JP2002350861A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability and display uniformity by preventing a low- temperature air-bubble defect. SOLUTION: The liquid crystal element has liquid crystal 18 held between two opposite substrates 11 and 12 having a seal material 24 arranged at their peripheries and also has its substrate interval prescribed by bringing column spacers 17 regularly arranged on a shading part on at least one substrate into contact with the opposite-side substrate 11 facing the substrate 12; and the product of the contact area (μm<2> ) of one column spacer 17 on the opposite-side substrate 11 and the arrangement density (piece/mm<2> ) of the column spacers 17 is 500 to 1,500 (μm<2> /mm<2> ). Consequently, defects such as display unevenness due to variation in substrate interval and air bubble generation at low temperature when a pressing load is placed on the liquid crystal display element are not generated. Further, a spot defect due to the cohesion of beads, a contrast decrease due to light escaping caused by a bead, and gap unevenness due to scattering unevenness of beams which were found before are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, liquid crystal display devices have been used for various display devices, and demands for pocket TVs, word processors, notebook computers and the like have been increasing.

In a conventional general liquid crystal display device, liquid crystal is sandwiched between two transparent electrode substrates, a voltage is applied between electrodes for the time being, and the alignment state of liquid crystal molecules is changed according to the applied voltage. This controls the light transmittance.

A general method of manufacturing a liquid crystal display element is to hold the liquid crystal on a substrate whose orientation is determined by a rubbing method in which the surface of an alignment layer of polyimide or the like formed on the substrate is rubbed with a resin fiber cloth. Apply sealing material for
A bead material for controlling the thickness between the substrates is dispersed. Then, the counter substrate subjected to the rubbing treatment is bonded to the substrate coated with the sealing material, and the sealing material is cured. Then, a liquid crystal material is sandwiched between the substrates by a vacuum injection method, and a polarizing plate is attached to the front and back surfaces of the panel according to the display mode and use of the liquid crystal display element, thereby completing the liquid crystal display element.

An example of the conventional liquid crystal display device shown in FIG. 3 has the following problems. First, the display quality is determined by the substrate spacing accuracy between the color filter substrate 12 having the light shielding layer 14 and the color layer 15 and the array substrate 11 having the switching elements 21. That is, if the liquid crystal display element has non-uniform substrate spacing, in-plane variations occur in the thickness of the liquid crystal layer 18.

Next, the color filter substrate 11 and the substrate 12
Of the beads 26 sandwiched between the beads 26, the beads dispersed in the display area 27 cause liquid crystal alignment disorder and light leakage,
This lowers the display quality such as roughness.

In the case of forming a panel as described above, in order to disperse the beads 26 on the substrate, the beads 26 are dispersed on one of the substrates by a dry or wet method. When spraying, bead 2
Due to the aggregation and uneven distribution of 6 and the inclusion of foreign matter, point defects and display unevenness occur in the liquid crystal display element, and the yield in the manufacturing process is deteriorated. In FIG. 3, 13 and 19 are glass substrates, 16 is a transparent electrode, 22 is a pixel electrode, 23 is an alignment film, and 24 is a sealing material.

Therefore, in order to solve the above-mentioned problems, instead of controlling the distance between the substrates by the conventional bead dispersion method, a method of forming column spacers 17 on the color filter substrate 12 in advance as shown in FIG. Has been proposed. According to this method, it is possible to prevent a decrease in display quality such as uneven thickness and roughness of the liquid crystal layer 18 caused by scattering of beads.

[0009]

However, in such a liquid crystal display element in which the space between the substrates is defined by the column spacers, if the column spacers are arranged in a larger number than necessary, the elasticity between the two electrodes becomes small. When the display element is exposed to a low temperature, the substrate spacing does not follow the volume contraction of the liquid crystal, and a low-temperature bubble defect occurs. On the other hand, if the density of the column spacers is reduced, the margin of low-temperature bubble generation is increased, but loads such as pressing and deformation are applied to the liquid crystal display element,
The load applied to the column spacers during the manufacturing process of the liquid crystal display element tends to change the thickness of the column spacers, causing a change in the distance between the substrates, causing display unevenness.

