JPH08146439A - Production of liquid crystal display element - Google Patents

Abstract

PURPOSE: To improve cell gap accuracy in a stage for pressurizing and curing a sealing material for which an air bag is used. CONSTITUTION: A sealing material 34 is held interposed between a first substrate 10 and a second substrate 20 and these substrates are installed in this state on a sealing and curing jig (lower plate) 1. A pressurizing plate 6 is set thereon. Air is introduced into the air bag 4 from an air introducing port 5 to inflate the air bag 4 and to pressurize the first and second substrates 10, 20. The size of the pressurizing plate 6 is set larger than the rage of the sealing material 34 and smaller than the outside shapes of the first and second substrates 10, 20. The adequate pressurizing power on the substrate existing on the outer side of the sealing material 34 is thereby obtd. and the cell gap accuracy is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art The structure of a liquid crystal display device of this type is shown in FIG. The liquid crystal display element has a structure in which a liquid crystal 30 is sealed between the first substrate 10 and the second substrate 20. First
The substrate 10 is formed by forming a color filter protective film 12, a color filter black mask 13, a color filter layer 14, a transparent electrode 15, an insulating film 16 and an alignment film 17 on a glass substrate 11. In addition, the second substrate 20 is configured by forming a transparent electrode 22, an insulating film 23, and an alignment film 24 on a glass substrate 21.

Further, spacers 31 and adhesive particles 32 are dispersed in the liquid crystal 30 in order to keep the distance between the first and second substrates 10 and 20 (hereinafter referred to as cell gap) constant. Furthermore, the first and second substrates 10 and 20
Around the space, a seal spacer 33 made of glass fiber and silica and a seal material 34 using epoxy are arranged.

The above liquid crystal display device is manufactured as follows. First, after forming the first and second substrates 10 and 20, the seal spacer 3 is provided between the first and second substrates 10 and 20.
3 and the sealing material 34 are formed, and the first and second substrates 1 are formed.
0 and 20 are sealed at a predetermined interval. Then, after cutting into a desired liquid crystal display element size, the liquid crystal 30 is injected through a liquid crystal injection port (not shown), and the liquid crystal injection port is sealed to manufacture a liquid crystal display device.

Here, in the assembly process in which the first and second substrates 10 and 20 are sealed with a sealant at predetermined intervals, the sealant is heated by uniformly applying pressure to the first and second substrates. Need to be cured. Therefore, JP-A-3-73
In the device disclosed in Japanese Patent No. 930, the first and second substrates 1 and 20 are uniformly pressed to the first and second substrates 10 and 20 by pressing them with an air bag using air pressure.
A space between 0 and 20 is sealed. By using such an air bag, it is possible to apply a more uniform force to the entire substrate as compared with the case of applying pressure by weight that has been used until then, and to solve the problem such as warpage of the liquid crystal panel. You can

FIG. 6 shows the structure of a seal hardening jig (or an air bag jig) according to this publication. In this figure, an air bag 103 is arranged on a seal hardening jig (lower plate) 101, a pressure plate (lower plate) 105 is arranged on the air bag 103, and a pressure plate (lower side) 105 is arranged on the pressure plate (lower side) 105. The first and second substrates 10 and 20 with the sealant interposed are installed, and a thin pressure plate (upper plate) 106 is provided on the first substrate 10.
Is placed, the airbag 104 is placed thereon, and a seal hardening jig (upper plate) 102 is covered and fixed by a stopper 107. After that, compressed air is injected into the air bags 103 and 104, and pressure is applied to the first and second substrates 10 and 20 to perform a sealing step with a sealing material.

[0007]

By applying pressure using the air bag described above, it is possible to surely make the cell gap between the first and second substrates uniform to some extent. However, it is still insufficient in the case of demanding higher accuracy of uniformity. For example, according to experiments by the inventors of the present application,
With the above configuration, a cell gap accuracy of up to ± 0.2 μm can be obtained, but when a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used as the liquid crystal, it is higher than that, for example, ± 0. 1 μm, preferably ± 0.05 μm
However, there is a problem in that the above configuration cannot be used.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a higher cell gap accuracy than the above-mentioned conventional one in the pressure hardening process of a sealing material using an air bag.

[0009]

The inventors of the present application have made various studies on improving the accuracy of the cell gap, and the relationship between the pressure plate and the lower plate of the jig outside the seal is that the cell gap outside the seal is large. It was found by experiment that it affects the. In addition, in the following experiments, as a liquid crystal,
Ferroelectric liquid crystal (hereinafter referred to as FLC) or antiferroelectric liquid crystal (hereinafter referred to as AFLC) is used.

