JPH0588187A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain a display having always high quality and to improve the contrast over the entire part of a screen by surely regulating the deformation to either the inner or outer side of substrates to eliminate the spacing between the substrates, thereby maintaining the spacing between the substrates always constant regardless of a volumetric change of a liquid crystal by ambient temp. or the impression of a driving electric field. CONSTITUTION:Solid spacers 9 which are crimped between the substrates 1 and 2 and regulate the spacing between the substrates and adhesive spacers 10 which adhere and bond the two substrates to regulate the spacing between the substrates are dispersedly disposed between a pair of the substrates 1 and 2. The total sum of the sectional areas of the solid spacers and adhesive spacers existing per 1mm<2> substrate area is specified to >=.0.0023mm<2> and <0.0043mm<2>; the total sum of the sectional areas of the adhesive spacers existing per 1mm<2> substrate area >=0.001mm<2> and to <0.003mm<2> and the sectional area parallel with the substrate surface per 1 piece of the adhesive spacers to <=0.0001mm<2>.

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.

[0002]

2. Description of the Related Art In a liquid crystal display device, display electrodes are formed on a pair of substrates which are arranged to face each other, an alignment film is formed on at least one of the substrates, and liquid crystal is sealed between the pair of substrates. It is configured.

In this liquid crystal display element, it is desired to make the gap (cell gap) between both substrates uniform in order to make the alignment state of the liquid crystal uniform. Therefore, in the above liquid crystal display element, A large number of spacers are dispersed and arranged between a pair of substrates, and the spacers regulate the gap between the substrates. FIG. 3 is a cross-sectional view of a conventional liquid crystal display device in which the spacer is arranged between both substrates.

In FIG. 3, reference numerals 1 and 2 denote a pair of transparent substrates made of glass or the like, and display electrodes 3 and 4 made of a transparent conductive film such as ITO are provided on one surface of the substrates 1 and 2, respectively.
Is formed, and further, on the electrode formation surfaces of both substrates 1 and 2,
Alignment films 5 and 6 for aligning the liquid crystal are formed. This liquid crystal display element is, for example, of a simple matrix type, the electrode 3 on one surface of the substrate (lower substrate in the figure) 1 is a scanning electrode, and the other substrate (upper substrate in the figure) 2
The surface electrode 4 is a signal electrode orthogonal to the scanning electrode 3.

The pair of substrates 1 and 2 are bonded to each other with a frame-shaped sealing material 7 with their electrode forming surfaces facing each other, and surrounded by the sealing material 7 between the two substrates 1 and 2. Liquid crystal 8 is enclosed in the area.

Further, a large number of transparent solid spacers 9 made of glass particles or the like are dispersed and arranged in the liquid crystal enclosing region between the pair of substrates 1 and 2, and each spacer 9 is arranged.
Are sandwiched between the substrates 1 and 2 (between the alignment films 5 and 6) to regulate the gap between the substrates 1 and 2.

FIG. 3 shows a liquid crystal display element in which the alignment films 5 and 6 are formed on the electrode formation surfaces of the pair of substrates 1 and 2, respectively. For example, the liquid crystal 8 is a ferroelectric liquid crystal or antiferroelectric liquid crystal. Some ferroelectric liquid crystal display elements using a dielectric liquid crystal have an alignment film provided on only one of the substrates.

[0008]

However, in the above-mentioned conventional liquid crystal display device, the spacer 9 for restricting the substrate gap is only sandwiched between the pair of substrates 1 and 2.
The spacers 9 can restrain the substrates 1 and 2 from being deformed inwardly, but the spacers 9 cannot restrain the substrates 1 and 2 from being swollen outward. Therefore, when the volume of the liquid crystal 8 expands, As a result, the substrate gap becomes large.

Therefore, the conventional liquid crystal display element has a problem that the substrate gap is changed due to the ambient temperature and the volume change of the liquid crystal 8 due to the application of the driving electric field, so that the alignment state of the liquid crystal is changed.

This is a problem particularly in a ferroelectric liquid crystal display device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, and in the ferroelectric liquid crystal display device, the substrate gap, that is, the layer thickness of the liquid crystal layer is Since the alignment state of the liquid crystal is greatly affected, the display quality is significantly deteriorated due to the change in the substrate gap.

