JPH06337405A - Liquid crystal electro-optical device and manufacture thereof - Google Patents

Abstract

PURPOSE:To uniformize display, and improve a contrast ratio by arranging a hydrophobic an/or gydrophilic part selectively on a surface of a substrate, and controlling a position to deposit uncured resin from mixture of a liquid crystal and unhardened resin. CONSTITUTION:Mixture of a biphenyl type ferroelectric liquid crystal material 118 and unhardened high polymer resin is injected into a cell constituted in such a way that a picture element electrode 113 and an active matrix 114 formed by using crystalline silicon TFT are formed on non-alkaline glass 111 and an ITO film 116 and an oriented film 117 are formed on the other substrate 112 and both substrates 111 and 112 are adhered and fixed to each other thorugh a spacer 119. In a process to form a resin spacer (polymerization column spacer, PCS) 120 cured into a column shape by depositing unhardened resin from this mexture, in the first place, a liquid crystal material is deposited and oriented in a part whose surface is not pressed and which holds a hydrophilic property, and next, resin is deposited in a part becoming a hydrophobic property by being pressed. Thereby, in an optional case, the PCS 120 can be deposited, and display can be uniformized.

Description

Detailed Description of the Invention

The present invention relates to a method of manufacturing a liquid crystal electro-optical device having a column-shaped resin formed by depositing and curing an uncured resin from a mixture of a liquid crystal material and an uncured resin.

[0002]

2. Description of the Related Art Recently, large-area liquid crystal displays have been receiving attention. However, when the area is increased, the substrate itself bends. For example, when a ferroelectric liquid crystal is used as the liquid crystal material, the ferroelectric liquid crystal has a layered structure, and thus the substrate is deformed to cause the layered structure to change. There was a problem that it could not be made large because it collapsed and display was hindered. This problem is not limited to ferroelectric liquid crystals,
This is basically true even when other liquid crystal materials are used.

Further, in the past, a spacer of silicon oxide held between the substrates was used in order to keep the distance between the substrates,
Further, in order to eliminate the flexure and bulge of the substrates, an organic resin internal adhesive material held between the substrates is also used. The spacer is, as the name implies, for holding the distance between the substrates, and the diameter of the spacer determines the distance between the substrates. Further, the organic resin used to bring the substrates into close contact with each other has a diameter larger than the required substrate spacing,
By crushing between the substrates, the upper and lower substrates are brought into close contact with each other.

In the conventional structure as described above, the substrates are first subjected to orientation treatment, then the spacers and the internal adhesive material are sprinkled on one of the substrates, and then the substrates are adhered to each other. The basic manufacturing method is to determine the distance, to bond the substrates to each other, and then to inject the liquid crystal between the substrates.

However, as a result of studying the above-mentioned conventional manufacturing process, when the liquid crystal changes its orientation and its state according to the alignment regulating force, the resin material for bringing the substrates into close contact with each other acts as the orientation liquid crystal. It turned out that it regulates.

[0006] The above two problems are as follows: -It is necessary to have a structure for keeping the substrate distance constant. -When aligning the liquid crystal, the material that brings the substrates into close contact with each other adversely affects the alignment of the liquid crystal. As a method for solving such a problem, there is an invention disclosed by the present inventors in Japanese Patent Application No. 5-55237.

The present invention provides a mixture of a liquid crystal material and an uncured resin between a pair of substrates, and an aligning means for aligning the liquid crystal material in a certain direction on the inner surface of at least one of the pair of substrates. The liquid crystal electro-optical device is characterized in that it has a column-shaped resin formed by depositing and curing an uncured resin mixed in the liquid crystal material.

According to the method of manufacturing the liquid crystal electro-optical device, a liquid crystal material is provided between a pair of opposed substrates which have been subjected to an alignment treatment.
By mixing and encapsulating with a resin material to which a reaction initiator has been added, orienting the liquid crystal, the resin component precipitated by UV irradiation etc. is cured, and this resin component is cured and formed into a column shape. To do.