This will be described according to the model shown in FIG. The first and second substrates 10 and 20 are placed on top of each other and placed on the seal curing jig 50. Further, the pressure plate 51 is installed on the first substrate 10. Here, the distance in the vicinity of the outside of the sealing material 34 is d1, and the distance in the outermost part of the substrate is d2. The distance between the sealing material 34 and the outer shape of the pressure plate 51 is L1, and the distance between the sealing material 34 and the outer shape of the substrate is L1.
Set to 2.

Then, the ratio of L1 and L2, that is, L1 /
FIG. 8 shows the result of investigating d2 -d1 using L2 (%) as a parameter. When L1 = 0, that is, when the seal range and the pressure plate size are the same, the pressing force is not transmitted to the substrate outside the seal, and the cell gap outside the seal increases toward the end face of the glass substrate.

On the other hand, as in the prior art, L1 / L2> 10
0%, that is, when the pressure plate size is larger than the substrate glass size, when the seal hardening pressure P is applied, there is no spacer outside the seal to support the substrates at an appropriate interval, and thus the cell gap increases toward the substrate glass end face. Becomes smaller. Therefore, as in the prior art, the glass substrate 11,
When the pressure plates 105 and 106 are used on both sides of the glass plate 21, the pressure applied causes the glass substrates 11 and 21 to be compressed as shown in FIG.
Ends of the bend. That is, when the entire glass substrate is pressed through the pressure plate, the display portion is supported by the spacer 31, and the seal portion is supported by the seal spacer 33 mixed in the seal material 34, and the pressure is applied. Further, only the spacers 31 scattered on the display unit at the same time as the spacers 31 are scattered outside the seal. Therefore, a space difference ΔH is generated outside the seal, and when pressure is applied in this state, the upper and lower pressure plates 105 and 106 are bent by the pressure, and further the glass substrates 11 and 21 are bent. Finally, ΔH = 0, that is, the spacer 31 shown in FIG.
It will be supported by.

Due to the bending of the glass substrates 11 and 21, the cell gap near the seal becomes non-uniform. The effect of this is uneven cell gap extending to the display area near the seal, resulting in display unevenness. FIG. 10 shows the influence of the cell gap d1 in the vicinity of the sealing material on the display cell gap uniformity. As is clear from this figure, it is understood that the uniform cell gap in the vicinity of the seal is indispensable for uniforming the display cell gap.

FIG. 11 shows experimental data showing the influence of d2 -d1 on the cell gap uniformity in the vicinity of the sealing material. d2
-D1 = 0 (no bending or spreading), d2-
Both d1> 0 and d2 −d1 <0, d1 and d2
As the difference between the two increases, the uniformity of the cell gap near the sealing material deteriorates. When the cell gap uniformity in the vicinity of the sealing material is deteriorated, the cell gap uniformity of the display part is also deteriorated as shown in FIG. Therefore, by controlling d2-d1, it is possible to make the entire cell (display part cell gap) uniform.

From the above results, it is possible to make the cell gap more uniform by setting the size of the pressure plate 51 such that the sealing range <the pressure plate size <the substrate size. When the average cell gap accuracy is ± 0.1 μm, the average cell gap in the vicinity of the sealing material is set to 0.3 μm or less from FIG. 10, and the seal external gap difference (d2 −d1) is set from FIG. It should be 2.5 μm or less. Therefore, from FIG. 8, it is necessary to set L1 / L2 to 30% or more. Also, the cell gap accuracy is averaged to 0.
In the case of the accuracy of 05 μm, the average cell gap in the vicinity of the sealing material is set to 0.2 μm or less from FIG.
The outer gap difference (d2-d1) of the seal is 1.5 μm
Must be: Therefore, from FIG. 8, L1 / L2
Needs to be 45% or more.

The present invention has been made based on the above consideration, and specifically has the following features. In the invention described in claim 1, after the first substrate (10) and the second substrate (20) are bonded together by using the sealing material (34) therebetween, the first and second substrates are added. In the method of manufacturing a liquid crystal display device, the sealing material is cured while being pressed, and then a liquid crystal (30) is injected between the first substrate and the second substrate to manufacture a liquid crystal display device. In the step of curing the sealing material while applying pressure to the first and second substrates, the pressure member (6, 1a) is located on at least one of the first and second substrates, and the airbag (4) is used. To pressurize the first and second substrates by using the pressurizing member in the forming range of the sealing material (B1 × B2, B3 × B4).
), And the outer shape of the first and second substrates (A1
XA2, A3 x A4) The above-mentioned pressurization is characterized as having an area in a smaller range.

