JPH0943607A - Production of liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a liquid crystal display element capable of averting the damage of the element and the deterioration in the characteristics of the element by the static electricity at the time of rubbing by eliminating the need for subjecting at least either of the substrates constituting liquid crystal cells to a direct rubbing treatment with respect to a novel orientation treatment technique capable of forming the liquid crystal display element with the substrates which are not subjected to the rubbing treatment. SOLUTION: A mother substrate 1 having an oriented structure subjected to the orientation treatment is prepd. and the sub-substrate 5 which is not subjected to the orientation treatment is prepd. This process has a transfer stage of arranging the mother substrate 1 and the sub-substrate 5 opposite to each other, holding the primary liquid crystal material 8 of an isotropic state between the substrates and transferring the oriented state corresponding to the oriented state of the mother substrate 1 to the sub-substrate 5 in the state of impressing an electric field between the substrates 1 and 5.

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 for a liquid crystal display (LCD) or the like, a so-called liquid crystal cell, changes a specific molecular arrangement of liquid crystal into another different molecular arrangement by an external action such as an electric field, The changes in optical characteristics during that time are used for display as visual changes. Generally, an alignment treatment is performed on the surface of a glass substrate holding liquid crystal in order to arrange liquid crystal molecules in a specific alignment state.

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

For example, as shown in FIG. 8, a rubbing roller 10 having a rubbing cloth such as cotton cloth wound on its surface is mounted on a substrate 1.
By touching the alignment film 11a on 1 and moving it on the substrate surface while rotating it in the direction of arrow A, the entire surface of the alignment film 11a can be uniformly aligned in the direction of arrow B.

In the TN type liquid crystal cell, as shown in FIG. 9, a rubbing process 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 the polarization axes thereof are parallel to one rubbing direction. A polarizing plate having a crossed Nicols arrangement is arranged such that its polarization axis is parallel to the rubbing direction of the adjacent substrate.

[0007]

SUMMARY OF THE INVENTION A liquid crystal cell adopting an active drive system, which includes a TFT (thin film transistor) and an M
IM (Metal Insulator Metal)
When rubbing a substrate having drive elements such as a diode) or wiring formed on the surface, if the entire surface is simultaneously rubbed as shown in FIG. 8, it is inevitable that those elements are rubbed at the same time. In such a case, there is a possibility that the element or its wiring is destroyed or its characteristics are deteriorated due to static electricity generated by rubbing. Rubbing tends to generate fine dust. If these dusts adhere to the substrate surface, it is not easy to completely remove them.

In addition, when the conventional rubbing process is performed, since the orientation direction of the liquid crystal molecules is uniform, the angle at which the display is easy to see (viewing direction) when an observer views the screen is limited to a specific angle range. Viewing angle characteristics are produced.

For example, when an isocontrast curve representing a viewing angle characteristic of a conventional twisted nematic liquid crystal display cell (TN-LCD) is measured, a viewing angle region having high contrast is biased toward a specific angle region. Therefore, such a liquid crystal cell has a viewing angle dependency such 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 dependence is used as a display device, the contrast is extremely reduced 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 a viewing angle characteristic is as follows.
This is because rubbing causes pretilt in liquid crystal molecules. The direction in which the liquid crystal molecules have a pretilt coincides with the rubbing vector direction.

In the rubbing method shown in FIG. 8, 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 liquid crystal molecules 14 rise in the same direction as shown in FIG. Therefore, the degree of standing of the liquid crystal molecules differs depending on the viewing direction of the observer 17 (viewing angle indicated by an arrow), and thus viewing angle dependency occurs.

In order to reduce the viewing angle dependency and increase the viewing angle, it has been proposed to perform a split orientation. For example, this is an alignment processing technique that divides one pixel into a plurality of small regions and reverses or changes the alignment direction of the small regions to obtain a substantially isotropic viewing angle characteristic as a whole pixel.

10 and 11 show examples of two-division orientation (for example, Japan Display 1992 591).
See page). FIG. 10 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. After forming the alignment film 23 on the entire surfaces of the substrates 20 and 21, the alignment film 22 having a large pretilt angle is selectively formed. The alignment films 22 and 2
3 may be reversed, or each may be patterned.

