JP2008026416A - Method of manufacturing liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a liquid crystal display element capable of suppressing a defective fraction while reducing a dead space. <P>SOLUTION: A sealant is applied onto at least either one of a pair of substrates. The pair of glass substrates are superposed on each other, the sealant is cured and the pair of glass substrates are stuck to each other with an interval. After the surface of the pair of glass substrates is scribed at a nearly center part on the cured sealant, the pair of glass substrates are warmed in a furnace. The glass substrates are cut by giving impact upon or applying pressure to the scribed surface of the pair of glass substrates to expose the sealant at each glass edge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a device using liquid crystal, and more particularly to a method for manufacturing a liquid crystal display element.

The liquid crystal cell has a structure in which liquid crystal is sandwiched between two glass substrates provided with a transparent electrode for display and an alignment film for aligning liquid crystal. In the conventional method, these two glass substrates are bonded to each other with a sealant. Conventional sealing agents have been applied at some distance from the glass edge. Reasons for placing a certain distance from the glass edge are as follows: (1) If the seal edge has poor linearity, and a part of the sealant is applied to the scribe line when the cell is scribed / cut from the glass substrate, that part is the starting point. There is a greater risk of being cut off the predetermined scribe line.
(2) When multi-chamfering is used, if there is some distance between the sealing agents between adjacent cells, cut defects will occur, or if adjacent sealing agents stick together, they will be left behind during firing of the sealing agent. The seal may break due to expansion of the air.
Etc.

  Therefore, in a conventional liquid crystal cell, a certain amount of space (usually 0.5 mm to 1.0 mm) must be provided outside the seal, and therefore, the space between the effective display area and the cell edge must be divided by the seal width and the space outside the seal. There is. In practice, this space is a dead space.

  In view of the design of the liquid crystal panel or in terms of space, it is desired to reduce the dead space from the standpoint of reducing the distance between the effective display area and the cell edge as much as possible and from the viewpoint of effective use of materials. In particular, in small portable electronic devices, the demand for liquid crystal cells with little dead space is increasing. Japanese Patent Application Laid-Open No. 2003-255362 proposes a method of cutting a liquid crystal cell by inserting scribe lines on the upper and lower substrates so as to overlap the sealing agent. In this method, a space outside the sealant is not necessary, and therefore, the dead space can be reduced.

JP 2003-255362 A

  Currently, other methods for reducing dead space are also being studied. The objective of this invention is providing the manufacturing method of the liquid crystal display element which can suppress a defect rate, reducing dead space.

  According to one aspect of the present invention, a step of applying a sealant to at least one of a pair of glass substrates, the pair of glass substrates are overlapped, the sealant is cured, and the pair of glass substrates are attached with a gap. A step of combining, a step of scribing at a substantially center on the cured sealant on the surface of the pair of glass substrates, and then heating the pair of glass substrates in a furnace, and a scribed surface of the pair of glass substrates A method of manufacturing a liquid crystal display element is provided, which includes a step of cutting the glass substrate by applying an impact to the substrate or pressurizing the glass substrate, and placing the sealing agent on the glass edge.

  Dead space around the sealant can be reduced. Further, the occurrence rate of cut defects can be suppressed.

(Example 1)
FIG. 1 is a conceptual diagram showing a cutting process of a liquid crystal cell according to the first embodiment. In this embodiment, as shown in FIG. 1, after scribing a glass substrate (large plate) 1 at the position of the sealant 2, the large plate 1 is heated in a heating furnace 3 and then cut. The defect rate is reduced by suppressing defects.

  FIG. 2 is a plan view showing a substrate structure in the case of manufacturing a one-chamfered liquid crystal display element from the large plate 1. A liquid crystal cell before being cut out surrounded by the sealant 2 is disposed at substantially the center of the large plate 1. An alignment film for aligning liquid crystal molecules is applied to a portion surrounded by the sealant 2, and the portion becomes an effective display region 4. However, since the orientation of the sealant 2 may be disturbed, the effective display area 4 is an area 0.5 mm or more inside the sealant 2 inner wall.

  Assuming that the seal width in the finished design is 1 mm, the scribing / cutting is performed at the center of the sealant 2 (excluding the side with the terminal), so the width of the sealant 2 before the cut is 2 mm.

