JP2000081621A - Manufacture of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suitable alignment treatment without rubbing in a manufacture of a liquid crystal display device. SOLUTION: In a manufacture of a liquid crystal display device equipped with a pair of substrates 12, 14 opposing each other with a certain gap, an electrode 18 and an alignment film 20 formed on one of the substrate 12, an electrode 22 and an alignment film 24 formed on the other substrate 14 and liquid crystal 16 held between the pair of substrates 12, 14, a construction is made by forming the alignment films 20, 24 containing a polymer which realizes vertical alignment properties on the substrates, by irradiating the alignment films with a non-polarized ultraviolet ray with 30-120 mJ/cm2 exposure per 1% content of the polymer realizing vertical alignment properties on the substrates, from an oblique direction with an angle <=45 deg. with respect to surfaces of the alignment films.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly to an alignment processing technique for an alignment film of a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device comprises a pair of substrates facing each other at an interval, an electrode and an alignment film formed on one substrate, and an electrode and an alignment film formed on the other substrate. And a liquid crystal inserted between the substrates. The electrode on one substrate is a common electrode, and the electrode on the other substrate is formed as a pixel electrode. The pixel electrode can be provided together with the active matrix. The electrodes may be provided on only one substrate (for example, IPS mode). Further, a black matrix or a color filter is provided on one of the substrates.

In a conventional TN liquid crystal display device, the alignment film is rubbed so that the liquid crystal is aligned in a predetermined direction. However, rubbing involves rubbing the alignment film with a cloth such as rayon, and bringing the cloth such as rayon into a clean room generates dust. Further, rubbing generates static electricity, which may destroy the TFT (thin film transistor) of the active matrix. In view of this, Japanese Patent Application No. 9-354940, which is a prior application of the present application, proposes performing an alignment treatment by irradiating ultraviolet rays. The problem of rubbing can be solved by performing the alignment treatment by ultraviolet irradiation. In this proposal, by irradiating non-polarized ultraviolet rays to the vertical alignment film, part of the alkyl side chains that achieve vertical alignment are destroyed, and the alignment film is subjected to alignment treatment by leaving a part. Is going. In the case of a horizontal alignment film, it is difficult to achieve alignment processing by irradiating ultraviolet rays.

[0004]

In the case where the alignment treatment of the vertical alignment film is performed by irradiating ultraviolet rays, there is a great difference in the alignment depending on the exposure amount of the ultraviolet rays. As a result of the study, it was found that it is desirable to irradiate ultraviolet rays with an appropriate exposure amount. For example, when the exposure amount is smaller than the appropriate value, the pretilt angle indicated by the alignment film is high (closer to the substrate surface). As a result, when the spacers are scattered to maintain the cell gap of the liquid crystal panel, the orientation of the portion around the spacers is disturbed by the spacers. For this reason, during display, the orientation is such that a black spot is generated around the spacer, resulting in display failure.

On the other hand, when the exposure amount is larger than the appropriate value, the pretilt angle of the alignment film becomes low. However, when the amount of exposure is excessive, a portion that is horizontally oriented is generated, and an injection streak occurs when the liquid crystal is injected, and a trace may be left. Further, there is a problem that desired vertical alignment cannot be obtained and horizontal alignment occurs.

Further, when irradiating the surface of the alignment film with ultraviolet light, the angle of irradiation of the ultraviolet light is not limited to any angle. Only a part of the alkyl side chain cannot be selectively left, and the orientation in a desired direction cannot be obtained. An object of the present invention is to provide a method for manufacturing a liquid crystal display device capable of performing an appropriate alignment treatment without rubbing.

Another object of the present invention is to provide a method of manufacturing a liquid crystal display device having an alignment film having a plurality of domains in one pixel by one irradiation of ultraviolet rays.

[0008]

According to the present invention, there is provided a method of manufacturing a liquid crystal display device, comprising: a pair of substrates facing each other at an interval;
An alignment film formed on one substrate, an alignment film formed on the other substrate, and a method of manufacturing a liquid crystal display device including a liquid crystal inserted between the pair of substrates, the method comprising: An alignment film containing a polymer for realizing vertical alignment is formed, and the surface of the alignment film is exposed at an exposure of 30 to 120 mJ / cm ² per 1% of the content of the polymer for realizing vertical alignment of the alignment film. The alignment film is irradiated with unpolarized ultraviolet light from an oblique direction of 45 degrees or less.

According to the present invention, by irradiating the surface of the vertical alignment film obliquely with unpolarized ultraviolet light, an alignment with a pretilt angle is realized without a rubbing step.
In the irradiation of the non-polarized ultraviolet light according to the present invention, the irradiation direction of the ultraviolet light is set to an oblique direction of 45 degrees or less with respect to the surface of the alignment film, and the content of the polymer having an alkyl side chain for realizing the vertical alignment of the alignment film is 1%. 30 to 120 mJ / c per%
Irradiate unpolarized ultraviolet light with an exposure amount of m ² . That is,
The irradiation amount of the ultraviolet ray is set according to the actual amount of the alkyl side chain for realizing the vertical alignment of the alignment film.

[0010] This makes it possible to provide the alignment film with an appropriate pretilt angle for vertically aligning the liquid crystal without disturbing the alignment around the spacer and without changing the alignment to the horizontal alignment. In the case of this condition, even if the amount of the polymer having an alkyl side chain for realizing the vertical alignment contained in the alignment film changes, an appropriate pretilt angle is obtained by changing the exposure correspondingly. be able to.

In the above method, preferably, the exposure amount of the non-polarized ultraviolet light applied to the alignment film surface is 40 to 90 mJ.
/ Cm ² . Further, it is preferable that the exposure amount of the unpolarized ultraviolet light applied to the alignment film surface is in the range of 80 to 120 mJ / cm ² . The amount of exposure to ultraviolet light is such that the pretilt angle of the liquid crystal with respect to the surface of the alignment film is 89.5 degrees or less. Preferably, the liquid crystal has a pretilt angle of 89.5.
Be in the range of degrees to 89 degrees.

Preferably, the wavelength of the ultraviolet light applied to the alignment film is 280 nm or less. Further, a method for manufacturing a liquid crystal display device according to another feature of the present invention includes a pair of substrates facing each other at an interval, an alignment film formed on one substrate, and an alignment film formed on the other substrate. A method for manufacturing a liquid crystal display device comprising a liquid crystal inserted between the pair of substrates, wherein an alignment film is formed on the substrate, and the main body is provided in the main body corresponding to the pixel pitch. Each surface of the alignment film is irradiated with ultraviolet light from an oblique direction using a mask having an optical path changing portion having a different refractive index from the main body portion.

According to this method, it is possible to perform alignment division in which liquid crystal molecules are aligned in different directions within one pixel by one liquid crystal alignment process. Preferably,
Each of the light path changing portions has a sawtooth shape with an isosceles triangular cross section whose base is the length of the pixel pitch, and a light shielding film is formed on a portion of the light path changing portion located at the top of the isosceles triangle. ing. Alternatively, each of the optical path changing portions has a trapezoidal saw-tooth cross-sectional shape whose bottom is the length of the pixel pitch, and a light shielding film is formed on a portion located on the upper side of the trapezoid.

In this case, the refractive index of the main body portion is n ₁ , the refractive index of the optical path changing portion is n ₂ , the apex angle of the sawtooth cross section is θ ₁ , and the alignment film is irradiated through the optical path changing portion. Assuming that the incident angle of the ultraviolet light to be incident is θ ₂ , the following expression (1) is satisfied when θ ₁ ≦ 60. _{n 1 cos (3θ 1/2} ) = n 2 sin (θ 2 -θ 1/2) (1) θ 1> case 60, satisfying the following formula (2).

[0015] _{n 1 cos (3θ 1/2} ) = n 2 sin (θ 1/2-θ 2) (2) In addition, the refractive index of the body portion n _1, the refractive index of the optical path changing portion n ₂ The following relationship exists between θ _{1 and} the apex angle of the sawtooth cross-sectional shape. cos θ ₁ > = n ₂ / n ₁ (5) Further, the optical path changing portion may be made of air.

[0016] Preferably, the main body portion of the mask includes a first portion.
A flat surface, a second surface opposite the first surface, and a plurality of cavities provided in the second surface, wherein each cavity is separated from the first surface by the second surface. A first and a second bevel that are inclined so as to widen each other when viewed in a direction toward the surface of the cavities, each cavity having a center line between the first and the second bevels, The optical path changing portion is formed by the cavity and a substance contained in the cavity. Ultraviolet rays that are incident on the main body from the first surface and pass through the first slope are applied to the alignment film obliquely from a first direction, and ultraviolet rays that pass through the second slope are aligned with the alignment film. Irradiation is performed obliquely from a second direction opposite to the first direction.