An object of the present invention is to reliably control the deformation of the inside or outside of the substrate to eliminate the change in the substrate gap, and to prevent the substrate gap from changing regardless of the ambient temperature or the volume change of the liquid crystal due to the application of a driving electric field. It is an object of the present invention to provide a liquid crystal display device which can maintain a constant value and can always obtain a high-quality display and which has a good contrast on the entire screen.

[0012]

A liquid crystal display device of the present invention
Is sandwiched between the two substrates in the liquid crystal filling area between the pair of substrates.
The solid spacers that regulate the gap between the substrates
Separated from the adhesive spacers that bond with each other and regulate the substrate gap.
Dispersed and arranged, and board area 1 mm² Exist around
The solid spacer and the adhesive spacer are cut parallel to the substrate surface.
Total area is 0.0023mm² 0.0043mm or more² Less than the substrate area
1 mm² If there is a flat surface on the substrate surface of the adhesive spacer
Total cross-section area 0.001mm² 0.003mm or more² Less than
The cross-sectional area parallel to the substrate surface per adhesive spacer is 0.0001
mm² It is characterized by the following.

[0013]

According to the liquid crystal display element of the present invention, a solid spacer sandwiched between both substrates and regulating the substrate gap and a solid spacer sandwiched between the substrates and the two substrates are adhesively bonded to each other in the liquid crystal enclosing region between the pair of substrates. Since the regulating adhesive spacers are arranged in a dispersed manner, the inward deformation of the substrate is regulated by the solid spacer and the adhesive spacer, and the outward deformation of the substrate is also regulated by the adhesive spacer. Because
A high-quality display can always be obtained by keeping the substrate gap constant regardless of the ambient temperature or the volume change of the liquid crystal due to the application of a driving electric field.

In this case, the force that restricts the inward deformation of the substrate is determined by the area of the solid spacer and the adhesive spacer (the cross-sectional area parallel to the substrate surface) in the unit area. Area 1 mm ² The total cross-sectional area of the solid spacer and the adhesive spacer existing in the area is 0.0023 mm ² With the above, the deformation of the substrate due to the volume contraction of the liquid crystal can be sufficiently regulated.

Further, the force for restricting the outward deformation of the substrate,
That bond strength between the substrates by the adhesive spacer is determined by the adhesion area between the adhesive spacers and the substrates occupied in a unit area, as described above, the substrate area 1 mm ² The total cross-sectional area of the adhesive spacer present in the area is 0.001 mm ² According to the above, it is possible to secure a sufficient bonding area between the adhesive spacer and both substrates, and to bond both substrates with a bonding force sufficient to withstand the deformation force due to the volume expansion of the liquid crystal.

Further, if there is a spacer in the liquid crystal sealed area, the alignment state of the liquid crystal around the spacer is disturbed, so that the display contrast around the spacer is lowered, but as described above, the substrate area is 1 mm ² The total cross-sectional area of the solid spacer and the adhesive spacer existing in the area is 0.0043 mm ² Less than, board area 1mm
² The total cross-sectional area of the adhesive spacer present in the area is 0.003 mm.
² And the cross-sectional area per adhesive spacer is 0.
0001mm ² In the case of the following, the deterioration of the contrast around the spacer is hardly noticeable.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a liquid crystal display device of this embodiment, and FIG. 2 is a partially cutaway plan view showing a spacer distribution state. In addition, in FIG. 1 and FIG.
The same components as those of the conventional liquid crystal display element shown in FIG.

The liquid crystal display element of this embodiment is sandwiched between the pair of substrates 1 and 2 in a liquid crystal enclosing region (region surrounded by the sealing material 7) to regulate the substrate gap. A large number of transparent solid spacers 9 and transparent adhesive spacers 10 that bond the two substrates 1 and 2 together to regulate the gap between the substrates are dispersed and arranged. In this embodiment, the solid spacers 9 are Glass particles or the like used in a conventional liquid crystal display element are used, and a thermosetting resin such as an epoxy resin is used as the adhesive spacer 10.

