JP3500547B2 - Method of manufacturing liquid crystal display panel and liquid crystal display panel - Google Patents

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 panel and a liquid crystal display panel , and in particular, a viewing angle range is improved by giving a predetermined pretilt angle to liquid crystal by using a substrate which is not subjected to rubbing treatment. The present invention relates to a method for manufacturing an active matrix type TN (Twisted Nematic) type liquid crystal display panel and a liquid crystal display panel .

[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 comparable to that of a CRT, it is actively applied to mobile TVs, personal computers and the like.

The basic structure of such an active matrix type liquid crystal display panel will be described with reference to FIG. Referring to FIG. 4, after the pixel electrodes 12 and the gate bus lines 13 forming the TFT are provided on the TFT substrate 11 made of a glass substrate or the like (data bus lines are not shown), an alignment film 25 is formed so as to cover the surface thereof. This TFT substrate 1 is provided
1. The counter electrode 15 and the alignment film 26 are provided on the facing surface of the counter substrate 14 made of a glass substrate or the like facing 1 to provide the TF of these.
A TN type liquid crystal is sealed between the T substrate 11 and the counter substrate 14 to complete the basic structure of the liquid crystal. Incidentally, reference numerals 28 and 29
Is a polarizing film, and in the case of color display, a color filter may be provided on the counter substrate 14 side.

In this case, in order to stabilize the display characteristics,
The alignment films 25 and 26 were rubbed with a cloth such as rayon in a constant direction substantially orthogonal to each other to orient the liquid crystal molecules in advance and give a predetermined pretilt angle.

However, in this state, the transmittance-voltage characteristics are different between when the liquid crystal display panel is viewed from the front and when it is viewed from the upper side or the lower side, and the transmittance is reversed at a certain portion, so that the display is not possible. It will look inverted,
There was a drawback that the viewing angle range for proper viewing was narrow.

This situation will be described with reference to FIG. The solid line in FIG. 5 is the transmittance-voltage characteristic when the liquid crystal display panel is viewed from the front, and the broken line is the transmittance-voltage characteristic when the liquid crystal display panel is viewed from the upper direction of 40 °. The contrast due to the voltage is slightly smaller than that when viewed from the front, but the characteristics are similar.

However, the transmittance-voltage characteristics of the liquid crystal display panel shown by the alternate long and short dash line in the figure from the downward direction of 40 ° have a bump in the large voltage portion, and when viewed from the downward direction of 40 °, In this voltage region, the reverse contrast opposite to the original contrast can be obtained.

This is because the liquid crystal director of the liquid crystal molecule (vector in the long axis direction of the liquid crystal molecule) changes as the voltage rises, and becomes parallel to 40 ° downward at a certain voltage value, and the transmittance becomes minimum. This is because, when the voltage further increases, the liquid crystal director becomes non-parallel again and the transmittance increases.

Conventionally, in order to improve the problem of such a narrow viewing angle range, that is, in order to improve the viewing angle characteristics, when a pixel is divided into two and the directions of the pretilt angles of the liquid crystal molecules are made different, a voltage is applied to the liquid crystal, It has been proposed (alignment division method) to make liquid crystal molecules rise from different directions.

FIG. 6 is an explanatory view of a liquid crystal display panel adopting the alignment division method. FIG. 6 (a) shows a schematic structure of one pixel portion of the liquid crystal display panel, and FIG. 6 (b) shows a voltage. 6C shows the state of the liquid crystal molecules when no voltage is applied, and FIG. 6C shows the state of the liquid crystal molecules when a voltage is applied.