  The rectangular frame-shaped sealing agent surrounding the effective display area 4 is provided with one or more cuts, and the cuts serve as an inlet for introducing liquid crystal in a subsequent vacuum injection process. Called.

  A method for manufacturing a liquid crystal display element will be described. An alignment film is applied and fired on each of the pair of large plates 1 having electrodes made of indium tin oxide (ITO). Thereafter, each large plate 1 is rubbed as necessary.

  An epoxy-based thermosetting sealant 2 is applied to at least one of the pair of large plates 1 after rubbing, a gap control material is applied, the pair of large plates 1 are overlapped, and the sealant 2 is baked and cured. Let A pair of large plates 1 are bonded together by the sealant 2, and a space for accommodating liquid crystal is formed between the large plates. The sealing agent 2 serves as a wall on the side surface except for the injection port 5.

  Next, the large plate 1 is scribed. For example, a superalloy wheel cutter is used for scribing. The scribe line 6 is basically formed at the center in the seal width direction.

  The liquid crystal display element has a portion connected to an external drive circuit, that is, a terminal 7. In this embodiment, a so-called single-terminal type liquid crystal display element having terminals only on one side will be described. The scribe line 6 on the side to which the terminal 7 belongs is formed so as to be shifted by the terminal width on the upper and lower substrates. That is, the scribe line 6 on the side of the substrate on which the terminal 7 is not provided is formed along the sealant 2, and the scribe line 6 is formed so that the terminal comes out of the sealant 2 on the other substrate. The scribe lines 6 on the other sides are formed at the same position vertically.

  Next, as shown in FIG. 1, the scribed large plate 1 is placed in a hot air circulation type heating furnace (constant temperature furnace) 3 and heated at 120 ° C. for 10 minutes. In addition, as for the temperature to heat, as a result of experiment, it turns out that 100 degreeC or more is preferable.

  FIG. 3 is a schematic sectional view showing the cutting method. As shown in FIG. 3, the pair of large plates 1 bonded together with the sealing agent 2 is cut along the scribe lines 6. The cutting is performed by placing the large plate 1 on a stage 8 having an appropriate elasticity such as rubber and pressing it from above with a squeegee 9 having an appropriate hardness such as rubber or by hitting it from above. Do. Thereby, the sealing agent 2 is cut | disconnected with a glass substrate, and the sealing agent 2 is arrange | positioned at the edge (terminal part) of a liquid crystal cell.

  Finally, liquid crystal is injected, and the injection port 5 is sealed to complete a liquid crystal display element.

  FIG. 4 shows a plan view of the completed liquid crystal display element. The dimensions are 28.5 mm long x 85 mm wide x 1.4 mm thick. Since the center of the seal width of 2 mm is scribed and cut, the cell seal width is 1 mm. No extra space is created outside the sealant 2. The effective display area 4 is an area 1 mm inside from the inner wall of the sealant 2. Accordingly, the distance between the effective display area 4 and the cell edge is 2 mm, and so-called dead space other than the effective display area 4 can be reduced.

  FIG. 5 shows a cross-sectional view of the liquid crystal display element. A segment substrate 1S, which is an upper substrate, and a common substrate 1C, which is a lower substrate, are bonded with a sealant 2, and liquid crystal 12 is sealed between the upper and lower substrates with the sealant 2 as a side wall. An upper electrode 10t (lower electrode 10u) is formed under (upper) the upper substrate 1S (lower substrate 1C). Since the lower substrate 1C and the lower electrode 10u have portions to be terminals, the vertical or horizontal length is longer than that of the upper substrate 1S, and the sealant 2 is applied in accordance with the position of the upper substrate 1S.

  Alignment films 11t and 11u are formed inside the upper and lower electrodes 10t and 10u, respectively.

  Note that a method called a dropping injection method may be used in which a predetermined amount of liquid crystal is dropped in advance before bonding the upper and lower substrates and a liquid crystal display element is manufactured without providing an injection port by superposing them in a vacuum.

FIG. 6 is a plan view showing a one-chamfered substrate structure formed by a dropping injection method. As shown in FIG. 6, when the dropping injection method is used, it is not necessary to provide an injection port, so that the sealing agent 2 has a complete rectangular frame shape. Similar to the vacuum injection method, a scribe line 6 is provided at the center in the width direction of the sealant 2.
(Example 2)
An example in the case of so-called multi-chamfering, in which a plurality of liquid crystal display elements having the same shape are manufactured from a large plate will be described.

