JPH06230345A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display device which is free from the deterioration in characteristics, etc., in spite of an environmental change and has excellent reliability by making the volume of a liquid crystal material equal to or larger than the volume of a flowable material. CONSTITUTION:A potting material 101 is disposed on a liquid crystal driving element layer 103. A transparent glass 102 is placed on this potting material 101. The transparent glass 102 is fixed by a frame material 104 to hermetically enclose the potting material 101. The volume of the potting material 101 is equal or smaller than the volume of the liquid crystal layer 105 at this time. While the flowable material (potting material) is essential for the purpose of reinforcement, the volume of the liquid crystal material is required to be equal to or larger than the volume of the flowable material. The reason thereof lies in that the thermal expansion and change by atm. pressure of the flowable material do not deform the liquid crystal cell, etc., and that the display characteristics stable to the environmental change are realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device using liquid crystal.

[0002]

2. Description of the Related Art A cathode ray tube (CRT) has dominated most of electronic displays until recently, but it is not possible to meet various needs accompanying the rapid progress of miniaturization technology and the expansion of applications. Research and development of electronic displays based on this display principle have become active.

Above all, as an image display device which replaces a CRT, a liquid crystal display device which can be thinned and reduced in weight has been attracting attention.

However, due to changes in the environment such as atmospheric pressure and temperature due to the gap of the liquid crystal layer and the deformation of the driving transistor, the image quality is deteriorated and further the reliability is lowered.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device which is less likely to be deteriorated in characteristics even with the above environmental changes and which is excellent in reliability.

[0006]

The present invention has two substrates sandwiching a liquid crystal drive element layer, and a liquid crystal material is provided between one of the substrates and the liquid crystal drive element layer and the other of the substrates. A liquid crystal display device, each having a fluid material between the liquid crystal driving element layer, wherein the two substrates are transparent substrates, and the volume of the liquid crystal material is equal to or larger than the volume of the fluid material. The main feature is a characteristic liquid crystal display device.

Flowable materials are essential for reinforcement,
The volume of the liquid crystal material is required to be equal to or larger than the volume of the fluid material. This is because the thermal expansion of the fluid material and the change due to the atmospheric pressure do not deform the liquid crystal cell and the like, and realize stable display characteristics against environmental changes.

Furthermore, in the present invention, when the refractive index of the fluid material is n, its thickness is d, and the wavelength λ used as a display device,

[0009]

[Equation 2] It is preferable that the following relation be satisfied (where m is a natural number and λ is 550, which has the highest human visual sensitivity).
About 0Å is usually used. ). The reason is that the transmittance is highest at this wavelength.

The display system of the present invention is TN type, ST type.
Shape, ECB type, ferroelectric type, etc. are targeted.

The materials, required characteristics, forming conditions and the like of each part of the device of the present invention will be described in detail below with reference to examples.

[0012]

【Example】

(Example 1) A liquid crystal display device according to the present invention comprises a liquid crystal cell portion for image display and a potting cell portion for injecting a potting material (fluid material) to reinforce the liquid crystal cell. In this example, a method for manufacturing a liquid crystal display device according to the present invention will be sequentially described with reference to FIG.

The liquid crystal cell portion is a portion surrounded by the transparent substrate 106, the liquid crystal driving element layer 103 and the frame member 108. The transparent substrate 106 is provided with a color filter and a light-shielding layer that shields light between the color filters, and a transparent electrode for applying a voltage to the liquid crystal. In the liquid crystal drive element layer 103, a pixel electrode is provided in the pixel portion, a thin film transistor (TFT) for applying a signal to the electrode, a signal line for sending a signal to the TFT, a drive line for driving the TFT, and a horizontal line for driving the pixel TFT. , A vertical shift register and the like. Liquid crystal layer 105
Is the frame member 108, the transparent substrate 106, and the liquid crystal drive element layer 10.
It is enclosed in the gap of 3.