FIG. 11 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 is performed in the same direction. 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 divisional alignment treatment as shown in FIGS. 10 and 11, since it is necessary to pattern the divisional small regions for each substrate by a photolithography process using a photoresist, the number of liquid crystal cell manufacturing processes is increased. However, it was a cause of cost increase.

Also, in the case of the split orientation, it is more than 4 than in the case of 2 splits.
It is considered that the division is better because more isotropic viewing angle characteristics can be obtained. However, the method of FIG. 10 is limited to two divisions. Further, the method of FIG. 11 is actually difficult to realize because the number of alignment treatment steps is twice as large as usual.

An object of the present invention is to manufacture a liquid crystal display device which can avoid device damage and characteristic deterioration due to static electricity at the time of rubbing by making it unnecessary to directly perform rubbing treatment on at least one of the substrates constituting the liquid crystal cell. Is to provide a way.

[0019]

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 and a child substrate not subjected to the alignment treatment. In the process, the mother substrate and the daughter substrate are arranged so as to face each other, the primary liquid crystal material in the isotropic state is sandwiched between the substrates, and the alignment state corresponding to the alignment state of the mother substrate is applied in the state where the electric field or the magnetic field is applied between the substrates. And a transfer step of transferring to a child substrate.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A desired orientation treatment is performed in advance on a mother substrate side which is an original plate. A sub-substrate used for an actual liquid crystal cell and a mother substrate subjected to alignment treatment are arranged to face each other, and a primary liquid crystal material is injected between the two substrates. When an alignment state corresponding to the alignment state of the mother substrate is transferred to the daughter substrate while an electric field or magnetic field is applied between the two substrates, the primary liquid crystals are aligned according to the mother substrate alignment treatment and the electric field or magnetic field, and the interface of the daughter substrate is obtained. Also, the liquid crystal molecules are aligned. The orientation state once transferred is preserved (memory effect) by the liquid crystal molecules adsorbed on the interface of the child substrate even when the mother substrate and the child substrate are separated. Therefore, if one mother substrate is prepared in advance, a large number of alignment-processed daughter substrates can be manufactured without rubbing by transferring the alignment state. The child substrate once manufactured may be used as the next mother substrate.

[0021]

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. 1 (A) to 5 (H) in order.

FIG. 1A shows a process of manufacturing a mother substrate to be an original plate. An ITO (indium tin oxide) film 2 is formed on a glass substrate 1. Further, the alignment film 3 is formed on the ITO film 2. The ITO film 2 is a transparent conductive film.

The ITO film 2 and the alignment film 3 can be formed by a known method. For example, the ITO film 2 can be formed by sputtering or vapor deposition. The alignment film 3 can be formed of a film of polyimide, polyamide, polypeptide alcohol or the like by spin coating or printing.

First, as shown in FIG. 1A, while rubbing roller 4 is rotated in the direction of arrow R1 (clockwise direction), rubbing is performed on substrate 1 on which ITO film 2 and alignment film 3 are formed, The rubbing roller 4 and the substrate 1 are relatively moved in the direction of arrow T1, and the alignment film 3 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 process using the rubbing roller 4. In the rubbing process of FIG. 1A, rubbing is performed with the direction from right to left in the drawing as the alignment direction. Thus, a mother substrate serving as an original is completed.

The mother substrate is ITO on the glass substrate 1.
Since the film 2 and the alignment film 3 are directly formed, the manufacturing process is simpler than the case where the electrodes, active elements, etc. are once formed on the substrate and then the alignment film is formed thereon. Further, since a flat surface is obtained, uniform rubbing can be easily realized.