The solid spacer 9 and the adhesive spacer 10 have a substrate area of 1 mm ² The total sum of the cross-sectional areas of all the solid spacers 9 and the adhesive spacers 10 present in the vicinity parallel to the substrates 1 and ² is 0.0023 mm ² 0.0043 mm ² or more Less than and board area 1mm ² All adhesive spacers 10 present in the area
The total cross-sectional area parallel to the substrate surfaces 1 and ² is 0.001 mm ² that's all
0.003 mm ² It is distributed by an amount that falls within the range of less than. The cross-sectional area of each of the adhesive spacers 10 parallel to the surfaces of the substrates 1 and 2 is 0.0001 mm ² It is said that

The cross-sectional area of the spacers 9 and 10 is
It is the cross-sectional area of the largest diameter portion of the spacers 9 and 10, and the cross-sectional area of the adhesive spacer 10 is the cross-sectional area in the cured state of the adhesive spacer 10. This liquid crystal display element is manufactured as follows.

First, on one of the pair of substrates 1 and 2 on which the electrodes 3 and 4 and the alignment films 5 and 6 are formed, a sealing material 7 made of a thermosetting resin such as an epoxy resin is applied to the solid spacer 9 described above.
And a solid spacer 9 on one of the pair of substrates 1 and 2 (on the alignment film) and a spherical shape slightly larger in diameter than the solid spacer 9. The adhesive spacers 10 thus placed are sprayed by a predetermined amount.

Next, the substrates 1 and 2 are overlapped and pressed, and in this state, the sealing material 7 and the adhesive spacer 10 are heated to the softening temperature to crush the sealing material 7 and the adhesive spacer 10. Meanwhile, the substrates 1 and 2 are brought into contact with the solid spacer 9 so that the gap between the substrates 1 and 2 is a gap regulated by the solid spacer 9.

Next, the heating temperature is raised to the curing temperature of the sealing material 7 and the adhesive spacer 10 while maintaining the above-mentioned pressurized state so that the sealing material 7 and the adhesive spacer 10 are cured and both substrates 1, 2 Sealant 7 and adhesive spacer 1
Bond with 0. After this, the liquid crystal 8 is placed between the substrates 1 and 2.
Is injected to complete the liquid crystal display element.

In this liquid crystal display element, a solid spacer 9 which is sandwiched between the pair of substrates 1 and 2 to regulate the gap between the substrates and a pair of the substrates 1 and 2 are provided in a liquid crystal enclosure region between the pair of substrates 1 and 2.
Adhesive Spacer 10 that Adhesively Bonds and Regulates the Substrate Gap
Are dispersed, so that the inward deformation of the substrates 1 and 2 is regulated by the solid spacer 9 and the adhesive spacer 10, and the outward deformation of the substrates 1 and 2 is also regulated by the adhesive spacer 10. Can therefore be
Regardless of the change in volume of the liquid crystal 8 due to the ambient temperature or the application of the driving electric field, the gap between the substrates can be kept constant and a high-quality display can always be obtained.

In this case, the force for restricting the inward deformation of the substrates 1 and 2 is determined by the areas of the solid spacer 9 and the adhesive spacer 10 in a unit area (cross-sectional area parallel to the substrate surface). , The board area is 1mm ² The total cross-sectional area of the solid spacer 9 and the adhesive spacer 10 present in the area is 0.0023 mm ² With the above, the deformation of the substrate due to the volume contraction of the liquid crystal 8 can be sufficiently regulated.

Further, the force for restricting the outward deformation of the substrates 1 and 2, that is, the bonding force between the substrates 1 and 2 by the adhesive spacer 10 is the adhesive spacer 10 and the substrates 1 and 2 occupying a unit area. It is determined by the adhesion area between, as described above, the substrate area 1 mm ² Adhesive spacer 10 present in the area
Total cross-sectional area of 0.001mm ² With the above, a sufficient bonding area between the adhesive spacer 10 and the substrates 1 and 2 can be secured, and the substrates 1 and 2 can be bonded with a bonding force that can sufficiently withstand the deformation force due to the volume expansion of the liquid crystal 8.

Further, if there is a spacer in the liquid crystal sealed area, the alignment state of the liquid crystal around the spacer is disturbed, so that the display contrast around the spacer is lowered, but as described above, the substrate area is 1 mm ² The total cross-sectional area of the solid spacer 9 and the adhesive spacer 10 present in the area is 0.0043 mm ² Less, substrate area 1mm ² The total cross-sectional area of the adhesive spacer 10 present in the area is 0.003 mm ² And the cross-sectional area of each adhesive spacer 10 is 0.0001 mm ² In the case of the following, the deterioration of the contrast around the spacer is hardly noticeable.

