JP2739041B2 - Manufacturing method of liquid crystal display device and liquid crystal display device - 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 device and a liquid crystal display device, and more particularly to a method of manufacturing a liquid crystal display device characterized by forming a liquid crystal alignment film and a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device has a structure in which liquid crystal is sealed between a pair of transparent substrates spaced at a predetermined interval. That is, the liquid crystal molecules have an elongated shape and have anisotropy in refractive index. Therefore, a pixel can be formed from a difference between a state where the liquid crystal is aligned along the direction of the voltage applied to the liquid crystal and a state where no voltage is applied. An alignment film is formed on the substrate to align liquid crystal molecules. For this alignment film, a polymer material represented by polyimide is used. For example, this polymer material is rubbed with a cloth or the like to give an alignment direction (so-called rubbing).
There is a liquid crystal display device in which an alignment film is formed by this. In this liquid crystal display device, the liquid crystal molecules are aligned in the rubbing direction of each alignment film of the pair of substrates. Usually, the rubbing directions of a pair of substrates are opposed to each other so as to intersect,
Liquid crystal molecules are spirally arranged from one substrate to the other.

When a halftone between a black level and a white level is displayed, the liquid crystal molecules are obliquely aligned with respect to the substrate by the balance between the electric field and the force from the alignment film. For this reason, the apparent angle of the liquid crystal molecules with respect to the substrate differs depending on the viewing angle, and the brightness looks different. Also, in the case of color display, they appear as different colors.

For this reason, in recent liquid crystal display devices, in order to improve visual characteristics such as obtaining a high contrast at a wide viewing angle, one pixel is divided into a plurality of pixels, and the liquid crystal is controlled by an electric field in each divided region. It has been proposed to form a liquid crystal display device by a method called multi-domain in which the directions of inclined planes are respectively changed.

[0005] This method includes a mask rubbing method in which a rubbing is performed while moving a mask of a predetermined shape (K. Ta).
katori et. al., "A Complementary TN LCD with Wide
-Viewing Angle Grayscale ", Japan Display '92, pp59
1), method by applying multiple alignment film materials (T. Kamada e
t. al., "Wide Viewing Angle Full-Color TFT LCDs",
Japan Display '92, pp886), a method of changing the characteristics of an alignment film by irradiation with ultraviolet rays or the like (Japanese Patent Laid-Open No. 5-210099)
Publication). The steps and processes of the method using mask rubbing and the method of applying a plurality of alignment film materials are complicated.

Further, these methods only change the tilt angle (so-called pretilt angle) of the liquid crystal when the alignment film is formed to form two symmetrical pretilt angles, and have a single alignment direction. The improvement of the viewing angle is limited to a predetermined direction.

[0007] On the other hand, there is an alignment method called amorphous twist nematic in which the alignment direction is completely random and is oriented so that only twist is performed to improve the viewing angle (Y. Kato, T. Sugiyama, K. et al. Katoh, Y.Iimura, a
nd S. Kobayashi, "TN-LCDs Fabricated by Non-Rubbing
Showing Wide and Homogeneous Viewing Angular Chara
cteristics and Excellent Voltage Holding Ratio, SID
93 Digest, 622 (1993), Y. Toko, T. Sugiyama, K. Katoh,
Y.Iimura, and S.Kobayashi, "Amorphous twistednematic
-loquid-crystal displays and fabricated by nonrubb
ing showing wide and uniform viewing-angle charact
erristics Recommended excellent voltage hoilding
ratios, J. Appl. phys. 74, 2071 (1993)).

[0008]

However, in the liquid crystal display device formed by the above-described alignment method in which the alignment direction is completely random and twisted only, the formed alignment direction is the same as that of the polarizing plate. Since there is no specific relationship, the black level becomes lighter (or the white level becomes darker), and the contrast decreases.

In view of the above, it is an object of the present invention to provide a method of manufacturing a liquid crystal display device having an improved viewing angle without lowering the contrast, and to obtain a liquid crystal display device.

Another object of the present invention is to provide a liquid crystal display device having an improved method for forming an alignment film.