Since the liquid crystal driving element layer 103 is formed on the Si substrate 107, it is opaque to visible light. Therefore, next, the opening 109 is hollowed by etching so that visible light can be transmitted. An aqueous solution of tetramethylammonium hydride (TMAH) was used as the etching solution. Etching conditions are TMAH 22% aqueous solution, 9
It is 0 ° C. for 10 hours. As the Si substrate 107,
A structure in which a thin insulating layer is present on a silicon substrate and a single crystal silicon layer is further overlaid on the thin insulating layer (Silicon O
When a silicon substrate having an n insulator structure (SOI) is used, the insulating layer serves as an etching stop layer and is effective for uniform etching, which is desirable. (Here, any one may be used as the etching solution as long as it has a sufficient selection ratio of Si and SiO ₂ such as KOH.)
A method of manufacturing the potting cell part will be described. The process can be broadly divided into three processes of a frame manufacturing process for filling a potting material, a potting material injection process, and an injection port sealing process. Hereinafter, description will be made in this order.

The frame manufacturing process will be described. First, S
An adhesive (frame member 104) is applied on the silicon substrate 107 around the opening 109 formed by etching the display region of the i substrate 107. As the frame material 104, an epoxy resin (Mitsui Toatsu Chemicals, Inc., Structbond EH45) is used.
4NF) was used. The frame made of an adhesive may be formed by either discharging the injection needle tip with a dispenser to trace the shape or by squeegee printing. A glass substrate 102 cut into a desired size was placed thereon, pressed to obtain a desired gap, and baked in an oven at 80 ° C. for 2 hours to form a potting material filled region. Here, the glass substrate 102 is a silicon substrate 10
The use of a material having a coefficient of thermal expansion close to that of No. 7 is effective for suppressing warpage of the liquid crystal display device and is desirable. In the present embodiment, as the glass substrate 102, AL glass manufactured by Asahi Glass Co., Ltd. (coefficient of thermal expansion 36 × 10 ⁻⁷ ;
32 × 10 ⁻⁷ ) was used as Si. The gap was controlled by sandwiching a gap material (glass, injection needle, etc.) having a desired thickness between the glass substrate and the silicon substrate. Further, when a very narrow gap (about 10 μm) is required, beads having a diameter of about 10 μm (Sekisui Fine Chemical Co., Ltd., Micropearl SP) were mixed in an epoxy resin to form a frame 104 to obtain a desired gap thickness.

Next, an injection process for filling the potting material into the frame 104 formed as described above will be described. The potting material should be vacuum degassed (10 ^-3 Tor) before injection.
(r, 12 hours) was performed to make it free from bubbles.
The liquid crystal display device (liquid crystal cell) in which the frame has been formed and the potting material placed in a petri dish are set in a vacuum device, and vacuumed to a degree of vacuum of about 10 ⁻³ Torr.
The evacuation time was set to 1 to 24 hours after reaching 10 ⁻³ Torr. Then, in a vacuum state, the liquid crystal cell is inserted into a petri dish containing a potting material and immersed in the potting material. The potting material is injected into the potting frame 104 to some extent by the capillary phenomenon. After the equilibrium state of the injection due to the capillary phenomenon was reached, the vacuum device was slowly leaked over 20 minutes to 1 hour to sufficiently inject the potting material into the frame. Potting material is 1 as above
It is injected in a vacuum of about 0 ^-3 Torr. Therefore, it is necessary to have a low vapor pressure and be transparent. for that reason,
As potting materials, liquid crystal, polyethylene glycol (Kanto Chemical Co., Inc., polyethylene glycol # 20)
0), silicone oil (Shin-Etsu Chemical Co., Ltd., Shin-Etsu Silicone) was used.

The sealing is performed as follows. Remove the liquid crystal cell from the vacuum device and wipe the inlet well with acetone to degrease it. The potting material injection port was filled with a sealing material and sealed. When liquid crystal or polyethylene glycol is used as the potting material, epoxy resin (Structbond ES280, Mitsui Toatsu Chemical Co., Ltd.) or UV curable resin is used as the potting material, and silicone bond is used when silicone oil is used as the potting material (Shin-Etsu Chemical Co., Ltd.). Shin-Etsu Silicone Co., Ltd.) was used as the sealing material. Curing was done at room temperature for 12 hours when using an epoxy resin. In the case of a silicone resin, it was carried out at 80 ° C. for 2 hours. On the other hand, since the sealing time of the ultraviolet curable resin is about 1 minute by exposing it to ultraviolet rays, the sealing can be performed firmly in a short time, which is very effective.