The present invention further provides a pair of substrates facing each other at an interval, an alignment film formed on one substrate, an alignment film formed on the other substrate, and a plurality of substrates provided on the one substrate. A liquid crystal display device comprising: a bus line; and a liquid crystal inserted between the pair of substrates, wherein an alignment film is formed on the substrate, and the main body portion and the main body correspond to the pixel pitch. Providing a mask having a plurality of light path altering portions provided on a portion thereof, wherein a body portion of the mask includes a first flat surface, a second surface opposite the first surface, and a second surface. A plurality of cavities provided on the second surface, each cavity being on both sides of a vertical plane perpendicular to the first surface, in a direction from the first surface to the second surface. The first and second slopes are inclined so as to be widened from each other when viewed from above. Is formed by the cavity and a substance contained in the cavity, and for one substrate having the bus line, a vertical plane between the first slope and the second slope is on the bus line. Thus, a method for manufacturing a liquid crystal display device is provided, wherein the mask is superimposed on the substrate, and the surface of the alignment film of the substrate is irradiated with ultraviolet light obliquely through the mask.

As described above, when the alignment film is obliquely irradiated with the ultraviolet light, the position of the mask and the position of the substrate are appropriately adjusted so that the liquid crystal molecules located in the vicinity of the bus line can be aligned during use. It is no longer disturbed by the influence of the force lines. The present invention further provides a pair of substrates facing each other at an interval, an alignment film formed on one substrate, an alignment film formed on the other substrate, and a plurality of bus lines provided on the one substrate. And a liquid crystal display device comprising a liquid crystal inserted between the pair of substrates, wherein an alignment film is formed on the substrate, and the main body is provided on the main body corresponding to the pixel pitch. Prepare a mask having a plurality of optical path changing portions, the main body portion of the mask,
A first flat surface, a second surface opposite the first surface, and a plurality of cavities provided in the second surface, each cavity being relative to the first surface. A first and a second slope on both sides of a vertical surface which are perpendicular to each other, and which are inclined so as to expand from each other when viewed from the first surface toward the second surface. For the other substrate formed by the cavity and the material contained in the cavity and not having the bus line, an end of the first slope on the second surface and a second end of the second slope are Superimposing the mask on the substrate such that the end on the surface of 2 is on a line passing through the bus line, and irradiating the surface of the alignment film of the substrate with ultraviolet light obliquely through the mask. Provided is a method for manufacturing a liquid crystal display device characterized by the following.

Also in this case, when the alignment film is obliquely irradiated with ultraviolet light, the position of the mask and the position of the substrate are appropriately adjusted so that the liquid crystal molecules located in the vicinity of the bus line during use can be aligned with the bus line. It will not be disturbed by being affected by the electric field lines. And, the above-described alignment processing for one substrate having a bus line and the alignment processing for the other substrate having no bus line,
Can be used in combination. Alternatively, the above-described orientation treatment for one substrate having a bus line and the orientation treatment for the other substrate having no bus line can be used without being combined.

Preferably, the cavity has a saw-tooth shape having an isosceles triangular cross section, and a light shielding film is formed at a portion located at the top of the isosceles triangle. Alternatively, the cavity has a sawtooth shape having a trapezoidal cross section, and a light-shielding film is formed at a portion located on the upper side of the trapezoid. Further, the alignment film has a vertical alignment property. The liquid crystal has Δε <0.

The present invention further provides a pair of substrates facing each other at an interval, an alignment film formed on one substrate, an alignment film formed on the other substrate, and a plurality of substrates provided on one substrate. A liquid crystal display device comprising: a bus line; and a liquid crystal inserted between the pair of substrates, wherein an alignment film is formed on the substrate, and the main body portion and the main body correspond to the pixel pitch. Providing a mask having a plurality of light path altering portions provided on a portion thereof, wherein a body portion of the mask includes a first flat surface, a second surface opposite the first surface, and a second surface. A plurality of cavities provided on the second surface, wherein each cavity is on both sides of the first vertical surface among first and second vertical surfaces perpendicular to the first surface and perpendicular to each other. In the direction from the first surface to the second surface. A first and second surface inclined to,
On either side of a second vertical plane, the second surface
A third and a fourth inclined surface which are inclined so as to be widened when viewed in a direction toward the surface of the substrate, wherein the optical path changing portion is formed by the cavity and a substance contained in the cavity, and And irradiating the surface of the alignment film of the substrate with ultraviolet rays from the oblique direction through the mask.

According to this method, it is possible to perform alignment division in which liquid crystal molecules are aligned in four different directions within one pixel by one liquid crystal alignment process. Preferably, the cavity has at least one of a sawtooth shape having an isosceles triangular cross section and a sawtooth shape having a trapezoidal cross section. In the embodiment, the first and second slopes are isosceles triangle slopes, and the third and fourth slopes are trapezoidal slopes. One substrate having a bus line is subjected to ultraviolet irradiation in the above-described steps to perform alignment processing, and the other substrate having no bus line is not subjected to ultraviolet irradiation in the above-described steps.

[0023]

FIG. 1 is a view showing a liquid crystal display device obtained according to the present invention. The liquid crystal display device 10 includes a pair of transparent glass substrates 12 and 14 facing each other at an interval,
The liquid crystal layer 16 is sandwiched between the substrates 12 and 14. On one substrate 12, a transparent pixel electrode 18 and a transparent alignment film 20 are formed, and on the other substrate 14, a transparent common electrode 22 and a transparent alignment film 24 are formed. The substrate 14 is further provided with a color filter 26. Polarizers 28 and 30 are disposed outside of substrate 12 and substrate 14. The pixel electrodes 18 of the substrate 12 are formed together with the active matrix, and FIG. 1 shows a data bus line 32 of the active matrix. Three
4 is an insulating film. Note that the electrode may be provided only on one substrate (for example, in the case of the IPS mode).

Each of the alignment films 20 and 24 is an alignment film exhibiting vertical alignment, and realizes an alignment with a pretilt angle without rubbing as described below. FIG. 2 shows an alignment processing device 60 for the alignment film 20 (24). The alignment processing device 60 includes a light source 62 for irradiating unpolarized ultraviolet light, a mirror 64, and a holder 66 for supporting the substrate 12 (14) provided with the alignment film 20 (24). The holder 66 holds the substrate 12 obliquely with respect to the optical axis.
Support (14). That is, parallel ultraviolet rays from the light source 62 enter the alignment film 20 (24) at an angle of 45 degrees (or 45 degrees or less).

The light source 62 includes a parabolic reflector 62a and irradiates unpolarized ultraviolet light substantially in parallel. A preferred spectral distribution of the light source 62 is shown in FIG. This spectrum distribution has a peak near a wavelength of 250 nm. It is preferable that the irradiated ultraviolet light contains a component having a wavelength of 280 nm or less. The alignment film 20 (24) processed by the alignment processing device 60 is an alignment film exhibiting vertical alignment, and the alignment with a pretilt angle is realized by irradiating unpolarized ultraviolet light from an oblique direction.

The alignment film 20 (24) is an alignment film exhibiting a vertical alignment when coated and baked, and contains the following polymer.

[0027]

Embedded image

FIG. 4 is a view showing the principle of the alignment treatment, and FIG. 5 is a simplified view of FIG. The alignment film 20 (24) shown in Chemical Formula 1 includes a polymer having an alkyl side chain (alkyl group) R for realizing vertical alignment. The alkyl group R is designated by the numeral 70 in FIG. Alkyl group 7
It is considered that 0 is randomly projected on the surface of the alignment film 20 (24).

The ultraviolet rays 68 are applied obliquely to the alignment film 20 (24) from the X direction, and the pretilt direction (azimuth line) of the liquid crystal is parallel to the incident direction of the ultraviolet rays 68. The unpolarized ultraviolet light 68 includes P-wave and S-wave polarized light,
The S wave does not contribute to the directionality of the orientation. That is, the S wave does not act at all in the X direction and acts in the Y direction, but the magnitude of the action is the same in the plus direction and the minus direction of the Y axis. Does not contribute to

The P-wave acts on a portion including the alkyl group 70 on a plane parallel to the incident direction of the ultraviolet light 68, and affects the directionality of the orientation. FIG. 5 is a part of FIG. 4 taken along a plane parallel to the incident direction of the ultraviolet rays 68, that is, a plane parallel to the vibration plane of the P wave. In FIG. 5, the alkyl group 70
Can be divided into two inclined in opposite directions with respect to the vibration direction of the P-wave of the ultraviolet light 68.

