates 11 and 13 Normally white mode in which two polarizing plates that are orthogonal to each other are provided (when the applied voltage is smaller than the threshold value, the tilt of the liquid crystal molecules 28 does not change, and therefore, it is in a bright state, and when the threshold value is sufficiently exceeded. Shows the characteristics when driven in a dark state).

[0014] FIGS. 7 (a) and (b) the solid line in the reference diagram curve A, the transmittance in the case of viewing the liquid crystal display panel 30 from the front - the voltage characteristic, the one-dot chain line curve B and a broken line curve C Is a transmittance-voltage characteristic when viewed from a direction deviated from the front by 30 °.

When viewed from the directions A to C, the transmittance decreases to about 0 as the applied voltage increases, but only in the case of B, the transmittance once decreases to 0 on the way and then increases. It shows a bump-like characteristic that turns to and then drops again, and the display may appear to be reversed on an actual display panel.

This is because the liquid crystal director of the liquid crystal molecules (the vector in the long axis direction of the liquid crystal molecules) changes as the applied voltage increases, becomes parallel to the B direction at a certain voltage value, and the transmittance becomes the minimum. This is because the liquid crystal director becomes non-parallel again and the transmittance increases when the voltage further increases.

Therefore, an object of the present invention is to provide a liquid crystal display panel having excellent viewing angle characteristics by eliminating display inversion depending on the viewing direction of the liquid crystal display panel.

[0018]

FIG. 1 is a diagram showing the principle configuration of the present invention. The present invention will be described with reference to FIG. 1 (a).
The means for solving the problem will be described. 1 (a) (1) The present invention relates to a method for manufacturing a liquid crystal display panel,
The liquid crystal 5 on one of the substrates 3 sandwiching the liquid crystal 5
The first alignment film 4 is formed on the facing surface, and
The liquid crystal 5 on the other substrate 1 between the substrates 1 and 3 that sandwich the liquid crystal 5
A flat surface with a smaller dielectric constant than the alignment film material
By applying a second alignment film material containing a particulate substance
The first region 6 composed only of the second alignment film
And a second alignment film containing the flat material.
And a second region 7 formed therein.

[0019]

[0020]

( 2 ) Further, according to the present invention, in the method of manufacturing a liquid crystal display panel, a first alignment film is formed on a surface of one of the substrates 1 and 3 sandwiching the liquid crystal 5 facing the liquid crystal 5. At the same time, a second alignment film material and a third alignment film material having a dielectric constant smaller than that of the second alignment film material are formed on the surface of the other substrate 1 of the substrates 1 and 3 sandwiching the liquid crystal 5 facing the liquid crystal 5. The first region 6 composed of the second alignment film material and the third region
The second region 7 made of the alignment film material is formed.

[0022]

By forming one of the alignment films 2 and 4 provided on the surface of the substrates 1 and 3 facing the liquid crystal 5 by the first region 6 and the second region 7 having different dielectric constants, Since the effective voltages applied to the liquid crystal 5 in the regions corresponding to the region 6 and the second region 7 are different from each other, the transmittance-voltage characteristics of the entire display panel are as follows. Since the characteristics and the transmittance-voltage characteristics of the second region 7 are averaged, the bumps disappear and the viewing angle characteristics are improved.

This situation will be described with reference to FIG. See FIG. 1B. When the display panel is viewed from the direction B in FIG. 7 of the related art, the transmittance-voltage characteristic of the second region 7 is represented by a curve a.
The transmittance-voltage characteristic of the region 6 is represented by the curve b, but the overall transmittance-voltage characteristic is represented by the curve c, and the positions of the bumps of the curve a and the curve b are deviated and averaged. As a result, the bump disappears, and therefore, the display inversion does not occur when the display panel is viewed from either direction.
That is, the viewing angle characteristics are improved.

That is, in the second region 7 having a low dielectric constant, the component of the applied voltage to the alignment film 2 itself is D = εE (D: electric flux density, ε: permittivity, E: electric field). )
This is because the transmittance-voltage characteristic is shifted to the high voltage side because the second area 6 has a higher dielectric constant than the first area 6 according to the above relationship.

[0025] In this case, the first region 6 consists only the second alignment layer 2, and a second alignment layer containing a second region 7 small flat material dielectric constant than the second alignment layer 2 With this configuration, the voltages effectively applied to the liquid crystal 5 in the first region 6 and the second region 7 can be made different.

Further, the first region 6 is made of the second alignment film material, and the second region 7 is made of the third alignment film material having a dielectric constant smaller than that of the second alignment film material.
The voltages effectively applied to the liquid crystal 5 in the first region 6 and the second region 7 can be made different.

