WO2019240136A1

WO2019240136A1 - Liquid crystal display device

Info

Publication number: WO2019240136A1
Application number: PCT/JP2019/023133
Authority: WO
Inventors: 諒祐加藤; 山口　稔
Original assignee: 凸版印刷株式会社
Priority date: 2018-06-12
Filing date: 2019-06-11
Publication date: 2019-12-19
Also published as: TW202004299A; TWI703389B; JP2019215410A

Abstract

This liquid crystal display device includes: first and second substrates (11, 12); a liquid crystal layer (13) that is held between the first and second substrates (11, 12); a first seal material (21) that surrounds the liquid crystal layer (13) and that seals the liquid crystal layer (13) between the first and second substrates (11, 12); and a second seal material (22) that surrounds the first seal material (21) at an interval therefrom.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device.

Liquid crystal display devices are used not only for normal life specifications such as watches and calculators, but also for in-vehicle applications that require high reliability. Since the in-vehicle liquid crystal display device has severe conditions of use environment, it is necessary to perform a reliability test before product shipment under severe conditions. Reliability testing includes environmental testing.

In a typical liquid crystal display device, when an environmental test is performed in a high temperature and high humidity environment for a long time, moisture permeates the sealing material of the liquid crystal display device and moisture enters the liquid crystal layer. As a result of the specific resistance of the liquid crystal layer being lowered due to the moisture, a region where the retention rate of the capacitance is lowered is generated. As a result, a display defect occurs in the liquid crystal display device.

Japanese Patent No. 4302238 Japanese Unexamined Patent Publication No. 2005-156752

The present invention provides a more reliable liquid crystal display device.

A liquid crystal display device according to an aspect of the present invention includes first and second substrates, a first liquid crystal layer sandwiched between the first and second substrates, and the first liquid crystal layer. A first sealing material that seals the first liquid crystal layer between the second substrates; and a second sealing material that surrounds the first sealing material with a space therebetween.

According to the present invention, a more reliable liquid crystal display device can be provided.

FIG. 1 is a plan view of the liquid crystal display device according to the first embodiment. FIG. 2 is a cross-sectional view of the liquid crystal display device taken along line AA ′ of FIG. FIG. 3 is a diagram illustrating a specific cross-sectional structure of the liquid crystal display device. FIG. 4 is a plan view of a liquid crystal display device according to a comparative example. FIG. 5 is a plan view of the liquid crystal display device according to the second embodiment. FIG. 6 is a plan view of the liquid crystal display device according to the third embodiment. FIG. 7 is a plan view of the liquid crystal display device according to the fourth embodiment. FIG. 8 is a cross-sectional view of the liquid crystal display device taken along line BB ′ of FIG. FIG. 9 is a plan view of the liquid crystal display device according to the fifth embodiment. FIG. 10 is a cross-sectional view of the liquid crystal display device taken along line AA ′ of FIG. FIG. 11 is a plan view of a liquid crystal display device according to the sixth embodiment. FIG. 12 is a cross-sectional view of the liquid crystal display device taken along line AA ′ of FIG. FIG. 13 is a plan view of the liquid crystal display device according to the seventh embodiment. FIG. 14 is a cross-sectional view of the liquid crystal display device taken along line AA ′ of FIG.

Hereinafter, embodiments will be described with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of the drawings are not necessarily the same as actual ones. Further, even when the same portion is represented between the drawings, the dimensional relationship and ratio may be represented differently. In particular, the following embodiments exemplify an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention depends on the shape, structure, arrangement, etc. of components. Is not specified. In the following description, elements having the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

[1] First Embodiment [1-1] Configuration of Liquid Crystal Display Device 10 FIG. 1 is a plan view of a liquid crystal display device 10 according to the first embodiment. FIG. 2 is a cross-sectional view of the liquid crystal display device 10 taken along line AA ′ of FIG. In the plan view of FIG. 1, the sealing material and the sealing material are indicated by solid lines and the liquid crystal layer is indicated by dot hatching so that the configuration can be easily understood. The same applies to plan views other than FIG.

