JP2005215306A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which is manufactured with high productivity, and is suppressed from the occurrence of defective injection of a liquid crystal material caused by deficiency in a sealing material. <P>SOLUTION: The liquid crystal display device includes a first substrate 1, a second substrate 2 placed opposite to the first substrate 1, a liquid crystal layer 3 disposed between them and a seal part 4 which bonds the first substrate 1 and the second substrate 2 to each other and further surrounds the liquid crystal layer 3. The seal part 4 has a seal pattern which surrounds the liquid crystal layer 3 as multiple seals. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to a highly productive liquid crystal display device.

  2. Description of the Related Art In recent years, liquid crystal display devices have been widely used for OA equipment such as personal computers and AV equipment such as video cameras, taking advantage of their thinness and low power consumption.

  A liquid crystal display device performs display by using electro-optical characteristics of a liquid crystal layer provided between a pair of substrates. As a method for forming a liquid crystal layer between substrates, a method called a vacuum injection method has been conventionally used. In the vacuum injection method, first, a pair of substrates are bonded together through a sealing material, then a liquid crystal material is injected from an opening (called an injection hole) provided in a part of the sealing material, and finally the opening Is sealed with a sealing material to form a liquid crystal layer.

  Recently, a technique called a liquid crystal dropping method as disclosed in Patent Document 1 has also been proposed. In the liquid crystal dropping method, first, a liquid crystal material is dropped on one substrate, and then this substrate is bonded to the other substrate provided with a sealant, thereby forming a liquid crystal layer.

In both the vacuum injection method and the liquid crystal dropping method, when the liquid crystal material is spread in the region surrounded by the sealing material, the region is in a vacuum state and is in a vacuum state with the outside under atmospheric pressure. The pressure difference from this region is used.
JP-A 63-179323

  However, in any of the methods, if a part of the sealing material is lost during the process, the atmosphere flows into a region surrounded by the sealing material, and the region cannot be kept in a vacuum state. For this reason, the liquid crystal material cannot be sufficiently spread over the entire region surrounded by the sealing material, resulting in poor injection of the liquid crystal material and a decrease in yield.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly productive liquid crystal display device in which the occurrence of defective injection of the liquid crystal material due to the loss of the sealing material is suppressed. is there.

  A liquid crystal display device according to the present invention includes a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, and the first substrate. A seal part that adheres the second substrate to each other and surrounds the liquid crystal layer, and the seal part has a seal pattern that surrounds the liquid crystal layer in multiple layers. Achieved.

  In a preferred embodiment, the seal pattern double surrounds the liquid crystal layer.

  In a preferred embodiment, the seal portion includes first and second seal materials each surrounding the liquid crystal layer, and the first and second seal materials form the seal pattern.

  Alternatively, the liquid crystal display device according to the present invention includes a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, and the first substrate. A first and a second sealing member provided to bond the substrate and the second substrate to each other and to surround the liquid crystal layer, the sealing portions being provided so as to surround the liquid crystal layer, respectively. The above object is achieved by having a sealing material.

  In a preferred embodiment, each of the first and second sealing materials is annular.

  The seal part preferably includes a plurality of intersections where the first seal material and the second seal material intersect.

  The seal part preferably has four or more intersecting parts.

  In a preferred embodiment, each of the first and second sealing materials includes a main sealing material having an opening for injecting a liquid crystal material, and an end sealing material that fills the opening of the main sealing material. Have

  In a preferred embodiment, each of the first and second sealing materials has only a main sealing material having no opening for injecting a liquid crystal material.

  The liquid crystal display device according to the present invention includes a seal portion having a seal pattern that wraps around the liquid crystal layer in multiple layers. Occurrence is suppressed. Therefore, the liquid crystal display device according to the present invention has a high yield and high productivity.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

  FIG. 1 schematically shows a cross-sectional structure of a liquid crystal display device 100 according to this embodiment. As shown in FIG. 1, the liquid crystal display device 100 includes a first substrate (for example, an active matrix substrate) 1, a second substrate (for example, a counter substrate (color filter substrate)) 2 that faces the first substrate 1, and a first substrate. A liquid crystal layer 3 provided between the substrate 1 and the second substrate 2, and a seal portion 4 that bonds the first substrate 1 and the second substrate 2 to each other and surrounds the liquid crystal layer 3 are provided. . The liquid crystal layer 3 in the present embodiment is formed using a so-called liquid crystal dropping method.