Accordingly, an object of the present invention is to solve such a problem, and to provide a liquid crystal display element which prevents a low-temperature bubble defect and is excellent in reliability and display uniformity.

[0011]

In order to achieve the above object, a liquid crystal display device according to claim 1 of the present invention comprises a liquid crystal sandwiched between two opposing substrates having a sealing material disposed therearound,
A column spacer regularly arranged in a light-shielding portion on at least one substrate is a liquid crystal display element that contacts a counter substrate facing the substrate having the column spacer and regulates a substrate interval, and includes a column spacer. The contact area (square μm) with the counter substrate and the arrangement density of the column spacers (pieces / square m)
m) is 500 to 1500 (square μm / square mm).

As described above, the product of the contact area (square μm) of one pillar spacer with the opposing substrate and the arrangement density (pieces / square mm) of the pillar spacer is 500 to 1500 (square μm / square).
(Square mm), so that when a pressing load is applied to the liquid crystal display element, defects such as display unevenness due to a change in the substrate interval and bubbles at a low temperature do not occur. That is, when the product of the contact area of the spacer with the opposing substrate and the arrangement density is smaller than 500 (square μm / square mm), the height of the spacer fluctuates due to the load of the manufacturing process, and display unevenness due to a gap failure occurs. Further, the product of the contact area of the spacer with the counter substrate and the arrangement density is 1500 (square μm / square m).
If it is larger than m), there are many spacers for defining the substrate interval, and in a low temperature state, the fluctuation of the substrate interval does not follow the volume contraction of the liquid crystal, and a vacuum bubble is generated in the liquid crystal display element.

Further, the column spacer can improve point defects due to aggregation of beads, reduction in contrast due to light leakage by beads, and gap unevenness due to uneven dispersion of beads, which were problems of the conventional liquid crystal display device using beads.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing a structure of a liquid crystal display element according to an embodiment of the present invention.

As shown in FIG. 1, this liquid crystal display device has
Two opposing substrates 1 around which a sealing material 24 is arranged
A column spacer 17 that sandwiches a liquid crystal 18 between the first and second substrates 12 and is regularly arranged at a light-shielding portion on at least one of the substrates comes into contact with the opposing substrate 11 that faces the substrate 12 having the column spacers 17. Is specified.

The active element T as a panel constituting substrate
A color filter substrate 12 was used as an opposite side to an array substrate 11 having an FT (Thin Film Transistor). The size of the display section of these substrates 11 and 12 is 10 inches diagonally. Color filter substrate 12
Is composed of a light-shielding film 14 provided on a glass substrate 13, a red-green-blue color layer film 15, a transparent electrode 16 and a column spacer 17 formed on the light-shielding layer 14. Spacer 1
The distance between the array substrate 11 and the opposing array substrate 11 is determined by 7. On the other hand, the array substrate 11 includes a glass substrate 19, switching elements 21 formed of signal lines and scanning lines, and pixel electrodes 22 formed thereon. Alignment films 23 are respectively formed on opposing surfaces of the array substrate 11 and the color filter substrate 12. The space between the substrates 11 and 12 is filled with a liquid crystal 18, and the periphery thereof is fixed with a sealant 24.

The manufacturing process of the liquid crystal display device shown in FIG.
First, as a color filter substrate 12, a glass substrate 13 is used.
After a light-shielding layer was formed on the entire surface of the substrate, the light-shielding layer 14 having a predetermined pattern was patterned by a general photolithography method. Generally, a black resin or a metal film is used as the light shielding layer film. In this embodiment, a chromium oxide film is used. Next, the red, blue, and green color layers 15 were formed in a predetermined pattern shape by applying, exposing, and developing a pigment resist, respectively. Next, a desired transparent electrode 16 was formed by an ITO sputtering apparatus with the metal mask set on the substrate. Next, after applying a photosensitive resin film, the spacer 17 was formed to have a thickness of 4.5 μm by performing exposure and development. The height of the column spacer 17 may be determined according to the substrate spacing design of the liquid crystal display element.
m height.

