JPH07281187A - Production of liquid crystal display element - Google Patents

Abstract

PURPOSE:To make direct rubbing treatment on one substrate unnecessary and to prevent damages in an element or deterioration of characteristics due to static electricity of rubbing by preparing a mother substrate having an oriented structure on its surface by orienting treatment and interposing a primary liquid crystal material between the mother substrate and a slave substrate not subjected to orienting treatment so as to transfer the oriented state of the mother substrate to the slave substrate. CONSTITUTION:A substrate 1 on which a photoresist film 3 and an oriented film 2 are formed is rubbed with a rubbing roller 4 rotated to subject the oriented film 2 to rubbing treatment. Then the photoresist film 3 is removed and a new photoresist film is applied. This photoresist film is patterned to form a photoresist pattern. Then the substrate 1 is rubbed with the rubbing roller 4 rotated in the counter direction so that the oriented film 2 subjected to orienting treatment corresponding to bisected subpixel regions PXa and PXb in opposite orienting directions to each other is formed on the substrate 1. Thus, the mother substrate as a master plate is obtd. and then the oriented state is transferred from the mother substrate to a slave substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a novel alignment treatment technique capable of producing a liquid crystal display device on a substrate which is not subjected to rubbing treatment.

[0002]

2. Description of the Related Art A liquid crystal display element used in a liquid crystal display or the like, a so-called liquid crystal cell, changes a specific molecular arrangement of liquid crystal into another different molecular arrangement by an action from the outside such as an electric field, and transmits an optical signal between them. The change in the physical characteristics is used as a visual change for display. In order to bring the liquid crystal molecules into a particular alignment state, it is usual to perform an alignment treatment on the surface of the glass substrate that sandwiches the liquid crystal.

In a conventional twisted nematic (TN) type liquid crystal cell or the like, as an alignment treatment, an alignment film such as polyimide is formed on the entire glass substrate sandwiching the liquid crystal, and the alignment film is rubbed with a rubbing cloth in one direction so-called rubbing method. Has been adopted.

For example, as shown in FIG. 9, a rubbing roller 10 having a rubbing cloth such as cotton cloth wound on the surface thereof is used as a substrate 1.
If the alignment film 11a on 1 is touched and moved on the substrate surface while rotating it in the direction of arrow A, the alignment process can be uniformly performed in the direction of arrow B on the entire surface of the alignment film.

In the TN type liquid crystal cell, as shown in FIG. 10, rubbing treatment is performed so that the in-plane orientation directions of the liquid crystal molecules 14 are orthogonal to each other between the upper and lower substrates 12 and 13 of the liquid crystal cell. The liquid crystal molecules 14 in contact with the substrate are aligned according to the alignment direction of the substrate.

When the liquid crystal cell is a negative display, the polarizing plates 15 and 16 arranged in parallel Nicols sandwiching the cell are arranged so that their polarization axes are parallel to one rubbing direction, and in the case of a positive display, Polarizing plates in the crossed Nicols arrangement are arranged so that their polarization axes are parallel to the rubbing direction of the adjacent substrate.

[0007]

A liquid crystal cell adopting an active driving system, such as a TFT (thin film transistor) or an M
IM (Metal Insulator Metal)
In the case of rubbing a substrate having drive elements such as a diode and wiring formed on the surface, if the entire surface is rubbed simultaneously as shown in FIG. 9, it is inevitable that those elements are rubbed at the same time. In that case, static electricity due to rubbing may damage the element or its wiring or deteriorate the characteristics. Also, rubbing tends to generate fine dust. If these dusts adhere to the substrate surface, it is not easy to completely remove them.

Further, when the alignment treatment is carried out by the conventional rubbing, since the alignment direction of the liquid crystal molecules is uniform, the angle (observation direction) at which the observer can easily see the display is limited to a specific angle range. A viewing angle characteristic is generated.

For example, when an isocontrast curve representing the viewing angle characteristics of a conventional twisted nematic liquid crystal display cell (TN-LCD) is measured, the viewing angle region with high contrast is biased to a specific angle region. Therefore, such a liquid crystal cell has a viewing angle dependency that it is easy to see from one direction and hard to see from another direction.

When a liquid crystal cell having such a viewing angle dependency is used as a display device, the contrast is extremely lowered at a certain angle with respect to the display screen, and in extreme cases, the contrast of the display is reversed. .

One of the causes of the liquid crystal cell having the viewing angle characteristic is
This is because the liquid crystal molecules are pretilted by rubbing. The direction in which the liquid crystal molecules have a pretilt corresponds to the vector direction for rubbing.