  There are two typical methods of multi-chamfering, a normal imposition method and a reversible imposition method. First, multi-chamfering using the reversible imposition method will be described.

  FIG. 7 is a plan view showing the multi-chamfering imposition by the reversible imposition method. The board to which the terminal belongs is the common board, the board to which the terminal does not belong is the segment board, the common board is represented by the symbol “A”, and the segment board is represented by “B”. The reversible imposition method is a method in which a common substrate and a segment substrate are formed on a single large plate, and A and B are arranged side by side (for example, A and B are arranged vertically and the terminals are in the middle) As shown in FIG. 7, the rows A and B are alternately imposed using a photomask (which is arranged in FIG. 7). The same can be used for the other large plate. However, attention must be paid to the direction so that A and B are overlapped with each other in a predetermined relationship when bonded. The reversible imposition method is an effective method for TN-LCD (twisted nematic liquid crystal display), STN-LCD (super twisted nematic liquid crystal display), vertical alignment type LCD and the like.

  FIG. 8 is a plan view showing a structure in the case of manufacturing a multi-faced liquid crystal display element from a large plate 1 having a prescribed size (length 150 mm × width 300 mm × thickness 0.7 mm) by a reversible imposition method. Here, the side to which the terminal 7 belongs is one side. A plurality of rectangular liquid crystal display elements surrounded by a sealing agent 2 are defined on the large plate 1. The shape of the sealing agent 2 is not a simple rectangular frame, but a frame shape formed by three sides of a straight line and one side including a convex portion (injection port 5) on the outside.

  A method for producing a liquid crystal display element will be described. A plurality of alignment films corresponding to the respective liquid crystal display elements are applied and fired on a pair of large plates 1 having a plurality of electrodes made of indium tin oxide (ITO). The planar dimension of the alignment film is the same as the planar dimension of the effective display area after completion, and is formed with a space for applying the sealant 2. Thereafter, the large plate 1 is rubbed as necessary.

  The epoxy thermosetting sealant 2 is applied to at least one of the pair of large plates 1 after rubbing in accordance with the size of the liquid crystal display element to be cut out, and after further spraying a gap control material, the pair of large plates 1 are stacked. In addition, the sealant 2 is baked and cured. A pair of large plates 1 are bonded together by the sealant 2, and a space for accommodating liquid crystal is formed between the large plates. The sealing agent 2 serves as a wall on the side surface except for the injection port 5.

  Next, the large plate 1 is scribed. The scribe line 6 is basically formed at the center in the seal width direction. However, when the vacuum injection method is used in multi-chamfering, the side to which the injection port 5 belongs, the side facing the injection port 5, and the side to which the terminal belongs cannot be scribed on the sealant 2. A scribe line 6 is formed on the sealant 2 only on one side.

  Next, as shown in FIG. 1, the scribed large plate 1 is placed in a hot air circulation type constant temperature furnace 3 and heated at 120 ° C. for 10 minutes. In addition, regarding the temperature to heat, it is the same as that of Example 1. FIG.

  Next, after taking out the large board 1 from a thermostat, it cuts according to each scribe line 6. The cutting method is the same as in Example 1.

  Liquid crystal is injected into each cut cell, and the injection port 5 is sealed to complete a liquid crystal display element.

  FIG. 9 is a plan view of the completed liquid crystal display element. The dimensions are 28.5 mm long x 85 mm wide x 1.4 mm thick. As for the sealing agent 2, only one side is arrange | positioned at the glass edge, The width | variety is 1 mm. The distance from the glass edge to the sealing agent 2 is 1 mm at the side where the sealing agent 2 is not present on the glass edge, and the distance from the inner wall of the sealing agent 2 in the effective display area 4 surrounded by the sealing agent 2 is 1 mm. .

  FIG. 10 is a plan view showing a substrate structure in a method for producing a multi-panel liquid crystal display element to which the dropping injection method is applied. As shown in FIG. 10, scribe lines 6 are formed so that cutting is performed on the sealant 2 on three sides excluding the side to which the terminal 7 belongs. When scribing and cutting in this way, the liquid crystal display element as shown in FIG. 4 is completed, and the dead space is reduced.