The component a of the alkyl group 70 is inclined so as to be nearly perpendicular to the vibration direction of the P wave, and the component b of the alkyl group 70 is inclined with respect to the vibration direction of the P wave. It is inclined so that it is almost horizontal. In general, it is unlikely that ultraviolet light will destroy the alkyl group itself.
It is easy to understand that it is considered that the part supporting the alkyl group or the part tilting the alkyl group is destroyed by ultraviolet rays. P
A part a (corresponding to the component a) in which the alkyl group is inclined so as to be close to the direction perpendicular to the vibration direction of the wave, and an alkyl group inclining so as to be close to parallel to the vibration direction of the P wave. The part b (corresponding to the component b) has a different ratio of being destroyed by ultraviolet rays.

The portion b in which the alkyl group is inclined is apt to receive energy and is easily broken by the energy of ultraviolet rays. Therefore, by irradiation with ultraviolet rays, the component b decreases, and the component a remains without being destroyed. Therefore, when the alignment film 20 (24) is used in the liquid crystal display device 10, the liquid crystal molecules
The pretilt is performed according to the gradient of the component a in the alkyl group 70 of (24).

FIG. 6 is a diagram showing a modification of FIG. FIG.
In FIG. 6, it is assumed that the components a and b of the alkyl group 70 are uniformly subjected to the action of ultraviolet irradiation, but FIG. 6 shows the components a and b of the components a and b of the alkyl group 70, respectively.
bb is particularly strongly affected by ultraviolet irradiation.
These portions aa and bb are bent opposite to most of the components a and b of the alkyl group 70, respectively.

Therefore, the portion aa is easily broken by the energy of the ultraviolet light, but the portion bb is hardly broken by the energy of the ultraviolet light. Therefore, the component b having the portion bb remains, and when the alignment film 20 (24) is used in the liquid crystal display device 10, the liquid crystal molecules are changed to the alkyl group 70 of the alignment film 20 (24).
Pretilt according to the gradient of the component b. In each of the cases of FIG. 5 and FIG. 6,
The liquid crystal molecules are oriented with a certain pretilt angle. Therefore, a vertical alignment film can realize alignment with a pretilt angle by obliquely irradiating unpolarized ultraviolet light without rubbing.

However, in FIGS. 5 and 6, it may be difficult to determine which of the component a and the component b is liable to be broken before irradiation with ultraviolet rays. However, when the ultraviolet rays are irradiated obliquely, one of the a component and the b component is destroyed, and the other remains, whereby when used as the liquid crystal display device 10, the liquid crystal molecules are aligned with a pretilt angle without rubbing. Become like

A feature of the present invention is that the amount of exposure to ultraviolet light when irradiating ultraviolet light is 30 to 120 mJ / per 1% (per 1 weight percent) of a polymer content for realizing the vertical alignment of the alignment films 20 and 24. It is determined within the range of cm ² . The above chemical formula (1) shows an example of a polymer for realizing the vertical alignment of the alignment films 20 and 24, and the alignment film contains another polymer other than the polymer shown in the chemical formula (1). The other polymer does not include a component for realizing vertical alignment like the alkyl group 70, for example, and has a structure in which the alkyl group 70 is substituted with a hydrogen group, for example. In the present invention, the content of the polymer that realizes the vertical alignment with respect to all the polymers constituting the alignment films 20 and 24 is checked, and the irradiation amount of ultraviolet rays is set per 1% of the content.

In the examples, samples containing 25% of a polymer realizing the vertical alignment of the alignment films 20 and 24 and samples containing 65% were prepared and used as the alignment films 20 and 24. First, the vertical alignment film 20
The substrate 12 (14) is formed by spin coating the material of (24).
At 1500 rpm. At this time, the alignment film 20
The film thickness of (24) is about 500 angstroms. This was fired at 180 ° C. for 1 hour. Next, the alignment film 20 (24) was irradiated with ultraviolet rays at an angle of 45 degrees with respect to the surface of the alignment film 20 (24) using the alignment processing device 60 of FIG. At this time, a deep UV irradiation device manufactured by Ushio Inc. was used as the light source 62. In this light source 62, the size of the ultraviolet light emitting portion was about 5 mm, and substantially parallel ultraviolet light was obtained by the reflector 62a.

Here, the content of the polymer having the alkyl group 70 for realizing the vertical alignment of the alignment films 20 and 24 is 1%.
A plurality of samples irradiated with several ultraviolet light exposures in the range of 30 to 120 mJ / cm ² were prepared and assembled as a liquid crystal display device. The first group was a sample with a polymer content of 25 percent and the second group was a sample with 65 percent.

FIG. 7 is a diagram showing the relationship between the amount of exposure and the pretilt angle of the sample thus manufactured. The first group of samples is plotted with curve X. Samples of the first group were irradiated with ultraviolet light at an exposure within the range of 500 to 2500 mJ / cm ² . The samples of the second group are plotted with curve Y. Samples in the second group were irradiated with ultraviolet light at an exposure within the range of 1200 to 6000 mJ / cm ² .

Observation of the orientation of the liquid crystal of the above samples reveals that the orientation around the spacer inserted to maintain the cell gap is generally small when the exposure amount is small (the region on the left end side in FIG. 7). In the case where a black spot was generated due to the disturbance and the exposure amount was large (the region on the right end side in FIG. 7), a streak during liquid crystal injection appeared. Those without black spots or injection lines are judged to have good orientation of the liquid crystal.

With respect to the samples of the first group, those in the range P in FIG. 7 were judged to have good orientation of the liquid crystal. For samples of the first group, those in range P are 1000
UV light was irradiated at an exposure amount within the range of ２2200 mJ / cm ² . Regarding the samples of the second group, those in the range Q in FIG. 7 were determined to have good orientation. Second
For group samples, 240 for range Q
Ultraviolet rays were irradiated at an exposure amount within the range of 0 to 5500 mJ / cm ² .

FIG. 8 is a graph in which the exposure amount is converted into a value per 1% of a polymer having an alkyl group for realizing vertical alignment.
FIG. That is, for the first sample, the exposure amount in FIG. 7 was divided by 25, and for the second sample, the exposure amount in FIG. 7 was divided by 65 to obtain the exposure amount per 1% of the polymer. The curve X indicating the relationship between the samples of the first group in FIG. 7 is plotted as a curve X ′ in FIG.
The exposure dose P 'for obtaining a good result of the alignment of the liquid crystal is 4% per 1% of the polymer having an alkyl group for realizing the vertical alignment.
It was within the range of 0 to 88 mJ / cm ² . The curve Y showing the relationship between the samples of the second group in FIG. 7 is plotted as a curve Y 'in FIG. The exposure dose Q ′ for obtaining a good result of the alignment of the liquid crystal is 37 to 85 mJ / cm ² per 1% of the polymer having an alkyl group for realizing the vertical alignment.
Was within the range.

From these results, it was found that the materials of the alignment films 20 and 24
Of polymers having alkyl groups to achieve vertical alignment
Alkyl group that realizes vertical alignment even if the content changes
Exposure amount per 1% of polymer having
If this is the case, it is possible to obtain good results
I understand. Preferred exposure dose is 40 to 90 mJ / cm ^Two 
Was found to be within the range.

In assembling the liquid crystal display device, the liquid crystal 1
6 is injected between the pair of substrates 12 and 14, and the injection port is sealed. The above-described embodiment is a result of a test in which a voltage is applied between the electrodes 18 and 22 as a liquid crystal display device in this state. After injecting and sealing the liquid crystal 16 between the pair of substrates 12 and 14,
Annealing by applying heat to the liquid crystal panel improves the alignment of the liquid crystal. As a result, it is possible to obtain a good result of the orientation of the liquid crystal in the range of the exposure amount wider than the above-mentioned range of the exposure amount. Table 1 below shows the results in this case.

Table 1 Types of Samples 25% Polymer 65% 65% Polymer Exposure Amount per 1% Black Spot Injection Black Spot Injection 9.6 ９ ─ × ○ 15.9 ─ ─ × ─ ○ 22.3 △ ○ △ ○ 38 .2 ○ ○ ○ ○ 54.1 ○ ○ ○ ○ △ 70.1 ○ ○ ○ ○ △ 86.0 ○ ○ △ ○ △ 101.9 ○ ○ △ ○ △ 117.8 ○ △ ○ △ 133.8 ○ × × × From this result, it can be seen that when ultraviolet light is irradiated at an exposure amount of 30 to 120 mJ / cm ² per 1% of the content of the polymer for realizing the vertical alignment of the alignment film, a favorable result of the alignment of the liquid crystal can be obtained. I understand. Further, the alignment film 20 (2
When ultraviolet light is irradiated at an exposure amount of 80 to 120 mJ / cm ² per 1% of the polymer content for realizing the vertical alignment property of 4), the pretilt angle of the liquid crystal molecules becomes 89 degrees or less, and the function of the vertical alignment film is stabilized. However, generation of a domain due to a lateral electric field can be prevented. At this exposure, the pretilt angle was generally in the range of about 89.6 degrees to about 89 degrees.