[0011]

A method of manufacturing a liquid crystal display device according to the present invention comprises the steps of applying a polymer material made of polyimide to a first substrate to form a polymer film, and forming the polymer film. First polarized light linearly polarized in a first partial region as a part of a region corresponding to each pixel, for a plurality of pixels included in a predetermined predetermined range of at least a part of the first substrate. Irradiating an electromagnetic wave in a second polarization direction crossing the first polarization direction to a second partial region as a part of a region corresponding to each pixel; Forming a polymer film by applying the polymer film to a second substrate, and for each of a plurality of pixels included in a predetermined range of at least a part of the second substrate on which the polymer film is formed, First partial area as part of the corresponding area Irradiating an electromagnetic wave of a first polarization direction is linearly polarized, the second intersecting the first polarization direction to a second partial region as part of a region corresponding to each pixel
Irradiating an electromagnetic wave having a polarization direction of: and the polymer film surfaces are opposed to each other, and the first substrate and the second substrate are brought into contact with the first partial region of the first substrate and the second substrate. Laminating at a predetermined interval so that at least a part of the second partial region of the substrate overlaps with the first substrate, and injecting liquid crystal between the first substrate and the second substrate. Have.

In the liquid crystal display device according to the present invention, a polymer film formed by applying a polymer material made of polyimide is linearly polarized in a first partial region as a part of a region corresponding to each pixel. An electromagnetic wave in a first polarization direction is irradiated, and a second partial region as a part of a region corresponding to each of the pixels is irradiated with an electromagnetic wave in a second polarization direction crossing the first polarization direction. A first substrate and a first partial region as a part of a region corresponding to each pixel of a polymer film formed by applying polyimide are irradiated with linearly polarized electromagnetic waves having a first polarization direction. A second partial region as a part of a region corresponding to each of the pixels is irradiated with an electromagnetic wave having a second polarization direction intersecting with the first polarization direction.
And the polymer films face each other, and the first
The first substrate and the second substrate are attached to each other at a predetermined interval so as to form one pixel from the first partial region of the substrate and the second partial region of the second substrate. And a liquid crystal injected between the first substrate and the second substrate.

[0013]

According to the present invention, a polymer material made of polyimide is applied to a first substrate to form a polymer film. A plurality of pixels included in a predetermined range of at least a part of the first substrate on which the polymer film is formed are linearly polarized in a first partial region as a part of a region corresponding to each pixel. Irradiating an electromagnetic wave having the first polarization direction to the second partial region as a part of the region corresponding to each of the pixels.
Irradiation of an electromagnetic wave in a second polarization direction that intersects with the polarization direction is performed. The linearly polarized electromagnetic wave forms an alignment in the polarization direction on the polymer alignment film. A polymer material made of polyimide is applied to the second substrate to form a polymer film. A plurality of pixels included in a predetermined range of at least a part of the second substrate on which the polymer film is formed are linearly polarized into a first partial region as a part of a region corresponding to each pixel. And irradiating a second partial region as a part of a region corresponding to each pixel with an electromagnetic wave having a second polarization direction intersecting with the first polarization direction. The first substrate and the second
Are bonded to each other at a predetermined interval so that the first partial region of the first substrate and the second partial region of the second substrate at least partially overlap with each other. Liquid crystal is injected between the first substrate and the second substrate. Therefore, a method for manufacturing a liquid crystal display device having a good viewing angle without lowering the contrast can be obtained.

Further, according to the present invention, the first partial region as a part of the region corresponding to each pixel of the polymer film formed by applying the polymer material composed of polyid is linearly polarized. The first electromagnetic wave of the first polarization direction is irradiated,
A first substrate is provided in which a second partial region as a part of a region corresponding to each of the pixels is irradiated with an electromagnetic wave having a second polarization direction crossing the first polarization direction. Further, the first film as a part of a region corresponding to each pixel of the polymer film formed by applying a polymer material made of polyimide is formed.
Are irradiated with linearly polarized electromagnetic waves having a first polarization direction, and a second partial region as a part of a region corresponding to each of the pixels intersects with the first polarization direction.
And a second substrate irradiated with an electromagnetic wave having a polarization direction of.
The first substrate and the second substrate have polymer films opposed to each other and form one pixel from a first partial region of the first substrate and a second partial region of the second substrate. Are stuck together. The liquid crystal display further includes a liquid crystal injected between the first substrate and the second substrate. Therefore, a liquid crystal display device having a good viewing angle without lowering the contrast can be obtained.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this embodiment, the present invention is applied to a liquid crystal display device manufacturing apparatus for manufacturing a liquid crystal display device by a multi-domain method. In this embodiment, a so-called active matrix type liquid crystal display device (for example, a horizontally long rectangular shape having a diagonal length of 10 inches; 640 × 480 pixels) will be described.