In the rubbing method shown in FIG. 9, all liquid crystal molecules are aligned in the same direction with a pretilt angle. When a voltage is applied vertically to the liquid crystal layer, all the liquid crystal molecules 14 rise in the same direction as shown in FIG. Therefore, since the standing state of the liquid crystal molecules varies depending on the viewing direction (viewing angle indicated by the arrow) of the observer 17, viewing angle dependence occurs.

In order to reduce the viewing angle dependency and widen the viewing angle, it has been proposed to perform a split orientation. For example, it is an alignment processing technique in which one pixel is divided into a plurality of small regions and the orientation directions of the small regions are reversed or different to obtain substantially isotropic viewing angle characteristics as the entire pixel.

11 and 12 show examples of two-divided orientation (for example, Japan Display 1992 591).
See page). FIG. 11 shows an example in which the alignment film 22 having a large pretilt angle and the alignment film 23 having a small pretilt angle are selectively exposed in one pixel region of the upper and lower substrates 20 and 21. Although the case where the alignment film 22 is selectively formed after the alignment film 23 is formed on the entire surface is shown, the alignment films 22 and 23 may have an inverse relationship or may be patterned.

FIG. 12 shows a case where rubbing is performed in different directions in one divided pixel area. An alignment film 23 is formed on the entire surface of the upper substrate 20, and rubbing in the same direction is performed. An alignment film 22 is formed on the entire surface of the lower substrate 21,
Each pixel is divided into two and rubbing in opposite directions is performed.

In the divided alignment treatment as shown in FIGS. 11 and 12, since it is necessary to pattern the divided small regions for each substrate by a photolithography process using a photoresist, the manufacturing process of the liquid crystal cell is increased. However, it was a cause of cost increase.

In the case of split orientation, it is 4 rather than 2 split.
It is considered that the division is better because a more isotropic viewing angle characteristic can be obtained. However, the method of FIG. 11 has a limit of two divisions. Further, in the method of FIG. 12, the alignment treatment step is twice as many as usual, so that it is actually difficult to realize.

An object of the present invention is to manufacture a liquid crystal display device which does not require rubbing treatment directly on at least one of substrates constituting a liquid crystal cell and can avoid device damage and characteristic deterioration due to static electricity during rubbing. Is to provide a method.

Another object of the present invention is to provide a method for manufacturing a liquid crystal display device capable of realizing a split alignment process which can achieve isotropic viewing angle characteristics without complicating the manufacturing process.

[0020]

A method of manufacturing a liquid crystal display device according to the present invention comprises a step of preparing a mother substrate having an alignment structure subjected to an alignment treatment on its surface, a child substrate not subjected to the alignment treatment and the mother substrate. And a transfer step of interposing a primary liquid crystal material between the substrate and the substrate and transferring an alignment state corresponding to the alignment state of the mother substrate onto the daughter substrate.

[0021]

The desired orientation treatment is performed on the mother substrate side, which is the original plate, in advance. A sub-substrate used for an actual liquid crystal cell and a mother substrate subjected to an alignment treatment are arranged to face each other, and a primary liquid crystal material is injected between both substrates. Since the primary liquid crystal is aligned according to the alignment treatment of the mother substrate and the liquid crystal molecules are aligned at the interface of the child substrate,
The alignment state corresponding to the alignment state of the mother substrate is transferred to the child substrate side without any particular alignment treatment. The orientation state once transferred is stored (memory effect) by the liquid crystal molecules adsorbed on the interface of the child substrate even if the mother substrate and the child substrate are separated. Therefore, if you make one mother board in advance,
By transferring the orientation state, a large number of child substrates that do not require rubbing can be manufactured. The once prepared sub-substrate may be used as the next mother substrate.

[0022]

EXAMPLE A method of manufacturing a liquid crystal display device according to an example of the present invention will be described with reference to FIGS. 1A to 4B. In the present embodiment, the case of a two-divided orientation as shown in FIG. 1C will be described as an example. The liquid crystal display device LCD includes a large number of pixels PX arranged in a matrix. Each pixel PX is, for example, a rectangle such as a square, and includes two sub-pixel regions PXa and PXb whose orientation directions are opposite to each other.

1A and 1B show a process of manufacturing a mother substrate to be an original plate. Alignment film 2 directly on glass substrate 1
To form. Further, a photoresist pattern 3 that covers one sub-pixel region PXa and exposes the other sub-pixel region PXb is formed on the alignment film 2.

The alignment film 2 and the photoresist pattern 3 can be formed by a known method. For example, the alignment film 2 can be formed of a film of polyimide, polyamide, polypeptide alcohol, or the like by spin coating or printing. The photoresist pattern 3 can be formed by applying a general photoresist, for example, OFPR800 manufactured by Tokyo Ohka Co., Ltd. on the substrate by spin coating or roll coating, and removing unnecessary regions by exposure and development.