The liquid crystal display device 10 includes a TFT substrate 11 on which TFTs, pixel electrodes, and the like are formed, and a color filter substrate (CF substrate) 12 on which color filters, common electrodes, and the like are formed and disposed opposite to the TFT substrate 11. Each of the TFT substrate 11 and the CF substrate 12 is composed of a transparent substrate (for example, a glass substrate or a plastic substrate).

The liquid crystal layer 13 is filled between the TFT substrate 11 and the CF substrate 12. Specifically, the liquid crystal layer 13 is sealed in a region surrounded by the TFT substrate 11 and the CF substrate 12 and the

sealing materials

21 and 22. The specific configuration of the

sealing materials

21 and 22 will be described later.

The liquid crystal material constituting the liquid crystal layer 13 changes its optical characteristics by manipulating the orientation of liquid crystal molecules according to the electric field applied between the TFT substrate 11 and the CF substrate 12. Various liquid crystal modes such as a VA (Vertical Alignment) mode, a TN (Twisted Nematic) mode, and a homogeneous mode can be applied as the liquid crystal mode.

A plurality of switching elements (not shown) corresponding to a plurality of pixels are provided on the liquid crystal layer 13 side of the TFT substrate 11. The plurality of pixels are arranged in a matrix. The configuration of the switching element will be described later. An insulating layer 15 is provided on the plurality of switching elements.

On the insulating layer 15, a plurality of pixel electrodes 16 corresponding to the plurality of pixels are provided. One pixel electrode 16 is provided over substantially the entire pixel area.

A color filter (not shown) is provided on the liquid crystal layer 13 side of the CF substrate 12. The configuration of the color filter will be described later.

The common electrode 20 is provided on the color filter. The common electrode 20 is formed in a planar shape over the entire display area of the liquid crystal display device 10.

(Specific cross-sectional structure of the liquid crystal display device 10)
FIG. 3 is a diagram for explaining a specific cross-sectional structure of the liquid crystal display device 10. FIG. 3 is a sectional view in which a part of the display area inside the

sealing materials

21 and 22 is extracted, and is a sectional view along the X direction.

A plurality of switching elements 14 corresponding to the plurality of pixels are provided on the liquid crystal layer 13 side of the TFT substrate 11. As the switching element 14, for example, a TFT (Thin-Film-Transistor) is used, and an n-channel TFT is used. FIG. 3 shows the TFT 14 in a simplified manner. Specifically, the TFT 14 includes a gate electrode functioning as a scanning line, a gate insulating film provided on the gate electrode, a semiconductor layer (for example, an amorphous silicon layer) provided on the gate insulating film, and a semiconductor layer. A source electrode and a drain electrode provided in contact with each other and spaced apart from each other; The source electrode is electrically connected to a signal line (not shown).

A contact plug (contact hole) 17 electrically connected to the pixel electrode 16 is provided in the insulating layer 15 and on the drain electrode of the TFT 14.

An alignment film (not shown) for controlling the initial alignment of the liquid crystal layer 13 is provided on the insulating layer 15 and the plurality of pixel electrodes 16.

A color filter 18 is provided on the liquid crystal layer 13 side of the CF substrate 12. The color filter 18 includes a plurality of coloring filters (coloring members), and specifically includes a plurality of red filters 18-R, a plurality of green filters 18-G, and a plurality of blue filters 18-B. A general color filter is composed of three primary colors of light, red (R), green (G), and blue (B). A set of three colors R, G, and B adjacent to each other is a display unit (pixel), and any single color portion of R, G, B in one pixel is a minimum called a subpixel (subpixel). It is a drive unit. The TFT 14 and the pixel electrode 16 are provided for each subpixel. In this specification, the sub-pixel is referred to as a pixel unless it is particularly necessary to distinguish between the pixel and the sub-pixel.

A black matrix (light shielding layer) 19 for light shielding is provided at the boundary portion of the red filter 18-R, the green filter 18-G, and the blue filter 18-B, and the boundary portion of the pixel (sub pixel). That is, the black matrix 19 is formed in a mesh shape. For example, the black matrix 19 has a function of shielding unnecessary light between the coloring members and improving the contrast.

An alignment film (not shown) for controlling the initial alignment of the liquid crystal layer 13 is provided on the common electrode 20.