As shown in FIG. 1, the apparatus 30 for manufacturing a liquid crystal display device includes an ultraviolet irradiation device 60 for emitting ultraviolet light, and a polarization direction rotating device 32 is provided on the emission side of the ultraviolet irradiation device 60. Have been.

In this embodiment, as shown in FIG.
As the ultraviolet irradiation device 60, an ultraviolet laser device 62 that emits a circularly polarized laser beam having an ultraviolet wavelength region as an oscillation wavelength region is used. The polarization direction rotating device 32
Is a device for rotating a half-wave plate 63 having a half-wave plate 63 as a polarization element in the optical path S. The half-wave plate 63 is rotated by driving the polarization direction rotating device 32 that is driven to rotate in response to an input signal from the control device 50. Therefore, the polarization direction rotating device 3
The ultraviolet light emitted from 2 is a laser beam that is linearly polarized in a predetermined direction and can change the polarization direction. When an ultraviolet laser device that emits a linearly polarized laser beam is used as the ultraviolet irradiation device 60, the polarization direction rotating device 32 rotates the ultraviolet laser device main body without providing the half-wavelength plate 63. do it.

As shown in FIG. 2B, as the ultraviolet irradiation device 60, an ultraviolet light source 62A such as a mercury lamp irradiated with an electromagnetic wave including an ultraviolet wavelength range can be used. When the ultraviolet light source 63A is used, the polarization direction rotating device 32 includes a linear polarization element 62A such as a Wollaston prism as a polarization element in the optical path S, and makes the linear polarization element 63A rotatable. This linear polarizing element 63A
The ultraviolet light emitted from the polarization direction rotating device 32 is linearly polarized in a predetermined direction by the linear polarization element 6.
The direction of polarization of ultraviolet light emitted by rotation of 3A can be changed. When an ultraviolet light source 62A such as a mercury lamp is used as the ultraviolet irradiation device 60, the ultraviolet light source 62A
Since A is a divergent light source, the collimator lens 62B
And it is preferable to emit collimated ultraviolet rays.

As shown in FIG. 1, on the exit side of the polarization direction rotating device 32, a condenser lens 34 for condensing the incident ultraviolet light, and whether to pass, transmit or block the incident ultraviolet light. Are switched in sequence.

The shutter 36 can be a mechanical shutter. Further, an optical element (a photochromic element, an electrochromic element, or the like) capable of changing the transmittance of ultraviolet light may be used to change the amount of transmitted ultraviolet light. Further, the shutter 36 may switch between passing and blocking ultraviolet rays by reflection from a mirror. Further, a combination of these may be switched to pass, transmit, or block incident ultraviolet light.

A substrate (color filter substrate 12 or TFT substrate 14) for orienting by irradiation of ultraviolet rays is located near the position where the ultraviolet rays condensed by the condenser lens 34 are collected, as described later. This substrate is detachably fixed to the moving stage 38. The moving stage 38 includes a one-axis moving stage 38A that moves in a predetermined direction (the direction of the arrow A in FIG. 1) and a one-axis moving stage 38A.
And a two-axis orthogonal stage in which a one-axis moving stage 38B that moves in a direction orthogonal to the direction (arrow B direction in FIG. 1) is combined. Note that the orthogonal two-axis stage is not limited to intersecting at right angles, and may be a stage where two axes intersect.

The above-described polarization direction rotating device 32 and shutter 3
6, and each one-axis stage 38A of the moving stage 38, 3
The control device 50 is connected to 8B. For details,
The control device 50 includes an orientation control device 52, a rotation drive control device 54, a stage drive control device 56, and a shutter drive control device 58, each of which includes a microcomputer. The orientation control device 52 is connected to the rotation drive control device 54, the stage drive control device 56, and the shutter drive control device 58, and can exchange data and commands with each control device. The rotation drive control device 54 is connected to the polarization direction rotation device 32. Stage drive controller 56
Are connected to the moving stage 38. The shutter drive control device 58 is connected to the shutter 36.

Here, a schematic structure of the liquid crystal display device 10 according to the present embodiment will be described. As shown in cross section in FIG.
The liquid crystal display device 10 according to the present embodiment includes a color filter substrate 1.
Nematic liquid crystal 16 between TFT 2 and TFT substrate 14
Has been injected. On the color filter substrate 12, a color filter (not shown) is formed on an inner surface of a glass substrate 13, a plurality of common electrodes 18 such as an ITO film are formed on the color filters, and a polyimide orientation is formed on the common electrode 18. A film 20 is formed.