The columnar resin deposited from the liquid crystal material as described above is a columnar resin spacer and is referred to as a polymerized column spacer (Polymerized Column Spacer, P).
Abbreviated as CS).

The outline of the above configuration will be described with reference to FIG.
FIG. 1 shows an active matrix type liquid crystal display device. In FIG. 1, 101 and 102 are translucent substrates 103 and 106, pixel electrodes, 104 is a switching element, 106 is an alignment means for arranging the liquid crystal material in a certain direction, and 109 is a liquid crystal material. Liquid crystal material 1
09 is uniaxially oriented according to the orientation means 107. On the other hand, the resin 110 separated and precipitated from the liquid crystal material has a columnar shape (columnar shape) and is adhered to the alignment means 107 on the two substrates 101 and 102. When the aligning means is formed only on one of the substrates, the resin 110 is adhered to the aligning means 107 and the translucent substrate 102 or the substrate and the electrode 103, for example.

In order to manufacture this liquid crystal electro-optical device, the electrodes 10 whose substrate spacing is determined by the spacer 108 are used.
A mixture of a liquid crystal material and an uncured resin to which a reaction initiator is added is sandwiched between a pair of translucent substrates 101 and 102 each having No. 3 and 106, and the uncured from the mixture is sandwiched between the translucent substrates. By depositing a resin, the liquid crystal material is aligned along the alignment means. Then, by applying a means for curing the deposited uncured resin, the uncured resin is cured to form a column (indicated by 110) to bond the both substrates.

When the configuration shown in FIG. 1 is adopted, the resin is cured after the liquid crystal material 109 is aligned according to the alignment means 107, so that a good alignment state before curing can be maintained, and the resin after curing is aligned. It has very little effect.
The column-shaped cured resin 110 has the effects of maintaining the substrate spacing and improving the adhesiveness, and the effects of improving the orientation of the liquid crystal.

[0013]

[Problems of the Prior Art] Although the above construction is excellent,
The position where the column-shaped resin is deposited cannot be controlled at all, and if the deposition positions of the liquid crystal material and the resin are biased, the uniformity of the display state is lost. Further, in a liquid crystal electro-optical device having a switching element such as a thin film transistor, uneven deposition of resin on the pixel electrode causes a reduction in aperture ratio.

Further, when a ferroelectric liquid crystal is used as the liquid crystal material, the layer structure may be collapsed due to the bias of the resin deposition location, and an alignment defect may occur, which leads to a decrease in the contrast ratio.

[0015]

SUMMARY OF THE INVENTION The present invention provides a liquid crystal electro-optical device having a column-shaped resin formed by precipitating and curing an uncured resin from a mixture of a liquid crystal material and an uncured resin. The purpose is to arbitrarily control the deposition position of the cured resin.

[0016]

In order to solve the above-mentioned problems, according to the present invention, a mixture of a liquid crystal material and an uncured resin is sandwiched between a pair of substrates, and the uncured resin is columnized from the mixture. In the case of precipitating into a shape and then curing, selectively providing a hydrophobic portion and / or a hydrophilic portion on the surface of the surface of at least one of the pair of substrates which is in contact with the liquid crystal mixture. Is used to control the deposition position of the uncured resin.

[0017]

[Function] The present inventors have developed a polymer column spacer (PCS).
When manufacturing, the position where the uncured resin is deposited in a column shape from the mixture of the liquid crystal material and the uncured resin (hereinafter referred to as the liquid crystal mixture) is a hydrophobic portion of the substrate surface in contact with the liquid crystal mixture. I have found In other words, by intentionally forming a hydrophobic portion on the surface of the substrate that is in contact with the liquid crystal mixture, the resin can be deposited at that portion to form a column-shaped resin spacer. That is, the position where the resin is deposited can be controlled arbitrarily.

As a method of making a part of the surface of the substrate hydrophobic, for example, when a screen-printing plate used for printing a sealing material that surrounds the substrate is brought into contact with the substrate, warp yarns of the plate and A portion A where the weft thread contacts and a portion B other than that occur, and as a result, two portions A and B having different surface states are generated.