That is, the following [Table 1] shows that the amount of the solid spacers 9 is the same (the substrate area is 1 mm ² Solid Spacer 9
Total cross-sectional area of 0.0013 mm ² ), Liquid crystal display elements of four kinds of modes A to D in which the amount of the adhesive spacer 10 is changed are manufactured, and the results of the evaluation test of the alignment state of each liquid crystal display element are shown. The circle marks in the column indicate “good”, and the cross marks indicate “bad”.

[0029]

[Table 1]

Here, the substrate gap (diameter of the solid spacer 9) of each liquid crystal display element is 2 μm, and the cross-sectional area per adhesive spacer of each liquid crystal display element is 50 μmm ^2. (0.00005mm
² ), Each liquid crystal display element is subjected to a temperature shock of 80 ° C. → −5 ° C. and a load of applying a rectangular wave voltage of 3 to 1000 KHz to inspect the change of the alignment state, and the change of the alignment state of the liquid crystal with respect to the temperature change (substrate gap) Change), and when the pulse waveform by the two-field drive method is applied,
1 dot when OFF (about 2.46 mm ² The contrast of 5) or more was evaluated as “good”.

As a result of the above evaluation test, in the A-mode liquid crystal display element, the adhesive bond strength between the substrates 1 and 2 by the adhesive spacer 10 was insufficient, and the liquid crystal alignment state was changed due to the change in the substrate gap. .. In addition, in the D-mode liquid crystal display element, the adhesive bonding force between the substrates 1 and 2 by the adhesive spacer 10 is sufficient, but the amount of the adhesive spacer 10 is too large, and therefore the alignment state of the liquid crystal around the spacer is disturbed. There are many areas where the contrast is reduced due to, and therefore, the reduction of the contrast on the entire screen is conspicuous, and the display quality is significantly reduced.

On the other hand, in both the B-mode and C-mode liquid crystal display elements, the adhesive bonding force between the substrates 1 and 2 by the adhesive spacer 10 is sufficient, and the change in the liquid crystal alignment state due to the change in the substrate gap does not occur. In addition, the deterioration of the contrast due to the disorder of the alignment state of the liquid crystal around the spacer was hardly noticeable, and the contrast of the entire screen was sufficient.

In the above embodiment, the adhesive spacer 1
Although a thermosetting resin is used for the adhesive layer 10, the adhesive spacer 10 may be a thermoplastic resin. Further, the present invention is
The invention can be applied not only to liquid crystal display elements using ferroelectric liquid crystal (or antiferroelectric liquid crystal) but also to liquid crystal display elements using nematic liquid crystal or the like.

[0034]

According to the liquid crystal display device of the present invention, the inward deformation of the substrate is restricted by the solid spacer and the adhesive spacer, and the outward deformation of the substrate is restricted by the adhesive spacer. Therefore, regardless of the ambient temperature and the volume change of the liquid crystal due to the application of the driving electric field, the substrate gap can be kept constant and a high-quality display can always be obtained, and the alignment state of the liquid crystal around the spacer is disturbed. The contrast deterioration due to is hardly noticeable, so that the contrast on the entire screen is good.

[Brief description of drawings]

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

FIG. 2 is a partially cutaway plan view showing a spacer distribution state.

FIG. 3 is a cross-sectional view of a conventional liquid crystal display element.

[Explanation of symbols]

1, 2 ... Substrate, 3, 4 ... Transparent electrode, 5, 6 ... Alignment film, 7
... sealing material, 8 ... liquid crystal, 9 ... solid spacer, 10 ... adhesive spacer.

Claims (1)

[Claims] 1. A liquid crystal display device comprising display electrodes formed on a pair of substrates arranged opposite to each other, an alignment film formed on at least one of the substrates, and liquid crystal sealed between the pair of substrates. A solid spacer, which is sandwiched between the two substrates and regulates the substrate gap, and an adhesive spacer, which is adhesively bonded to the two substrates to regulate the substrate gap, are dispersedly arranged between the pair of substrates, and the substrate area is 1 mm ² The total of the cross-sectional areas of the solid spacer and the adhesive spacer existing in the vicinity parallel to the substrate surface is 0.0023 mm ²
0.0043 mm ² or more Less than, substrate area 1mm ² 0.001 mm ² The sum of the cross-sectional area parallel to the substrate surface of the adhesive spacers present in the per 0.003mm ² or more
Less than 0.00, the cross-sectional area parallel to the substrate surface per adhesive spacer is 0.00
01 mm ² A liquid crystal display device characterized by the following.