The pixel electrode 16, the contact plug 17, and the common electrode 20 are made of transparent electrodes, and for example, ITO (indium tin oxide) is used. As the insulating layer 15, a transparent insulating material is used, for example, silicon nitride (SiN).

[1-2] Specific Configuration of

Sealing Materials

21 and 22 The specific configuration of the above-described

sealing materials

21 and 22 will be described with reference to FIGS. 1 and 2.

The sealing material 21 is provided in contact with the insulating layer 15 and the CF substrate 12. The sealing material 21 has a frame shape and a quadrangle, for example. That is, the sealing material 21 includes two sides extending in the X direction and two sides extending in the Y direction orthogonal to the X direction. The area inside the sealing material 21 is a display area where an image can be displayed.

The sealing material 22 is provided in contact with the insulating layer 15 and the CF substrate 12. The sealing material 22 has, for example, a frame shape and a quadrangular shape. The sealing material 22 is configured to surround the sealing material 21. The sealing material 22 is disposed outside the sealing material 21 with a space from the sealing material 21.

A liquid crystal layer 23 is provided between the sealing material 21 and the sealing material 22. The liquid crystal layer 23 is made of the same material as the liquid crystal layer 13, for example.

The sealing material 21 has, for example, an injection port (opening) for injecting liquid crystal at the center of the upper side (side extending in the X direction) in FIG. The inlet of the sealing material 21 is composed of two sealing

materials

21A and 21B extending in the Y direction from a part of the rectangular sealing material. The sealing materials 21 A and 21 B extend to the end of the TFT substrate 11.

The sealing material 22 has, for example, an injection port for injecting liquid crystal at the center of the upper side (side extending in the X direction) in FIG. The inlet of the sealing material 22 is composed of two sealing

materials

22A and 22B extending in the Y direction from a part of the rectangular sealing material. The sealing

materials

22A and 22B extend to the end of the TFT substrate 11.

The sealing

materials

21 and 22 are formed by printing, for example. The sealing material is made of, for example, an ultraviolet curable resin, a thermosetting resin, or an ultraviolet / heat combination type curable resin, and is printed on the TFT substrate 11 and / or the CF substrate 12 in the manufacturing process, and then irradiated with ultraviolet rays or heated. Can be cured.

The sealing material 24 seals the inlet of the sealing material 21 and the inlet of the sealing material 22. The sealing material 24 is made of, for example, an ultraviolet curable resin. After the liquid crystal is injected between the TFT substrate 11 and the CF substrate 12, the sealing material 24 is applied so as to fill the injection port of the sealing material 21 and the injection port of the sealing material 22. Thereafter, the sealing material 24 is cured by ultraviolet irradiation.

As a liquid crystal injection method, for example, a vacuum injection method can be used. In the vacuum injection method, liquid crystal is injected from the inlets of the sealing

materials

21 and 22.

In the liquid crystal display device 10 configured as described above, moisture can be prevented from entering the liquid crystal layer 13 from the outside.

[1-3] Modification The outer sealing material 22 may be made of a material having a higher barrier property. The sealing material 22 is composed of a sealing material containing an inorganic material. As the inorganic material, a material that does not transmit moisture is selected. The inner sealing material 21 is made of resin, for example.

In the modified example, the barrier property of the sealing material 22 can be further increased. Thereby, it can suppress more that the liquid crystal layer 13 permeates moisture.

[1-4] Comparative Example FIG. 4 is a plan view of a liquid crystal display device according to a comparative example.

The liquid crystal layer 13 is sealed between the TFT substrate 11 and the CF substrate 12 by a single layer of sealing material 22. The inlet of the sealing material 22 is sealed with a sealing material 24.

The liquid crystal display device may be mounted on, for example, a vehicle having a severe use environment. High reliability is required for an in-vehicle liquid crystal display device. For this reason, a reliability test (environmental test) is performed under more severe conditions.

As an example of an environmental test, a test for maintaining a high-temperature and high-humidity environment (for example, 85 degrees, 85% RH (relative humidity)) for 2000 hours (hours) is performed.