At this time, on the surface of the substrate, the polarity of the surface tension changes between the portion A where the surface is pressed by the plate and the other portion. Especially, the pressed portion tends to be hydrophobic.

A mixture of a liquid crystal material and an uncured resin is injected into a liquid crystal cell having two portions having different surface states of the substrate as described above at a temperature exhibiting an isotropic phase and slowly cooled to room temperature. First, when the mixture transitions from the isotropic phase to the liquid crystal phase, the liquid crystal material is deposited in the above-mentioned part B, and when it is further cooled, the uncured resin is deposited in the above-mentioned part A.

In addition, coating with a coupling agent or the like,
The deposition position of the column-shaped resin can be specified by forming a film of carbon, fluorine, etc., or by irradiating a laser, etc., and optionally providing a hydrophilic or hydrophobic part on the surface of the substrate in contact with the liquid crystal mixture. it can.

As described above, according to the present invention, it becomes possible to arbitrarily control the position where the column-shaped resin is formed, which could not be conventionally controlled. Examples will be shown below.

[0023]

【Example】

FIG. 2 shows the structure of the liquid crystal cell. One substrate 111 of the liquid crystal cell is alkali-free glass, and an active matrix 114 using pixel electrodes 113 and crystalline silicon TFTs was formed on the substrate. The size of the pixel electrode was 100 μm □. The size of the matrix divided by the scanning electrodes and the signal electrodes connected to the TFT was 108 μm □. Note that the insulating film 115 was formed over the substrate. ITO on the entire surface of the other substrate 112
The film 116 was formed. An alignment film 117 was formed on the substrate on which only the electrodes were formed. The distance between the substrates was 1.5 μm.

The alignment film material is a polyimide resin such as LQ-5200 (manufactured by Hitachi Chemical Co., Ltd.), LP-64 (manufactured by Toray), RN-305 (manufactured by Nissan Kagaku), and LP-64 is used here. . The orientation film was diluted with a solvent such as n-methyl-2-pyrrolidone and applied by spin coating. The coated substrate is 250 to 300 ° C., here 28
The coating was imidized and cured by heating at 0 ° C. for 2.5 hours to dry the solvent. The film thickness after curing was 300Å.

Next, the alignment film is rubbed. For rubbing, use a roller wrapped with a cloth such as rayon or cotton for 450-90.
Rubbing was performed in one direction at a rotation speed of 0 rpm, here 450 rpm.

Next, as spacers 119 for keeping the cell intervals constant, a sphere having a diameter of 1.5 μm (manufactured by Catalysis Kasei) was sprayed on the substrate on the side where the alignment film was applied.
On the other substrate, in order to fix the two substrates, a two-component epoxy adhesive is applied as a sealant by screen printing around the substrates, and then the two substrates are bonded. Fixed At this time, the alignment was performed so that the warp yarns and the weft yarns of the screen plate were overlapped with the scanning electrodes and the signal electrodes, respectively. In the present embodiment, the mesh of the screen plate (the number of spaces surrounded by vertical and horizontal threads per 25.4 mm) is 230, and therefore the distance between the threads is one side of a rectangular space separated by the scanning electrodes and the signal electrodes. The length is 108 μm, which is the same length, and the wire diameter of the thread forming the screen is 35 μm.

A mixture of the liquid crystal material 118 and the uncured polymer resin is injected into the cell. Biphenyl-based ferroelectric liquid crystal was used as the liquid crystal material. This liquid crystal has a phase sequence of Iso-SmA-SmC * -Cry. Structural formula _{C 8 H 17 O-C 6} H 4 -C 6 H 4 -COO-C * HCH
_{3 C 2 H 5 C 10 H} 21 O-C 6 H 4 -C 6 H 4 -COO-C * HCH
₃ C ₂ H ₅ , which is a 1: 1 mixture of the above two materials. A commercially available ultraviolet curable resin was used as the polymer resin. The weight ratio of liquid crystal material and uncured polymer resin is 8
Mix at a ratio of 5:15. The mixture was stirred at a temperature at which it became an Iso (isotropic) phase so that it was uniformly mixed. In the mixture, the transition point from the Iso phase to the SmA phase was lowered by 5 to 20 ° C. as compared with the case where only the liquid crystal material was used.