On the other hand, the TFT substrate 14 has a glass substrate 1
5 has a plurality of pixel electrodes 22 and a well-known T (not shown).
An FT element is formed, and a polyimide alignment film 24 is formed on the pixel electrode 22.

As shown in FIG. 3, the liquid crystal display device 10
Then, light is transmitted from the TFT substrate 14 side, and the observer H views the display from the color filter substrate 12 side. In the following figures, the direction of arrow L is the left direction when the observer H looks at the liquid crystal display device 10 at the normal position, and the direction of the arrow R is the direction when the observer H looks at the liquid crystal display device 10 at the normal position. The arrow D direction is the downward direction when the observer H looks at the liquid crystal display device 10 at the normal position, and the arrow U direction is the same when the observer H looks at the liquid crystal display device 10 at the normal position. An upward direction shall be indicated.

Here, it is considered that the alignment of the liquid crystal by the irradiation of the linearly polarized ultraviolet light to the polymer film is based on the following mechanism.

A1 When crosslinking is caused by irradiation with ultraviolet rays, crosslinking of the polymer occurs in a direction parallel to the polarization direction,
The molecular length in this direction increases. When the molecular length is longer, the alignment force of the liquid crystal becomes stronger, so that the liquid crystal is aligned in parallel with the polarization direction.

B2 In the case where the molecular chain is broken or the benzene ring is broken by the irradiation of the ultraviolet ray, the molecular chain in the direction parallel to the polarization direction absorbs the ultraviolet ray more. The benzene ring is broken.
When the molecular chain is short or the number of benzene rings is small, the alignment force of the liquid crystal is weakened, and the liquid crystal is aligned perpendicular to the polarization direction.

Since the orientation is induced by the above mechanism, the tilt pretilt angle of the liquid crystal with respect to the substrate is 0 ° without being induced. For this reason, the direction in which the liquid crystal molecules tilt when an electric field is applied is undefined, and the liquid crystal molecules rotate clockwise (see FIG. 11A) or counterclockwise (see 11B).

However, in an actual liquid crystal cell, the upper and lower substrates are not completely parallel, and have a small angle that varies depending on the location. In addition, the horizontal electric field between the pixels is also oriented in various directions, and the rotation direction of the liquid crystal molecules is approximately 1/2.
It is considered that the clockwise or counterclockwise rotation is performed with each probability.
Even in a region irradiated with ultraviolet rays having the same polarization direction, the region is rotated clockwise or counterclockwise depending on the location. For this reason, the apparent rotation angles of the liquid crystal molecules are averaged, and the viewing angle characteristics are improved. The same applies to the above-described amorphous twisted nematic, and the viewing direction characteristic is improved because the rotation direction is not controlled and is random (see FIG. 11C).

In the present invention, the contrast can be improved in addition to the improvement of the viewing angle characteristics of the amorphous twisted nematic method by giving the control of the alignment direction using the linearly polarized ultraviolet light.

In this method, the liquid crystal is oriented in a direction parallel (cross-linking type) or perpendicular (resolving type) to the polarization direction of the linearly polarized light, and the right and left rotations in this direction are averaged.
The viewing angle characteristics in the alignment direction of the liquid crystal are improved. For this reason,
If the direction of the linearly polarized ultraviolet light for irradiation is changed in the same pixel to realize multi-domains of various orientation directions, the same image quality can be obtained at all viewing angles.

However, since the polarizing plate has various directions, the contrast is reduced.
For this reason, the improvement of the viewing angle characteristics and the maintenance of the contrast become opposite, and it is necessary to change the number of domains in a pixel as required. When importance is placed on contrast, one pixel is divided into two to improve only the viewing angle characteristics in the left, right, up and down directions. What is necessary is just to improve the viewing angle characteristics.

FIG. 5 shows the polarization direction of the ultraviolet light applied when one pixel is divided into two parts. That is, the upper alignment film 20A in one pixel is irradiated with ultraviolet rays in a predetermined polarization direction, and the lower alignment film 20B is irradiated with ultraviolet light in a polarization direction orthogonal to the predetermined polarization direction. When irradiated with such polarized light, the cross-linked polymer has an upper alignment film 20 shown in FIG.
A and a liquid crystal alignment as shown by the solid line in the lower alignment film 20B occurs, and when an electric field is applied, the pretilt angle is 0 °, so that the upper alignment film 20A and the lower alignment film 20
In each of the regions B, the liquid crystal molecules are tilted by turning left or right, and the viewing angle characteristics in the vertical and horizontal directions can be improved.