  Next, the structure of the seal portion 4 will be described in detail with reference to FIGS. 1 and 2. FIG. 2 is a top view schematically showing the liquid crystal display device 100, and a region surrounded by a broken line in FIG. 2 is a display region.

  As shown in FIGS. 1 and 2, the seal portion 4 has a seal pattern that doublely surrounds the liquid crystal layer 3. Specifically, the seal portion 4 includes a first seal material 4 a and a second seal material 4 b provided so as to surround the liquid crystal layer 3. Each of the first seal material 4a and the second seal material 4b is formed in an annular shape (frame shape), and the first seal material 4a and the second seal material 4b form the above-described seal pattern. .

  Here, the structure of the seal portion of the conventional liquid crystal display device is shown in FIG. In the conventional liquid crystal display device 500 shown in FIG. 3A, the seal portion 504 has a seal pattern that surrounds the liquid crystal layer 503 in a single layer. Accordingly, as shown in FIG. 3B, if a part of the sealing material constituting the seal portion 504 is lost during the manufacturing process, the liquid crystal material is expanded in the region surrounded by the seal portion 504 (originally Atmosphere flows from the outside into the area maintained in a vacuum state), resulting in poor injection of the liquid crystal material.

  On the other hand, the liquid crystal display device 100 according to the present embodiment includes a seal portion 4 having a seal pattern that doublely surrounds the liquid crystal layer 3 as shown in FIGS. 1 and 2. Therefore, as shown in FIGS. 4A and 4B, even if a part of one of the first sealing material 4a and the second sealing material 4b is lost during the manufacturing process, the sealing is performed. The region surrounded by the portion 4 is isolated from the outside by the other sealing material. For this reason, in the step of expanding the liquid crystal material, the atmosphere does not flow from the outside into the region surrounded by the seal portion 4, and the occurrence of defective injection of the liquid crystal material can be suppressed. In the liquid crystal display device 100, an injection failure occurs only when a defect occurs in both the first sealing material 4a and the second sealing material 4b. It becomes possible to make it about 1/2.

  Next, a preferable structure of the seal portion 4 will be described with reference to FIG.

  The seal portion 4 shown in FIG. 5 has a plurality of intersecting portions a, b, c, and d where the first seal material 4a and the second seal material 4b intersect with each other. Different from part 4. Even when the seal part 4 shown in FIG. 5 is used, as shown in FIGS. 6 (a) and 6 (b), poor injection occurs when a defect occurs in one of the first seal material 4a and the second seal material 4b. Can be prevented. When the seal portion 4 shown in FIG. 5 is used, since the first seal material 4a and the second seal material 4b intersect at a plurality of locations, the first seal material 4a and the second seal material 4b are used. Even if a defect occurs in both of them, there is an advantage that an injection defect does not occur unless both the defect portions are located between the same intersections. For example, when a defect occurs between the intersecting part a and the intersecting part b in the first sealing material 4a, even if a defect occurs in the second sealing material 4b, the missing part is the intersecting part a and the intersecting part b. As long as it is not between, injection failure does not occur. Therefore, when the seal part 4 employs a configuration having a plurality of intersections of the first seal material 4a and the second seal material 4b, it is possible to more reliably suppress the occurrence of poor injection. For example, when the seal part 4 has four intersections as shown in FIG. 5, the probability of injection failure is reduced to about 1/4 compared to the case where the seal part 4 has no intersections as shown in FIG. be able to.