Here, the generation of the domain by the lateral electric field will be described. The liquid crystal which is aligned at a pre-tilt angle close to vertical by the alignment films 20 and 24 is affected by the horizontal electric field from the bus line of the substrate having the TFT. It will be easier. In order to reduce the influence of the lateral electric field, it is necessary to set the pretilt angle of the alignment film with respect to the alignment film surface as small as possible. However, this is not to say that the pretilt angle should just be lowered. If the pretilt angle is reduced to some extent (for example, about 85 degrees), the blackness decreases when a polarizing plate is attached with crossed Nicols to display black. The contrast is reduced.

As shown in FIGS. 7 and 8, the pretilt angle when irradiating unpolarized ultraviolet light tends to decrease as the irradiation amount increases. Further, as shown in FIG. 9, the pretilt angle tends to decrease as the irradiation angle of the unpolarized ultraviolet light becomes shallower with respect to the alignment film surface. Then, under certain irradiation conditions, the alignment film containing 25% of the polymer containing an alkyl group is irradiated,
When applied to an FT panel, under the irradiation conditions of an irradiation angle of 10 degrees and an exposure amount of about 1800 mJ / cm ² , it was possible to obtain a good display in which generation of domains was extremely small. The pretilt angle at this time was about 89 degrees with respect to the alignment film surface.

In order to minimize the influence of the lateral electric field, a pretilt angle of 89 degrees or less is desired. For this purpose, the amount of ultraviolet irradiation to the alignment film is required to be about 80 mJ / cm ² or more per 1% of the polymer containing an alkyl group in the alignment film. However, as described above, if the amount of irradiation of ultraviolet rays is too large, there is a problem that an injection streak occurs when the liquid crystal is injected and traces thereof remain. In FIG. 8, 90
Although the condition where the implanted line remains at mJ / cm ² or more, as described above, by performing post-injection annealing, 89 to 120 mJ / cm ² can be obtained without the implanted line.
The irradiation conditions are such that a pretilt angle of less than or equal to degree is obtained.

The spectral distribution shown in FIG.
A wavelength component around m was included, and this component was effective. As described above, a short arc lamp is used as a light source, and ultraviolet rays near 250 nm are mainly used. The parallelism of the ultraviolet rays is adjusted to ± 10 degrees or less, preferably ± 3 degrees or less by a reflector. A test in which the light source light having the spectral distribution shown in FIG. 3 was used as it was and a test in which ultraviolet light in which wavelength components of 300 nm or more were cut out of the light source light were performed, and the results were compared. Expression was confirmed. From this result, the vertical alignment film 2
To express the pretilt at 0 (24), 280
Irradiation with ultraviolet light of nm or less was found to be effective.

FIG. 9 is a diagram showing the relationship between the irradiation angle of ultraviolet rays and the pretilt angle. The alignment films of the first group of samples (25%) and the first group of samples (65%) were irradiated with ultraviolet light at an exposure of 1800 mJ / cm ² , and the pretilt angle due to the difference in the irradiation angle was reduced. Tested for change. It has been found that a good alignment can be obtained by irradiating the alignment film surface with ultraviolet rays at an angle of 45 degrees or less. As for the pretilt angle, the lower the irradiation angle with respect to the alignment film surface, the lower the pretilt angle can be obtained. In this case, the pretilt angle at the irradiation angle at which the orientation of the liquid crystal becomes good is 89.5 degrees or less. Considering the above, it is preferable to set the pretilt angle to 89.5 degrees or less in order to prevent the spacer from being adversely affected by the orientation.

In this embodiment, the pre-tilt expression was able to be imparted to the vertical alignment film 20 (24) by using unpolarized ultraviolet light. Although it can be said that only the P wave of the unpolarized ultraviolet light is actually effective, the advantage of using the unpolarized ultraviolet light is great. Conventionally, there has been a proposal to impart a pretilt property by irradiating a polarized ultraviolet ray to the horizontal alignment film. In this case, however, it was not possible to obtain a pretilt property using a non-polarized ultraviolet ray. For that purpose, a polarizer for obtaining polarized ultraviolet light is required, and such polarizers are currently only available in the form of a Gran Taylor type polarizer, but the Gran Taylor type polarizer cuts out naturally occurring calcite It is not suitable for actual use. Therefore, it is extremely preferable that the alignment treatment can be performed using non-polarized ultraviolet light, since it is not necessary to use a polarizer for ultraviolet irradiation.

In this embodiment, the unpolarized ultraviolet light is uniformly applied to the entire surface of the vertical alignment film 20 (24). Therefore, two different orientation domains A in one pixel,
In order to perform orientation division having B, as shown in FIG. 10, ultraviolet rays 68A and 68B are irradiated from opposite directions for each of the divided domains A and B. In this way, as shown in FIG. 11, two domains A and B in which liquid crystal molecules located in the middle are tilted in opposite directions are obtained. In this case, there is no difference between the pretilt angles of the liquid crystal molecules in the two domains A and B. By performing the orientation division, the viewing angle characteristics are improved.

FIG. 12 shows an example in which ultraviolet rays 68A and 68B are simultaneously irradiated from the opposite direction for each of the domains A and B. In this case, a mask 74 having an opening 74A is used. Ultraviolet rays 6 in the opposite direction from one opening 74A
8A and 68B enter, but ultraviolet rays 68A and 68 in opposite directions.
The conditions under which B is just distributed to two domains A and B are as follows. The pitch of the openings 74A of the mask 74 (the pitch of one pixel) is P, and the mask 74 and the alignment film 2
When the interval from 0 (24) is Q, and the incident angles of the ultraviolet rays 68A and 68B are θ, Q = (P / 4) sin θ.

As shown in FIG. 13, when this principle is applied, by simultaneously irradiating ultraviolet rays from four directions, four different domains Aa, Ab,
Ba and Bb can also be formed. In this case, one pixel is divided into a plurality of domains Aa, Ab, Ba, and Bb, and the alignment directions of the liquid crystals in the plurality of domains Aa, Ab, Ba, and Bb are set with respect to the center of the pixel as indicated by arrows. It is radial. In FIG. 13, the alignment direction of the liquid crystal is directed outward from the center of the pixel as indicated by the arrow. The alignment direction of the liquid crystal may be directed inward toward the center of the pixel. Thus, by providing four domains Aa, Ab, Ba, and Bb in one pixel, the viewing angle characteristics can be improved.

FIG. 14 is a view showing an alignment process of an alignment film according to another embodiment of the present invention. In this embodiment, as shown in FIG. 1, a pair of substrates 12 and 14, an electrode 18 formed on one substrate, and an alignment film 20, an electrode 22 formed on the other substrate, and The present invention can be applied to a liquid crystal display device including the alignment film 24 and the liquid crystal 16 inserted between the pair of substrates 12 and 14. The alignment films 20 and 24 are subjected to alignment treatment by irradiating ultraviolet rays obliquely in the same manner as in the previous embodiment. However, as shown in FIG. A and B are included.

In this embodiment, in manufacturing a liquid crystal display device, after forming an alignment film 20 (24) on a substrate 12 (14), a mask 80 is used when irradiating ultraviolet rays obliquely. The mask 80 has a main body portion 82 and an optical path changing portion 84 embedded in the main body portion 82 and having a different refractive index from the main body portion 82. Each of the optical path changing portions 84 is 2
It has a sawtooth shape with an isosceles triangular cross section, and the length h of the base corresponds to the length of the pixel pitch. Further, the optical path changing portion 8
A light-shielding film 86 is formed at a portion located at the top of the isosceles triangle 4.

FIG. 15 is a diagram showing the relationship between the mask 80 and the pixels used in FIG. First and second substrates 1
One of the substrates 2 and 14 is a TFT substrate, and TF
The T substrate has a pixel electrode 18, a drain bus line 32, and a gate bus line 33. The TFT (not shown) is provided at the intersection of the drain bus line 32 and the gate bus line 33. The pixel pitch h is the distance between the centers of two adjacent drain bus lines 32, and the length h of the bottom of the optical path changing portion 84 corresponds to the pixel pitch h. It should be noted that the pixel pitch h is set between two adjacent gate bus lines 3.
3 may be the distance between the centers.

In FIG. 14, the mask 80 is arranged so that the bottom surface of the isosceles triangle of the optical path changing portion 84 is on the alignment film 20 (24), and parallel ultraviolet rays are applied to the alignment film 20 as indicated by arrows. Incident on the mask 80 in a vertical direction. The incident ultraviolet light is reflected on the slope of the isosceles triangle of the optical path changing portion 84, travels toward the slope of the isosceles triangle of the adjacent optical path changing portion 84, and enters the optical path changing portion 84 from the slope.