First, as shown in FIG. 1A, the rubbing roller 4 is rubbed on the substrate 1 on which the photoresist film 3 and the alignment film 2 are formed while rotating the rubbing roller 4 in the direction of arrow R1 (clockwise direction). 4 and substrate 1 relative to each other by arrow T1
Then, the alignment film 2 is rubbed.

The rubbing roller 4 is formed by sticking a rubbing cloth such as cotton cloth on the surface of the roller. A known method can be used for the rubbing treatment using the rubbing roller 4. In the rubbing process of FIG. 1A, only the exposed region of the alignment film 2 which is not covered with the photoresist film 3 is rubbed with the direction from right to left in the drawing as the alignment direction.

Next, the photoresist film 3 in FIG. 1A is removed and a new photoresist film is applied. As shown in FIG. 1B, the photoresist film is patterned so as to cover the already rubbed sub-pixel region PXb and expose the other sub-pixel regions PXa to form a photoresist pattern 3 ′.

This time, the rubbing roller 4 is rubbed on the substrate 1 while rotating in the opposite direction (counterclockwise direction) indicated by the arrow R2, and the substrate 1 and the rubbing roller 4 are relatively moved in the direction indicated by the arrow T2. Then, the alignment film 2 is rubbed. In the rubbing process of FIG. 1B, only the exposed region of the alignment film 2 that is not covered with the photoresist pattern 3 ′ is rubbed with the direction from left to right in the drawing as the alignment direction.

Photoresist pattern 3'on the alignment film 2
Is removed, the two-divided sub-pixel regions PXa and PXb whose orientation directions are opposite to each other are formed on the substrate 1 as shown in FIG. 1C.
The alignment film 2 subjected to the alignment treatment corresponding to is formed. With this, a mother substrate to be an original plate is formed.

Since the alignment film 2 is directly formed on the glass substrate 1 as the mother substrate, a manufacturing process is different from the case where the electrodes, active elements, etc. are once formed on the substrate and the alignment film is formed thereon. Is easier. Further, since a flat surface can be obtained, it is easy to realize uniform rubbing.

In the case of a pattern in which two sub-pixel regions having different alignment directions are separated from each other by a region that does not require alignment treatment and are spaced apart from each other, the region that does not require alignment treatment is covered with a photoresist pattern. It is also possible to change the orientation direction only by controlling the rotation direction of the rubbing roller 4 for each sub-pixel area. In this case, the photoresist pattern may be formed only once.

If the position control accuracy of the rubbing area by the rubbing roller 4 is considerably high, it is possible to directly perform the split alignment process by controlling the position of the rubbing roller 4 without using the photoresist pattern. Of course, rubbing treatment may be performed by rubbing the alignment film 2 with a means other than the rubbing roller 4.

The mother substrate thus manufactured is used for transferring a pattern to the daughter substrate and is not combined with an actual LCD. Therefore, in principle, the mother substrate can be used any number of times. Therefore, the cost for manufacturing the mother substrate in the cost for manufacturing the liquid crystal cell can be reduced.

The method is not limited to the two-divided orientation such as the four-divided orientation shown in FIG. 1D, and more multi-divided orientation is performed, or a method other than rubbing which is not so mass-producible (oblique vapor deposition film, Langmuir-Bloat film). Even if the alignment structure of the mother substrate is produced using a jet (LB film), a photo-alignment film, a stretched polymer film, etc., it is possible to make the actual productivity hardly affected.

Next, the process of transferring the alignment state from the mother substrate to the daughter substrate will be described with reference to FIGS. 2A-2C. As shown in FIG. 2A, the mother substrate 1 created in the steps of FIGS. 1A and 1B and the child substrate 5 to be transferred are arranged to face each other. An alignment film 6 which is not subjected to the alignment treatment is formed on the child substrate 5. The alignment film 6 is formed of, for example, a polyimide film, a polyamide film, a polyvinyl alcohol film, a SiO ₂ film, an ITO (indium-tin-oxide) film, or the like. The child substrate 5 is a substrate used for a liquid crystal display device and has an electrode structure and the like necessary for display.

FIG. 1C shows a structural example of the child board. Wirings or electrodes W, pixel electrodes P, and thin film transistors Q are formed on the glass substrate 5a. Wiring W is transistor Q
Is connected to the pixel electrode P via. For example, the wiring W and the pixel electrode P are made of ITO, the electrode portion of the thin film transistor is made of doped polysilicon, the channel portion is made of polysilicon, and the gate insulating film is made of a silicon oxide film.

It is not necessary to fix and seal the space between the mother substrate 1 and the daughter substrate 5 with a sealing material or the like. In this case, the gap between the substrates is not particularly limited, but it is desirable that the gap be as narrow and uniform as possible in order to perform a clean transfer.