Next, the operation of the liquid crystal display device manufacturing apparatus 30 of this embodiment will be described. That is, a process of forming a multi-domain liquid crystal cell in which the alignment direction is changed in one pixel by irradiating each substrate (12, 14) constituting the liquid crystal display device 10 with ultraviolet rays will be described.

First, a substrate (color filter substrate 12 or TFT substrate 14) having an alignment film formed on its surface is prepared. In this embodiment, a soluble polyimide (Nippon Synthetic Rubber, Optmer AL1256) is used as a polymer material for forming the alignment film. In order to simplify the following description, the TFT substrate 14 will be described as an example of a substrate to be used.

In this embodiment, soluble polyimide is used as a polymer material for forming the alignment film.
The present invention is not limited to polyimide, and polyvinyl alcohol or the like may be used.

Further, in the present invention, the orientation of the liquid crystal is changed by changing the state of the molecular chains of the polymer film formed by applying the polymer material by irradiating ultraviolet rays. Any of those that are crosslinked by ultraviolet irradiation and those that are cut by ultraviolet irradiation may be used.

The TFT substrate 14 on which the alignment film is formed is set on a moving stage 38, and the manufacturing apparatus 3 (not shown)
When the 0 start switch is pressed, the multi-domain liquid crystal cell forming process routine of FIG.

In step 100, the number of domain divisions and the division method are set. The domain refers to a region that provides the same orientation direction, and in this case, a region on the TFT substrate 14 that can be recognized from substantially the same direction when the TFT substrate 14 is viewed. This domain division number represents the division number when the TFT substrate 14 is divided. Therefore, in this embodiment, it is assumed that one screen is formed by the TFT substrate 14, and the orientation is changed in at least two directions for each liquid crystal cell in a region corresponding to the pixel.
The double value (640 × 480 × 2) is set as the number of domain divisions. The dividing method is a method based on the shape of the divided region when dividing the TFT substrate 14, and in the present embodiment, a dividing method for dividing one pixel up and down is set.

For the setting in step 100, a predetermined value may be read or specified by an operator. Since the setting of the number of domain divisions and the division method can be changed, it is possible to freely set the size of the domain and the division method on the TFT substrate 14, that is, in the pixel.

In the present embodiment, the spot diameter of the focused ultraviolet light is set in advance so as to have a size corresponding to the upper area (or lower area) of one pixel on the TFT substrate 14. Therefore, when irradiating a region larger than the upper region (or lower region) of one pixel, the irradiation may be performed continuously according to the region. In addition, according to the set value in step 100, a magnification changing device such as a magnification switching device for switching to a condenser lens having a different magnification or a zoom lens is provided in relation to the condenser lens to change the size of the domain. It may be.

In the above step 100, the TFT
The amount (time) of ultraviolet irradiation to the substrate 14 is also set. That is, the irradiation amount of the ultraviolet light varies depending on the composition of the polymer material applied to the TFT substrate 14 in order to make the amount of crosslinking or cutting of the polymer material a predetermined amount. For this reason, in step 100 of the present embodiment, the irradiation amount of the ultraviolet rays to be irradiated is set according to the type of the applied polymer material as described below.

Next, in step 102, according to the set number of domain divisions and the division method, the TFT substrate 14
The position and orientation direction (polarization direction) of the upper one pixel are calculated. That is, when one screen is formed by the TFT substrate 14, for example, the polarization direction is rotated by 45 ° or 90 ° with respect to an adjacent domain so that a predetermined region on the TFT substrate 14 does not have the same polarization direction. By alternately setting the polarization directions of two orthogonal directions.
The position and orientation direction of one pixel are calculated.

In this setting, the relationship between the position of each pixel on the TFT substrate 14 and the alignment direction may be set in advance, and the setting may be read. TFT pattern and order of polarization direction
The positions and orientations of the pixels may be determined in advance according to the pattern or the order in advance as the entire substrate 14.

In the next step 104, the TFT substrate 14
It is determined whether or not ultraviolet rays as electromagnetic waves described below have been applied to all the pixels set above, and this routine ends when all the pixels have been irradiated with ultraviolet rays.

If a negative determination is made in step 104 and there is an unirradiated pixel, in step 106, position data representing the position of the pixel calculated in step 102 is output to the stage drive controller 56. Thus, the stage drive control device 56 controls the moving stage 38 so that the condensed spot is located at the position of the TFT substrate 14 corresponding to the input position data. By the movement of the moving stage 38, the focused spot of the ultraviolet light is moved to the target pixel domain calculated in step 102.