  Depending on the missing portion of the sealing material, as shown in FIG. 4A and FIG. 6B, the liquid crystal material flows between the first sealing material 4a and the second sealing material 4b, The amount of liquid crystal material injected into the region where the liquid crystal material is originally to be injected is insufficient, and the cell gap (thickness of the liquid crystal layer 3) may vary accordingly. When the first sealing material 4a and the second sealing material 4b intersect at a plurality of locations, as shown in FIG. 5, the first sealing material 4a and the second sealing material 4b are crossed by the intersection. The enclosed area is divided into a plurality of areas. Therefore, as can be seen by comparing FIG. 4A and FIG. 6B, the amount of liquid crystal material flowing between the first sealing material 4a and the second sealing material 4b is reduced, The amount of the insufficient liquid crystal material can be reduced, and the variation amount of the cell gap can be reduced.

  Although FIG. 5 illustrates the case where the seal portion 4 is provided with four intersections, the number of intersections is not limited thereto. The above-described effects can be obtained by providing a plurality (two or more) of intersecting portions in the seal portion 4. Therefore, two or three intersections may be provided, or more than four intersections may be provided as shown in FIG. From the viewpoint of more reliably suppressing the occurrence of poor injection and further reducing the amount of change in the cell gap due to the shortage of liquid crystal material, the number of intersections is preferably large, and is preferably 4 or more.

  The liquid crystal display device 100 according to the present invention can have the same configuration as a known liquid crystal display device except for the structure of the seal portion 4. Therefore, the liquid crystal display device according to the present invention can be manufactured by forming the seal portion 4 so as to have a seal pattern that doublely surrounds the liquid crystal layer 3 in a known liquid crystal display device manufacturing method. it can.

  The seal portion 4 may be formed using, for example, a screen printing method, or may be formed by applying a material using a dispenser. The same applies to the case where the seal portion 4 has an intersection of the first seal material 4a and the second seal material 4b. When the screen printing method is used, the first sealing material 4a, the second sealing material 4b, and the intersecting portions thereof are formed at the same time, so that the intersecting portions can be provided without any particular limitation. When using a dispenser, after forming one sealing material among the first sealing material 4a and the second sealing material 4b, the other sealing material is formed. Therefore, from the viewpoint of suitably forming the intersecting portion, it is preferable that the height of the sealing material formed first is less than 50 μm. In the case of using a dispenser, since application is generally performed while controlling the application gap with a laser displacement meter, it is easy to form the intersection of the sealing materials.

  It has already been described that the liquid crystal material flows into the region between the first sealing material 4a and the second sealing material 4b and the cell gap varies depending on the missing portion of the sealing material. Therefore, the distance between the first sealing material 4a and the second sealing material 4b and the number of intersections thereof are determined by the inflow of the liquid crystal material between the first sealing material 4a and the second sealing material 4b. It is preferable to determine that the variation amount of the cell gap is within the allowable range even if the error occurs. Hereinafter, this point will be specifically described with reference to FIGS. 8A to 8C in the case where the seal portion 4 has four intersecting portions as shown in FIG.

As shown in FIG. 8 (a), when the seal material is free of defects, the cell gap x ₁ is defined by assuming that the length of the long side of the region surrounded by the seal portion 4 is A and the length of the short side is B. And the injection amount V of the liquid crystal material satisfy the relationship of V = A · B · x ₁ .

As shown in FIG. 8B, when a defect occurs in a portion that defines the long side of the region surrounded by the seal portion 4 in the second seal material 4b, this portion of the second seal material 4b Assuming that the distance from the first sealing material 4a is C and the injection amount of the liquid crystal material is invariable (= V), the cell gap x _{2 at} this time has a relationship of V = (B + C) · A · x ₂ . Satisfied. Accordingly, the ratio between the cell gap x ₁ and the cell gap x ₂ satisfies the relationship x ₁ : x ₂ = (B + C): B.

As shown in FIG. 8C, when a defect occurs in a portion that defines the short side of the region surrounded by the seal portion 4 in the second seal material 4b, this portion of the second seal material 4b Assuming that the distance from the first sealing material 4a is D and the amount of liquid crystal material injected is unchanged (= V), the cell gap x _{3 at} this time is expressed as V = (A + D) · B · x ₃ . Satisfied. Therefore, the ratio between the cell gap x ₁ and the cell gap x ₃ satisfies the relationship x ₁ : x ₃ = (A + D): A.