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

Next, the process of transferring the alignment state from the mother substrate 1 to the daughter substrate 5 will be described with reference to FIG. FIG.
As shown in FIG. 1B, the mother substrate 1 created in the step of FIG. 1A and the child substrate 5 to be transferred are arranged to face each other. The ITO film 6 is formed on the child substrate 5. Further, an alignment film 7 which is not subjected to the alignment treatment is formed on the ITO film 6. The alignment film 7 is formed of, for example, a polyimide film, a polyamide film, a polyvinyl alcohol film or a SiO ₂ film. In particular, it is preferable to form a polyimide film with a side chain.

In addition, the alignment films 3 and 7 are not formed, and the substrates 1 and
You may form only the ITO films 2 and 6 on 5 respectively.
In that case, the ITO films 2 and 6 function as an alignment film.

Although the ITO film 6 is shown in a simplified manner in FIG. 1B, the ITO film 6 is actually a pixel electrode connected to a thin film transistor formed on the child substrate 5, and is separated for each pixel. Is provided. Note that a plurality of segment electrodes or common electrodes may be formed on the child substrate 5, or the ITO film 6 may be formed on the entire surface of the child substrate 5.

FIG. 2 shows a structural example of the child substrate 5 having a pixel electrode. Wirings or electrodes 6a, pixel electrodes 6b, and thin film transistors Q are formed on the glass substrate 5a. The electrode 6a and the pixel electrode 6b correspond to the ITO film 6 in FIG. The wiring 6a is connected to the pixel electrode 6 via the transistor Q.
connected to b. For example, the wiring 6a and the pixel electrode 6b 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.

In FIG. 1B, the AC power source 9 is connected between the ITO film 2 on the mother substrate 1 and the ITO film 6 on the daughter substrate 5. For the child substrate 5, the thin film transistors corresponding to all the pixels are turned on, and all the pixel electrodes 6 on the child substrate 5 are turned on.
An electric field is generated between the ITO film 2 and the ITO film 2 on the mother substrate 1.

Between the mother board 1 and the daughter board 5, 2V, 20
A square wave AC voltage of 0 Hz is applied. Here, the threshold value of the liquid crystal cell is 1.7V. The voltage applied between the substrates is preferably in the range from the threshold of the liquid crystal cell to twice the threshold.

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 interval between the two substrates is not particularly limited, but is desirably as narrow and uniform as possible in order to perform a clean transfer.

Then, the fluorine-type mixed nematic liquid crystal material (NI point 98 ° C.) 8 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 which are arranged facing each other. The liquid crystal can be injected between the substrates by a method such as vacuum injection or capillary injection. Alternatively, liquid crystal may be provided on one substrate, and the other substrate may be overlaid thereon.

After the liquid crystal material 8 is injected, the liquid crystal material 8 is gradually cooled to a temperature below the phase transition temperature (for example, room temperature) to cause a phase transition to a nematic phase. The liquid crystal material 8 gradually transmits the alignment state on the mother substrate 1 toward the daughter substrate 5. FIG.
As shown in (C), all the liquid crystal molecules 8 correspond to the alignment treatment direction of the mother substrate 1 and are aligned in a direction slightly raised in the electric field direction by the AC power supply 9. That is, the mother board 1
The tilt angle of the liquid crystal molecules 8 can be increased by applying an electric field between the substrate 5 and the child substrate 5.

The liquid crystal material 8 transfers the alignment state from the mother substrate 1 to the daughter substrate 5, whereby 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 lower temperature than the child substrate 5. In that case, since the mother substrate 1 is at a lower temperature than the daughter substrate 5, the liquid crystal material 8 first undergoes a phase transition from the isotropic phase to the nematic phase at the interface with the mother substrate 1. After that,
The phase transition progresses toward the interface with the child substrate 5. By sequentially changing the phase of the liquid crystal material 8 from the mother substrate 1 to the daughter substrate 5, the alignment state of the mother substrate 1 can be satisfactorily transferred to the daughter substrate 5.

In the above case, since the liquid crystal material 8 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 obtained. Will be transferred to the side. However, the tilt angle is opposite. In order to form a desired tilt angle on the daughter substrate 5, the tilt angle of the mother substrate 1 needs to be reversed.