In the next step 110, step 1
The direction data representing the orientation direction calculated in 02 is output to the rotation drive control device 54. Accordingly, the rotation drive control device 54 controls the polarization direction rotation device 32 so that the polarization direction of the ultraviolet light applied to the TFT substrate 14 becomes the polarization direction corresponding to the input direction data. Due to the rotation of the polarization direction rotating device, the polarization direction of the focused spot of the ultraviolet light applied to the TFT substrate 14 is changed to Step 106.
Can be radiated to the domain positioned at step 102 as ultraviolet rays of the polarization direction set in step 102.

In the next step 114, the above step 1
02, the irradiation time data corresponding to the ultraviolet irradiation amount set on the TFT substrate 14 is stored in the shutter drive control device 5.
8 is output. As a result, the shutter 36 is operated, and the set irradiation amount of ultraviolet rays is irradiated on the TFT substrate 14.

Therefore, with respect to one pixel on the TFT substrate 14, the focused spot of the ultraviolet light is positioned in the domain of the target pixel, and the ultraviolet ray of the polarization direction in which the polarization direction of the focused spot of the ultraviolet light is set is aligned. The TFT substrate 14 is irradiated with an irradiation amount according to the type of the film.

FIG. 7 schematically shows the flow of the above-described processing for a partial area on the TFT substrate 14. The condensed spot 44 of the light beam 48 condensed by the condensing lens 34 is moved to one uniaxial stage 38 of the moving stage 38.
It moves in the main scanning direction (directions of arrows R and L in FIG. 7) due to the movement of A, and moves in the sub-scanning direction (directions of arrows U and D in FIG. 7) due to the movement of the other one-axis stage 38B. At the time of this movement, as described above, each domain of the positioned target pixel is irradiated with ultraviolet rays in a set polarization direction at a dose corresponding to the type of the alignment film. In the example of FIG. 7, the polarization direction is rotated by 45 ° for each domain included in one pixel and adjacent to the main scanning direction.

The above processing is performed for all the pixels set on the TFT substrate 14, and the color filter substrates that have been subjected to the same processing are adhered to each other. Is formed.

Next, a method of manufacturing the liquid crystal display device 10 including the multi-domain liquid crystal cell in which the alignment direction is changed in each pixel described above will be described with reference to the flowchart of FIG.

When the production of the liquid crystal display device 10 is started,
In step S1, the color filter substrate 12 and the TFT
An alignment film is formed on the substrate 14.

First, about 60 μm of a polyimide solution is applied to the side of the TFT substrate 14 where active elements (not shown) are formed.
Apply 0 Angstrom. The application of the polyimide solution can be performed by printing or spin coating. The polyimide solution applied to the TFT substrate 14 is dried by infrared irradiation or a drying device (for example, a hot plate) not shown. With this, TFT
A polyimide alignment film 24 is formed on the substrate 14. In this way, it is possible to obtain the alignment film 24 of the polyimide applied substantially uniformly.

Next, the alignment film 20 is formed on the color filter substrate 12 in the same manner as the TFT substrate 14.

When the alignment films 20 and 24 are formed as described above, in the next step S2, an ultraviolet irradiation process is performed.
This is performed as described above in the liquid crystal display device manufacturing apparatus 30 (see FIG. 6). This ultraviolet irradiation treatment corresponds to a rubbing treatment. However, as described above, the pretilt angle is 0 °.

Since the polarization directions of the ultraviolet rays applied to the upper alignment film 20A and the lower alignment film 20B intersect at about 90 °, it is possible to obtain the alignment film 20 having the property that the alignment directions differ by 90 ° in the same pixel. it can. The alignment film 20
Since the pretilt angle that induces is 0 °, when an electric field is applied to the liquid crystal 16 aligned by the alignment film, the liquid crystal molecules rotate in different directions of tilting left and right in the same alignment direction. Will happen.

When the ultraviolet irradiation process is completed, the next step S
In 3, the alignment film 20 and the alignment film 24 face each other, and the color filter substrate 12 and the TFT substrate 14 that have been irradiated with linearly polarized ultraviolet rays (rubbing treatment) are arranged to face each other with a predetermined cell gap. The distance between the substrates at this time may be within a range in which the liquid crystal is aligned, and may be generally a cell gap of several microns to several tens of microns. In this embodiment, a 12-micron polyethylene film is interposed as a spacer. When the substrates face each other, in order to obtain a twist orientation rotated by 90 °, as shown in FIG. 9, the polarization directions irradiated into the liquid crystal cells corresponding to the pixels when superimposed are substantially orthogonal. To do it.

