JPH04340927A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To smoothly inject liquid crystal, to eliminate an air pocket, and to obtain a uniform cell gap and superior shock resistance by providing joining parts so that they are distributed at random when viewed from the plane side of a substrate. CONSTITUTION:The liquid crystal display element 1 is constituted by providing a black mask 3, a color filter 4, a transparent electrode 5, and an orientation film 6 on a transparent substrate 2 in this order, providing a transparent electrode 8 and an orientation film 9 on a transparent substrate 7 in this order, and charging the liquid crystal 10 in the gap between the orientation films 6 and 9. The orientation films 6 and 9 are connected at the spot-shaped joining parts 11. Transparent electrode 5 and 8 are beltlike and cross each other at right angles. Color filters 4 are provided in the order of 4R, 4G, 4B, 4R, 4G, 4B.... Then the orientation films are connected together at the spot-shaped joining parts 11 with a cementing agent and the joining parts 11 are distributed at random when viewed from the plane side of the substrate 20.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having uniform cell gaps and excellent shock resistance.

0002

[Prior Art] Liquid crystal display elements conventionally used in watches, televisions, computer displays, etc. basically have the following characteristics:
Two transparent substrates each having at least a transparent electrode and an alignment film on one side are arranged such that the alignment films face each other,
It has a structure in which liquid crystal is sealed in the gaps between alignment films. Various types of liquid crystals have been used as this liquid crystal, but recently, ferroelectric liquid crystals with high-speed response are expected.

[0003] In order to exhibit high-speed response, the cell gap of a liquid crystal display element must be as thin as 1 to 4 μm. Furthermore, since ferroelectric liquid crystal has properties closer to crystals than conventional nematic liquid crystal, even if you lightly touch the center of the liquid crystal display element, the alignment of the liquid crystal will be broken and it will not return to its original state. It has the problem that it is inferior to

In order to solve these problems, the applicant of the present patent has filed a patent application for a cell for a liquid crystal display element in which gaps are provided between the alignment films and the cells are bonded at point-like bonding sites ( For example, see JP-A-64-18126, JP-A-64-18127, JP-A-64-23226, and JP-A-1-142617). Liquid crystal display elements manufactured using these cells exhibit good shock resistance without disrupting the alignment of the liquid crystal even when subjected to a drop impact, but in some cases, when liquid crystal is injected into the cell, Due to the air in the gap, the flow of the liquid crystal becomes non-uniform, and air pockets sometimes exist within the plane of the obtained liquid crystal display element.

As a result of detailed research into the behavior of liquid crystal when it is injected into the above cell, the present inventors found that
The flow of the liquid crystal is affected by the adhesive part provided in the gap between the cells for the above-mentioned liquid crystal display element, and the tip of the liquid crystal in the cell is not straight, and in particular, the adhesive part is continuous between the band-shaped transparent electrodes. It has been found that when this happens, the surrounding liquid crystal tends to wrap around first and form an air pocket.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display element in which liquid crystal can be smoothly injected, there are no air pockets, cell gaps are uniform, and the liquid crystal display element has excellent shock resistance.

[0007]

[Means for Solving the Problems] The present invention provides two substrates each having a plurality of strip electrodes and an alignment film on one side (however,
At least one of the substrates is a transparent substrate provided with transparent band-shaped electrodes), which are arranged so that the electrodes cross each other and the alignment films face each other, and a liquid crystal is placed in the gap between the alignment films. It is a matrix-type liquid crystal display element formed by encapsulation, in which the alignment films are bonded to each other at point-like joints with a bonding agent,
The liquid crystal display element is characterized in that the bonding portions are randomly distributed when viewed from the plane side of the substrate.

Preferred embodiments of the present invention are as follows. (1) The above-mentioned liquid crystal display element, wherein the dot-like joints have a diameter of 10 to 150 μm when viewed from the plane side of the substrate.

(2) The liquid crystal display element described above, wherein the dotted junctions are present at a density of 0.3 to 50 points per 1 mm2 of the plane of the liquid crystal display element.

(3) The liquid crystal display element described above, wherein the bonding agent is an adhesive alone or an adhesive containing powder spacers (preferably spherical, rod-shaped, etc.).