Here, the three optical path changing portions 84A, 84
Looking at B and 84C, the left optical path changing portion 84A
UV light reflected on the right side of the slope
4B, the light enters the optical path changing portion 84B from the slope. On the other hand, the ultraviolet light reflected on the left slope of the right optical path changing portion 84C is reflected by the central optical path changing portion 84C.
Go to the right slope of B, and from that slope, change the optical path 8
4B. Ultraviolet rays that have entered the optical path changing portion 84B from the left and right slopes of the central optical path changing portion 84B obliquely enter the surface of the alignment film 20 (24).
Therefore, similarly to the above-described embodiment, the alignment film 20 (24) is obliquely irradiated with ultraviolet light, thereby obtaining the alignment film 20 (2).
4) An orientation treatment can be performed.

The shape of the isosceles triangle of the light path changing portion 84 and the light shielding film 86 are reflected by the right slope of the left light path changing portion 84A, and the ultraviolet light incident on the left slope of the central light path changing portion 84B is reflected by the light. Through the light path changing portion 84B,
The alignment film 20 (24) is formed so as to be incident on a half area of one pixel. Similarly, the right optical path changing portion 84
Ultraviolet rays reflected on the left slope of C and incident on the right slope of the central light path changing portion 84B are reflected by the light path changing portion 84B.
It is formed so as to pass through B and enter the remaining half region of one pixel of the alignment film 20 (24). Therefore, FIG.
As described with reference to FIG. 0 and FIG. 11, the orientation division is performed.

Here, the refractive index of the main body portion 82 is n ₁ , the refractive index of the optical path changing portion 84 is n ₂ , the apex angle (vertical angle of an isosceles triangle) of the sawtooth cross section is θ ₁ , and the optical path changing portion is Assuming that the incident angle of the ultraviolet light irradiating the alignment film 20 through 84 is θ ₂ , the following expression (1) is satisfied when θ ₁ ≦ 60. _{n 1 cos (3θ 1/2} ) = n 2 sin (θ 2 -θ 1/2) (1) θ 1> case 60, satisfying the following formula (2).

[0062] _{n 1 cos (3θ 1/2} ) = n 2 sin (θ 1/2-θ 2) (2) Further, in order to alignment division is satisfied, the optical path changing serrated shape of isosceles triangle cross-section Assuming that the pitch of the portions 84 is h, the light-shielding film 86 has a height i shown in the following equation (3) from the vertex of the isosceles triangle.

[0063]

(Equation 1)

FIG. 16 is a view showing a modification of the mask 80. The mask 80 has a main body portion 82 and an optical path changing portion 84 embedded in the main body portion 82 and having a different refractive index from the main body portion 82. In this case, the optical path changing portion 84 has a sawtooth cross-sectional shape with a trapezoidal cross section, and a light shielding film 86 is formed at a portion located on the upper side of the trapezoid. Figure 14 shows the trapezoid
Assuming that the top of the isosceles triangle is cut out, the trapezoidal slope and the light shielding film 86 operate in the same manner as the embodiment of FIG.

In this case, if the two oblique lines of the trapezoid are extended and the apex angle formed by the extension line is the apex angle θ ₁ of the sawtooth cross-sectional shape, the above equations (1) and (2) are This is also true. The apex angle θ ₁ may be determined without forming an extension line, by utilizing the fact that the angle between the hypotenuse and the base of the trapezoid is (π−θ ₁ ) / 2. In the case of a trapezoid, the length j of the light shielding film 86 is the dimension of the upper side of the trapezoid, and is expressed by the following equation (4).

[0066]

(Equation 2)

Further, in both the case of an isosceles triangle and a trapezoid, the refractive index of the main body portion 82 is n ₁ , the refractive index of the optical path changing portion 84 is n ₂ , and the apex angle of the sawtooth cross-sectional shape is θ. There is the following relationship between ₁ . cos θ ₁ ≧ = n ₂ / n ₁ (5) Here, a specific example will be described. The material of the main body portion 82 of the mask 80 was glass having a refractive index n ₁ = 1.5, and the optical path changing portion 84 was air having a refractive index n ₂ = 1.0. That is, the main body portion 82 of the mask 80 had a concave shape corresponding to the optical path changing portion 84, and the concave portion contained air.

The pixel pitch h is, for example, 100 μm.
The optical path changing portions 84 were similarly provided continuously at a pitch of 100 μm. When irradiating the alignment film 20 (24) with ultraviolet rays, as shown in FIG. 15, the top of the isosceles triangle of the optical path changing portion 84 of the mask 80 is
(Or the base corner of the isosceles triangle is aligned with the center of the bus line 32), and the mask 80
Is adhered to the substrate 12 (14) on which the alignment film 20 (24) is formed.

When the parallel ultraviolet rays are irradiated through the mask 80, the angle between the light when the ultraviolet rays first enter the slope of the optical path changing portion 84 of the mask 80 and the slope of the optical path changing portion 84 is θ ₁ /. It becomes 2. Angle θ of the vertex of an isosceles triangle
_{When 1 is set} to 50 degrees, when parallel ultraviolet rays are irradiated perpendicularly to the upper surface of the mask 80 from the upper surface of the mask 80, the inclined surface of the optical path changing portion 84 is 65 degrees (25 degrees to the inclined surface)
Incident. Ultraviolet rays incident at this angle are totally reflected because the incident angle exceeds the critical angle of 41.8 degrees (cos θ = 0.666) at the boundary surface. The reflected light is incident on the slope of the adjacent optical path changing portion 84 at an incident angle of 15 degrees, is refracted, and enters the optical path changing portion 84. The ultraviolet light transmitted through the optical path changing portion 84 is incident on the surface of the alignment film 20 (24) at an angle of about 47.8 degrees. The height i of the light-shielding film 86 needs to be 23.9 μm so that ultraviolet rays incident from both slopes of the optical path changing portion 84 irradiate exactly half of the surface of the alignment film 20 (24). The light shielding film 86 is formed of carbon black or the like.

As described above, reflection and refraction occur at the interface between the main body portion 82 and the optical path changing portion 84, and the alignment film is reduced by about 4 mm.
Irradiate at an angle of 7.8 degrees. Thus, within one pixel, half of the alignment film is irradiated at an angle of about 47.8 degrees, and the other half is irradiated at an angle of about 47.8 degrees from the opposite direction. Therefore, the alignment film 20 (2
4) is divided and irradiated at an angle of about 47.8 degrees from the opposite direction. The alignment films 20 and 24 thus formed
Are bonded together, and liquid crystal is injected to form a panel. The electrodes may be provided on both substrates, or may be provided on only one substrate.

If the angle θ ₁ of the apex angle of the isosceles triangle is 44 degrees, the incident angle θ _{2 with} respect to the alignment film 20 (24) is 5
9.8 degrees. In this case, the height i = 0 of the light shielding film 86
Is satisfied, and the light shielding film 86 becomes unnecessary. FIG.
7 shows this state. The configuration described with reference to FIGS. 14 to 17 can be restated as follows. The body portion 82 of the mask 80 has a first flat surface 8
2a and a second surface 82b opposite the first surface 82a
And a plurality of cavities 8 provided in the second surface 82b.
2c. Each cavity 82c has a first surface 82
The first and second slopes 82d and 82e are inclined so as to expand from each other when viewed from the direction a to the second surface 82b.

Each cavity 82c has a first slope 82d.
The optical path changing portion 84 is formed of the cavity 82c and a substance (for example, air) contained in the cavity 82c. Therefore,
Ultraviolet rays that are incident on the main body portion 82 from the first surface 82a and transmitted through the first slope 82d are applied obliquely to the alignment film 20 from the first direction, and ultraviolet rays transmitted through the second slope 82e are emitted from the alignment film 20. Is irradiated obliquely from a second direction opposite to the first direction.

FIG. 18 shows the orientation of liquid crystal molecules in the liquid crystal display device 10 when the substrate 12 which has been subjected to the orientation process described with reference to FIG. 14 is used. For example, as described with reference to FIG. 1, one substrate (TFT substrate) 12 has a pixel electrode 18, a data bus line 32, a gate bus line, and an alignment film 20, and the other substrate (color filter substrate) 14 Has a common electrode 22 and an alignment film 24. The other substrate 14 has no bus line. However, the other substrate 14 has a black matrix 32B or the like at a position corresponding to the data bus line 32 and the gate bus line on the one substrate 12. Therefore, also for the other substrate 14,
The position corresponding to the data bus line 32 and the gate bus line can be specified.