The injection of the above mixture was carried out under vacuum at 100 ° C. for the liquid crystal cell and the mixture. 2 liquid crystal cells after injection
It was gradually cooled at a rate of -20 ° C / hr, here 3 ° C / hr.

When the alignment state of this liquid crystal cell was observed under a crossed Nicols with a polarization microscope, the extinction position at a certain rotation angle, that is, the light incident on one of the polarizing plates did not pass through the other polarizing plate, and it was as if it was light. A state in which the power was cut off was obtained. This indicates that the liquid crystal material has a uniform orientation (the liquid crystal molecules are oriented in one direction between the substrates).

The uncured resin is used between pixels, that is, T
It was found that the resin was deposited only on the FT and the electrode wiring portion, and almost no resin was deposited on the pixel electrode portion. Since the uncured resin does not exhibit birefringence, it did not transmit light under a polarizing microscope and appeared black. In this state, the liquid crystal material and the uncured resin can be separated.

As described above, the liquid crystal material is likely to be deposited in the non-pressed portion, and it is expected that the surface polarity is different between the pressed portion and the other portion. For this reason, a change in surface polarity due to pressing was simulated. In the experiment, the surface of the alignment film was pressed by a cylindrical rod, and the surface tension after that was measured. The alignment film was the same as that described above, and a coating film was formed on a glass substrate under the same alignment film forming conditions and rubbing conditions. Then, the alignment film was pressed with a cylindrical rod having a diameter of 1 cm. Table 1 shows the pressure and the polar term component of the surface tension of the pressed portion, and the polar term component of the surface tension of the unpressed portion.

[0033]

[Table 1]

As shown in Table 1, the pressed portion has a smaller value of the polar term component than the other portions. This indicates that the pressed portion is hydrophobic. Also, with a certain pressure, especially 6 kgf in this experiment
When it was above / cm ² , there was a tendency that there was no change in the magnitude of the surface tension.

In the formation process of PCS, the liquid crystal material in the liquid crystal mixture is first aligned as described above, and the resin material is deposited as the slow cooling progresses. Therefore, in the process of depositing the resin on the pressed part, the liquid crystal material is first deposited and aligned on the unpressed hydrophilic part of the surface, and then the resin is deposited on the pressed part that becomes hydrophobic. It is explained to do.

At this time, almost no alignment defects such as zigzag defects were observed in the liquid crystal material.

Next, ultraviolet rays were irradiated to cure the polymer resin of the cell. Irradiation intensity is 3 to 30 mW / c
m ² , here 10 mW / cm ² , and the irradiation time is 0.1.
5 to 5 minutes, here 1 minute.

After irradiation with ultraviolet rays, the alignment state of the liquid crystal cell was observed under a polarizing microscope in the same manner as described above, but the alignment state was hardly changed. No effect of UV irradiation on the alignment was observed.

The optical characteristics of the above liquid crystal cell were measured. The measuring method is to detect the transmitted light intensity of the liquid crystal cell with a photomultiplier under a crossed Nicols by a polarization microscope using a halogen lamp as a light source. The results are shown in Table 2. According to the results shown in Table 2, the cured polymer resin (hereinafter referred to as PCS: Polymerized Column spacer) 120 is almost absent in the electrode portion, so that the aperture ratio is high and the contrast ratio is high.

[0040]

[Table 2]

Further, the area around each pixel was displayed in black like a black matrix.

The display state of the produced cell did not change even when the cell was made vertical. This is because the PCS scattered in the liquid crystal material internally adheres the two substrates to each other to keep the distance between the substrates constant and prevent the cells from expanding like a gourd.

Next, the cross section of the liquid crystal cell was observed with a scanning electron microscope. The liquid crystal material was extracted with alcohol. According to the observation result, the PCS was formed between the two substrates in a wall shape except on the pixel electrode.