(4) The liquid crystal display element as described above, wherein the bonding portion is formed by printing and solidifying the bonding agent on an alignment film provided on a substrate.

(5) The liquid crystal display element described above, wherein the bonding agent is a photoresist, which is formed on an alignment film provided on a substrate by pattern exposure and development.

The present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an enlarged and schematic cross-sectional view of a part of an embodiment of a liquid crystal display element of the present invention. In FIG. 1, a liquid crystal display element 1 includes a black mask 3, a color filter 4, a transparent electrode 5 (for example, an ITO electrode), and an alignment film 6 provided on a transparent substrate 2 (for example, a glass substrate) in this order. On the other hand, a transparent electrode 8 and an alignment film 9 are provided in this order on a transparent substrate 7, and a gap between the alignment film 6 and the alignment film 9 is filled with liquid crystal 10. The alignment film 6 and the alignment film 9 are joined by point-like joints 11 . The transparent electrode 5 and the transparent electrode 8 are strip-shaped and are orthogonal to each other. The color filters 4 are provided in the order of color filters 4R, 4G, 4B, 4R, 4G, 4B, . . . .

FIG. 2 is a diagram schematically showing the inside of circle A in FIG. 1 in more detail. In FIG. 2, a black mask 3 is provided on a transparent substrate 2, a color filter 4 is provided between adjacent black masks 3 on the black mask 3, and a transparent electrode is provided on the color filter 4. 5 is provided, and an alignment film 6 is provided on the transparent electrode 5. The upper surface of the alignment film 6 is recessed between adjacent color filters 4 and/or between transparent electrodes 5 (grooves are formed in the direction perpendicular to the plane of the paper), and grooves 12 are formed in the direction perpendicular to the plane of the paper. are doing. The alignment film 9 and the alignment film 6 provided on the transparent electrode 8 provided on the transparent substrate facing the transparent substrate 2 (lower side in FIG. 2) are the parts above the transparent electrode 5, They are joined by dotted joints 11. A gap between the alignment film 6 and the alignment film 9 is filled with liquid crystal 10 .

FIG. 3 is a plan view schematically showing an enlarged part of one embodiment of the liquid crystal display element shown in FIG. Figure 3
In order to facilitate understanding of the features of the present invention,
Only the transparent electrode 5, transparent electrode 8, and bonding portion 11 in FIG. 1 are shown. In FIG. 3, a plurality of band-shaped transparent electrodes 5 and a plurality of band-shaped transparent electrodes 8 intersect at right angles,
Display pixels are formed at the electrode intersections.

The bonding portions 11 are randomly distributed over the entire surface of the liquid crystal display element.

If a junction exists between adjacent transparent electrodes 5 like the junction 11x, when liquid crystal is injected into the cell from the direction of arrow B, the flow of the liquid crystal will be poor below the junction 11x. The liquid crystal passing through the transparent electrodes 5 on both sides may wrap around above the junction 11x, and air near the junction 11x may be drawn into the liquid crystal, forming an air pocket. Therefore, in the liquid crystal display element of the present invention, it is preferable that the bonding portion 11x in FIG. 3 is not present as much as possible between adjacent strip-shaped transparent electrodes when viewed from the plane side of the transparent substrate.

Furthermore, when two junctions are located close to each other on the same electrode gap line, such as 11x and 11z,
The probability of air pockets occurring becomes extremely high. In order to avoid this, one possible method is to adjust the electrode pattern and the joint pattern so that the bonded object is never located in the gap between the electrodes, and to print the bonding agent with precise alignment. Doing so is extremely disadvantageous in terms of productivity. This is because such a bonding agent pattern inevitably becomes a periodic pattern, so if the alignment is even slightly misaligned, many bonding parts will be periodically located in the electrode gap, which will actually increase the probability of air pocket generation. This is because it increases

As in the present invention, if the bonding agent is printed randomly, the number of bonding parts located in the electrode gap will remain within a certain probability range even without special consideration of the positional accuracy of bonding. , the probability that closer junctions will be located in the same electrode gap becomes much smaller. As a method of randomizing the bonding patterns, strict distribution may be determined using a random number table, but sufficient effects can also be obtained by simply arranging the bonding patterns without artificial regularity.