After the alignment film material is printed on the color filter substrate 12 having the column spacers 17 as described above and the array substrate 11 on which the switching elements 21 and the electrodes 22 are formed, an alignment process is performed. The liquid crystal display element epoxy adhesive 24 was screen-printed on one of the substrates so as to have a liquid crystal injection port, and was bonded to the opposing electrode substrate to form an empty liquid crystal element, and the epoxy adhesive 24 was cured by heating. Liquid crystal was injected into the empty liquid crystal display element by a vacuum injection method, and the injection port was sealed with a photocurable adhesive to obtain a liquid crystal display element.

On the color filter substrate with spacers 12 for manufacturing the liquid crystal display element, a liquid crystal display element having a different spacer shape and spacer arrangement density as shown in Table 1 was manufactured, and the uniformity of the gap and the low-temperature storage reliability were obtained. The sex was evaluated.

[0020]

[Table 1]

The product of the spacer size (the contact area of the spacer with the opposing substrate) and the arrangement density shown in Table 1 is 500.
If it is smaller than (square μm / square mm), the height of the spacer fluctuates due to the load of the manufacturing process, and display unevenness due to a gap defect occurred. When the product of the size of the spacer and the arrangement density is larger than 1500 (square μm / square mm), as shown in FIG. In addition, a change in the distance between the substrates did not follow the volume contraction of the liquid crystal, and a vacuum bubble was generated in the liquid crystal display element.

In the liquid crystal display device according to the embodiment of the present invention, the product of the size of the spacer and the arrangement density is 500 to 15
By setting the value to 00 (square μm / square mm), a liquid crystal display element free of low-temperature bubbles and display unevenness due to a manufacturing process could be provided.

FIG. 2 is a graph created based on the evaluation results in Table 1. In the figure, ○ indicates gap uniformity, and △ indicates the occurrence of low-temperature air bubbles. The upper position is good and the lower position is bad. Panels C, D, G, J, and M had spacer size × arrangement density in the range of 500 to 1500 (μm ² / mm ² ), and had good gap uniformity and low-temperature bubble generation. Panels A, B, and F had a spacer size × arrangement density smaller than 500 (μm ² / mm ² ), good low-temperature bubble generation, and poor gap uniformity. Panel E,
H, I, K, L, and N are the size of the spacer × the arrangement density is 1
It was larger than 500 (μm ² / mm ² ), the gap uniformity was good, and the low-temperature bubble generation was poor.

In this embodiment, the spacer was formed on the color filter substrate. However, similar results were obtained when the spacer was formed on the array substrate. In addition, a TN (Twisted Nematic) type liquid crystal display element or an STN (Super Twisted Nema)
A similar result was obtained with the tic) type liquid crystal display element.

[0025]

According to the liquid crystal display element of the first aspect of the present invention, the contact area (square μm) of one column spacer with the opposing substrate and the arrangement density of the column spacer (pieces / square m)
m) is 500 to 1500 (square μm / square mm), so that when a pressing load is applied to the liquid crystal display element,
Defects such as display unevenness due to fluctuations in the substrate spacing and generation of bubbles at low temperatures do not occur.

The column spacer can improve the point defect due to the aggregation of the beads, the decrease in the contrast due to the light leakage by the beads, and the uneven gap due to the uneven dispersion of the beads, which have been problems of the conventional liquid crystal display device using the beads.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a graph created based on the evaluation results in Table 1.

FIG. 3 is a schematic sectional view of a liquid crystal display element in which low-temperature bubbles are generated.

FIG. 4 is a schematic sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 11 array substrate 12 color filter substrate 13 glass substrate 14 light shielding layer 15 color layer 16 transparent electrode 17 pillar spacer 18 liquid crystal 19 glass substrate 21 switching element 22 pixel electrode 23 alignment film 24 sealing material 26 bead material 27 display area

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Matsukawa 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 2H089 LA09 NA09 NA37 QA14 TA01 TA04 TA09

Claims (1)

[Claims] A liquid crystal is sandwiched between two opposing substrates around which a sealing material is disposed, and a column spacer regularly disposed on a light-shielding portion on at least one of the substrates is provided on a substrate having the column spacer. A liquid crystal display element which is in contact with an opposing opposing substrate and regulates the distance between the substrates, wherein a contact area of one column spacer with the opposing substrate (square μm) and an arrangement density of the column spacers (pieces / square mm) The product of 500 to 1500
(Square μm / square mm).