When a twisted nematic liquid crystal display device is produced, a chiral agent may be added to the nematic liquid crystal material in an appropriate amount and injected in the isotropic phase. The liquid crystal remaining on the child substrate can be of the same type as the liquid crystal used thereafter. In this case, a twist angle depending on the added amount of the chiral agent, the gap distance, and the electric field is generated in the liquid crystal molecules, so that 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.

After the liquid crystal material 8 is sufficiently cooled, FIG.
As shown in (D), the AC power supply 9 connected between the substrates is removed to turn off the electric field. When the electric field is turned off, the tilt angle of the liquid crystal molecules 8 becomes slightly smaller. However, this pretilt angle is larger than the original pretilt angle of the mother substrate 1 before transfer. The liquid crystal molecules 8 on the child substrate 5 are aligned in a uniform alignment state having an appropriate pretilt angle.

The pretilt angle on the child board 5 is determined by the AC power source 9
Can be controlled by the electric field condition and the pretilt angle of the mother substrate 1. For example, the higher the voltage applied between the substrates, the larger the pretilt angle. However, if a too high voltage (8 V or more) is applied, the orientation on the child substrate 5 is disturbed, which is not preferable.

The pretilt angle of the child substrate 5 can be controlled depending on the type of the alignment film 7 on the child substrate 5.
If a polyimide film with a side chain is used as the alignment film 7, a large pretilt angle can be obtained.

The liquid crystal molecules at the interface have a property that they are not easily moved once they are adsorbed on the substrate surface. This is generally called a memory effect. Therefore, the liquid crystal near the interface between the sub-substrate 5 and the liquid crystal layer thus manufactured is adsorbed by the alignment film 7 on the substrate, and the initial alignment state is preserved (memory effect).

Next, the mother substrate 1 and the daughter substrate 5 are separated.
If this separation is performed in a nematic state or a low temperature state of the liquid crystal 8, the liquid crystal alignment state on the transferred substrate may be disturbed. Therefore, as shown in FIG. 4 (E), once the liquid crystal is heated to a high temperature state, especially above the NI point to make the liquid crystal 8'other than the interface into an isotropic phase, and then the separation is carried out, the liquid crystal 8'is separated on the transfer substrate. The alignment state of the liquid crystal 8 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 increases, the viscosity and elastic constant of the liquid crystal decrease, and particularly, the elastic constant of the liquid crystal sharply decreases above the NI point. Therefore, it is considered that even if the bulk liquid crystal moves during separation, it does not affect the liquid crystal alignment on the transfer substrate.

Further, as shown in the figure, the liquid crystal molecules 8 near the interface of the substrate are considered to remain adsorbed on the substrate (nematic state) even when the temperature of the bulk liquid crystal reaches the isotropic state. . However, when heating is further performed, the liquid crystal molecules at the interface may start to move due to thermal vibration, and the transferred alignment state may be disturbed. For this reason, it is preferable that the temperature of the liquid crystal at the time of separation be within a certain range of the NI point or higher.

Next, as shown in FIG. 4F, the mother substrate 1
The liquid crystal layer 8 is left on the sub-substrate 5 by separating the sub-substrate 5 and the extra liquid crystal material 8 ′. The liquid crystal molecules 8 remaining on the child substrate 5 are kept adsorbed by the alignment film 7 and remain aligned as shown in FIG. With the above, the production of the child substrate 5 is completed.

When the mother substrate 1 and the daughter substrate 5 are separated, the nematic state may be maintained without heating the liquid crystal 8 to bring it into the isotropic state. In that case, be careful not to disturb the alignment state on the substrate,
Need to be separated.

Two sub-boards 5 thus obtained are shown in FIG.
As shown in (G), cells are manufactured by facing each other at a predetermined interval. The alignment film 7 is not rubbed, but the adsorbed liquid crystal molecules 8 form an alignment structure.

Next, as shown in FIG.
When a liquid crystal material (secondary liquid crystal) 8 ″ is injected between the child substrates 5, the remaining liquid crystal molecules 8 act as an alignment structure, and the LCD is completed.