In FIG. 14, in the alignment process, the data bus line 32 is located at the bottom (both ends of the bottom) of the oblique side of the isosceles triangle or trapezoid forming the optical path changing portion 84 of the mask 80. The interval between two adjacent data bus lines 32 corresponds to the pixel pitch. The black matrix 32B at a position corresponding to the bus line is also in the vertical plane including the data bus line 32. The apex angle of the isosceles triangle or the center of the trapezoidal upper surface is located between two adjacent data bus lines 32.

In FIG. 14, UV light is applied to the domain A in one pixel from upper left to lower right, and UV light is applied to the domain B from upper right to lower left. The irradiation direction of the ultraviolet light determines the direction of pretilt of the liquid crystal molecules when the liquid crystal display device 10 is used. As a result, as shown in FIG. 18, the liquid crystal molecules 16A of the domain A in one pixel tend to pretilt from the upper left to the lower right, and the liquid crystal molecules 16B of the domain B tend to pretilt from the upper right to the lower left. When a voltage is applied, the liquid crystal molecules fall in the direction of the arrow based on the pretilt direction. Although the alignment processing of the alignment film of the other substrate 14 is not shown, the alignment processing of the alignment film of the other substrate 14 is performed so that the liquid crystal molecules behave in the same manner in each of the domains A and B. This is performed according to the orientation treatment of the film.

As shown in FIG. 18, when a voltage is applied, not only an electric field is generated between the pixel electrode 18 and the common electrode 22, but also between two adjacent data bus lines 32 (and between gate bus lines). Generates an electric flux line EL.
The electric lines of force EL extend transversely across one pixel,
The liquid crystal molecules 16C located adjacent to the data bus lines 32 (gate bus lines) are affected by the lines of electric force EL. The liquid crystal molecules 16C try to fall along the lines of electric force EL, and this is caused by the domain A to which the liquid crystal molecules 16C belong.
Is opposite to the direction in which the liquid crystal molecules 16A fall. Therefore,
In a portion adjacent to the data bus line 32 (gate bus line), there is a problem that disclination occurs in display.

FIG. 19 is a view showing the alignment of liquid crystal molecules when the corrected alignment processing is performed. In FIG. 19, the liquid crystal molecules 16A of the domain A within one pixel tend to pretilt from the upper right to the lower left, and the liquid crystal molecules 16B of the domain B
Attempts to pretilt from top left to bottom right. When a voltage is applied, the liquid crystal molecules fall in the direction of the arrow based on the pretilt direction. That is, the orientation process of FIG. 19 is performed within one pixel with respect to the data bus line 32 as shown in FIG.
8 is performed in a direction opposite to that of the alignment treatment. for that reason,
In FIG. 19, the liquid crystal molecules 16C located at positions adjacent to the data bus lines 32 (gate bus lines) fall in the direction along the lines of electric force EL, but the liquid crystal molecules 16A in the domain A to which the liquid crystal molecules 16C belong fall. The direction is the same as the direction. Accordingly, display disclination does not occur even in a portion adjacent to the data bus line 32 (gate bus line).

FIG. 20 is a view showing a process of performing an alignment process of the alignment film of the color filter substrate 14 having no bus line for obtaining the alignment of the liquid crystal of FIG. Similarly, FIG. 21 is a view showing a process of performing an alignment process of an alignment film of the TFT substrate 12 having a bus line for obtaining the alignment of the liquid crystal of FIG. In this embodiment, the alignment films 20, 24 are formed on the substrates 12, 14, but the alignment films 20, 24 are omitted in the figure. As described with reference to FIGS. 14 to 17, the alignment films 20 and 24 are irradiated with ultraviolet light obliquely to perform the alignment process. In this embodiment, when the alignment process is performed, the mask 80, the data bus line 32 (and the gate bus line), the black matrix 32B, etc.
This is different from the previous example in that the positional relationship with is set.

FIGS. 20 and 21 show the case where the optical path changing portion 84 of the mask 80 is an isosceles triangle. Substrates 12, 14
After forming the alignment films 20 and 24, a mask 80 having a main body portion 82 and a plurality of optical path changing portions 84 provided on the main body portion corresponding to the pixel pitch is prepared. The body portion 82 of the mask 80 includes a first flat surface 82a, a second surface 82b opposite the first surface 82a, and a plurality of cavities 82c provided in the second surface 82b. Each cavity 84c is located on both sides of a vertical plane perpendicular to the first surface 82a (a plane perpendicular to the plane of FIG. 20 and passing through the apex angle of an isosceles triangle), and is separated from the first surface 82a by the second surface. First and second slopes 82d and 82e that are inclined so as to spread together when viewed in a direction toward the surface 82b,
The optical path changing portion 84 is formed by the cavity 84c and a substance (air) contained in the cavity.

In FIG. 20, for the color filter substrate 14 having no bus line, the first slope 82d
Of the second surface 82b (the bottom corner of an isosceles triangle)
The mask 80 is formed such that the end of the second slope 82e on the second surface 82b is on the black matrix 32b.
Is applied to the substrate 14. In other words, the apex angle of the isosceles triangle is located at an intermediate position between two adjacent data bus lines 32. When the surface of the alignment film 24 of the substrate 14 is irradiated with ultraviolet light from a diagonal direction via the mask 80, the liquid crystal molecules are aligned with a pretilt in the diagonal direction.

In FIG. 21, T having a bus line
As for the FT substrate 12, the mask 80 is applied to the substrate 12 such that the vertical plane between the first slope 82d and the second slope 82e is on the data bus line 32. That is, the apex angle of the isosceles triangle is set at a position overlapping the data bus line 32. When the surface of the alignment film 24 of the substrate 14 is irradiated with ultraviolet light from a diagonal direction via the mask 80, the liquid crystal molecules are aligned with a pretilt in the diagonal direction. In this case, one pixel is not a region defined by the base of the isosceles triangle, but a region defined by two adjacent data bus lines 32.

The color filter substrate 14 shown in FIG.
When the liquid crystal 16 is injected between the substrates 12 and 14, the alignment of the liquid crystal shown in FIG. 19 is obtained. The data bus line 32 and the black matrix 32B are located on the same plane. If the color filter substrate 14 does not have the black matrix 32B or the like, the color filter substrate 14 may be provided with a positioning mark that is located on the same plane as the data bus line 32 when assembled, and the exposure is performed by a precision tool such as a stepper. Therefore, it is not always necessary to provide such positioning marks at the same pitch as the data bus lines 32.

FIGS. 22 and 23 show an example in which the optical path changing portion 84 of the mask 80 is trapezoidal. Other features are the same as those in the examples of FIGS. In FIG. 22, with respect to the color filter substrate 14 having no bus line, the end (the end of the base of the trapezoid) of the first slope 82d on the second surface 82b and the second slope 82e of the second slope 82e. The mask 80 is applied to the substrate 14 such that the end on the surface 82b is on the black matrix 32b. That is, the center of the trapezoid is set to the two adjacent data bus lines 32.
Is in the middle of Therefore, the alignment film 2 of the substrate 14
When the surface of No. 4 is irradiated with ultraviolet light from a diagonal direction via a mask 80, the liquid crystal molecules are aligned with a pretilt in the diagonal direction.

In FIG. 23, T having a bus line
As for the FT substrate 12, the mask 80 is applied to the substrate 12 such that the vertical plane between the first slope 82d and the second slope 82e is on the data bus line 32. That is, the center of the trapezoid is located at a position overlapping the data bus line 32. When the surface of the alignment film 24 of the substrate 14 is irradiated with ultraviolet light from a diagonal direction via the mask 80, the liquid crystal molecules are aligned with a pretilt in the diagonal direction.

When one of the pair of opposed alignment films is properly aligned, the liquid crystal molecules are aligned even if the other alignment film is not aligned. It has been found that the alignment is performed according to the alignment process. Therefore, the liquid crystal display device 10 is formed by combining the substrate 14 having the alignment film processed by the alignment processing method shown in FIG. 20 and the substrate 12 having the alignment film processed by the alignment processing method shown in FIG. It is preferable to make. However, a combination of the substrate 14 having the alignment film processed by the alignment processing method shown in FIG. 20 and the substrate 12 having the alignment film not subjected to the alignment processing, or Even when the liquid crystal display device 10 is manufactured by combining the substrate 12 having the alignment film processed by the alignment processing method shown in FIG. 21, the liquid crystal display device 10 having the characteristics shown in FIG. 19 can be obtained.

Similarly, a substrate 14 having an alignment film processed by the alignment processing method shown in FIG. 22 and a substrate 12 having an alignment film processed by the alignment processing method shown in FIG. Making the display device 10 is preferred. However, a combination of the substrate 14 having the alignment film processed by the alignment processing method shown in FIG. 22 and the substrate 12 having the alignment film not subjected to the alignment processing, or Even when the liquid crystal display device 10 is made by combining the substrate 12 having the alignment film treated by the alignment treatment method shown in FIG. 23, the liquid crystal display device 10 having the characteristics shown in FIG. 19 can be obtained.