Then, the nematic liquid crystal material 7 containing no chiral agent is heated to be in an isotropic state, and is injected between the mother substrate 1 and the daughter substrate 5 arranged opposite to each other. The liquid crystal can be injected between the substrates by a method such as vacuum injection or capillary injection. Alternatively, the liquid crystal may be poured on one substrate and the other substrate may be stacked thereon.

After the liquid crystal material 7 is injected, the liquid crystal material 7 is gradually cooled to a temperature below the phase transition temperature (for example, room temperature) to cause a phase transition to a nematic phase. Then, as shown in FIG. 2B,
The liquid crystal molecules 8a on the interface of the mother substrate are aligned according to the alignment treatment direction of the mother substrate 1. Left and right sub-pixel regions PXa, PX
In b, they are oriented with opposite tilt angles. The orientation gradually extends over the entire thickness of the liquid crystal layer. The liquid crystal molecules 8 at the interface of the alignment film 6 of the daughter substrate 5 facing the mother substrate 1 are similarly aligned. As a result, the alignment state of the mother substrate 1 is transferred to the daughter substrate 5. The mother substrate 1 may be gradually cooled while being kept at a temperature lower than that of the daughter substrate 5. It is easy to obtain a better orientation.

In this case, since the liquid crystal material 7 containing no chiral agent was used, the liquid crystal molecules 8 were not twisted in the thickness direction, and the state substantially the same as the orientation of the mother substrate 1 was found on the child substrate 5 side. Will be transferred to. However, as apparent from FIG. 2B, the tilt angles are opposite. It is preferable to prepare the mother substrate so that a desired tilt angle can be obtained on the daughter substrate.

The orientation state may be further transferred by using the once-prepared child substrate as the second-generation mother substrate and the un-oriented substrate as the second-generation child substrate. In this case, the substrate as the second-generation mother substrate may have no electrodes or drive elements, like the mother substrate. The tilt angle of the second generation substrate returns to that of the first generation mother substrate.

A chiral agent may be added to the nematic liquid crystal material in an appropriate amount and injected in the isotropic phase. Since a twist angle is generated in the liquid crystal molecules according to the amount of addition and the gap interval, the alignment state in which the twist angle is added to the alignment state of the mother substrate 1 is transferred to the child substrate 5 side.

When a liquid crystal containing a chiral agent is used, if the cell thickness at the time of transfer is not uniform, the orientation direction of the liquid crystal on the daughter substrate will vary depending on the location. Therefore, when using a liquid crystal containing a chiral agent, it is preferable to strictly control and manage the gap interval.

The liquid crystal molecules at the interface have the property of not easily moving once they are adsorbed on the substrate surface. This is generally called a memory effect. Therefore, the liquid crystal near the interface of the child substrate 5 thus manufactured is adsorbed by the alignment film 6 on the substrate,
The initial orientation state is saved (memory effect).

As shown in FIG. 3B, the mother substrate 1 and the daughter substrate 5
When and are separated and the excess liquid crystal material 7 is removed, the liquid crystal layer remains on the substrate. The liquid crystal molecules 8 remaining on the child substrate 5 are kept adsorbed by the alignment film and remain aligned as shown in FIG. 2B. When a new liquid crystal material is brought into contact with the child substrate 5, the remaining liquid crystal molecules 8 act as an alignment structure.

However, if this separation is performed in a nematic state or a low temperature state of the liquid crystal, the liquid crystal alignment state on the transferred substrate may be disturbed. Therefore, as shown in FIG. 3A, once the liquid crystal is heated to a high temperature, in particular, at or above the NI point to make the liquid crystal other than the interface into an isotropic phase, and then the separation of FIG. It was found that the orientation states can be separated with almost no disturbance.

It is considered that this is because the anchoring energy of the liquid crystal orientation on the transfer substrate, especially the anchoring in the azimuth direction is weak, and is influenced by the movement of the bulk liquid crystal when the substrate is moved during separation, and It is considered that the orientation of is disturbed. As the temperature rises, the viscosity and elastic constant of the liquid crystal decrease, and the elastic constant of the liquid crystal sharply decreases especially above the NI point. Therefore, it is considered that even if the bulk liquid crystal moves during separation, the liquid crystal does not affect the liquid crystal orientation on the transfer substrate.

Further, as shown in the figure, it is considered that the liquid crystal molecules near the substrate interface remain adsorbed on the substrate (nematic state) even when the temperature of the bulk liquid crystal reaches the isotropic state. However, if heating is further performed than that, liquid crystal molecules at the interface may start to move due to thermal vibration, and the transferred alignment state may be disturbed. Therefore, it is preferable that the liquid crystal at the time of separation has a temperature range within the range of NI points or more.