In the next step S5, a liquid crystal 16 sealed around the periphery and added with a predetermined chiral agent is injected between both substrates by using a capillary phenomenon while maintaining a liquid crystal phase. A polarizing plate (not shown) for display is attached to the outer surfaces of the substrate 12 and the TFT substrate 14 so as to form a crossed Nicols, thereby completing the liquid crystal display device 10.

The liquid crystal display device 10 thus obtained is
, A uniform image quality can be obtained with a very wide viewing angle.

As described above, in the present embodiment, since each polarization direction can be changed by changing the polarization direction of the ultraviolet light applied to the substrate in the pixel,
It is possible to easily realize a multi-domain in which the liquid crystal is partially orientated in various directions on the substrate. Also,
In this embodiment, the polarization direction can be continuously changed without using a mask or a resist film which is usually used in order to realize the multi-domain by irradiating the ultraviolet rays. Therefore, even when the types of changes in the orientation direction are increased, the manufacturing process does not become complicated.

As described above, the type of change in the alignment direction can be easily increased by rotating the polarization direction rotating device 32. For this reason, the orientation direction can be easily set in the pixel in order to obtain the viewing angle required by the liquid crystal display device, and the viewing angle dependency can be greatly improved.

Further, since the alignment direction can be freely set and controlled when the substrate is formed, the alignment direction can be set assuming that a display polarizing plate is provided, and the display polarizing plate and the display polarizing plate can be fixed at a fixed angle. Can maintain relationships. For this reason,
The contrast of the obtained liquid crystal display device does not decrease.

Furthermore, in contrast to the conventional rubbing treatment such as rubbing, in the present embodiment, a treatment corresponding to the rubbing treatment can be performed only by non-contact ultraviolet irradiation, so that there is no contact with the substrate and the alignment film. Therefore, no scratch, static electricity and dust are generated.

In this embodiment, since it is only necessary to be able to change the molecular chain formation state of the polymer film formed by applying the polymer material by irradiating ultraviolet rays, a variety of high-performance alignment films can be used. A molecular material can be used, and the alignment itself can be controlled by the composition or combination of the polymer material.

In the above embodiment, the case where the position of the converging spot on the substrate is changed by moving the moving stage 38 which moves in the orthogonal coordinate system has been described. However, the present invention is not limited to this. The ultraviolet light to be irradiated may be moved, or a combination of these may be used.
In order to move the ultraviolet side to be irradiated, a main scanning device such as a polygon that scans at a high speed in the main scanning direction is provided, and a sub-scanning such as a galvanometer mirror that scans at a low speed in a direction orthogonal to the main scanning direction is provided. The substrate may be irradiated with ultraviolet rays through the scanning device described above.

As a combination of these, FIG.
As shown at 0, a single-axis moving stage 40 having the TFT substrate 14 attached at a predetermined position, and a galvanometer mirror 42 located above the single-axis moving stage 40 may be provided. The rotation axis 42A of the galvanomirror 42 is parallel to the moving direction of the one-axis moving stage.
The main scanning is performed by the swing of the rotary shaft 42A around the rotation axis 42A, and the sub-scanning is performed by the step movement of the one-axis moving stage 40, thereby enabling the two-dimensional scanning of the laser beam 48. The galvanomirror 42 receives the ultraviolet light from the ultraviolet irradiation device 60 through the shutter 36, the polarization direction rotating means 32 and the condenser lens 34.
Reach through.

Next, the polyimide alignment film modified by irradiation of linearly polarized ultraviolet light will be described in detail. The present inventors have obtained from a variety of measurement experiments that a specific transformation occurs by irradiating linearly polarized ultraviolet light to a polyimide used for forming an alignment film.

Although polyimide is used in the above embodiment, the present invention is not limited to this, and polymers other than polyimide, such as PVA (polyvinyl alcohol), PET (polyethylene terephthalate), nylon, cellulose, and Teflon, are used. Or a mixture of a plurality of kinds of polyimides or a combination of polymers.

[0071]

As described above, according to the present invention, a rotatable linearly polarized electromagnetic wave is radiated to each partial region constituting each pixel of the polymer material on the substrate, and each partial region is polarized in the polarization direction of the electromagnetic wave. Therefore, there is an effect that it is possible to provide a liquid crystal display device in which the viewing angle is improved without lowering the contrast and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a manufacturing apparatus of a liquid crystal display device according to an embodiment of the present invention.

