JP7058534B2 - LCD panel - Google Patents

Description

The present invention relates to a liquid crystal panel.

A liquid crystal panel (ferroelectric liquid crystal panel) using a ferroelectric liquid crystal such as a chiral smetic liquid crystal having a ferroelectricity has a fast response speed to a change in electric field and has a bi-stability characteristic. It is expected to be used in various fields.

Ferroelectric liquid crystal panels have a phase (phase) called a smectic phase in the operating temperature range, which is different from the liquid crystal materials conventionally used in large-sized televisions and the like, and in that phase (smetic phase), Since the viscosity is higher than that of the conventional liquid crystal and the structure is close to that of a crystal, the order of the center of gravity of the liquid crystal molecule is high, and a special structure called a layer structure (layer structure 22) as shown in FIG. 2 is formed. Will be done. Note that FIG. 2 is a schematic cross-sectional view of a liquid crystal panel showing a layer structure of a ferroelectric liquid crystal.

In order to orient the ferroelectric liquid crystal display, an organic material called an alignment film is thinly applied to the inner surface of two opposing substrates, and a cloth such as cotton or rayon is wrapped around this surface. Using a method called rubbing, which is rubbed in one direction (rubbing direction 23) with a roll, an order is imparted to the surface thereof so that the liquid crystal molecules (liquid crystal molecules 21) can be easily oriented.

Further, in order to uniformly orient the smectic phase having such a layer structure, a method called a temperature gradient method has been conventionally used, and it exists on the higher temperature side than the smectic phase after liquid crystal injection. A method is known to achieve defect-free orientation by cooling very slowly from the anisotropy to the smectic phase on the low temperature side.

For that purpose, it is necessary to uniformly cool the entire liquid crystal panel, and if this cooling state becomes non-uniform, orientation defects called zigzag defects that appear because the inclination of the layers is not uniform often occur.

On the other hand, in a liquid crystal panel, usually two opposed substrates are bonded together with an adhesive, a constant gap is maintained between the two substrates, and liquid crystal is injected between the two substrates. Therefore, a part of the adhesive has a hole called an injection port for injecting the liquid crystal between the two bonded substrates. After injecting the liquid crystal from this hole, in order to prevent the liquid crystal from leaking from the hole again, the hole is closed with a material different from the material used for bonding the two substrates to seal the hole.

As shown in FIG. 1, the adhesive is generally provided inside the outer periphery of the two substrates so that the adhesive does not leak to the outside of the substrate after bonding, while the liquid crystal display is injected. An opening portion (hole) for the purpose is provided at the end of the outer peripheral portion of the substrate.

Further, in the structure of the liquid crystal panel as described above, the injection port has a uniform structure because different materials are used because there is a problem in the process of making the panel with the adhesive for bonding the two substrates. Therefore, it is difficult to cool the liquid crystal panel with a uniform temperature gradient from high temperature to low temperature. Therefore, it is well known that a non-uniform temperature gradient is generated during cooling and an orientation defect is generated from the vicinity of the injection port.

As a technique for preventing such orientation defects, for example, in Patent Document 1, in order to alleviate the strain generated due to the non-uniformity of cooling, rather, in order to positively generate orientation defects in the injection port of the liquid crystal panel. The part of is provided.

Japanese Patent Laid-Open No. 2004-309871

However, in the configuration shown in Patent Document 1 above, as a result of various experiments by the inventor of the present invention, it is extremely difficult to generate such an orientation defect only outside the effective pixel region, which is effective. Orientation defects generated outside the pixel region often grow and invade into the effective pixel region.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal panel capable of suppressing the expansion of orientation defects generated in a liquid crystal injection port to an effective pixel region. ..