For the surface film formed on the child substrate to be transferred and the liquid crystal (primary liquid crystal) used for transfer, it is desirable to use a material having a strong binding force against heat or the like. For example, SE-510 (manufactured by Nissan Chemical) as a polyimide surface film and S as a liquid crystal.
R-9152 (manufactured by Chisso, NI point 108 ° C.) was used. In the case of these materials, when heated to 160 ° C. or higher, the orientation disorder on the transfer element substrate occurs. Therefore, 10
It is desirable to perform the separation step in the range of 8 to 160 ° C.

Two sub-boards 5 thus obtained are shown in FIG. 4A.
A cell is manufactured by arranging the cells facing each other at a predetermined interval as shown in FIG.
The alignment film 6 is not rubbed, but the adsorbed liquid crystal molecules form an alignment structure. Next, when the liquid crystal material 9 is injected between the two child substrates, a two-divided orientation with different pretilt angles is formed as shown in FIG. 4B.

In the liquid crystal cell of FIG. 4B, the tilt angle changes within the liquid crystal layer. It has a mirror-symmetrical orientation direction 2
This is because the substrates are combined. If two types of mother substrates are prepared and transferred from each of them, a liquid crystal cell in which the tilt angle is constant in the thickness direction of the liquid crystal layer can be formed.

In addition, as shown in FIG. 1C, when the alignment structure of the mother substrate is a periodic repeating pattern and the sub-pixel regions in the pixels are line-symmetric in the plane, two types are shifted by one sub-pixel region. The same effect can be achieved by producing the transfer substrate of.

5A and 5B show a process of assembling a liquid crystal cell using such a transfer substrate. As shown in FIG. 5A, the transfer substrate 5a and another transfer substrate 5b are superposed and liquid crystal (secondary liquid crystal) is injected preferably in an isotropic phase.

The liquid crystal alignment structure 8a on the substrate 5a and the liquid crystal alignment structure 8b on the other substrate 6b are in translation relation with each other. The isotropic phase liquid crystal layer 9 fills the gap between the alignment structures 8a and 8b. Since the liquid crystal molecules in the alignment structures 8a and 8b are adsorbed to the alignment films 6a and 6b, they do not move freely within a predetermined temperature range and maintain the alignment state even at the NI point or higher.

As shown in FIG. 5B, when the liquid crystal cell is gradually cooled, the liquid crystal layer 9 becomes a nematic phase and the alignment structures 8a, 8 are formed.
LCD aligned according to b and having a predetermined liquid crystal alignment state
Can be produced.

The liquid crystal may be injected in the nematic phase, but the transferred orientation may have defects because the anchoring energy is not sufficiently strong. From this point, it is preferable to inject in the isotropic phase as described above.

In this example, a nematic liquid crystal containing no chiral agent was injected to produce an antiparallel cell with uniform alignment. When manufacturing a twisted nematic cell (TN or STN-LCD), the orientation direction of the counter substrate may be adjusted to a predetermined direction and an appropriate amount of chiral agent may be added. Further, the primary liquid crystal and the secondary liquid crystal may be the same or different.

Of the pair of substrates forming the liquid crystal cell, only one of the substrates may be a sub-substrate formed by transferring the alignment state of the mother substrate. In that case, the other substrate in FIG. 4B may be a substrate in which the alignment film is not subjected to the alignment treatment or a substrate having no alignment film. Alternatively, only one of the substrates shown in FIG. 4B may be composed of a daughter substrate on which the orientation of the mother substrate is transferred, and the other substrate may be composed of a substrate subjected to a normal rubbing treatment. In that case, it is preferable that an active element such as a TFT or a narrow electrode is formed on the child substrate, and the substrate for rubbing is a substrate that does not have a structure vulnerable to static electricity.

6A and 6B show a method of manufacturing a liquid crystal display device according to another embodiment. As shown in FIG. 6A, the transfer substrate 5 having the alignment structure 8a manufactured in the same manner as the above-mentioned embodiment.
The liquid crystal cell is formed by making a and the substrate 5c which has not been subjected to any alignment treatment face each other. A liquid crystal as a secondary liquid crystal is injected into this liquid crystal cell in an isotropic phase to form a liquid crystal layer 9 between the substrates.

As shown in FIG. 6B, when the liquid crystal cell is gradually cooled, the liquid crystal layer 9 is aligned according to the alignment structure 8a on the substrate 5a, and the alignment state extends to the interface of the alignment film 6c on another substrate 5c. In this way, a liquid crystal cell having an oriented liquid crystal layer can be prepared.