In the liquid crystal display device according to the comparative example, as shown in FIG. 4, at the time when several hundred hours have passed, the capacitance of the display region (particularly, at the four corners of the sealant 22 near the sealant 22) is reduced. An area with a reduced retention rate is created. This is because moisture in a high-temperature and high-humidity environment penetrates the sealing material 22 and enters the liquid crystal layer 13, and the specific resistance of the liquid crystal is reduced due to the moisture, resulting in a decrease in capacitance retention. It is.

In the region where the retention rate of the capacitance is lowered, the electric field applied to the liquid crystal layer becomes low, and it becomes difficult to control the alignment of the liquid crystal layer. As a result, the liquid crystal display device according to the comparative example cannot realize a normal display operation.

On the other hand, the liquid crystal display device 10 according to the present embodiment has a structure in which moisture hardly enters the liquid crystal layer 13 from the outside. For example, since moisture that has passed through the sealing material 22 is absorbed by the liquid crystal layer 23, it is possible to suppress moisture from entering the liquid crystal layer 13 through the sealing material 21.

[1-5] Effects of First Embodiment As described in detail above, in the first embodiment, the liquid crystal display device 10 includes the liquid crystal layer 13 sandwiched between the TFT substrate 11 and the CF substrate 12 and the liquid crystal layer 13. A sealing material 21 that encloses and seals the liquid crystal layer 13 between the TFT substrate 11 and the CF substrate 12, a sealing material 22 that surrounds the sealing material 21 with a space therebetween, and a liquid crystal layer 23 provided between the sealing

materials

21 and 22. With.

For example, when an environmental test is performed on the liquid crystal display device 10, moisture that has passed through the outer sealing material 22 is absorbed by the liquid crystal layer 23 and blocked by the sealing material 22. Thereby, it is possible to suppress moisture from entering the liquid crystal layer 13. According to 1st Embodiment, it can suppress that the liquid crystal display device 10 becomes defective, and the liquid crystal display device 10 with higher reliability is realizable. The liquid crystal display device 10 according to the present embodiment is particularly effective for applications that require high reliability such as in-vehicle use.

Further, the inlet of the sealing material 21 and the inlet of the sealing material 22 are arranged at the same position. Thereby, the injection | pouring process of the liquid crystal layers 13 and 23 can be performed together. Further, the two liquid crystal layers 13 and 23 can be sealed using one sealing material 24. As a result, an increase in manufacturing steps can be suppressed.

[2] Second Embodiment FIG. 5 is a plan view of a liquid crystal display device 10 according to a second embodiment.

The sealing material 21 has an opening 21C in the center of the lower side (side extending in the X direction) of FIG. Unlike the first embodiment, the sealing material 21 is not provided with an inlet in the center of the upper side (side extending in the X direction) in FIG.

The sealing material 22 has an inlet at the center of the upper side (side extending in the X direction) in FIG. The liquid crystal is injected between the TFT substrate 11 and the CF substrate 12 from the injection port of the sealing material 22. The liquid crystal injected inside the sealing material 22 is further injected inside the sealing material 21 through the opening 21 C of the sealing material 21. The sealing material 24 seals the inlet of the sealing material 22.

Much moisture may enter from the vicinity of the sealing material 24. In the second embodiment, since the opening 21 C of the sealing material 21 is arranged at a position that is larger than the inlet of the sealing material 22, moisture that has entered the liquid crystal layer 23 from the vicinity of the sealing material 24 Invasion inside can be suppressed.

[3] Third Embodiment FIG. 6 is a plan view of a liquid crystal display device 10 according to a third embodiment.

In the third embodiment, the liquid crystal display device 10 does not include the sealing material 24 for sealing the liquid crystal shown in the first embodiment.

The sealing material 21 has, for example, a frame shape and a square shape. The sealing material 21 does not have an injection port for injecting liquid crystal. The sealing material 22 has, for example, a frame shape and a quadrangular shape. The sealing material 22 does not have an injection port for injecting liquid crystal. A liquid crystal layer 23 is provided between the sealing material 21 and the sealing material 22.

In the third embodiment, an ODF (one drop fill) method is used as a liquid crystal injection method. In the case of the ODF method, a liquid crystal injection port is unnecessary. In the ODF method, after a sealing material is printed on one or two substrates, a liquid crystal is filled in a region surrounded by the sealing material. Thereafter, the two substrates are bonded together.