Two substrates facing each other, an alignment film provided on the opposite surfaces of the two substrates, an adhesive for adhering the two substrates, and a liquid crystal injection port provided in the adhesive. A liquid crystal panel comprising, and a liquid crystal display injected into a region surrounded by the adhesive, such that the liquid crystal injection port projects toward the outer peripheral portion of the two substrates. The first extending portion is formed by a first extending portion and a second extending portion of the adhesive, and the first extending portion has a first end portion located on the opening end side of the liquid crystal injection port, and the second extending portion. The extending portion is located on the side opposite to the second end portion in the extending direction of the second extending portion and the second end portion located on the opening end side of the liquid crystal injection port, and the second extending portion. The alignment film has a bending point that bends in a direction intersecting with the direction in which the existing portion extends, and the alignment film has an orientation order that orients the strong dielectric liquid crystal display along a predetermined orientation regulation direction. The length of the straight line connecting the first end portion and the intersection point to the intersection where the straight line extending from the first end portion along the orientation restriction direction intersects the straight line passing through the bending point and the second end portion. Let L be, the length of the straight line connecting the bending point and the second end portion be X, and the angle formed by the direction orthogonal to the extending direction of the first extending portion and the orientation restricting direction. When set to θ,

L ・ Sin θ ≤ X

It is a liquid crystal panel that holds the relationship of.

The direction to which the alignment order is given may be the liquid crystal panel which is the rubbing direction of the alignment film.

According to the present invention, it is possible to prevent the alignment defect generated in the liquid crystal injection port from expanding to the effective pixel region.

It is a schematic plan drawing of the liquid crystal panel which concerns on 1st Embodiment of this invention. It is a schematic cross-sectional view of the liquid crystal panel which shows the layer structure of a ferroelectric liquid crystal. It is a schematic plan view of the liquid crystal panel which shows the layer normal and the rubbing direction of a ferroelectric liquid crystal. It is a conceptual diagram for demonstrating the growth of the orientation defect which occurs in the inlet. It is a schematic plan view for demonstrating the growth of the orientation defect which occurs in the inlet. It is a schematic plan view for demonstrating the growth of the orientation defect which occurs in the inlet. It is a schematic cross-sectional view of the liquid crystal panel which concerns on 1st Embodiment of this invention.

[Explanation of the first embodiment: FIG. 1, FIG. 4-1 to FIG. 4-3, FIG. 5]
The liquid crystal panel according to the first embodiment of the present invention will be described with reference to FIGS. 1, 4-1 to 4-3, and FIG. 1 is a schematic plan view of the liquid crystal panel according to the first embodiment of the present invention, and FIGS. 4-1 to 4-3 are schematics for explaining the growth of orientation defects generated in the injection port. FIG. 5 is a schematic plan view of the liquid crystal panel according to the first embodiment of the present invention.

As shown in FIG. 5, the liquid crystal panel 17 according to the present embodiment has a silica material having a particle size called a spacer 54, which acts as a column, in order to provide a certain distance between the glass substrate 51 and the silicon substrate 52. It has a structure in which the mixed ultraviolet curable adhesive 53 is applied to the silicon substrate 52 by printing, and then the glass substrate 51 is bonded and irradiated with ultraviolet rays for a certain period of time to cure the adhesive 53. The adhesive material 53 is applied to the inside of the outer peripheral portion of the glass substrate 51 and the silicon substrate 52 in order to prevent the 53 from leaking to the outer peripheral portion of the substrate when the glass substrate 51 and the silicon substrate 52 are bonded to each other. ..

A transparent electrode 56 for applying a voltage to the liquid crystal 55 is provided on the inside of the glass substrate 51 (the surface facing the silicon substrate 52), and also on the inside of the silicon substrate (the surface facing the glass substrate 51). A plurality of pixel electrodes 57 made of aluminum or the like for applying a voltage to the liquid crystal 55 are provided, and a voltage based on the display data can be applied to the pixel electrodes 57 at any timing, and the applied voltage can be applied. The size and timing can be controlled by a semiconductor electric circuit provided inside the silicon substrate 52. Although not shown in FIG. 5, a part of the alignment film 59 and other insulating films are interposed in the gaps between the plurality of pixel electrodes 57.