When liquid crystal is injected in the nematic phase in this embodiment, flow alignment defects are likely to occur. It is preferable to inject the liquid crystal in the isotropic phase as described above. Although the case of injecting the nematic liquid crystal has been described, the chiral nematic liquid crystal can be injected.
If an appropriate amount of chiral agent is added to the nematic liquid crystal, and the mixture is injected into the liquid crystal cell and then slowly cooled, the liquid crystal layer shows a twist according to the added amount of the chiral agent, and the twisted nematic (T
N) or super twisted nematic (STN) liquid crystal display cells can be made.

At this time, since there is no force for determining the direction of the liquid crystal molecules on the side of the substrate 5c having no alignment structure, the alignment direction on the substrate 5c depends on the pitch of the chiral agent added to the liquid crystal and the substrate spacing. Can be decided For example, to make a 90 ° twisted TN-LCD, the cell thickness d
And the chiral pitch p are adjusted so that d / p≈1 / 4.

When the chiral nematic liquid crystal is used, it is preferable that the primary liquid crystal and the secondary liquid crystal are made of the same material. The thickness of the liquid crystal layer forming the alignment structure does not affect the twist angle. Therefore, the control of d / p becomes easy. However, the primary liquid crystal and the secondary liquid crystal do not necessarily have to be made of the same material.

It is not necessary to form electrodes or active elements on the mother substrate 1 used for transfer. Once the mother substrate is manufactured, it can be used semipermanently as long as the oriented structure can be maintained.
By using only one mother substrate 1, the transfer onto the daughter substrate 5 can be performed virtually any number of times. Therefore, even if a mother substrate having a plurality of alignment regions in one pixel is manufactured by using photolithography or the like, the cost burden can be reduced.

In the above embodiment, the liquid crystal material 7 is injected in the isotropic phase in the transfer process, but the liquid crystal material 7 may be injected in the nematic phase (liquid crystal phase). In that case, it is preferable to perform re-orientation treatment by heat treatment or the like in order to remove the flow pattern.

In FIG. 7A, a mother substrate 1 having an alignment film 2 having an alignment structure formed by rubbing or the like and a sub-substrate 5 having an alignment film 6 but having no alignment structure face each other to form a liquid crystal cell. Shows a state in which a nematic liquid crystal containing no chiral agent or a nematic liquid crystal 7 containing an appropriate amount of chiral agent is injected in a nematic phase.

Since the liquid crystal of the nematic phase is injected, the flow of the liquid crystal at the time of injection remains in the flow orientation F as it is. This flow alignment is not easily erased by the memory effect between the alignment film 6 and the liquid crystal molecules.

However, when energy such as heat higher than the binding force is applied to the liquid crystal molecules on the interface of the alignment film 6, the liquid crystal molecules on the interface of the alignment film 6 can move to some extent. The energy applied to the liquid crystal molecules need not be limited to heat, and may be light, ultrasonic waves, or the like as long as it can give sufficient kinetic energy to the liquid crystal molecules.

The materials described in the above examples (SE-51
0, SR-9152), the liquid crystal molecules can be realigned by heating at 160 ° C. or higher. FIG. 7B shows a state in which the liquid crystal layer is heated and the liquid crystal molecules are realigned in this way. In this state, the flow orientation disappears.

Then, when the liquid crystal cell is gradually cooled, an alignment structure in which the liquid crystal layer 7 is aligned according to the alignment structure on the substrate 1 and liquid crystal molecules are aligned at the interface on the substrate 5 is obtained as shown in FIG. 2B. After that, the same steps as those in the above-described embodiment may be performed.

Although the case of injecting in the nematic phase when forming the child substrate from the mother substrate and then extinguishing the memory effect has been described, the same method can be performed when forming the liquid crystal display device.

In FIG. 8A, a substrate 5a on which an alignment structure 8a formed by the same method as that of the above-mentioned embodiment is transferred and a substrate 5c having no alignment structure are opposed to each other to form a liquid crystal cell, and a nematic is formed therebetween. A state in which a liquid crystal or a nematic liquid crystal 9 added with a chiral agent is injected in a nematic phase is shown. Since the liquid crystal of the nematic phase was injected, the flow alignment was generated in the liquid crystal cell.

By applying energy to the liquid crystal molecules to eliminate the memory effect, the flow orientation can be eliminated. However, the alignment film 6 having the alignment structure 8a formed by the memory effect
The orientation state on a may also disappear. Therefore, the transferred alignment structure on the substrate 5a is not disturbed, and the substrate 5
It is necessary to perform the re-orientation treatment under the condition that the flow orientation on c is re-oriented.

Specifically, this treatment can be performed by changing the alignment film on each substrate. When the above-mentioned surface film (SE-510) is used for the child substrate 5a, the liquid crystal material (SR-
9152), a film that reorients at less than 160 ° C. may be used.