Further, the second alignment film material containing a flat material having a smaller dielectric constant than the alignment film material on the surface of one of the substrates 1 and 3 sandwiching the liquid crystal 5 on the side facing the liquid crystal 5. By coating the first regions 6 having different dielectric constants from each other.
The second region 7 can be easily formed.

Further, on the surface of one of the substrates 1 and 3 sandwiching the liquid crystal 5 on the side facing the liquid crystal 5, the second alignment film material and the third alignment having a dielectric constant smaller than that of the second alignment film material. By applying the alignment film material mixed with the film material, the first region 6 and the second region 7 having different dielectric constants can be easily formed.

[0029]

EXAMPLE A first example of the present invention will be described with reference to FIG. Note that FIG. 2A is a schematic sectional view of the liquid crystal display panel, and FIG. 2B is a top view of the lower alignment film in FIG.
The direction connecting A ′ represents the same direction.

2 (a) and 2 (b) First, two glass substrates 11 and 13 constituting an active matrix type liquid crystal display panel are prepared, and a TFT, a gate bus line and a data are formed on one glass substrate 11. A bus line and a pixel electrode (neither is shown) are provided, and a common electrode (counter electrode) is provided on the surface of the other glass substrate 13.

Next, with respect to the alignment film material AL3046 (trade name: manufactured by Japan Synthetic Rubber Co., Ltd.), the flat material Mica M-
Alignment film 12 is obtained by applying a mixture of JV (product name: manufactured by Merck & Co., Inc.) in an amount of 5 to 15 wt%, preferably 10 wt% to glass substrate 11 by transfer printing and firing.
A first region 16 consisting solely of a second and a second containing flat material 18
The regions 17 are formed by being dispersed evenly so that the region 17 becomes approximately 1: 1.

On the other hand, on the other glass substrate 13, only the alignment film material AL3046 (trade name: manufactured by Japan Synthetic Rubber Co., Ltd.) is applied by transfer printing and baked to form the alignment film 14.

Next, the alignment film 1 on the glass substrates 11 and 13
After rubbing the surfaces of 2 and 14, the glass substrate 11 and the glass substrate 13 are bonded together via a spacer (not shown) having a diameter of 5 μm, and the liquid crystal 15 is sealed.

By using AL3046 (trade name: manufactured by Japan Synthetic Rubber Co., Ltd.) as the material for the alignment film, the pretilt angle can be increased and the flat material 18 can be used.
By using mica M-JV (trade name: manufactured by Merck & Co., Inc.) as the material, the dielectric constant of the flat material 18 can be made smaller than that of the alignment film 12.

The average major axis of the flat material 18 is 3
Since the area is 10 μm, which is sufficiently smaller than the area of one pixel 100 × 290 μm, the first region 16 and the second region 17 are evenly dispersed in one pixel evenly within 1: 1. Can be made.

In this case, in the second region 17, since the flat material 18 having a low dielectric constant and the thin alignment film material are present thereon, the effective voltage applied to the liquid crystal 15 is higher than that in the first region 16. The voltage becomes small, and an averaged transmittance-voltage characteristic without bumps is obtained for the entire pixel, and the problem of display inversion disappears.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that FIG. 3A is a schematic sectional view of the liquid crystal display panel, and FIG. 3B is a top view of the lower alignment film in FIG.
The direction connecting A ′ represents the same direction.

3 (a) and 3 (b) First, as in the first embodiment, two glass substrates 11 and 1 are used.
3 is prepared, TFTs, gate bus lines, data bus lines, and pixel electrodes (all not shown) are provided on one glass substrate 11, and the other glass substrate 13 is provided.
A common electrode (not shown) is provided on the surface of the.

Next, a first alignment film material 19 made of an alignment film material SE-7792 (trade name: manufactured by Nissan Chemical Industries, Ltd.) and an alignment film material AL1051 (trade name: manufactured by Nippon Synthetic Rubber Co., Ltd.).
A mixture of the second alignment film material 20 made of and a ratio of 1: 1 is applied onto the glass substrate 11 by transfer printing,
By firing, the first region 16 made of the first alignment film material 19 and the second region 17 made of the second alignment film material 20.
Are formed so as to be evenly dispersed so that and are approximately 1: 1.

On the other hand, on the other glass substrate 13, only the alignment film material SE-7792 (trade name: manufactured by Nissan Chemical Industries, Ltd.) is applied by transfer printing and baked to form the alignment film 14.