Referring to FIG. 6A, the pixel portion of such an active matrix type liquid crystal display panel has a data bus line 10 and a gate bus line 13 arranged in directions substantially orthogonal to each other, and a rectangular area formed by these bus lines. The pixel electrode 12 and the TF
The TFT 23 is composed of a drain region 20 and a source region 22 made of polycrystalline silicon, and a gate electrode 21 connected to the gate bus line 13. It

Referring to FIG. 6B, this pixel is divided into a first region 18 and a second region 19, and an alignment film (not shown) is rubbed in different rubbing directions 30 so that different directions are obtained. To have a pretilt angle θ. As shown in the figure, in the TN liquid crystal display panel, the rubbing process is performed in different directions on the TFT substrate side and the counter substrate side.

See FIG. 6C. When a voltage is applied to the pixel in this state, the liquid crystal molecules rise in opposite directions, the liquid crystal directors of the liquid crystal molecules are more inclined, and the transmittance becomes higher as the voltage becomes higher. descend.

In the reference diagram of FIG. 5, the transmittance-voltage characteristics indicated by the chain double-dashed line indicate that the liquid crystal display panel adopting such an alignment division method is oriented in the upward direction 40.
Shows the characteristics when viewed from 40 ° or 40 ° in the downward direction.
A viewing angle at which a characteristic that is obtained by averaging the characteristics when viewed from 0 ° (dashed line) and 40 ° downward (dashed-dotted line) is obtained, a bump that causes display inversion is not seen, and a constant contrast is obtained The range is greatly improved.

However, when such an orientation division method is adopted, the first region 1 and the second region 19 have different pretilt angles θ, so that the first region 1 has a different direction.
8 and the second region 19 need to be provided with different kinds of alignment films, and a photolithography process must be used for that purpose, which causes a problem of increasing the number of manufacturing processes, and rubbing as a means for aligning liquid crystal molecules. However, there is a problem in that it depends largely on experience, which hinders improvement in manufacturing yield.

In order to solve such a problem of rubbing, it has been considered to orient the liquid crystal molecules without rubbing. For example, a fine groove is formed in the alignment film by using a photolithography process and the shape thereof is formed. Depending on the effect
A method for orienting liquid crystal molecules in different directions has been proposed.

As another method, linearly polarized U
A method has also been proposed in which liquid crystal molecules are aligned by irradiating the alignment film with V light (ultraviolet light) and unifying the directions in which the molecules of the alignment film are aligned.

However, when the liquid crystal molecules are aligned by using fine grooves formed in the alignment film or UV light linearly polarized without rubbing, the liquid crystal molecules are aligned, but the liquid crystal molecules and the substrate are aligned. There is a problem that the pretilt angle with the interface hardly appears, and even if this method was applied to an alignment division type liquid crystal display panel, it was not possible to immediately form an alignment division type liquid crystal display panel with good characteristics. .

As a method of imparting and holding a predetermined pretilt angle, a small amount of UV curable resin is mixed in the liquid crystal material, the liquid crystal is sealed in the liquid crystal cell, and then a voltage is applied to the liquid crystal molecules. U while giving a predetermined pretilt angle
There has been proposed a method of irradiating V light to cure a UV curable resin to form a polymer network, and imparting an alignment regulating force to liquid crystal molecules by the polymer network for alignment.

However, when a UV curable resin is used,
Although effective as a method of maintaining the pretilt angle, rubbing treatment is first required to give alignment to the liquid crystal molecules, which basically solves the problem in the conventional alignment division type liquid crystal display panel shown in FIG. I couldn't.

In recent years, in order to solve such a problem, the rubbingless alignment method as described above is used, and a new alignment division for aligning liquid crystals by providing alignment control electrodes around or in the vicinity of the pixel electrodes. Since the method has been proposed, this proposal will be described with reference to FIG.

Referring to FIG. 7, liquid crystal is sealed between the TFT substrate 11 made of a glass substrate or the like provided with the pixel electrode 12 and the counter substrate 14 made of a glass substrate provided with the counter electrode 15 and the TFT substrate 11 is covered. The orientation control electrode 32 is provided so as to surround the pixel electrode 12 or sandwich the pixel electrode 12 with the insulating layer 31 provided in between.