In the third embodiment, since there is no sealing material, it is possible to prevent moisture from entering from the vicinity of the sealing material.

[4] Fourth Embodiment FIG. 7 is a plan view of a liquid crystal display device 10 according to a fourth embodiment. FIG. 8 is a cross-sectional view of the liquid crystal display device 10 taken along the line BB ′ of FIG.

The sealing material 21 has, for example, an injection port for injecting liquid crystal at the center of the right side (side extending in the Y direction) in FIG. The inlet of the sealing material 21 is composed of two sealing

materials

21A and 21B extending in the X direction from a part of the rectangular sealing material. The sealing materials 21 A and 21 B extend to the end of the TFT substrate 11.

The sealing material 22 has, for example, an injection port for injecting a substance at the center of the upper side (side extending in the X direction) in FIG. The inlet of the sealing material 22 is composed of two sealing materials 22 A and 22 B extending in the Y direction from the central portion of the upper side of the sealing material 22. The sealing

materials

22A and 22B extend to the end of the TFT substrate 11. The right side of the sealing material 22 is divided by the sealing

materials

21A and 21B, and the divided portions of the sealing material 22 are in contact with the sealing

materials

21A and 21B.

Between the sealing material 21 and the sealing material 22, a filling layer (absorbing material) 26 made of a substance different from the liquid crystal layer 13 and having water absorption is provided. The filling layer 26 has a function of absorbing moisture that has passed through the sealing material 22. Examples of the packed layer 26 include silica gel for solids and polyvinyl alcohol or polyethylene glycol for polymers.

The liquid crystal layer 13 is injected from the inlet of the sealing material 21. The filling layer 26 is injected from the inlet of the sealing material 22.

The sealing material 25 seals the inlet of the sealing material 21. The sealing material 24 seals the inlet of the sealing material 22. The sealing

materials

24 and 25 are made of, for example, an ultraviolet curable resin.

In the fourth embodiment, moisture that has passed through the sealing material 22 is absorbed by the filling layer 26. Thereby, it is possible to suppress moisture from entering the liquid crystal layer 13.

[5] Fifth Embodiment FIG. 9 is a plan view of a liquid crystal display device 10 according to a fifth embodiment. FIG. 10 is a cross-sectional view of the liquid crystal display device 10 taken along line AA ′ of FIG.

The shapes of the sealing

materials

21 and 22 are the same as those in the third embodiment.

An air layer 27 is provided between the sealing material 21 and the sealing material 22. That is, no substance is injected between the sealing material 21 and the sealing material 22.

The outer sealing material 22 is made of a material having higher barrier properties, for example, a sealing material containing an inorganic material. The inner sealing material 21 is made of resin, for example.

In the fifth embodiment, the ODF method is used as the liquid crystal injection method. Also in the fifth embodiment, moisture can be prevented from entering the liquid crystal layer 13.

[6] Sixth Embodiment FIG. 11 is a plan view of a liquid crystal display device 10 according to a sixth embodiment. FIG. 12 is a cross-sectional view of the liquid crystal display device 10 taken along the line AA ′ of FIG.

The liquid crystal display device 10 includes three layers of sealing

materials

21, 22, and 28.

The sealing material 28 is provided in contact with the insulating layer 15 and the CF substrate 12. The sealing material 28 has a frame shape and a quadrangle, for example. The sealing material 28 is configured to surround the sealing material 22. The sealing material 28 is disposed outside the sealing material 22 with a space from the sealing material 22. A liquid crystal layer 29 is provided between the sealing material 22 and the sealing material 28.

The sealing material 28 has an injection port for injecting liquid crystal at the same position as the injection ports of the sealing

materials

21 and 22. That is, the inlet of the sealing material 28 is constituted by two sealing

materials

28A and 28B extending in the Y direction from the central portion of the upper side of the sealing material 28. The sealing

materials

28A and 28B extend to the end of the TFT substrate 11.

According to the sixth embodiment, the liquid crystal display device 10 includes the three layers of sealing

materials

21, 22, and 28, and the two layers of liquid crystal layers 23 and 29, so that moisture enters the liquid crystal layer 13. It can be suppressed more.