In general, the reorientation temperature becomes lower as the surface energy (polarity) of the surface film becomes smaller. The surface energy (52 dyn / c) of the surface film (SE-510) of the child substrate 5a.
m), a surface film having a smaller surface energy, for example, polyimide SE-150 having a surface energy (48 dyn / cm).
(Manufactured by Nissan Kagaku) is used.

This surface film material is a liquid crystal material SR-915.
2 reorients at 140 ° C. or higher. Therefore, 2
The temperature of the next reorientation treatment is set to 140 ° C or higher and lower than 160 ° C,
Then, if it is slowly cooled, the flow orientation on the substrate 5c can be erased without impairing the orientation on the child substrate 5a.

Further, if a material having a low glass transition point or low polarity is used, the temperature range of the secondary reorientation treatment can be widened. It was found that when a polyimide having a polarity of 23 dyn / cm was used, reorientation was possible at 110 ° C. or lower.

Also, the liquid crystal cell may be manufactured by using the liquid crystal material 7 injected in the transfer step as it is even after the mother substrate 1 is separated from the child substrate 5. Furthermore, by changing the direction and position of the sub substrates 5 facing each other or adding a chiral agent to the injected liquid crystal, a TN type liquid crystal cell or STN
Different kinds of liquid crystal display devices such as a liquid crystal cell can be manufactured.

The case where the alignment film such as a polyimide film is formed on the substrate and the alignment structure is formed by rubbing has been described, but the alignment structure may be formed by another method. For example,
The alignment structure may be formed by rubbing without providing the alignment film or selectively irradiating the optical polarization memory film with polarized light. It is desirable that the alignment structure has a property of easily adsorbing liquid crystal molecules, having a high memory property for keeping the adsorbed state, and having no anisotropy in the initial stage. The alignment film can be formed by spin-coating, printing, sputtering or the like a film of polyimide, polyamide, polyvinyl alcohol, SiO ₂ , ITO or the like. However, the alignment film is not always necessary. For example, the glass substrate surface can be used as it is for the orientation structure.

Although the above embodiment is an example of a plurality of divided orientations, it is needless to say that the present invention can be applied to the case of the ordinary uniform orientation of the entire substrate, and the mother substrate 1 can be divided into four divisions shown in FIG. 1D and other divided orientations. It is possible to transfer the alignment structure to the child substrate by changing the alignment pattern of the.

It is obvious to those skilled in the art that the configurations, materials and the like of the embodiments described above are merely examples, and the present invention is not limited to these and various changes, improvements, combinations and the like are possible. Let's do it.

[0082]

According to the present invention, it is basically unnecessary to perform an alignment treatment such as a rubbing treatment on a substrate which constitutes a cell, or a substrate on which a driving active element such as a TFT or MIM is formed is unnecessary. It becomes unnecessary to rub. Therefore, the problems of element destruction and characteristic deterioration due to static electricity in the rubbing process are reduced.

Further, once the mother substrate is prepared, it can be semipermanently used as an original plate. In the case of split orientation, if only the mother substrate is subjected to alignment treatment by a process such as photolithography, the child substrate to be transferred does not require any alignment treatment other than transfer. The effect can be improved and the cost can be reduced.

It is also possible to use a four-divided orientation which has better viewing angle characteristics than the two-divided orientation.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a process of manufacturing a mother substrate having a two-divided orientation according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a liquid crystal cell for explaining a process of transferring an alignment state from a mother substrate having a two-division alignment to a child substrate according to an embodiment of the present invention.

FIG. 3 is a sectional view schematically showing an alignment structure of a transferred child substrate according to an embodiment of the present invention.

FIG. 4 is a sectional view illustrating an assembly process of a liquid crystal display cell according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a process of assembling a liquid crystal display cell according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating an assembly process of a liquid crystal display cell according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating an assembly process of a liquid crystal display cell according to an embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating a process of assembling a liquid crystal display cell according to an embodiment of the present invention.

FIG. 9 is a perspective view showing a rubbing process according to a conventional technique.

FIG. 10 is a cross-sectional view of a liquid crystal display element manufactured by a conventional technique.

FIG. 11 is a cross-sectional view of a liquid crystal display device having a two-divided orientation prepared by a conventional technique.

FIG. 12 is a cross-sectional view of a liquid crystal display device having a two-divided orientation prepared by a conventional technique.

[Explanation of symbols]

 1 Mother Substrate 2 Alignment Film 3,3 'Photoresist 4 Rubbing Roller 5 Substrate 6 Alignment Film 7 Liquid Crystal Material 8 Liquid Crystal Molecules 9 Liquid Crystal Material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Ando 1-3-1 Eda Nishi, Aoba-ku, Yokohama-shi, Kanagawa Stanley Electric Co., Ltd.