Further, an organic material made of polyimide is applied to the surfaces of the transparent electrode 56 and the pixel electrode 57 using a spinner to a thickness of about 100 A in order to facilitate the orientation of liquid crystal molecules, and then fired at a temperature of about 250 ° C. Then, the alignment film 59 is further formed on each surface by subjecting the surface to a treatment called a rubbing treatment in which the surface is rubbed with a roll wrapped with a cloth. The alignment film 59 is provided with anisotropy for orienting the liquid crystal molecules along a predetermined orientation restricting direction by a rubbing treatment.

After the substrates on which the alignment film 59 is formed are bonded together, a ferroelectric liquid crystal that is in an isotropic state at a high temperature of about 100 ° C. is injected from the injection port 14 and the temperature is increased. When the temperature drops to room temperature, the injection port 14 is closed with a sealing material 58 made of a UV curable adhesive or the like so that the liquid crystal does not leak from the injection port 14.

The injection port 14 is formed so as to project toward the outer peripheral portion of the two substrates in order to efficiently inject the liquid crystal between the two substrates. As shown in FIGS. 4-2 and 4-3, the injection port 14 is formed as a space between the first extending portion 16a and the second extending portion 16b of the extending portions of the adhesive 16 facing each other. ing. The first extending portion 16a of the adhesive 16 is provided with a first end portion 11 in contact with the outer periphery of the two substrates, and the second extending portion 16b of the adhesive 16 is provided with the outer periphery of the two substrates. A second end 13 in contact is provided. Further, in the second extending portion 16b of the adhesive 16, the second extending portion 16b is located on the side opposite to the second end portion 13 in the extending direction thereof, and the second extending portion 16b is the other extending portion of the adhesive 16. A bending point 12 connected so as to intersect (for example, orthogonally) with the bending point 12 is provided.

Further, the intersection of a straight line extending from the first end portion 11 of the first extending portion 16a along the rubbing direction 18 intersects with a straight line passing through the second end portion 13 of the second extending portion 16b and the bending point 12. The length of the straight line connecting the intersection 19 and the first end portion 11 of the first extending portion 16a is L, and the straight line connecting the second end portion 13 of the second extending portion 16b and the bending point 12 is set to 19. When the length of is X and the angle formed by the direction orthogonal to the extending direction of the first extending portion 16a and the rubbing direction 18 is θ.

L ・ Sin θ ≤ X

Meet the relationship. In the present embodiment, the direction orthogonal to the extending direction of the first extending portion 16a is parallel to the extending direction of one side of the outer periphery of the two substrates that is in contact with the injection port 14.

For example, if θ is 30 °, L is 600um, and X is 320um, L × Sin 30 ° = 300um <320um = X, and the relationship of L and Sin θ ≦ X is satisfied. In addition, "um" is "micrometer".

[Explanation of effect: Fig. 4-1 to Fig. 4-3]
Since the ferroelectric liquid crystal has a high viscosity, when the liquid crystal is injected between two opposing substrates in the case of the above-mentioned panel structure, it is in a higher temperature state and a phase (nematic) having a temperature higher than that of the smectic phase. Infused in phase or isotropic phase). After that, the smectic phase develops when the temperature is still cooled near the room temperature used as a module. However, since the smectic phase has a high order and has a structure close to a crystal structure called a layer structure as shown in FIG. 2, an orientation defect occurs when this cooling state is not uniform. In particular, the injection port is closed with a sealing material made of a material different from the adhesive used to bond the two substrates in order to prevent the liquid crystal material from leaking after the temperature of the liquid crystal panel has dropped. However, until it is closed, there is no sealing material in this part and it is exposed to the outside, and after sealing, the material used for the sealing material is different from the adhesive material that adheres the two substrates. When the temperature drops from the high temperature when the liquid crystal is injected to near room temperature, or when the temperature drops from the high temperature when the liquid crystal is reheated to around room temperature after sealing, the cooling state of this injection port is different. It will be different from the cooling state of this part, and orientation defects are likely to occur in this injection port part.