Next, the alignment film 1 on the glass substrates 11 and 13
After rubbing the surfaces of 2 and 14, the glass substrate 11 and the glass substrate 13 are bonded together via a spacer (not shown) having a diameter of 5 μm, and the liquid crystal 15 is sealed.

Since the alignment film material SE-7792 (trade name: manufactured by Nissan Chemical Industries, Ltd.) has a higher dielectric constant than the alignment film material AL1051 (trade name: manufactured by Japan Synthetic Rubber Co., Ltd.),
In the region 17, the effective voltage applied to the liquid crystal 15 is smaller than that in the first region 16, and the average transmittance-voltage characteristic without bumps is obtained for the entire pixel, and the problem of display inversion disappears. .

Further, in this case, it is necessary to prevent the first alignment film material 19 and the second alignment film material from being completely mixed, so that the average major axis of the first region 16 and the second region is 20 μm or less. You can do it. Since this average major axis is sufficiently smaller than the area of one pixel 100 × 290 μm, the first region 16 and the second region 17 are also within one pixel.
It can be dispersed evenly so that and are approximately 1: 1.

[0044] In the above first and second embodiments, one of the glass substrate 11 side, i.e., an alignment film 12 having a dielectric constant on the TFT substrate side is different from the first region 16 and second region 17 from each other Although the example of providing is described, the alignment film 14 including the first region 16 and the second region 17 having different dielectric constants only on the other glass substrate 13 side, that is, the counter substrate side.
May be provided.

Further, although the active matrix type liquid crystal display panel has been described as an example in the first and second embodiments, the technical idea of the present invention is not limited to the active matrix type liquid crystal display panel, and the active matrix type liquid crystal display panel is not limited to the active matrix type liquid crystal display panel. The present invention is also applied to a liquid crystal display panel of the type that does not use elements, and the liquid crystal used is not limited to the TN type liquid crystal, and is also applied to the case of using another liquid crystal.

[0046]

According to the present invention, since the <br/> alignment film provided on one substrate side dielectric constant is different two types of realm or al structure, the transmittance of the liquid crystal display panel - in the voltage characteristic Since the bumps disappear and the display inversion does not occur, it is possible to provide a liquid crystal display panel having excellent viewing angle characteristics.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a principle configuration of the present invention.

FIG. 2 is an explanatory diagram of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of an alignment mechanism of liquid crystal molecules.

FIG. 5 shows the twist direction of liquid crystal molecules when the pretilt angle is 0 .
FIG.

FIG. 6 shows the twist direction of liquid crystal molecules when the pretilt angle is θ .
FIG.

FIG. 7 is a view of a transmittance-voltage characteristic of a conventional liquid crystal display panel.
It is a clear view.

[Explanation of symbols]

1 substrate 2 Alignment film 3 substrates 4 Alignment film 5 liquid crystal 6 First area 7 Second area 11 glass substrate 12 Alignment film 13 glass substrate 14 Alignment film 15 LCD 16 First area 17 Second area 18 Flat material 19 First alignment film material 20 Second alignment film materialFee Two 8 Liquid crystal molecules 29 Rubbing direction 30 liquid crystal display panel

─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Takemune Mayama 1015 Kamitadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Within Fujitsu Limited (72) Inventor Ikuo Tomita 1015 Kamitadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Stock In-company (72) Makoto Ohashi, 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited (56) References JP-A-2-22623 (JP, A) JP-A-6-82773 (JP, A) JP-A-7-84244 (JP, A) JP-A-1-262526 (JP, A) JP-A-6-43462 (JP, A) JP-A-6-258645 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/13-1/141

Claims (2)

(57) [Claims] 1. The liquid crystal of one of the substrates sandwiching the liquid crystal
Forming a first alignment film on the surface facing
The surface of the other substrate of the substrates that sandwich the liquid crystal facing the liquid crystal
In addition, it contains a flat material whose dielectric constant is smaller than that of the alignment film material.
By applying a second alignment film material,
First region composed only of the alignment film of
A second region composed of a second alignment film containing a quality
A method for manufacturing a liquid crystal display panel, the method comprising: forming. 2. The liquid crystal on one of the substrates sandwiching the liquid crystal
Forming a first alignment film on the surface facing
The surface of the other substrate of the substrates that sandwich the liquid crystal facing the liquid crystal
In comparison with the second alignment film material and the second alignment film material,
Apply an alignment film material that is a mixture of a third alignment film material with a low electric conductivity.
The second alignment film material is formed by applying a cloth.
And a second region composed of the third alignment film material.
And a liquid crystal display panel characterized by forming a region
Build method.