Here, for example, assuming that the ideal cell gap is 4.0 μm and the allowable range of the variation amount of the cell gap is 0.2 μm, it is preferable that x ₁ / x ₂ ≦ 4.0 / 3.8, _{Since 1} : x ₂ = (B + C): B, it is preferable that C ≦ (1/19) · B. That is, the interval C is preferably 1/19 or less of the short side length B of the region surrounded by the seal portion 4. Similarly, D ≦ (1/19) · A is preferable, and the distance D is preferably 1/19 or less of the length A of the long side of the region surrounded by the seal portion 4.

  The preferable conditions for the intervals C and D differ depending on the ideal cell gap and the allowable range of the variation amount of the cell gap. For example, if the ideal cell gap is also 4.0 μm and the allowable range of variation is 0.1 μm, the interval C is preferably 1/39 or less of the short side length B, and the interval D is The long side length A is preferably 1/39 or less. Further, when the ideal cell gap is 5.0 μm and the allowable range of variation is 0.2 μm, the interval C is preferably 1/24 or less of the short side length B, and the interval D is It is preferable that it is 1/24 or less of the length A of the long side. Since the allowable range of the cell gap (ideal cell gap) and the variation amount of the cell gap differs for each panel, it is preferable to determine the structure of the seal portion 4 in consideration of these.

  The first sealing material 4a and the second sealing material 4b are typically formed inside the terminal portion located on the outer periphery of the liquid crystal display device, but the first sealing material 4a and the second sealing material are formed. One of the materials 4b may be formed inside the terminal portion and the other may be formed outside the terminal portion.

  The cause of the loss of the seal part 4 is that the pressure difference between the area surrounded by the seal part 4 at the time of bonding and pressing of the substrate and the outside, and the foam during application using screen printing or a dispenser Examples include chewing. Also in the structure of the conventional seal part 504 shown in FIG. 3A, the seal part 504 is not damaged due to a pressure difference by increasing the width of the seal part 504 (the width of the seal material constituting the seal part 504). Although it can suppress and a yield can be raised to some extent, in this case, the defect | deletion of the seal part 504 by bubble biting cannot be suppressed. On the other hand, the liquid crystal display device 100 according to the present invention is excellent in that an injection failure can be suppressed even if the seal part 4 is lost due to the bubble biting.

  In the above description, the present invention has been described with respect to the case where the liquid crystal layer 3 is formed using the liquid crystal dropping method. However, the present invention is also used when the liquid crystal layer 3 is formed using the vacuum injection method. be able to.

  9A and 9B show another liquid crystal display device 100 'according to the present invention. In the liquid crystal display device 100 ′ shown in FIGS. 9A and 9B, the liquid crystal layer 3 is formed using a vacuum injection method.

  As shown in FIGS. 9A and 9B, the seal portion 4 ′ included in the liquid crystal display device 100 ′ also includes a first seal material 4a and a second seal material 4b that surround the liquid crystal layer 3, respectively. The liquid crystal layer 3 has a sealing pattern that doublely surrounds it. However, each of the first sealing material 4a and the second sealing material 4b includes a main sealing material having an opening e for injecting a liquid crystal material and an end sealing material filling the opening e of the main sealing material. Have. In FIGS. 9A and 9B, the end seal material is not shown, but the opening e of the main seal material is actually sealed by the end seal material (also called a seal material), The liquid crystal layer 3 is completely surrounded by each of the first sealing material 4a and the second sealing material 4b. In the liquid crystal display device 100 in which the liquid crystal layer 3 is formed by the liquid crystal dropping method, the first sealing material 4a and the second sealing material 4b are only main sealing materials that do not have openings for injecting the liquid crystal material. have.

  Since the liquid crystal display device 100 ′ also includes the seal portion 4 ′ having a seal pattern that doublely surrounds the liquid crystal layer 3, as in the liquid crystal display device 100, the occurrence of defective injection of the liquid crystal material can be suppressed. And high productivity. From the viewpoint of more reliably suppressing the occurrence of defective injection of the liquid crystal material and further reducing the amount of fluctuation of the cell gap, the seal portion 4 ′ has the first seal material 4 a and the second seal material as shown in FIG. The configuration in which the seal portion 4 ′ has a plurality of intersections between the first seal material 4a and the second seal material 4b as shown in FIG. Is preferred.