[7] Seventh Embodiment FIG. 13 is a plan view of a liquid crystal display device 10 according to a seventh embodiment. FIG. 14 is a cross-sectional view of the liquid crystal display device 10 taken along line AA ′ of FIG.

The liquid crystal display device 10 includes three layers of sealing

materials

21, 22, and 28.

An air layer 27 is provided between the sealing material 21 and the sealing material 22. That is, no substance is injected between the sealing material 21 and the sealing material 22. For example, the air layer 27 is sealed by the sealing material 21 and the sealing material 22.

The sealing

materials

21 and 28 have an injection port for injecting liquid crystal at the same position (for example, the central portion of the upper side in FIG. 1).

The upper side of the sealing material 22 is divided by the sealing

materials

21A and 21B.

Also in the seventh embodiment, moisture can be prevented from entering the liquid crystal layer 13.

The first to seventh embodiments can be combined as appropriate. For example, a sealing material having an inorganic material may be applied to one or more of the plurality of sealing materials of the first to seventh embodiments. Further, a filling layer having water absorption may be applied to the liquid crystal layers of the first to seventh embodiments.

Further, the type of liquid crystal display device is not limited, and can be applied to various types of liquid crystal display devices. For example, the liquid crystal display device may be a simple matrix type. In this case, the sealing material is configured to contact two opposing substrates.

The present invention is not limited to the embodiment described above, and can be embodied by modifying the constituent elements without departing from the scope of the invention. Further, the above embodiments include inventions at various stages, and are obtained by appropriately combining a plurality of constituent elements disclosed in one embodiment or by appropriately combining constituent elements disclosed in different embodiments. Various inventions can be configured. For example, even if some constituent elements are deleted from all the constituent elements disclosed in the embodiment, the problems to be solved by the invention can be solved and the effects of the invention can be obtained. Embodiments made can be extracted as inventions.

Claims

First and second substrates;
A first liquid crystal layer sandwiched between the first and second substrates;
A first sealing material surrounding the first liquid crystal layer and sealing the first liquid crystal layer between the first and second substrates;
And a second sealing material surrounding the first sealing material with a space therebetween.
The liquid crystal display device according to claim 1, further comprising a second liquid crystal layer provided between the first and second sealing materials.
The first sealing material has a first opening,
The liquid crystal display device according to claim 2, wherein the first liquid crystal layer and the second liquid crystal layer are continuous through the first opening.
The second sealing material has a second opening for injecting liquid crystal,
The liquid crystal display device according to claim 3, wherein the first opening is disposed on a side of the first sealing material that is far from the second opening.
The first sealing material has a first opening for injecting the first liquid crystal layer,
The second sealing material has a second opening for injecting the second liquid crystal layer,
The liquid crystal display device according to claim 2, wherein the first opening and the second opening are arranged at the same position.
The liquid crystal display device according to claim 1, wherein the second sealing material includes an inorganic material.
The liquid crystal display device according to claim 1, further comprising a filling layer provided between the first and second sealing materials and made of a material different from that of the first liquid crystal layer.
The first sealing material has a first opening for injecting the first liquid crystal layer,
The second sealing material has a second opening for injecting the filling layer,
The liquid crystal display device according to claim 7, wherein the first opening and the second opening are arranged at different positions.
The liquid crystal display device according to claim 1, further comprising a third sealing material surrounding the second sealing material with a space therebetween.
A second liquid crystal layer provided between the first and second sealing materials;
The liquid crystal display device according to claim 9, further comprising: a third liquid crystal layer provided between the second and third sealing materials.
The first sealing material has a first opening for injecting the first liquid crystal layer,
The second sealing material has a second opening for injecting the second liquid crystal layer,
The third sealing material has a third opening for injecting the third liquid crystal layer,
The liquid crystal display device according to claim 10, wherein the first opening, the second opening, and the third opening are arranged at the same position.
An air layer provided between the first and second sealing materials;
The liquid crystal display device according to claim 9, further comprising: a second liquid crystal layer provided between the second and third sealing materials.
The first sealing material has a first opening for injecting the first liquid crystal layer,
The third sealing material has a second opening for injecting the second liquid crystal layer,
The first opening and the second opening are arranged at the same position,
The liquid crystal display device according to claim 12, wherein the air layer is sealed by the first sealing material and the second sealing material.