According to a second aspect of the invention, in the first aspect of the invention, the pressure member (6) is located on the first substrate (10), The air bag (4) is characterized by applying pressure. According to a third aspect of the present invention, in the first aspect of the present invention, the pressure member (1a) is located below the second substrate (20), and the pressure member (1a) is located above the second substrate. It is characterized in that the air bag (4) applies pressure.

According to a fourth aspect of the invention, in the invention according to any one of the first to third aspects, the liquid crystal (3
As 0), a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used, and the distance from the forming range of the sealing material to the outer shape of the pressing member is L1, and the outer shapes of the sealing material and the first and second substrates. L1 / L2 is 30% when the distance to is L2
It is characterized by the above.

According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the liquid crystal (3
As 0), a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used, and the distance from the forming range of the sealing material to the outer shape of the pressing member is L1, and the outer shapes of the sealing material and the first and second substrates. When the distance to is L2, L1 / L2 is 45%
It is characterized by the above.

The reference numerals in parentheses of the above means indicate the corresponding relationship with the concrete means described in the embodiments described later.

[0021]

According to the inventions of claims 1 to 3, when the sealant is cured by applying pressure to the first and second substrates using an air bag, the first and second substrates are The pressing member located on at least one side has an area that is larger than the forming range of the sealing material and smaller than the outer shapes of the first and second substrates.

Therefore, when the first and second substrates are pressed by the pressure member, the cell gap accuracy can be improved by appropriately adjusting the pressure applied to the substrate located outside the sealing material. According to the invention of claim 4, a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used as the liquid crystal, and the distance from the forming range of the sealing material to the outer shape of the pressing member is L1,
When the distance between the seal material and the outer shapes of the first and second substrates is L2, L1 / L2 is 30% or more. Therefore, from FIGS.
It can be 0.1 μm.

Further, according to the invention of claim 5,
L1 / L2 is set to 45% or more. Therefore, FIGS.
From 0 and 11, average cell gap accuracy is ± 0.05
It can be μm.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the liquid crystal is FLC or A.
The liquid crystal display element shown in FIG. 5 is constructed using FLC. Here, in the method of manufacturing the liquid crystal display element according to the present embodiment, in the assembly step of curing the sealing material while pressing the first and second substrates 10 and 20, the seal curing jig (or airbag) shown in FIG. 1 is used. Jig) is used. In this embodiment, unlike the conventional one shown in FIG. 6, the pressure plate is provided only on the upper side.

In FIG. 1, a seal hardening jig (lower plate) 1 and a seal hardening jig (upper plate) 2 are held by columns 3. In addition, the airbag 4 using silicone rubber
Is provided on the seal hardening jig (upper plate) 2, and air (air or nitrogen gas) is introduced from the air introduction port 5. Then, the spacer 31 is sprinkled on one of the first and second substrates 10 and 20, the seal material 34 is printed on the other, and the two substrates are overlaid and the seal curing jig (lower plate) 1 The first and second substrates 10 and 20 with the sealing material 34 interposed therebetween are placed on the top, and the pressure plate 6 is set on the first substrate 10. After that, air is introduced into the airbag 4 from the air introduction port 5 to inflate the airbag 4 and
The substrates 10 and 20 are pressurized. Then, the sealing material 34 is fired at a temperature necessary for curing the sealing material 34, for example, 140 to 160 ° C. to cure the sealing material 34.

The pressure plate 6 is made of glass or ceramic, and has a plate thickness of 5 to 20 mm and flatness of ± 0.05 μm or less. In addition, the size of the pressure plate should be within the seal range <
The pressure plate size is smaller than the substrate size, and in this embodiment, L1 / L2 is in the range of 60 to 80%.

The first and second seal hardening jigs are used.
By curing the sealant while applying pressure to the substrates 10 and 20, it is possible to obtain a highly accurate cell gap. Further, FIG. 2 shows another embodiment of the seal hardening jig. In the structure shown in FIG. 2, the pressure plate 6 has a size larger than those of the first and second substrates 10 and 20, and instead, the seal hardening jig (lower plate) 1 is provided with the pressure portion 1a. The range is <size of pressing portion 1a <size of substrate. According to this embodiment, the accuracy of the cell gap can be increased as in the case shown in FIG.