FIG. 24 is a view showing a mask 80 in a case where an alignment process including four domains is performed according to still another embodiment of the present invention. FIG. 25 shows one of the masks 80 of FIG.
26 is a perspective view showing one optical path changing portion 84, FIG. 26 is a plan view showing the optical path changing portion 84, and FIGS. 27 and 28 are sectional views of the optical path changing portion 84. 14 to 23, the mask 80 of this embodiment is used for obliquely irradiating the alignment films 20, 24 of the substrates 12, 14 of the liquid crystal display device 10 with ultraviolet rays. The mask 80 has a main body portion 82 and a plurality of optical path changing portions 84. The optical path changing portion 84 is formed as a cavity 82c of the main body portion 82. In the previous embodiment, each cavity 82c has a first
A pair of slopes 82d and 82e that are inclined so as to spread apart when viewed from the surface 82a toward the second surface 82b.
In this embodiment, each cavity 82c has two pairs of slopes.

That is, each of the cavities 82c is the first vertical surface 82x of the first and second vertical surfaces 82x and 82y which are perpendicular to the first surface 82a and perpendicular to each other.
From the first surface 82a to the second surface 82
b, which are inclined so as to spread toward each other when viewed in the direction toward
And second slopes 82d and 82e, and a second vertical face 82y.
From the first surface 82a to the second surface 82
Third inclined to spread toward each other when viewed in the direction toward b
And fourth slopes 82f and 82g. The optical path changing portion 84 is formed by the cavity 82c and a substance (air) contained in the cavity 82c. This mask 80
Is superimposed on the color filter substrate 14, and ultraviolet light is applied to the surface of the alignment film 24 of the color filter substrate 14 via a mask 80 from an oblique direction. In this case, it is preferable that the alignment film of the TFT substrate 12 is not subjected to the alignment treatment.

In the embodiment shown in FIGS. 24 to 28, the first and second slopes 82d and 82e have the same function as the mask 80 having the isosceles triangle cross section shown in the previous embodiment. Third and fourth slopes 82f, 82g
Is a mask 8 having the trapezoidal cross-sectional shape shown in the previous embodiment.
Has an action equal to zero. In one pixel, ultraviolet rays are irradiated in four directions, and the first and second slopes 82d and 82d are provided.
2e by ultraviolet rays obliquely applied to the alignment film through 2e.
Different domains of one orientation are formed, the third and fourth
Ultraviolet rays obliquely applied to the alignment film through the slopes 82f and 82g form domains having two different orientations. Thus, a total of four different domains with different orientations are formed, and the display can be viewed fairly well even if the display is viewed from all directions at a considerable viewing angle.

FIGS. 29 and 30 show modifications of the optical path changing portion 84. FIG. 26 has a rectangular base shape of a × e (a is the length of the short side, e is the length of the long side), and has a peak 82p corresponding to the upper side of the trapezoid. The light path changing portion 84 in FIGS. 29 and 30 corresponds to the peak 8 in FIG.
This corresponds to the case where the length of 2p is set to 0. Further, FIG.
Alternatively, the optical path changing portion 84 in FIG. 30 may be changed to use an optical path changing portion 84 having an a × a square base shape.

FIG. 31 shows an example in which a light shielding film 86 is provided in the optical path changing portion 84 of FIGS. The effect of the light-shielding film 86 is that ultraviolet rays that have passed through the first and second slopes 82d and 82e and the third and fourth slopes 82f and 82g and entered the portion of the alignment film corresponding to one pixel overlap with each other. Not
This is to cover a portion of the alignment film corresponding to exactly one pixel.

In order for the light shielding film 86 to achieve this function, it is desirable that the following relationship be satisfied. As shown in FIG. 32, both ends of the peak 82p corresponding to the upper side of the trapezoid are points A and B. First and second slopes 82d, 8
2e, a light shielding film 8 extending in parallel with the peak 82p
The corners of the portion 6 are points C, D, E, and F. Points C, D,
E lies in a vertical plane perpendicular to peak 82p and passing through point A;
It is assumed that points D and F are on a vertical plane perpendicular to point 82p and passing through point B. Points G and H are corners of the light-shielding film 86 in the third and fourth slopes 82f and 82g and in the vertical plane including the peak 82p. The light-shielding film 86 has a point C,
It is obtained by drawing a line from D, E, F, G, H to the corner of the rectangular base shape of the optical path changing portion 84.

To obtain the points C, D, E, F, G and H, the distances d and f may be determined. Distance d is peak 82p
And the distance between the points C, D, E, and F in a plane parallel to the first surface 82a (as viewed from above). The distance f corresponds to the peak 82p and the first surface 82a between each point G and H.
Is a distance (as viewed from above) in a plane parallel to. The distance d is obtained from the following relations (6) and (7), and the distance f
Is obtained from the following relationships (8) and (9).

[0094]

(Equation 3)

[0095]

(Equation 4)

Here, the refractive index of the main body portion 82 of the mask 80 is n ₁ , the refractive index of the optical path changing portion 84 is n ₂ , the apex angle of an isosceles triangle in a vertical plane is θ ₁ , The irradiation angle is θ ₂ , and the base angle of the trapezoid in the vertical plane is θ ₃
And It is also necessary that the following expressions (1) and (2) hold.

[0097]

(Equation 5)

[0098]

As described above, according to the present invention,
The alignment treatment using ultraviolet irradiation can be performed on the entire substrate without causing poor alignment, and a simple alignment treatment can be performed without performing a conventional rubbing step. Further, a region (domain) having two alignment directions can be formed in one pixel by one irradiation of ultraviolet light, so that the cost of the apparatus can be reduced and the manufacturing tact can be shortened.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a liquid crystal display according to an embodiment of the present invention.

FIG. 2 is a side view showing an ultraviolet irradiation device.

FIG. 3 is a diagram showing a spectrum distribution of ultraviolet light used in the apparatus of FIG. 2;

FIG. 4 is a view showing the principle of an alignment treatment of an alignment film.

FIG. 5 is a simplified diagram of FIG. 4;

FIG. 6 is a diagram showing a modification of FIG. 4;

FIG. 7 is a diagram illustrating a relationship between an exposure amount of ultraviolet rays and a pretilt angle.

8 is a diagram showing the relationship in FIG. 7 in which the exposure amount is converted into a value per 1% of a polymer having an alkyl group for realizing vertical alignment.

FIG. 9 is a diagram illustrating a relationship between an irradiation angle of ultraviolet rays and a pretilt angle.

FIG. 10 is a diagram showing that one pixel is subjected to an alignment process having two domains.

FIG. 11 is a diagram illustrating the orientation division achieved by the orientation process of FIG.

FIG. 12 is a view showing a mask for performing the alignment processing shown in FIGS. 10 and 11;

FIG. 13 is a diagram showing a modification of FIG. 10;

FIG. 14 is a view illustrating an alignment process of an alignment film according to another embodiment of the present invention.

FIG. 15 is a diagram showing a relationship between a mask and pixels used in FIG.

FIG. 16 is a view showing a modification of the mask of FIG. 14;

FIG. 17 is a view showing a modification of the mask of FIG. 14;

FIG. 18 is a diagram showing the orientation of liquid crystal molecules in a liquid crystal display device using a substrate that has been subjected to the orientation process described with reference to FIG.

FIG. 19 is a diagram showing the alignment of liquid crystal molecules when a modified alignment process is performed according to another embodiment of the present invention.

20 is a diagram illustrating a step of performing an alignment process on an alignment film of a color filter substrate to obtain the alignment of the liquid crystal in FIG. 19;

21 is a diagram illustrating a process of performing an alignment process on an alignment film of a TFT substrate to obtain the alignment of the liquid crystal in FIG. 19;

FIG. 22 is a diagram showing a modification of the alignment process of FIG.

FIG. 23 is a view showing a modification of the alignment processing of FIG. 21;

FIG. 24 is a plan view showing a mask when performing an alignment process including four domains according to another embodiment of the present invention.

FIG. 25 is a perspective view showing one optical path changing portion of the mask of FIG. 24;

FIG. 26 is a plan view showing an optical path changing portion of FIG. 25.

27 is a cross-sectional view of the optical path changing portion of FIG. 26 taken along the line XXVII-XXVII.

28 is a cross-sectional view of the optical path changing portion of FIG. 26 taken along the line XXVIII─XXVIII.

FIG. 29 is a plan view showing a modification of the optical path changing portion.

30 is a perspective view showing an optical path changing portion in FIG. 29.

FIG. 31 is a perspective view showing an example in which a light-shielding film is provided in the optical path changing part in FIGS. 25 and 26.