FIGS. 2A and 2B are block diagrams showing a schematic configuration of an ultraviolet irradiation system used in an apparatus for manufacturing a liquid crystal display device. FIG. 2A shows a case where an ultraviolet laser device is used, and FIG. 2B shows a case where an ultraviolet light source is used. Shows the case.

FIG. 3 is a cross-sectional view illustrating a liquid crystal display device.

FIG. 4 is an enlarged sectional view of a pixel portion of the liquid crystal display device.

FIG. 5 is a partial plan view of the liquid crystal display device as viewed from a color filter substrate side.

FIG. 6 is a flowchart illustrating a process flow of a liquid crystal display device manufacturing apparatus according to the present embodiment.

FIG. 7 is a perspective view of a substrate for explaining laser beam scanning.

FIG. 8 is a flowchart illustrating a flow of a manufacturing process when manufacturing the liquid crystal display device according to the present embodiment.

FIG. 9 is a perspective view showing a polarization direction in the case of twist alignment of the liquid crystal display device of the present embodiment.

FIG. 10 is a block diagram illustrating another example of a schematic configuration of the manufacturing apparatus of the liquid crystal display device according to the example.

11A and 11B are explanatory diagrams for explaining that liquid crystal molecules tilt in a liquid crystal display device. FIG. 11A shows that liquid crystal molecules tilt to the right, and FIG. 11B shows that liquid crystal molecules tilt to the left. (C) shows the state where the apparent rotation angles of the liquid crystal molecules are averaged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 28 Pixel 30 Liquid crystal display device manufacturing device 32 Polarization direction rotating device 34 Condensing lens 36 Shutter 38 Moving stage 50 Control device 60 Ultraviolet irradiation device

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoichi Taira 1623-14 Shimotsuruma, Yamato-shi, Kanagawa Prefecture IBM Japan, Ltd. Tokyo Research Laboratory (56) References JP-A-7-72484 (JP, A) JP-A-2-309321 (JP, A) JP-A-6-194665 (JP, A) JP-A-5-232473 (JP, A)

Claims (2)

(57) [Claims] 1. A step of applying a polyimide to a first substrate to form a polymer film, wherein the polymer film is included in a predetermined range of at least a part of the first substrate on which the polymer film is formed. For a plurality of pixels, a first partial area as a part of an area corresponding to each pixel
Irradiating an electromagnetic wave of a first polarization direction linearly polarized in the region,
A second partial area as a part of an area corresponding to each of the pixels;
In the second region of the second polarization direction intersecting with the first polarization direction.
A step of irradiating a magnetic wave, a step of applying a polyimide to a second substrate to form a polymer film, and a step of applying a polyimide film within a predetermined range of at least a part of the second substrate on which the polymer film is formed. For a plurality of included pixels, a first partial region as a part of a region corresponding to each pixel
Irradiating a linearly polarized electromagnetic wave in the first polarization direction to the region,
A second partial area as a part of an area corresponding to each of the pixels;
In the second region of the second polarization direction intersecting with the first polarization direction.
Irradiating a magnetic wave, and causing the polymer film surfaces to face each other , and holding the first substrate and the second substrate in a first partial area of the first substrate .
Laminating at predetermined intervals such that the region and the second partial region of the second substrate at least partially overlap; and applying a liquid crystal between the first substrate and the second substrate. A method of manufacturing a liquid crystal display device, comprising the steps of: 2. A first film as a part of a region corresponding to each pixel of a polymer film formed by applying polyimide .
An electromagnetic wave in the first polarization direction linearly polarized in the partial region is illuminated.
As part of the area corresponding to each of the pixels
A first substrate having a second partial region irradiated with an electromagnetic wave having a second polarization direction crossing the first polarization direction, and a pixel corresponding to each pixel of a polymer film formed by applying polyimide; A straight line in the first partial area as part of the area
The polarized electromagnetic wave of the first polarization direction is irradiated,
Second partial area as a part of the area corresponding to each pixel
A second polarization direction intersecting with the first polarization direction.
A second substrate irradiated with waves, the polymer films facing each other, and a first portion of the first substrate.
1 pixel from the distribution area and the second partial region of the second base plate
The first substrate and the second substrate are partially
A liquid crystal display device , which is attached at a constant interval and further includes: a liquid crystal injected between the first substrate and the second substrate.