  On the other hand, in the conventional liquid crystal display device 600 as shown in FIG. 10, since the seal portion 604 has a seal pattern that surrounds the liquid crystal layer 603 in a single layer, the seal portion 604 is provided during the manufacturing process. If a part of the sealing material constituting the chip is lost, in the process of expanding the liquid crystal material, the atmosphere flows from the outside into the region surrounded by the seal portion 604 (the region that is originally kept in a vacuum state), and the liquid crystal material is poorly injected. Will occur.

  As described above, the liquid crystal display devices 100 and 100 ′ according to the present invention have a high yield and high productivity. In the present embodiment, a seal pattern that doublely surrounds the liquid crystal layer 3 is shown. However, the seal pattern may surround the liquid crystal layer 3 in multiple layers, and the seal pattern may surround the liquid crystal layer 3 more than triple. . By using a seal pattern that surrounds the liquid crystal layer 3 in multiple layers, the yield can be increased and the productivity can be improved.

  According to the present invention, there is provided a liquid crystal display device with high productivity in which occurrence of defective injection of a liquid crystal material due to a sealing material defect is suppressed. The present invention

It is sectional drawing which shows the liquid crystal display device by this invention typically. It is a top view which shows typically the liquid crystal display device by this invention. (A) is a top view which shows typically the structure of the seal | sticker part of the conventional liquid crystal display device, (b) has a defect | deletion in the sealing material which comprises a seal part in the conventional liquid crystal display device. It is a figure which shows a mode typically. (A) And (b) is a figure which shows typically a mode that the defect | deletion has arisen in the sealing material in the liquid crystal display device by this invention. It is a top view which shows typically the other structure of the seal | sticker part with which the liquid crystal display device by this invention is provided. (A) And (b) is a figure which shows typically a mode that the defect | deletion has arisen in the sealing material in the liquid crystal display device by this invention. It is a top view which shows typically the other structure of the seal | sticker part with which the liquid crystal display device by this invention is provided. (A), (b) and (c) is a figure for demonstrating the suitable dimension of a seal | sticker part. (A) And (b) is a top view which shows typically the other liquid crystal display device by this invention. It is a top view which shows typically the structure of the seal | sticker part of the conventional liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 2nd board | substrate 3 Liquid crystal layer 4, 4 'Seal part 4a 1st sealing material 4b 2nd sealing material 100, 100' Liquid crystal display device

Claims (9)

A first substrate;
A second substrate facing the first substrate;
A liquid crystal layer provided between the first substrate and the second substrate;
A seal part for adhering the first substrate and the second substrate to each other and surrounding the liquid crystal layer;
The liquid crystal display device, wherein the seal portion has a seal pattern surrounding the liquid crystal layer in multiple layers.   The liquid crystal display device according to claim 1, wherein the seal pattern doublely surrounds the liquid crystal layer.   3. The liquid crystal display device according to claim 2, wherein each of the sealing portions includes first and second sealing materials that surround the liquid crystal layer, and the first and second sealing materials form the sealing pattern. A first substrate;
A second substrate facing the first substrate;
A liquid crystal layer provided between the first substrate and the second substrate;
A seal part for adhering the first substrate and the second substrate to each other and surrounding the liquid crystal layer;
The liquid crystal display device, wherein the seal portion includes first and second seal materials provided so as to surround the liquid crystal layer.   5. The liquid crystal display device according to claim 3, wherein each of the first and second sealing materials is annular.   6. The liquid crystal display device according to claim 3, wherein the seal portion includes a plurality of intersecting portions where the first seal material and the second seal material intersect.   The liquid crystal display device according to claim 6, wherein the seal portion has four or more intersections.   Each of the first and second sealing materials has a main sealing material having an opening for injecting a liquid crystal material and an end sealing material filling the opening of the main sealing material. A liquid crystal display device according to any one of the above. 8. The liquid crystal display device according to claim 3, wherein each of the first and second sealing materials has only a main sealing material having no opening for injecting a liquid crystal material.

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