When driving the liquid crystal display panel, the liquid crystal molecules 17 are divided into the first region 18 and the second region 19 by the electric field 16 formed by applying a voltage between the alignment control electrode 32 and the pixel electrode 12. Thus, they are oriented with predetermined pretilt angles opposite to each other.

[0024]

However, when the liquid crystal is aligned by the alignment control electrode 32, the alignment control electrode 32 needs to be provided separately from the gate bus line or the data bus line, and the liquid crystal display panel There is a problem that a voltage must be continuously applied to the orientation control electrode 32 during driving.

Therefore, in the present invention, the orientation control electrode is not used.
And to provide a by Lehigh direction division type liquid crystal display panel in a simple manufacturing process and simple electrode configuration for the principal.

[0026]

FIG. 1 is an explanatory view of the principle configuration of the present invention, and means and actions for solving the problems in the present invention will be described with reference to FIG. See FIG. 1 (1) The present invention relates to a method for manufacturing a liquid crystal display panel,
A plurality of liquid crystal alignment regions divided into the same pixel are formed by mixing a photo-curable resin in a liquid crystal material and irradiating light while applying a voltage between the bus line 3 and the pixel electrode 2.
However, within the same divided area, the liquid crystal pleats are moved in the same direction.
Has a tilt angle and pretilts in different liquid crystal alignment regions
The feature is that the directions of the corners are different .

(2) Further, according to the present invention, in the method for manufacturing a liquid crystal display panel, ultraviolet light curable liquid crystal (UV curable liquid crystal) is mixed in a liquid crystal material, and a voltage is applied between the bus line 3 and the pixel electrode 2. However, by irradiating with ultraviolet light, a plurality of liquid crystal orientations are divided into the same pixel.
Areas are formed, and in the same divided area, in the same direction
It has a liquid crystal pretilt angle, and each has a different liquid crystal alignment area.
It is characterized in that the directions of the pretilt angles are different .

(3) Further, in the present invention according to the above (1) or (2), by providing fine grooves in the alignment film provided on the surfaces of the substrates 1 and 4 sandwiching the liquid crystal material, rubbing-less liquid crystal molecules are provided. 7 is orientated.

(4) Further, in the present invention, in the above (1) or (2), the alignment film provided on the surfaces of the substrates 1 and 4 sandwiching the liquid crystal material is irradiated with linearly polarized light so as to be free from rubbing. It is characterized in that the liquid crystal molecules 7 are aligned.

(5) Further, the present invention is characterized in that, in any one of the above (1) to (4), the method has a step of providing a light shielding pattern for shielding the domain wall on the surface of the counter substrate 4.

[0031] (6) Further, the present invention provides a liquid crystal display panel, together with the liquid crystal layer is made of liquid crystal material and a photocurable resin, it is divided liquid crystal molecules 7 in the same pixel in the liquid crystal layer
Multiple divided liquid crystal alignment regions are formed and divided into the same region.
Within the liquid crystal pretilt angle in the same direction,
The directions of the pretilt angle are different in the crystal orientation regions.
Ri, and characterized in that the flop Rechiruto angle is inclined along the electric field 6 formed when a voltage is applied between the pixel electrode 2 and the bus line 3.

(7) In addition, in the liquid crystal display panel according to the present invention, the liquid crystal layer is made of a liquid crystal material and an ultraviolet curable liquid crystal, and the liquid crystal molecules 7 in the liquid crystal layer are divided into a plurality of liquid crystal alignments in the same pixel. Forming a region and before
The liquid crystal pre-tilt in the same direction in the same divided region.
Have different tilt angles and different pre-tilt angles in different liquid crystal alignment regions.
It has different directions, and characterized in that the flop Rechiruto angle is inclined along the electric field 6 formed when a voltage is applied between the pixel electrode 2 and the bus line 3.