When the liquid crystal 8 ″ is injected between the substrates, the liquid crystal 8 ″
May be in a nematic state or an isotropic state.
Preferably, the liquid crystal 8 ″ is injected in the isotropic state. Then, when the liquid crystal cell is gradually cooled, the liquid crystal layer 8 ″ becomes a nematic phase and is aligned according to the alignment structure 8. With the above, an LCD having a predetermined liquid crystal alignment state is completed.

The liquid crystal 8 ″ 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, as described above, isotropic It is preferred to inject in phase.

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 opposing substrate may be adjusted to a predetermined direction, and an appropriate amount of a chiral agent may be added. The primary liquid crystal and the secondary liquid crystal may be the same or different, but are preferably the same in order to precisely control the properties of the liquid crystal layer.

As a method of injecting the liquid crystal 8 ″, a vacuum injecting method, an injecting method utilizing a capillary phenomenon, or the like can be used. Of a pair of substrates constituting a liquid crystal cell, only one substrate is a mother (child). The substrate may be formed of a child substrate (grandchild) to which the orientation state of the substrate is transferred, in which case the other substrate in FIG. Alternatively, the substrate may not be provided, or FIG.
It is also possible to configure only one of the substrates as a child substrate on which the orientation of the mother substrate is transferred and the other substrate as a substrate that has been subjected to a normal rubbing treatment. In such a case, it is preferable that an active element such as a TFT or a narrow electrode is formed on the daughter substrate, and the substrate for rubbing does not have a structure that is susceptible to static electricity.

By performing the above steps, FIG.
As shown in (1), a liquid crystal cell with uniform alignment could be produced. When the pretilt angle of the completed LCD was measured by the retardation method, the pretilt angle was 6.5.
It was 8 °, and a very large value was obtained.

By the way, when the transfer is performed without applying a voltage between the substrates and when a different kind of polyimide (such as polyimide without side chains) is used as the alignment film, the pretilt angle is 1 ° or less. There wasn't.

Further, the surface of the liquid crystal cell was photographed with a polarization microscope when the liquid crystal cell was turned on and when it was turned off. Both the present example (2 V applied) and the comparative example (0 V applied) were photographed and compared.

When the liquid crystal cell was turned on, the comparative example had a small pretilt angle, so that a large number of reverse tilt disclination lines were generated immediately after the drive voltage (5 V) was applied (about several seconds). Since the pretilt angle of the present example is large and 6 ° or more, no defect due to the reverse tilt disclination line occurred.

When the liquid crystal cell is off, the present example and the comparative example have slight variations in micrographs as compared with a general LCD in which an alignment film is directly subjected to alignment treatment such as rubbing or photo-alignment. Although it is in the aligned state, it looks as a uniform aligned state to the naked eye, so there is no practical difference.

In the transfer process, 2V is applied between the substrates,
The case where a square wave AC voltage of 200 Hz is applied to increase the pretilt angle has been described, but other voltage values,
It may be a frequency or a waveform. DC may be used instead of AC.

A magnetic field may be applied instead of an electric field between the substrates. FIG. 6 shows a case where the electric field of FIG.
The step of using a magnetic field instead of performing the next liquid crystal injection will be described.

A magnetic field H is applied between the mother substrate 1 and the daughter substrate 5. The magnetic field can be generated, for example, by passing a current through the coil. Primary liquid crystal 8 under magnetic field
Are injected between the substrates, and then cooled and the magnetic field is set to 0 in the same manner as described above, liquid crystal molecules having a large pretilt angle are transferred to the child substrate 5.

The strength of the magnetic field is preferably within the range from the threshold value of the liquid crystal cell to twice the threshold value. Similar to the electric field, various parameters can be used for the magnetic field. When a magnetic field is used, the angle at which the magnetic field is applied can be further controlled arbitrarily, so the pretilt angle can be adjusted by the angle at which the magnetic field is applied.

