JPH06202122A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To inexpensively produce the liquid crystal device which is free from degradation and unequalness of a contrast and has high quality by providing grooves to substrates, thereby preventing the generation of angle corner defects. CONSTITUTION:The glass substrate 1a (or 1b) is provided with the groove 4 in order to relieve the pressure at the time of liquid crystal injection. This groove 4 is provided in a non-electrode part along a sealing agent 2 near the side of a rectangle facing a liquid crystal injection port P1 and has sizes of, for example, 1mm width, 200mm length and 1 to 100mum depth in parallel with transparent electrodes. The groove 4 is formed by a printing paste etching method using glass etching or a mechanical polishing method by a dresser (polishing stone). The depth of the groove 4 is preferably set larger than the spacing formed by two sheets of the transparent substrates 1a, 1b. Further, the volume of the groove 4 is preferably set larger than 0.05 times the volume of the spacing between the substrates 1a and 1b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device using a ferroelectric liquid crystal, and more particularly to a liquid crystal device in which the injection pressure generated when the ferroelectric liquid crystal is injected is relaxed.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal injecting step in a method of manufacturing a liquid crystal device is performed by bonding two transparent substrates at a predetermined gap and injecting liquid crystal into the space (hereinafter, the bonded state will be referred to as "bonded state"). A panel is referred to, and a state in which liquid crystal is injected into the panel is referred to as a liquid crystal device).
The bonding of the two transparent substrates is performed by applying a sealant to the peripheral edge of one transparent substrate, but the sealant is not applied to the part that will be the liquid crystal injection port, and the sealant is shaped like a "U". Has been applied. Then, another transparent substrate was made to face through a spacer or the like in order to form a predetermined gap, and heat treatment for curing the sealant was performed to bond them together. After that, the gap is decompressed, the liquid crystal heated to the phase transition temperature of the cholesteric phase or the smectic phase is immersed in the liquid crystal injection port, and the liquid crystal is sucked to inject the liquid crystal. After the liquid crystal injection is completed, the liquid crystal injection port is sealed and returned to normal temperature and pressure to complete the process.

[0003]

However, according to the above method, a ferroelectric liquid crystal (liquid crystal) is formed on a large size panel.
It is known that, when liquid crystal is injected, alignment defects (corner defects) are likely to occur at the corners P2 facing the liquid crystal injection port P1 as shown in FIG. This corner defect causes an abnormal orientation or a monostable tendency and causes a display defect during driving. The site where this corner defect occurs is the site where the liquid crystal is filled at the end when the liquid crystal is injected, and since the pressure distribution as shown in FIG. 6 is generated during the injection process,
It is speculated that the shape of the inside of the panel near the inlet regulates the alignment order of the liquid crystal and causes non-uniform alignment.

Therefore, it is an object of the present invention to provide a liquid crystal device in which a pressure distribution in a gap when liquid crystal is injected into a large-sized panel is relaxed to prevent occurrence of corner defects.

[0005]

The present invention has been made in view of the above-mentioned means, and two transparent substrates are opposed to each other with a predetermined gap, and a liquid crystal injection port for injecting liquid crystal into the gap is provided. In the liquid crystal device in which the periphery of the transparent substrate is pasted together, the transparent substrate relaxes pressure distribution in the gap generated at the time of liquid crystal injection at the opposite side portion facing the liquid crystal injection port. It is characterized by having.

Further, the transparent substrate has a strip-shaped transparent electrode, and the pressure relaxation means comprises a groove formed in a row in the transparent electrode, and the depth of the groove is equal to that of the two transparent substrates. The gap is set to be larger than the gap.

Further, the volume of the groove is set to be larger than 0.05 times the volume of the gap before the formation of the groove.

[0008]

According to the above structure, the transparent substrate is provided with the pressure relaxation means for relaxing the pressure distribution in the gap generated when the liquid crystal is injected to prevent the generation of the corner defect.

[0009]

Embodiments of the present invention will be described with reference to the drawings. Figure 1
Shows a top view of the panel, FIG. 2 shows its cross-sectional view, and FIG. 3 shows the cross-sectional view of the liquid crystal device after the liquid crystal is injected.
The liquid crystal device has a size of 300 mm × 300 mm.
Glass substrates (transparent substrates) 1a, 1b having a thickness of 1 mm
And has a film thickness of 1500 on the glass substrates 1a and 1b.
Strip-shaped transparent electrodes 5a and 5b made of In ₂ O ₃ or ITO of about Å are provided. Further, on top of that, insulator films 6a and 6b for preventing short circuit and an orientation control film 7 are formed.
a and 7b are sequentially formed.

The insulator films 6a and 6b for short-circuit prevention are formed by sputtering about 1000 liters of SiO ₂ . Insulator films 6a and 6b for short circuit prevention
As TiO ₂ , T having a film thickness of 200Å to 3000Å
An inorganic insulating material such as a ₂ O ₅ may be formed into a film by a sputtering method or the like, and Si, Ti, Ta, Zr, Al
It is also possible to use an inorganic insulating film obtained by coating and baking an organometallic compound containing at least one element of the above. For the alignment control films 7a and 7b, a polyimide forming liquid (LQ18028 manufactured by Hitachi Chemical Co., Ltd.) was applied by a spinner and heat treatment was performed to form a polyimide alignment film having a film thickness of 200 Å. In addition, as an orientation control film, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride,
Organic insulating materials such as polyamide, polystyrene, cellulose resin, melamine resin, urea resin and acrylic resin may be used.