In the liquid crystal display device according to the present invention manufactured as described above, the liquid crystal driving element built in the liquid crystal driving element layer 103 drives the liquid crystal 105 in the opening 109, and display is performed in the opening 109. Be seen. The Si substrate 107 and the liquid crystal drive element layer 10 defined by the frame material 108
Since the distance to 3 (hereinafter referred to as cell gap) affects the light transmittance, it is desirable that the cell gap is uniform over the entire surface of the opening 109 in order to perform uniform display on the entire surface. In this embodiment, the liquid crystal driving element layer 10
The thickness of 3 is 3 to 5 μm, and the opening is about 15 mm □. Therefore, the thickness of the liquid crystal driving element layer 103 is as thin as 1/1000 or less with respect to the opening, so that the liquid crystal driving element layer 103 is likely to be deformed and is easily cracked. Therefore, the structure for reinforcing by potting as shown in the present invention is very effective not only for improving the durability and reliability of the present liquid crystal display device but also for improving the image quality.

(Embodiment 2) FIG. 2 shows an embodiment of a liquid crystal display device according to the present invention.

A potting material 101 is arranged on the liquid crystal driving element layer 103. A transparent glass 102 is placed on the potting material 101, the transparent glass 102 is fixed by a frame material 104, and the potting material 101 is sealed. The manufacturing method was based on the method described above.

At this time, the volume of the potting material 101 is equal to or less than the volume of the liquid crystal layer 105. The present embodiment is characterized in that the volume of the potting material 101 is defined by the size of the transparent glass 102 and the size of the opening 109. The height of the frame material 108 is 10μ
The liquid crystal layer 105 has a volume of about 2.3 mm ³ . Therefore, the size of the opening 109 is 10 mm × 12.
Considering that the potting material 101 has a volume equal to or less than the volume of the liquid crystal layer 105, the distance between the transparent glass 102 in which the potting material 101 is encapsulated and the liquid crystal driving element layer 103 is 17 μm or less. And

Here, when the opening size of the bottom formed by etching the Si substrate 107 is L ₁ and the opening size of the upper part is L _2, and the size of the transparent glass 102 is x, L ₁ <x <L ₂ is sufficient, and the above TM is used on the Si substrate.
The above relationship can be easily formed by performing anisotropic etching of AH and KOH.

(Embodiment 3) FIG. 3 shows an embodiment of a liquid crystal display device according to the present invention.

The potting material 101 is arranged on the liquid crystal driving element layer 103. A transparent glass 102 is placed on the potting material 101, the transparent glass 102 is fixed by a frame material 104, and the potting material 101 is sealed. The manufacturing method was based on the method described above.

The present embodiment is the same as the second embodiment except that the potting material 101 has a transparent gap material (transparent beads) 110.
It is characterized by the provision of.

Since the layer thickness of the potting material 101 is made uniform by the transparent beads 110, there is an effect that a large-sized panel can be easily formed with a size larger than that described in the second embodiment.

By placing transparent beads having a uniform size in the potting material 101, the transparent glass 10
To keep the distance between 2 and the liquid crystal driving element layer 103 uniform,
The transparent glass substrate 106 and the liquid crystal driving element layer 103 on the opposite side
This means that the distance, that is, the liquid crystal cell gap described above is uniform, which is very effective in improving the image quality.

Further, as the potting material inlet, it is possible to fabricate the potting material inlet at the same time when the opening 109 is produced by silicon etching. This is effective and desirable for simplifying the process.

(Embodiment 4) FIG. 4 shows an embodiment of a liquid crystal display device according to the present invention.

The potting material 101 is arranged on the liquid crystal driving element layer 103. A transparent glass 102 is placed on the potting material 101, the transparent glass 102 is fixed by a frame material 104, and the potting material 101 is sealed. The fabrication was performed according to the method described above. However, the silicon substrate 10
No. 7 is a transparent glass 102 and a liquid crystal driving element layer 103 in which the volume of the potting material 101 is equal to or less than the volume of the liquid crystal layer 105 by grinding with a grinder just before the opening 109 is formed by silicon etching.
Was thinned to the interval of.