Although the case of transferring liquid crystal molecules of uniform alignment has been described above, it is also possible to transfer liquid crystal molecules of divided alignment. FIG. 7 shows a method for manufacturing a split orientation mother substrate. As a typical example, a case of a two-division orientation as shown in FIG. 7C will be described. The liquid crystal display device LCD includes a number of pixels PX arranged in a matrix. Each pixel PX
Is, for example, a rectangle such as a square.
It consists of one sub-pixel area PXa, PXb.

7 (A) and 7 (B) show a process of manufacturing a mother substrate to be an original plate. First, as before,
The ITO film 2 and the alignment film 3 are formed on the glass substrate 1. Further, one sub-pixel region PXa is formed on the alignment film 3.
And a photoresist pattern MK1 that covers the other sub-pixel region PXb is exposed.

The photoresist pattern MK1 is a general photoresist such as OFPR800 manufactured by Tokyo Ohka.
Can be formed by spin coating or roll coating on a substrate and removing unnecessary areas by exposure and development.

First, as shown in FIG. 7A, the rubbing roller 4 is rubbed against the rubbing roller 4 while rotating the rubbing roller 4 in the direction of arrow R1 (clockwise direction). The substrate 1 is relatively moved in the direction of the arrow T1, and the alignment film 3 is rubbed. By this rubbing process, only the exposed region of the alignment film 3 which is not covered with the photoresist film MK1 is rubbed with the direction from right to left in the drawing as the alignment direction.

Next, the photoresist film MK of FIG.
1 is removed and a new photoresist film is applied. As shown in FIG. 7B, 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 MK2.

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 3 is rubbed. Figure 7
In the rubbing step (B), the photoresist pattern M
Only the exposed region of the alignment film 3 which is not covered with K2 is rubbed with the direction from left to right in the drawing as the alignment direction.

Photoresist pattern MK on the alignment film 3
When 2 is removed, the two-divided sub-pixel regions PXa whose orientation directions are opposite to each other on the substrate 1 as shown in FIG.
An alignment film 3 having an alignment treatment corresponding to PXb is formed. This completes the mother board that is the original plate.

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 arranged 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 need only be formed once.

Further, if the position control accuracy of the rubbing area by the rubbing roller 4 is quite high, it is also possible to directly perform the split orientation 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 3 by means other than the rubbing roller 4.

A 4-divisional orientation such as shown in FIG.
Not only divisional orientation but also more multi-divisional orientation, and methods other than rubbing that are not very mass-producible (oblique vapor deposition film, Langmuir-Blodgett (LB) film, photo-alignment film, stretched polymer film, etc.) Even if the oriented structure of the mother substrate is produced by using (1), it is possible to have little effect on the actual productivity.

As described above, by performing the transfer from the mother substrate to the daughter substrate, it is possible to form an alignment state having a proper pretilt angle on the daughter substrate which is not directly subjected to the rubbing treatment. When performing this transfer, the pretilt angle can be controlled by applying an electric field or a magnetic field. Specifically, the pretilt angle is determined by the applied voltage, the magnitude of the applied magnetic field, and the applied angle of the magnetic field.

The pretilt angle of the daughter substrate is also determined by the pretilt angle of the mother substrate and the type of alignment film on the daughter substrate. If polyimide having a side chain is used for the alignment film of the child substrate, the pretilt angle becomes large.

Further, since it is not necessary to perform a rubbing process on the child substrate or the like to be transferred, the active element such as the TFT or the MIM is prevented from being damaged by rubbing, and L
A CD can be made. It is possible to prevent characteristic deterioration and dielectric breakdown due to static electricity, and prevent deterioration of the display quality of the LCD.

Once the mother substrate is produced, it can be used as an original plate for orientation in a semi-infinite manner. Therefore, if the mother substrate is manufactured once, the transfer substrate can be manufactured indefinitely in the same process, and even when the mother substrate of the divided orientation which requires complicated processes is manufactured, The cost is almost the same as the case. A split orientation LCD can also be manufactured at low cost.

The LCD of multi-divided orientation has excellent visual characteristics and can perform high quality display. In particular, a split-orientation LCD with four or more splits has the same visual characteristics when viewed from any direction.

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 and combinations can be made. Let's do it.