After the alignment control films 7a and 7b are formed, the surfaces of the alignment control films 7a and 7b are unidirectionally rubbed with a rubbing cloth made of nylon, so that the uniaxiality is substantially the same as the rubbing direction. The orientation axis was given. And
After the rubbing treatment, one glass substrate 1a (1b) is sprinkled with spacers 8 of silica beads having an average particle diameter of about 1.5 μm, and the other substrate 1b (1a) is coated with an epoxy resin sealant 2 by screen printing. Pasted together. On this occasion,
Strip-shaped transparent electrode 5 provided on two glass substrates 1a and 1b
a and 5b intersect so as to form a matrix, and
The pieces were laminated so as to hold a gap of 0.1 μm to 3 μm. As the spacer 8, silica beads, alumina beads, or the like may be used.

In the present embodiment, this glass substrate 1a
(Or 1b) groove 4 for the purpose of relaxing the pressure at the time of liquid crystal injection.
(Pressure relief means) is provided. The groove 4 is provided in the non-electrode portion along the sealant 2 near the rectangular side facing the liquid crystal injection port P1, and is parallel to the transparent electrode 5a (or 5b) in a width of 1 mm, a length of 200 mm, and a depth of 1 μm. 100 μm
Has the dimensions of. The groove 4 was produced by a printing paste etching method using glass etching or a mechanical grinding method using a dresser (polishing stone).

Ferroelectric liquid crystal 9 was injected into the panel thus manufactured. As the ferroelectric liquid crystal 9, a chiral smectic C phase (SmC ^* ), a chiral smectic F phase (SmF ^* ), a chiral smectic I phase (SmI ^* ) or a chiral smectic H layer (SmH).
^* ) Liquid crystal can be used. In this example, a mixed ferroelectric liquid crystal containing phenylpyrimidine as a main component was used, and this was slowly cooled to a chiral smectic phase for alignment. Here, the pyrimidine-based mixed liquid crystal has, for example, the following phase transition and phase transition temperature.

[0014]

[Outer 1] After injecting the liquid crystal, the liquid crystal device was prepared by further reorienting in the ISo state and gradually cooling.

Next, a method for evaluating the effect of the groove 4 described above will be described. [Driving Conditions and Evaluation Method] A liquid crystal device is manufactured by mounting a matrix drive circuit or the like on the liquid crystal device, and a pulse width of 2 is applied to the liquid crystal device.
A rectangular signal of 5 μs, voltage amplitude 20 V, and duty ratio 1/200 was applied. Then, the alignment defect observed in the corner portion P2 was evaluated by comparing the contrasts during white / black driving in the designated display area. As shown in FIG. 4, the measurement is performed in a region R1 (corner) and a region R2 of 30 mm × 30 mm.
(Center part) and the non-measurement area was displayed in black during the measurement. Table 1 shows the processing method of the groove 4 and the specifications of the liquid crystal device produced by changing the dimension of the groove 4, and Table 2 shows the evaluation results of the contrast and the contrast ratio defined by R1 / R2 = corner / center. Show. Here, L is the processing width of the groove 4,
D is the depth of the groove 4, A is the length of one of the two sides of the panel 4 which are perpendicular to the side having the inlet, and d is the distance between the upper and lower substrates.

[0016]

[Table 1]

[0017]

[Table 2] From the above results, the groove 4 provided in the glass substrate 1a (1b)
With this, the occurrence of corner defects can be suppressed and the deterioration of contrast can be suppressed. In particular, when the volume of the groove 4 is about 0.05 times or more the volume of the injected liquid crystal, the occurrence of corner defects is prevented. It will be possible.

[0018]

As described above, according to the present invention, by providing a groove in a glass substrate, it is possible to prevent the occurrence of corner defects, thereby reducing the contrast and reducing the cost of a high quality liquid crystal device without unevenness. Could be manufactured.

[Brief description of drawings]

FIG. 1 is a top view of a panel before liquid crystal injection applied to an explanation of an embodiment of the present invention.

FIG. 2 is a sectional view of a panel before liquid crystal injection, which is applied to the description of the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a panel after liquid crystal injection, which is applied to the description of the embodiment of the present invention.

FIG. 4 is a diagram showing an evaluation area of a liquid crystal device applied to the description of an embodiment of the present invention.

FIG. 5 is a top view of a liquid crystal device for explaining the problems of the conventional technique.

FIG. 6 is a diagram showing a pressure distribution at the time of injecting liquid crystal for explaining the problems of the conventional technique.

[Explanation of symbols]

 1a, 1b Glass substrate (transparent substrate) 4 Groove (pressure relaxation means) 5a, 5b Transparent electrode 9 Ferroelectric liquid crystal (liquid crystal) P1 Liquid crystal inlet

Claims (3)

[Claims] 1. Two transparent substrates are opposed to each other with a predetermined gap,
In a liquid crystal device in which a liquid crystal injection port for injecting liquid crystal into the gap is provided and the periphery of the transparent substrate is attached, the transparent substrate is generated at the time of liquid crystal injection at a side opposite to the liquid crystal injection port. A liquid crystal device, comprising a pressure relaxation means for relaxing the pressure distribution in the gap. 2. The transparent substrate has a strip-shaped transparent electrode,
2. The liquid crystal device according to claim 1, wherein the pressure relaxation means comprises a groove formed in a row in the transparent electrode, and the depth of the groove is set to be larger than the gap formed by the two transparent substrates. . 3. The liquid crystal device according to claim 2, wherein the volume of the groove is set to be larger than 0.05 times the volume of the gap before the formation of the groove.