In addition, as a multi-surface drawing method, a normal imposition method in which a large plate scribed only in the A row and a large plate scribed only in the B row may be used.
(Comparative example)
As a comparative example, a method of not heating the large plate 1 after scribing was performed. As a prior art, there is a method of scribing and cutting the large plate 1 without heating at the position of the sealing agent 2, and the method is the same as the above embodiment except for the step of heating in the heating furnace 3. . This technique has been applied to both single and multi-chamfering.
(Comparative example up to here)
In the scribe / cut method, when the substrate 1 is cut, the substrate 1 may be cut off from the scribe line 6. At that time, a non-defective product can be determined if the size of the manufactured liquid crystal display element is within the tolerance, but if it is not, it becomes defective. In addition, when the width of the sealant 2 is less than 0.5 mm, a failure is determined. However, the shape of the cut surface is not particularly limited. For example, even if the cut surface is slanted with respect to the substrate plane or the cut surface is stepped, a non-defective product is determined if the dimensions are within tolerance.

  Defects are likely to occur when the scribe lines 6 of the pair of large plates 1 are displaced up and down. In order to investigate the probability of occurrence of defects due to vertical displacement of the scribe line 6 of the large board 1, in the above comparative example, the scribe lines of the upper and lower substrates are shifted by 0.5 mm to obtain 80 sets of large boards (from 1 set to 12 sheets). The occurrence rate of defects (failure rate) was investigated. When there was no shift between the upper and lower scribe lines, the defect rate was 1.2%, whereas when there was a shift, the defect rate was 18.4%.

  On the other hand, by using this example, even when the scribe line 6 was shifted by 0.5 mm between the upper and lower large plates, an effect of reducing the defect rate to 1.6% was obtained. Furthermore, when an additional experiment was conducted, the defect rate could be suppressed to 1.3%.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, although the scribe line 6 is formed on both of the pair of large plates, the glass substrate 1 and the sealing agent 2 can be cut even if only one of them is scribed.

  Moreover, although the epoxy-type thermosetting sealing agent 2 is employed in the above-described embodiments, a sealing agent other than the epoxy-type thermosetting such as two-component type or UV-curing property can be used as long as a predetermined sealing performance can be obtained. It is considered possible to adopt.

  It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like can be made.

FIG. 1 is a conceptual diagram showing a cutting process of a substrate and a sealing agent in an example. FIG. 2 is a plan view showing a glass substrate (large plate) before cutting in the case of producing a one-sided liquid crystal display element. FIG. 3 is a schematic cross-sectional view showing a cutting method. FIG. 4 is a plan view of the liquid crystal display element. FIG. 5 is a cross-sectional view of the liquid crystal display element. FIG. 6 is a plan view showing the substrate before cutting in the case of one chamfering by the dropping injection method. FIG. 7 is a plan view showing the multi-chamfering imposition by the reversible imposition method. FIG. 8 is a plan view showing a large plate before cutting to which the vacuum injection method and the reversible imposition method are applied. FIG. 9 is a plan view showing a liquid crystal display element manufactured by using a vacuum injection method and multi-cavity. FIG. 10 is a plan view showing a substrate structure before cutting when a liquid crystal display element is formed by using a dropping injection method and multi-chamfering.

Explanation of symbols

1 Glass substrate (large plate)
1C Common substrate 1S Segment substrate 2 Sealing agent 3 Heating furnace 4 Effective display area 5 Inlet 6 Scribe wire 7 Terminal 8 Stage 9 Squeegee 10t, 10u Transparent electrode 11t, 11u Alignment film 12 Liquid crystal

Claims (3)

Applying a sealant to at least one of the pair of glass substrates;
Overlaying the pair of glass substrates, curing the sealant, and bonding the pair of glass substrates with a gap;
On the surface of the pair of glass substrates, after scribing at substantially the center on the cured sealant, heating the pair of glass substrates in a furnace;
Manufacturing a liquid crystal display element including a step of applying an impact to the scribed surfaces of the pair of glass substrates or applying pressure to cut the glass substrates to expose the sealant on the glass edges. Method.   The method for manufacturing a liquid crystal display element according to claim 1, wherein a temperature for heating the pair of glass substrates is 100 ° C. or more. further,
The manufacturing method of the liquid crystal display element of Claim 1 or 2 including the process of inject | pouring a liquid crystal between said pair of glass substrates by the dripping injection method.

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