[0081]

According to the present invention, by applying an electric field or a magnetic field between both substrates to be transferred, the alignment state according to the electric field or the magnetic field is transferred to the child substrate. By controlling the conditions of the electric field or the magnetic field, a desired orientation state can be transferred to the child substrate.

Further, since it is not necessary to perform an orientation treatment such as a rubbing treatment on the child substrate, there is no problem of active element destruction or characteristic deterioration of the child substrate due to static electricity in the rubbing process.

Further, once the mother substrate is prepared, it can be used semi-permanently as an original. 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.

[Brief description of drawings]

FIG. 1A is a sectional view illustrating a mother substrate alignment treatment process according to an embodiment of the present invention. FIG. 1B is a sectional view illustrating a primary liquid crystal injection process according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a child substrate used in the step of FIG.

FIG. 3C is a sectional view illustrating a first alignment transfer process according to an embodiment of the present invention. FIG. 3D is a sectional view illustrating a second alignment transfer process according to the embodiment of the present invention.

FIG. 4 (E) is a sectional view illustrating a first separation step according to the embodiment of the present invention. FIG. 4F is a sectional view for explaining the second separation step according to the embodiment of the present invention.

FIG. 5G is a cross-sectional view illustrating a process of assembling a liquid crystal cell according to an embodiment of the present invention. FIG. 5H is a sectional view illustrating a completed state of the liquid crystal display device (LCD) according to the embodiment of the present invention.

FIG. 6 is a sectional view illustrating another primary liquid crystal injection process according to an embodiment of the present invention.

FIG. 7 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. 8 is a perspective view showing a rubbing process according to a conventional technique.

FIG. 9 is a cross-sectional view of a liquid crystal display device manufactured by a conventional technique.

FIG. 10 is a cross-sectional view of a two-divided alignment liquid crystal display device manufactured by a conventional technique.

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

[Explanation of symbols]

 1 Mother Substrate 2,6 ITO Film 3,7 Alignment Film 4 Rubbing Roller 5 Substrate 8 Liquid Crystal Material 9 AC Power Supply MK Photoresist

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

Claims (11)

[Claims] 1. A step of preparing a mother substrate having an alignment structure subjected to an alignment treatment on its surface, a step of preparing a daughter substrate not subjected to the alignment treatment, and the mother substrate and the daughter substrate being arranged to face each other. A liquid crystal display device comprising: a primary liquid crystal material in an isotropic state sandwiched between substrates; and a transfer step of transferring an alignment state corresponding to the alignment state of the mother substrate to the child substrate in a state where an electric field is applied between the substrates. Manufacturing method. 2. A step of preparing a mother substrate having an alignment structure subjected to an alignment treatment on its surface, a step of preparing a child substrate not subjected to the alignment treatment, and disposing the mother substrate and the daughter substrate so as to face each other. A liquid crystal display device comprising: a primary liquid crystal material in an isotropic state sandwiched between substrates; and a transfer step of transferring an alignment state corresponding to the alignment state of the mother substrate to the daughter substrate in a state where a magnetic field is applied between the substrates. Manufacturing method. 3. 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 or 2. 4. The method of manufacturing a liquid crystal display element according to claim 3, 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. 5. The method of manufacturing a liquid crystal display element according to claim 3, wherein the secondary liquid crystal material contains a chiral agent in the step of manufacturing the cell. 6. The method of manufacturing a liquid crystal display device according to claim 5, wherein, in the transferring step, the primary liquid crystal material contains a chiral agent. 7. The method for 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 element according to claim 1, wherein the alignment treatment of the mother substrate is performed by a rubbing method. 9. The method for manufacturing a liquid crystal display device according to claim 1, wherein the alignment structure of the mother substrate has a plurality of regions having different alignment directions. 10. The method for manufacturing a liquid crystal display device according to claim 1, wherein the daughter substrate has a polyimide alignment film with a side chain formed on a surface thereof facing the mother substrate. 11. The mother substrate is formed by forming a transparent conductive film and an alignment film on a glass substrate.
11. The method for manufacturing a liquid crystal display element according to any one of 10.