[0033]

[Function] Mixing liquid crystal material with photo-curing resin, the bus line 3
Since the liquid crystal molecules 7 have a pretilt angle depending on the electric field 6 formed between the bus lines 3 and the pixel electrodes 2 by applying light to the liquid crystal molecules 7 while applying a voltage to them , the alignment control is performed.
Since the control electrode is not required and the manufacturing process is simplified , the manufacturing yield is improved. In this case, rubbing-less liquid crystal molecules
Pre-orienting 7 is desirable.

Even if UV curable liquid crystal is mixed in instead of the photo-curable resin, the same result as in the case of using the photo-curable resin can be obtained.

Further, by providing fine grooves in the alignment film provided on the surfaces of the substrates 1 and 4 sandwiching the liquid crystal material, the liquid crystal molecules 7 can be aligned without rubbing due to the shape effect. Is not required, the reproducibility is increased and the manufacturing yield is improved.

The liquid crystal molecules 7 can be aligned without rubbing by irradiating linearly polarized light instead of providing fine grooves in the alignment films provided on the surfaces of the substrates 1 and 4 which sandwich the liquid crystal material. Since no experience is required in the alignment process, reproducibility is improved and manufacturing yield is improved.

Further, by providing a light-shielding pattern on the surface of the counter substrate 4 on the domain wall generated at the boundary between the first region 8 and the second region 9 in which the directions of the pretilt angles of the liquid crystal molecules 7 are different, It is possible to shield the white line that is turned on and improve the display characteristics. In the figure, reference numeral 5 is a counter electrode.

[0038]

EXAMPLE A first example of the present invention will be described with reference to FIG. 2A is a top view illustrating an electrode structure of a pixel portion of a liquid crystal display panel, and FIG. 2B is a liquid crystal display taken along a dashed-dotted line AA ′ in FIG. FIG. 3 is a cross-sectional view of the panel, in which the liquid crystal display panel has 640 × 480 pixels and one pixel size of 100 × 29.
0 μm diagonal 10.4 inch (about 26.4 cm) TF
T liquid crystal display panel.

Referring to FIG. 2A, the electrode structure of the pixel portion of the liquid crystal display panel of the present invention is the same as that of the conventional active matrix type liquid crystal display panel, and extends in the data bus line 10 and a direction substantially orthogonal to the data bus line 10. It is composed of the existing gate bus line 13 and the pixel electrode 12, and the data bus line 10 is connected to the drain region 20 made of polycrystalline silicon which constitutes the TFT 23.
The gate electrode 21 is connected to the gate bus line 13, and the source region 22 is connected to the pixel electrode 12.

Referring to FIG. 2B, these electrodes 12 and 13 (and not shown 10) are provided on a TFT substrate 11 made of a glass substrate or the like, and an alignment film (made of polyimide or the like) is formed on the surface thereof. (Not shown), on the other hand, the TFT substrate 11 of the counter substrate 14 made of a glass substrate or the like facing the TFT substrate 11 is provided.
The counter electrode 15 is provided on the surface of the opposite side to, and an alignment film (not shown) is further provided on the surface.

Then, the alignment film is irradiated with linearly polarized ultraviolet light without rubbing the alignment film to unify the alignment direction of the molecules on the alignment film surface. The TFT substrate 1
Linearly polarized lights different from each other are irradiated so that the alignment film 1 provided on the side and the alignment film provided on the counter substrate 14 side are oriented in directions substantially orthogonal to each other.

Next, the TFT substrate 11 and the counter substrate 1
A TN type liquid crystal in which 1 to 10 wt%, preferably 3 wt% of an ultraviolet curing resin is mixed is sealed between the No. 4 and the No. 4. in this case,
Since the directions in which the molecules of the alignment film are aligned are unified by the irradiation of the linearly polarized ultraviolet light, the liquid crystal is aligned without rubbing, that is, without rubbing. In the drawings, the orientation directions of the TFT substrate 11 side and the counter substrate side 14 are shown to be the same in order to simplify the drawing.