Claims (23)

[Claims] 1. A step of preparing a mother substrate having an alignment structure subjected to an alignment treatment on its surface, and 1 between a mother substrate not subjected to the alignment treatment and the mother substrate.
And a transfer step of transferring an alignment state corresponding to the alignment state of the mother substrate onto the daughter substrate with a next liquid crystal material sandwiched therebetween. 2. A separation step of separating the mother substrate and the sub-substrate, and a pair of substrates, at least one of which is the sub-substrate to which the orientation state has been transferred, is arranged to face each other. And a step of injecting a secondary liquid crystal material between the pair of substrates to form a cell, the method of manufacturing a liquid crystal display element according to claim 1. 3. In the transferring step, the primary liquid crystal material is arranged between a mother substrate and a child substrate in an isotropic phase, and then the primary liquid crystal material is phase-transitioned into a liquid crystal phase and aligned. Item 2. A method for manufacturing a liquid crystal display element according to item 1. 4. A mother substrate and a sub-substrate, which further include a step of preheating the primary liquid crystal material to bring it into an isotropic phase, and thereafter, in the transferring step, the primary liquid crystal material of the isotropic phase is arranged to face each other. 4. The method for producing a liquid crystal display device according to claim 3, wherein the liquid crystal display device is injected into the liquid crystal and slowly cooled to a temperature not higher than the phase transition temperature for alignment. 5. The method of manufacturing a liquid crystal display device according to claim 1, wherein the primary liquid crystal material does not contain a chiral agent in the transferring step. 6. The method of manufacturing a liquid crystal display device according to claim 2, wherein the secondary liquid crystal material contains a chiral agent in the step of manufacturing the cell. 7. The method of manufacturing a liquid crystal display device according to claim 1, wherein the alignment structure of the mother substrate is subjected to an alignment treatment so as to be substantially semipermanently preserved. 8. The method of manufacturing a liquid crystal display device according to claim 7, wherein the alignment structure of the mother substrate has a plurality of regions having different alignment directions. 9. The method of manufacturing a liquid crystal display device according to claim 8, wherein the alignment treatment of the mother substrate is performed by a rubbing method. 10. The method of manufacturing a liquid crystal display element according to claim 2, wherein the primary liquid crystal material injected in the transfer step and the secondary liquid crystal material injected in the step of manufacturing the cell are the same material. 11. The method of manufacturing a liquid crystal display device according to claim 2, wherein the separating step is performed while keeping the liquid crystal in an isotropic phase. 12. In the transferring step, the primary liquid crystal material is injected between a mother substrate and a child substrate which are arranged to face each other in a liquid crystal phase, and energy is applied to the liquid crystal material after the injection to form a substrate and liquid crystal molecules. The method for producing a liquid crystal display device according to claim 1, wherein the memory effect between the two is eliminated, and then a phase transition to a liquid crystal phase is performed for orientation. 13. The method of manufacturing a liquid crystal display element according to claim 12, wherein the energy is heat. 14. The method of manufacturing a liquid crystal display device according to claim 11, wherein the primary liquid crystal material does not include a chiral agent in the transfer step. 15. The method of manufacturing a liquid crystal display device according to claim 11, wherein the secondary liquid crystal material contains a chiral agent in the step of manufacturing the cell. 16. The method of manufacturing a liquid crystal display device according to claim 11, wherein the alignment structure of the mother substrate is subjected to an alignment treatment so as to be substantially semipermanently preserved. 17. The method of manufacturing a liquid crystal display device according to claim 11, wherein the alignment treatment of the mother substrate is performed by a rubbing method. 18. The method of manufacturing a liquid crystal display element according to claim 2, wherein in the step of manufacturing the cell, the pair of substrates is the sub-substrate to which the alignment state has been transferred and another substrate that has not been subjected to alignment treatment. . 19. The method of manufacturing a liquid crystal display device according to claim 18, wherein the other substrate has a surface that allows free movement of liquid crystal molecules at an interface with lower energy as compared with the alignment structure of the child substrate. 20. In the step of manufacturing the cell, the secondary liquid crystal material is injected in a liquid crystal phase between a pair of substrates, the memory effect of the sub-substrate is not lost after the injection, and the memory effect on the other substrate is maintained. 20. The method for manufacturing a liquid crystal display device according to claim 19, further comprising applying energy to extinguish the liquid crystal and then gradually cooling the liquid crystal. 21. The method of manufacturing a liquid crystal display device according to claim 1, wherein the mother substrate has no electrodes. 22. The method of manufacturing a liquid crystal display device according to claim 21, wherein the mother substrate is a glass substrate on which an alignment film is directly formed. 23. The method of manufacturing a liquid crystal display device according to claim 22, wherein the alignment film is a film of polyimide, polyamide or polypeptide alcohol, and the alignment treatment is rubbing of the alignment film.