32A and 32B are a plan view and a cross-sectional view showing an optical path changing portion in FIG.

[Explanation of symbols]

 12, 14 ... substrate 16 ... liquid crystal layer 18, 22 ... electrode 20, 24 ... alignment film 60 ... alignment treatment device 62 ... light source 68 ... ultraviolet ray 70 ... alkyl group 80 ... mask 82 ... body part 84 ... optical path changing part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takemune Mayama 4-1-1, Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Fujitsu Limited

Claims (18)

[Claims] 1. A pair of substrates facing each other at an interval, an alignment film formed on one substrate, an alignment film formed on the other substrate, and a liquid crystal inserted between the pair of substrates. A method for manufacturing a liquid crystal display device, comprising: forming an alignment film containing a polymer for realizing vertical alignment on the substrate, wherein the content of the polymer for realizing the vertical alignment of the alignment film is 30 to 1%. With an exposure of 120 mJ / cm ² ,
A method for manufacturing a liquid crystal display device, comprising irradiating the alignment film with unpolarized ultraviolet light from an oblique direction of 45 degrees or less with respect to the surface of the alignment film. ^2. The method for manufacturing a liquid crystal display device according to claim 1, wherein the exposure amount of unpolarized ultraviolet light applied to the alignment film surface is in a range of 40 to 90 mJ / cm ² . 3. The method according to claim 1, wherein the exposure amount of the unpolarized ultraviolet light applied to the alignment film surface is in a range of 80 to 120 mJ / cm ² . 4. The method for manufacturing a liquid crystal display device according to claim 1, wherein the amount of exposure to ultraviolet light is such that the pretilt angle of the liquid crystal with respect to the surface of the alignment film is 89.5 degrees or less. 5. The wavelength of the ultraviolet light applied to the alignment film is 28.
The method for manufacturing a liquid crystal display device according to claim 1, comprising a component having a size of 0 nm or less. 6. A pair of substrates facing each other at an interval, an alignment film formed on one substrate, an alignment film formed on the other substrate, and a liquid crystal inserted between the pair of substrates. A method of manufacturing a liquid crystal display device, comprising: forming an alignment film on a substrate; providing a main body portion; and a plurality of main body portions provided in correspondence with the pixel pitch and having a different refractive index from the main body portion A method for manufacturing a liquid crystal display device, comprising irradiating each surface of the alignment film with ultraviolet light from an oblique direction using a mask having an optical path changing portion. 7. Each of the optical path changing portions has a saw-tooth shape having an isosceles triangular cross section with a pixel pitch length as a base, and a portion of the optical path changing portion located at the top of the isosceles triangle. 7. The method according to claim 6, wherein a light shielding film is formed. 8. Each of the optical path changing portions has a saw-toothed cross-sectional shape having a trapezoidal cross-section with the length of a pixel pitch as a base, and a light-shielding film is formed in a portion located on the upper side of the trapezoid. The method for manufacturing a liquid crystal display device according to claim 6, wherein: 9. The refractive index of the main body portion is n ₁ , the refractive index of the optical path changing portion is n ₂ , the apex angle of the sawtooth cross-sectional shape is θ ₁ ,
Assuming that the incident angle of the ultraviolet light irradiating the alignment film through the optical path changing portion is θ ₂ , when θ ₁ ≦ 60, the following formula (1) is used.
Satisfied, the case of _{n 1 cos (3θ 1/2} ) = n 2 sin (θ 2 -θ 1/2) (1) θ 1> 60, satisfying the following formula _{(2), n 1 cos (} 3θ _The method of manufacturing a liquid crystal display device according to claim 7, wherein (）) = n ₂ sin (θ ₁ / 2−θ ₂ ) (2). 10. The refractive index of said main body portion is n₁ , The optical path change
The refractive index of the further part is n _Two , The vertex angle of the sawtooth-shaped cross-section is θ₁ 
Has the following relationship, cos θ₁ > = N_Two / N₁ (5) The manufacturing of the liquid crystal display device according to claim 9, wherein
Method. 11. The body portion of the mask includes a first flat surface, a second surface opposite the first surface, and a second surface.
And a plurality of cavities provided on the surface of the first surface, each cavity having first and second slopes that are inclined so as to extend from each other when viewed from the first surface toward the second surface. Each cavity has a centerline between the first slope and the second slope, the optical path changing portion is formed by the cavity and a material contained in the cavity, Ultraviolet rays that are incident on the main body portion and pass through the first slope are applied to the alignment film obliquely from a first direction, and ultraviolet rays that pass through the second slope are applied to the alignment film in the first direction. 7. The method for manufacturing a liquid crystal display device according to claim 6, wherein the irradiation is performed obliquely from a second direction opposite to the above. 12. A pair of substrates facing each other at an interval,
An alignment film formed on one substrate, an alignment film formed on the other substrate, a plurality of bus lines provided on one substrate, and a liquid crystal inserted between the pair of substrates were provided. A method for manufacturing a liquid crystal display device, comprising: forming an alignment film on a substrate; preparing a mask having a main body portion and a plurality of optical path changing portions provided in the main body portion corresponding to the pixel pitch; The body portion includes a first flat surface, a second surface opposite the first surface, and a plurality of cavities provided in the second surface, wherein each cavity includes the first surface. First and second slopes on both sides of a vertical plane perpendicular to the first surface, the first and second slopes being inclined so as to extend from each other when viewed from the first surface toward the second surface; The optical path changing portion is formed by the cavity and a substance contained in the cavity. For one substrate having the bus line, the mask is superimposed on the substrate such that a vertical plane between the first slope and the second slope is on the bus line, and A method for manufacturing a liquid crystal display device, comprising irradiating an ultraviolet ray on a surface of an alignment film from an oblique direction through the mask. 13. A pair of substrates facing each other at an interval,
An alignment film formed on one substrate, an alignment film formed on the other substrate, a plurality of bus lines provided on one substrate, and a liquid crystal inserted between the pair of substrates were provided. A method for manufacturing a liquid crystal display device, comprising: forming an alignment film on a substrate; preparing a mask having a main body portion and a plurality of optical path changing portions provided in the main body portion corresponding to the pixel pitch; The body portion includes a first flat surface, a second surface opposite the first surface, and a plurality of cavities provided in the second surface, wherein each cavity includes the first surface. First and second slopes on both sides of a vertical plane perpendicular to the first surface, the first and second slopes being inclined so as to extend from each other when viewed from the first surface toward the second surface; The optical path changing portion is formed by the cavity and a substance contained in the cavity. For the other substrate having no said bus line, said first
Stacking the mask on the substrate such that an end of the slope on the second surface and an end of the second slope on the second surface are on a line corresponding to the bus line, A method for manufacturing a liquid crystal display device, comprising: irradiating ultraviolet light to a surface of the alignment film of a substrate from an oblique direction through the mask. 14. The cavity according to claim 1, wherein the cavity has a saw-tooth shape having an isosceles triangular cross section, and a light-shielding film is formed at a portion located at the top of the isosceles triangle.
14. The method for manufacturing a liquid crystal display device according to 2 or 13. 15. The liquid crystal display according to claim 12, wherein the cavity has a saw-tooth shape having a trapezoidal cross section, and a light-shielding film is formed in a portion located on an upper side of the trapezoid. Device manufacturing method. 16. A pair of substrates facing each other at an interval,
An alignment film formed on one substrate, an alignment film formed on the other substrate, a plurality of bus lines provided on one substrate, and a liquid crystal inserted between the pair of substrates were provided. A method for manufacturing a liquid crystal display device, comprising: forming an alignment film on a substrate; preparing a mask having a main body portion and a plurality of optical path changing portions provided in the main body portion corresponding to the pixel pitch; The body portion includes a first flat surface, a second surface opposite the first surface, and a plurality of cavities provided in the second surface, wherein each cavity includes the first surface. Of the first and second vertical surfaces perpendicular to each other and perpendicular to each other, the first and second vertical surfaces are on both sides of the first vertical surface and viewed from the first surface toward the second surface. First and second slopes that are inclined so as to spread each other, and on both sides of the second vertical surface, Third and fourth slopes that are inclined so as to be widened from each other when viewed from the first surface toward the second surface, wherein the optical path changing portion is formed by the cavity and a substance contained in the cavity. A method of manufacturing a liquid crystal display device, comprising: forming the mask on the substrate; and irradiating the surface of the alignment film of the substrate with ultraviolet light obliquely through the mask. 17. The method according to claim 19, wherein the cavity has at least one of a sawtooth shape having an isosceles triangular cross section and a sawtooth shape having a trapezoidal cross section. 18. The liquid crystal display device according to claim 19, wherein the first and second slopes are isosceles triangles, and the third and fourth slopes are trapezoidal slopes. Production method.