The wall of the PCS was almost immediately above the signal lines and scanning lines connecting the switching elements and the pixels, and surrounded the pixels.

In this embodiment, the case where the ferroelectric liquid crystal is used is described, but the constitution of the present invention is not limited to the ferroelectric liquid crystal, and other liquid crystal materials such as nematic liquid crystal are used. It is also effective in cases. Further, it is effective not only in the active matrix type but also in the simple matrix type.

[0046]

EFFECTS OF THE INVENTION According to the present invention, a resin spacer (polymerization column spacer = PC) is prepared by precipitating an uncured resin from a mixture of a liquid crystal material and an uncured resin in a cell and curing it in a column shape.
In the liquid crystal electro-optical device having S), it becomes possible to deposit PCS at any place, and the liquid crystal material and P
The positional relationship of CS is uniform over the entire liquid crystal display device, and the display state is uniform.

Further, the occurrence of alignment defects such as zigzag defects can be prevented and the contrast ratio is improved.

Further, in particular, it becomes possible to deposit the resin only on the portions other than the pixel electrodes. Particularly in the active matrix type liquid crystal electro-optical device in which a switching element such as a thin film transistor is connected to each pixel, the switching element other than the pixel electrode is used. PCS on scan electrodes, signal electrodes only
By forming the film, it was possible to improve the aperture ratio and the contrast ratio of the device.

When the PCS is formed on the switching element, since the PCS is optically isotropic,
In the liquid crystal electro-optical device, due to the polarizing plate, the PCS portion does not transmit light and is in a black state. As a result, in order to suppress the fluctuation of the conductivity due to the light to the switching element, it plays the same role as the light-shielding film usually formed on the substrate on the counter electrode side, and the formation of the light-shielding film is unnecessary.

In addition, a wall-shaped continuous P is formed on a portion other than the pixel.
Since CS can be formed, the periphery of the pixel electrode can be displayed in black as in the above-described light-shielding film function. Therefore, it also has a function like a black matrix which is particularly required in a color liquid crystal electro-optical device. The same effect can be obtained when a resin is formed between electrodes in a simple matrix type device.

[Brief description of drawings]

FIG. 1 shows a schematic view of a liquid crystal electro-optical device containing a polymerized column spacer.

FIG. 2 is a schematic view of a liquid crystal electro-optical device according to an example.

[Explanation of symbols]

 101, 111 ... Substrate 102, 112 ... Substrate 103, 113 ... Electrode 104, 114 ... Thin film transistor 105, 115 ... Insulating film 106, 116 ... Electrode 107, 117 ... Alignment Membrane 108, 118 ... Spacer 109, 119 ... Liquid crystal material 110, 120 ... Polymerization column spacer

Claims (4)

[Claims] 1. When a mixture of a liquid crystal material and an uncured resin is sandwiched between a pair of substrates, and the uncured resin is deposited in a column shape from the mixture and then cured, the mixture of the pair of substrates The deposition position of the uncured resin is controlled by selectively providing a hydrophobic portion and / or a hydrophilic portion on the surface of the surface of at least one of the substrates which is in contact with the liquid crystal mixture. A method for manufacturing a liquid crystal electro-optical device. 2. When a mixture of a liquid crystal material and an uncured resin is sandwiched between a pair of substrates, and the uncured resin is deposited in a column shape from the mixture and then cured, the mixture of the pair of substrates A liquid crystal electro-optical device characterized in that the deposition position of the uncured resin is controlled by pressing the surface of at least one of the substrates in contact with the liquid crystal mixture with a substance having a linear or lattice shape. Device manufacturing method. 3. A liquid crystal material between a pair of substrates, and an alignment means for uniaxially aligning the liquid crystal material on at least one inner surface of the pair of substrates, wherein the liquid crystal material is interposed between the substrates. A liquid crystal electro-optical device characterized in that it has a wall-shaped resin formed by depositing and curing an uncured resin mixed in. 4. The liquid crystal electro-optical device according to claim 3, wherein the wall-shaped resin is present around each pixel.