Note that when the liquid crystal is present between adjacent transparent electrodes 8 but not between adjacent transparent electrodes 5, as in the joint portion 11y, when injecting liquid crystal from the direction of arrow B, It does not interfere with the flow of liquid crystal.

Thickness of the joint 11 (the thickness of the joint 11 shown in FIG. 2)
height) is the same as the cell gap of a conventionally known liquid crystal display element, and the size of the joint part 11 when viewed from the plane side of the transparent substrate (the diameter of the joint part 11 shown in FIG. 3) is For example, in the case of a liquid crystal display element with a diagonal size of 10 to 14 inches, it is recommended that the diameter be 100 μm or less to prevent screen flickering. preferable. If the size of the liquid crystal display element is even larger, the size of the joint can be made even larger, and even in that case there is no problem with visual perception. Further, the lower limit of the size of the joint 11 is not particularly limited, but if the joint 11 is too small, it is necessary to increase the number of joints 11 in order not to reduce the shock resistance of the liquid crystal display element. It is preferable that the size of the joints 11 is such that even if the number of joints 11 is appropriately reduced, the joints 11 have the necessary strength. Although the lower limit of the size of the bonding portion 11 varies depending on the type of bonding agent used, it is generally preferable to have a diameter of 10 μm or more. In addition, Figure 2
The joint 11 shown in is for ease of understanding.
Its shape does not correspond to the dimensions described above.

The density of the bonded portion 11 is not particularly limited as long as it satisfies the conditions of the present invention, and can be changed depending on the size of the bonded portion 11, the type of bonding agent, the size of the liquid crystal display element, etc. In general, the density is preferably 0.3 to 50 pieces per 1 mm 2 of the plane of the liquid crystal display element.

[0023] As the bonding agent for forming the joint portion 11 and the method for forming the joint portion 11, those described in the above-mentioned patent publication related to the application filed by the present patent applicant can be adopted. .

For example, the bonding agent may be an adhesive (preferably
A thermosetting adhesive, an ultraviolet curable adhesive, etc.) may be used alone, or the adhesive may contain a spacer in the form of a powder (preferably spherical or rod-shaped) of an inorganic or organic substance. It may also be a bonding agent.

[0025] Such a bonding agent is printed on the alignment film 6 or the alignment film 9 by a method such as letterpress printing, planographic printing, intaglio printing, or stencil printing, and is solidified to form the bonding portion 11. be able to.

The bonding portion 11 can also be formed by pattern exposure, development, and drying on the alignment film 6 or the alignment film 9 using a photoresist as a bonding agent.

[0027] In the liquid crystal display element of the present invention, the substrates, electrodes, and alignment films used in conventional liquid crystal display elements are used, except that the alignment films facing each other are joined by a bonding portion located at a specified position. , liquid crystal and other components, other structures of the liquid crystal display element, methods of manufacturing them, driving methods of the liquid crystal display element, etc. can be used. for example,
At least one of the two substrates of the liquid crystal display element of the present invention is a transparent substrate provided with a transparent band-shaped electrode,
In addition to the structure of the liquid crystal display element exemplified above, an insulating film, a smoothing film, etc. may be provided, and a color filter or a black mask may be omitted.

[0028]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

[Example 1] Glass substrate (10 cm x 10
cm x 1 mm) on top of indium-tin oxide (IT
A band-shaped transparent electrode (width 120 μm, length 10
cm, thickness 0.1 μm) with a gap of 20 μm,
Polyimide resin (manufactured by Hitachi Chemical Co., Ltd., P
IX5400) and dry it to form an alignment film (thickness 0.1 μm).
m) was formed, and the alignment film was subjected to a rubbing treatment to produce a cell substrate. Two cell substrates were produced in the same manner.

To form a joint, a bonding agent prepared by kneading a powder spacer (Epostor GP20, manufactured by Nippon Shokubai Chemical Co., Ltd.) into an adhesive (Structbond X7490, manufactured by Mitsui Toatsu Chemical Co., Ltd.) was used. , dots were printed on the alignment film of the first cell substrate by letterpress printing. The shape of the joint is approximately circular with a diameter of about 70 μm when viewed from the flat side of the substrates after bonding the two cell substrates together.
The positions of the joints are randomly distributed when viewed from the flat side of the liquid crystal display element, and the average density is 1.98 pieces/mm2.
(as shown in Figure 3).