Next, the size of the pressure plate 6 (or the pressure portion 1a) will be described. In FIG. 3, the lateral size of the pressing plate 6 (or the pressing portion 1a) is defined as the sealing range (B
It should be larger than 1) and smaller than the board outline (A1). Also, the vertical size is larger than the seal range (B2),
Make it smaller than the board outline (A2). The panel outline shown by the dotted line in the figure shows a cut portion when the size of the liquid crystal display element is determined by cutting the glass substrates 10 and 20 after the sealing material is cured by the process of this embodiment.

Further, FIG. 4 shows an example in which four liquid crystal display elements are taken out from one substrate. in this case,
The lateral size of the pressing plate 6 (or the pressing portion 1a) is made larger than the sealing range (B3) and smaller than the substrate outer shape (A3). Also, the vertical size is the seal range (B4)
It should be larger and smaller than the board outline (A4). After the sealing material is cured, the portion shown by the dotted line in the figure is cut to take out four liquid crystal display elements.

Incidentally, in the case shown in FIGS. 3 and 4,
Make L1 / L2 equal in the horizontal and vertical sizes of the pressure plate 6 (or the pressure portion 1a) and set it to 30%.
With the above, the cell gap accuracy is ± 0.
The accuracy can be 1 μm. Further, if L1 / L2 is 45% or more, an accuracy of ± 0.05 μm can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a seal hardening jig showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the seal hardening jig.

FIG. 3 is an explanatory diagram for explaining a size of a pressure plate.

FIG. 4 is an explanatory diagram illustrating a size of a pressure plate when four liquid crystal display elements are taken out from one substrate.

FIG. 5 is a cross-sectional view showing a configuration of a liquid crystal display element.

FIG. 6 is a configuration diagram showing a conventional seal hardening jig.

FIG. 7 is a configuration diagram of an experimental device used in an experiment for obtaining the cell gap accuracy by changing the size of the pressure plate.

FIG. 8 is a graph showing a cell gap difference with respect to a ratio of L1 and L2.

9 is a partial configuration diagram showing bending at an end portion of a glass substrate when the conventional seal hardening jig shown in FIG. 6 is used.

FIG. 10 is a graph showing the relationship between the cell gap near the sealing material and the cell gap of the display unit.

FIG. 11 is a graph showing the relationship between the seal outer gap difference and the seal material neighboring cell gap.

[Explanation of symbols]

1 ... Seal hardening jig (lower plate), 2 ... Seal hardening jig (upper plate), 4 ... Air bag, 6 ... Pressure plate, 10 ...
First substrate, 20 ... Second substrate, 30 ... Liquid crystal, 31
…… Spacer, 33 …… Seal spacer, 34 …… Seal material.

Claims (5)

[Claims] 1. A first substrate and a second substrate are bonded together with a sealing material therebetween, and then the sealing material is cured while pressing the first and second substrates, and then the first substrate is bonded. A method of manufacturing a liquid crystal display device by injecting a liquid crystal between the first substrate and the second substrate to manufacture a liquid crystal display device, wherein the sealing material is cured while pressing the first and second substrates. Is for positioning a pressure member on at least one of the first and second substrates and applying pressure to the first and second substrates using an air bag. Larger than the range of seal material formation,
Further, the method of manufacturing a liquid crystal display element, wherein the pressing is performed with an area having a range smaller than the outer shapes of the first and second substrates. 2. The liquid crystal display element according to claim 1, wherein the pressure member is located on the first substrate, and pressure is applied by the airbag from above the pressure member. Manufacturing method. 3. The liquid crystal according to claim 1, wherein the pressure member is located below the second substrate, and pressure is applied by the airbag from above the second substrate. Display element manufacturing method. 4. A ferroelectric liquid crystal or an anti-ferroelectric liquid crystal is used as the liquid crystal, and the distance from the forming range of the sealing material to the outer shape of the pressure member is L1. When the distance from the outer shape of the second board is L2, L
The ratio 1 / L2 is 30% or more.
4. The liquid crystal display device according to any one of items 3 to 3. 5. A ferroelectric liquid crystal or an antiferroelectric liquid crystal is used as the liquid crystal, and the distance from the forming range of the sealing material to the outer shape of the pressing member is L1, and the sealing material and the first and second When the distance from the outer shape of the second board is L2, L
The ratio 1 / L2 is 45% or more.
4. The liquid crystal display device according to any one of items 3 to 3.