Next, while applying a 15V electrode between the gate bus line 13 and the pixel electrode 12, ultraviolet light is irradiated. In this case, an electric field 16 indicated by a broken line is formed between the gate bus line 13 and the pixel electrode 12 by applying a voltage, and the liquid crystal molecules 17 are inclined along the electric field 16 by the liquid crystal director. Since the liquid crystal molecules 17 are formed in plane symmetry with the alternate long and short dash line as the axis of symmetry, the liquid crystal molecules 17 also have plane symmetry, and the first region 18 and the second region 19 having different tilt directions are formed.

Further, by irradiating with ultraviolet light, a polymer network derived from the ultraviolet light curing resin is formed in the liquid crystal, so that the liquid crystal molecule 1 formed by the electric field 16 is formed.
The tilt of 7 is fixed and this tilt is stored as the pretilt angle. The pretilt angle in this case is 1 to 10
And more preferably 2 to 6 °.

Next, a domain wall is formed due to the disturbance of the liquid crystal molecules in the vicinity of the boundary between the first region 18 and the second region 19 (for example, Display and Imaging, vol. 2, 1994, pp. 235).
To 239), the light shielding pattern 24 is provided on the counter substrate 14 to complete the liquid crystal display panel.

In this case, the TFT substrate 11 and the counter substrate 1
4 can be given rubbing-less orientation, so there is no need to rely on experience in the orientation process, thereby
Reproducibility is increased and manufacturing yield is improved.

Further, unlike the conventional liquid crystal display panel shown in FIG. 7, it is not necessary to provide a special alignment control electrode 32 other than the gate bus line 13 in order to form the electric field 16 for giving a pretilt angle. The configuration and manufacturing process can be simplified.

Furthermore, since the white line generated on the domain wall is blocked by the light blocking pattern 24,
The display characteristics are improved.

Next, a second embodiment of the present invention will be described with reference to FIG. See FIG. 3. In the second embodiment, the data bus line 10 is used as the means for forming the electric field 16 instead of the gate bus line 13, and other basic configurations and operational effects are the same as those of the first embodiment. It is the same.

In this case, since an electric field is formed between the data bus line 10 and the pixel electrode 12, the first region 18 and the second region 19 having different pretilt angles are different from each other in the gate bus line 13. Will be formed along.

In the above embodiment, the liquid crystal molecules are aligned without rubbing by using the linearly polarized ultraviolet light, but the alignment method is not limited to such a method, and the photolithography process may be performed. Using TFT substrate 1
1 and fine grooves in the alignment film provided on the surface of the counter substrate 14,
For example, width 1-5 μm, preferably 1 μm, depth 0.1-
A groove of 1 μm, preferably 0.5 μm may be provided. In this case, the liquid crystal molecules 17 can be aligned along the direction of the groove by the shape effect based on the minute groove.

Further, in the above embodiment, the ultraviolet light curable resin is used, but an ultraviolet light curable liquid crystal may be used, and the mixing ratio thereof is 1 to 10 as in the ultraviolet light curable resin.
It may be wt%, preferably 3 wt%.

Further, although ultraviolet light is used for pretreatment of the alignment film or for curing the ultraviolet light curable resin, light of other wavelengths may be used, and accordingly, the ultraviolet light curable resin is also used. A photocurable resin corresponding to a wavelength other than ultraviolet light may be used, and “light” in this specification means ultraviolet light and light having a longer wavelength than that.

[0054]

According to the present invention, since the liquid crystal molecules are aligned without rubbing and the pretilt angle is fixed by using the ultraviolet curable resin or the ultraviolet curable liquid crystal, the alignment division can be performed by a simple structure and manufacturing process. Type liquid crystal display panel can be configured, and thereby a liquid crystal display panel with improved viewing angle characteristics can be provided at low cost with good reproducibility.