On the other hand, after bonding the two cell substrates onto the alignment film on the peripheral portion of the second cell substrate, a peripheral seal portion with a width of 2 mm is formed, and the peripheral seals on the two opposing sides The above bonding agent was printed by letterpress printing so that 5 mm long liquid crystal injection openings, 10 on each side, were formed in the sample.

[0032] The first cell substrate and the second cell substrate on which the bonding agent was printed in this way are aligned so that the alignment films face each other and the transparent electrodes provided on each substrate are orthogonal to each other. After that, both substrates are heat-pressed and the cell gap is 2.1.
A cell of 8±0.02 μm was fabricated.

[0033] One ferroelectric liquid crystal composition (CS-1015, manufactured by Chisso Corporation) was placed in the liquid crystal injection opening of this cell.
Contact at 00°C, inject liquid crystal into the cell, and heat at 0.5°C.
A liquid crystal display element was fabricated by cooling at a cooling rate of 1/min. In this way, three liquid crystal display elements were produced.

The number of air pockets in the obtained liquid crystal display elements was 3, 7, and 1 for each liquid crystal display element, and these air pockets could be repaired by partial heating. . The liquid crystal display device exhibited a uniform alignment state. 8.7 in the center of this liquid crystal display element
When a ball of No. g was dropped from a height of 55 cm, no disturbance of orientation occurred and good shock resistance was exhibited.

[Comparative Example 1] When printing a bonding agent on the alignment film of the first cell substrate, the position of the bonding portion was adjusted so that the distance between the centers of the transparent electrodes in both the longitudinal and width directions was 710 μm (1.5 μm). 9
8 pieces/mm2), and printed without considering the positional relationship between the dotted junctions and the transparent electrodes to produce a first cell substrate, and then fabricated a liquid crystal display in the same manner as in Example 1. The device was fabricated.

[0036] The obtained liquid crystal display element had many air pockets remaining, and the display quality was poor. When the air pocket portion was observed under a microscope, it was found that a bonded portion filled the gap between the transparent electrodes along the injection direction. Note that when this liquid crystal display element was tested for shock resistance in the same manner as in Example 1, it showed good shock resistance.

[0037]

[Effects of the Invention] In the liquid crystal display element of the present invention, the bonding portions are randomly distributed when viewed from the plane side of the substrate, so the accuracy in printing the bonding agent and bonding the cell substrates can be improved. Even if the height is not particularly high, there are no continuous junctions between the electrodes, liquid crystal can be smoothly injected into the cell, there are no air pockets in the liquid crystal layer, and the cell spacing is uniform. It is a liquid crystal display element that has excellent shock resistance and has the remarkable effect of preventing moiré from occurring on the display screen.

[Brief explanation of the drawing]

FIG. 1 is a schematic, enlarged cross-sectional view of a part of an embodiment of a liquid crystal display element of the present invention.

FIG. 2 is a diagram schematically showing the inside of circle A in FIG. 1 in more detail.

3 is a plan view schematically showing an enlarged part of one embodiment of the liquid crystal display element shown in FIG. 1; FIG.

[Explanation of symbols]

1 Liquid crystal display element 2 Transparent substrate 3. Black Mask 4 Color filter 5 Transparent electrode 6 Alignment film 7 Transparent substrate 8 Transparent electrode, 9 Alignment film 10 Liquid crystal, 11 Joint part 12 groove

Claims (1)

[Claims] Claim 1: Two substrates each having a plurality of strip-shaped electrodes and an alignment film provided on one side (provided that at least one of the substrates is a transparent substrate provided with a transparent strip-shaped electrode) are used as electrodes. This is a matrix type liquid crystal display element in which the alignment films are arranged so that they intersect and face each other, and liquid crystal is sealed in the gaps between the alignment films, and the alignment films are dot-like bonded with a bonding agent. 1. A liquid crystal display element characterized in that the bonded portions are randomly distributed when viewed from the plane side of the substrate.