As shown in FIG. 3, it is known that in a ferroelectric liquid crystal display, the rubbing direction 23 and the direction of the layer normal 31 of the layer structure 22 coincide with each other. On the other hand, when an orientation defect occurs in a certain portion, the orientation defect that occurs first becomes a nucleus, and as shown in FIG. 3, the defect grows in the direction of the layer normal 31 of the layer structure 22 of the ferroelectric liquid crystal display. Things are known. From this, if there is a structure in which the growth of the alignment defect is hindered in the direction in which the alignment defect grows (rubbing direction 23), the expansion of the alignment defect can be suppressed.

The effects of this embodiment will be described below with reference to FIGS. 4-1 to 4-3. The orientation defect generated at the end 11 of the injection port 14 grows along the rubbing direction, but as shown in FIG. The defect penetrates into the effective pixel region, but as shown in FIG. 4-2, at L · Sinθ = X, the bending point 12 of the adhesive 16 is located in the growth direction of the alignment defect, so that the growth of the alignment defect is hindered. Further, as shown in FIG. 4-3, when L · Sinθ <X, the growth of the alignment defect is surely hindered because the second extending portion 16b of the adhesive 16 is present in the growth direction of the alignment defect. In the present embodiment, since the state shown in FIG. 4-2 or FIG. 4-3 is realized, the orientation defect generated in the injection port 14 does not enter the effective pixel region.

In the above embodiment, between the first extending portion 16a of the adhesive 16 and the other extending portion, a bending point such as a bending point 12 provided in the second extending portion 16b of the adhesive 16 May be provided.

The alignment film 59 may be an inorganic alignment film formed by orthorhombic vapor deposition of silicon oxide.

The liquid crystal 55 may be a nematic liquid crystal or the like. However, the present invention is particularly suitable for a liquid crystal panel using a ferroelectric liquid crystal display.

11 First end 12 Bending point 13 Second end 14 Injection port 15, 58 Sealing material 16, 53 Adhesive 16a First extension 16b Second extension 17 Liquid crystal panel 18, 23 Rubbing direction 19 Intersection 21 Liquid crystal Molecules 22 Layer structure 31 Layer normal 41 Orientation defect 51 Glass substrate 52 Silicon substrate 54 Spacer 55 Liquid crystal 56 Transparent electrode 57 Pixel electrode 59 Alignment film

Claims (2)

Two substrates facing each other, an alignment film provided on the opposite surfaces of the two substrates, an adhesive for adhering the two substrates, and a liquid crystal injection port provided in the adhesive. A liquid crystal panel comprising, and a ferroelectric liquid crystal injected into the region surrounded by the adhesive.
The liquid crystal injection port is formed by a first extending portion and a second extending portion of the adhesive so as to project toward the outer peripheral portions of the two substrates .
The first extending portion has a first end portion located on the opening end side of the liquid crystal injection port.
The second extending portion is located on the side opposite to the second end portion in the extending direction of the second extending portion and the second end portion located on the opening end side of the liquid crystal injection port. The second extending portion has a bending point that bends in a direction intersecting with the extending direction, and has a bending point.
The alignment film has an orientation order that orients the ferroelectric liquid crystal along a predetermined orientation regulation direction.
The length of the straight line connecting the first end portion and the intersection point to the intersection where the straight line extending from the first end portion along the orientation restriction direction intersects the straight line passing through the bending point and the second end portion. Let L be, the length of the straight line connecting the bending point and the second end portion be X, and the angle formed by the direction orthogonal to the extending direction of the first extending portion and the orientation restricting direction. When set to θ,

L ・ Sin θ ≤ X

A liquid crystal panel characterized by the fact that the relationship is established. The liquid crystal panel according to claim 1, wherein the orientation control direction is the rubbing direction of the alignment film.

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