[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 a sectional view of a basic structure of an active matrix type liquid crystal display panel.

FIG. 5 is an explanatory diagram of transmittance-voltage characteristics in the liquid crystal display panel.

FIG. 6 is an explanatory diagram of a conventional orientation division method.

FIG. 7 is a cross-sectional view of a liquid crystal display panel using a conventional alignment control electrode.

[Explanation of symbols]

1 substrate 2 pixel electrodes 3 bus lines 4 substrates 5 Counter electrode 6 electric field 7 Liquid crystal molecules 8 First area 9 Second area 10 data bus lines 11 TFT substrate 12 pixel electrodes 13 gate bus line 14 Counter substrate 15 Counter electrode 16 electric field 17 Liquid crystal molecules 18 First Area 19 Second area 20 drain region 21 Gate electrode 22 Source area 23 TFT 24 shade pattern 25 Alignment film 26 Alignment film 27 LCD 28 Polarizing film 29 Polarizing film 30 rubbing direction 31 insulating layer 32 Orientation control electrode

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Sasabayashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (56) Reference JP-A-7-120728 (JP, A) JP-A-63-301922 (JP, A) JP-A-6-294954 (JP, A) JP-A-6-324338 (JP, A) JP-A-6-160801 (JP, A) JP-A-60-211427 (JP, A) Kaihei 7-72483 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/13-1/141

Claims (7)

(57) [Claims] 1. A plurality of liquid crystal alignments divided in the same pixel by mixing a photocurable resin in a liquid crystal material and irradiating light while applying a voltage between a bus line and a pixel electrode.
A region is formed, and within the divided same region, the same
Has a liquid crystal pretilt angle in the
A method of manufacturing a liquid crystal display panel, wherein the directions of pretilt angles are different from each other . 2. An ultraviolet light curing liquid crystal is mixed in a liquid crystal material, and the light is irradiated with the ultraviolet light while applying a voltage between the bus line and the pixel electrode, thereby dividing the same pixel.
Forming a plurality of liquid crystal alignment regions,
Within the region, the liquid crystal pretilt angle is in the same direction, but different
The direction of the pretilt angle should be different in the liquid crystal alignment region.
A method for manufacturing a liquid crystal display panel, characterized in that 3. The liquid crystal display according to claim 1, wherein the liquid crystal molecules are aligned without rubbing by providing fine grooves in an alignment film provided on a surface of a substrate sandwiching the liquid crystal material. Panel manufacturing method. 4. The liquid crystal molecule is aligned without rubbing by irradiating an alignment film provided on a surface of a substrate sandwiching the liquid crystal material with linearly polarized light. Liquid crystal display panel manufacturing method. 5. The liquid crystal display panel according to claim 1, further comprising the step of providing a light-shielding pattern for shielding the domain wall on the surface of the counter substrate which constitutes one of the substrates. Manufacturing method. 6. The liquid crystal layer comprises a liquid crystal material and a photocurable resin, and liquid crystal molecules in the liquid crystal layer are within the same pixel.
Forming a plurality of divided liquid crystal alignment regions,
In the same region, the liquid crystal pretilt angle is also in the same direction.
The direction of the pretilt angle is different in different liquid crystal alignment regions.
Different and and a liquid crystal display panel in which the pretilt angle, and being inclined along the electric field formed when a voltage is applied between the bus line and the pixel electrode. 7. The liquid crystal layer is composed of a liquid crystal material and an ultraviolet curing liquid crystal, and liquid crystal molecules in the liquid crystal layer form a plurality of liquid crystal alignment regions divided in the same pixel ,
In the same divided area, the liquid crystal pleats are arranged in the same direction.
Has a tilt angle and pretilts in different liquid crystal alignment regions
The directions of the angles are different , and the pretilt angle is
A liquid crystal display panel, which is inclined along an electric field formed when a voltage is applied between the bus line and the pixel electrode.