The feature of this embodiment is that the silicon substrate 107 is thinned by the method described above,
7 is to define the volume of the potting material 101 by the thickness.

The height of the frame member 108 is about 10 μm,
The liquid crystal layer 105 has a volume of about 2.3 mm ³ . Therefore,
Considering that the size of the opening 109 is 10 mm × 12 mm, the volume of the potting material 101 is the liquid crystal layer 105.
The silicon substrate 107 is ground to 17 μm or less so that the volume is equal to or less than the volume.

In the structure shown in this embodiment, since the volume of the potting material 101 is defined by the thickness of the silicon substrate 107, the potting material 101 can be produced without being influenced by the size of the glass substrate 102, and the production is easy. Further, since the silicon etching thickness of the opening 109 is also about 17 μm, the etching time is about 20 minutes, and the manufacturing time can be shortened.

Further, as the potting material inlet, it is possible to fabricate the potting material inlet at the same time when the opening 109 is produced by silicon etching. This is effective and desirable for simplifying the process.

(Embodiment 5) FIG. 5 shows an embodiment of the liquid crystal display device according to the present invention, which is exactly the same as Embodiment 4 except that the transparent beads 110 are arranged in the potting material 101.

By placing transparent beads of uniform size in the potting material 101, the distance between the transparent glass 102 and the liquid crystal driving element layer 103 is kept uniform, which is different from the transparent glass substrate 106 on the opposite side. Liquid crystal driving element layer 1
This means that the distance of 03, that is, the liquid crystal cell gap described above is uniform, which is very effective in improving the image quality.

Further, when polyethylene glycol was used as the potting material, the thickness of the potting material was set to about 1800 to 2000Å. This gives a wavelength of 5500
Å The transmittance of light is improved and bright display is possible. In this way, let the refractive index of the potting material be n, and the thickness of the potting material be

[0038]

[Equation 3] Then, a bright display was generally realized.

(Embodiment 6) FIG. 6 shows an embodiment of a liquid crystal display device according to the present invention.

The potting material 101 is arranged on the liquid crystal driving element layer 103. A transparent glass 102 is placed on the potting material 101, the transparent glass 102 is fixed by a frame material 104, and the potting material 101 is sealed. The fabrication was performed according to the method described above. However, the silicon substrate 10
No. 7 was usually removed by etching in the process of forming the opening 109.

The feature of this embodiment is that the silicon substrate 107 is removed by etching by the method described above.
The frame material 104 defines the volume of the potting material 101.

The height of the frame member 108 is about 10 μm,
The liquid crystal layer 105 has a volume of about 2.3 mm ³ . Frame material 10
No. 4 was arranged directly above the liquid crystal cell frame member 108 so that the film 103 was not deformed. The height of the frame member 104 was set to 10 μm so that the volume of the potting material 101 was equal to or less than the volume of the liquid crystal layer 105.

In the structure shown in this embodiment, the frame member 10
Since the volume of the potting material 101 is defined by the height of 4, the glass substrate 102 can be manufactured without being influenced by the size of the glass substrate 102, and the manufacturing is easy. Also, the silicon substrate 1
Since all 07 is removed by etching, the opening 10
It is not necessary to specify 9 and the production can be simplified.
Further, by using the same material for the transparent glass substrate 102 and the transparent glass substrate 104, it is possible to make the warpage of the liquid crystal display device extremely small. In this embodiment, AL is used as the material for the transparent glass substrates 102 and 104.
Since glass (made by Asahi Glass) was used, the amount of warpage of the liquid crystal display device was almost 0 μm.

(Embodiment 7) FIG. 7 shows an embodiment of the liquid crystal display device according to the present invention, which is exactly the same as Embodiment 6 except that the transparent beads 110 are arranged in the potting material 101.

By placing transparent beads of uniform size in the potting material 101, the distance between the transparent glass 102 and the liquid crystal driving element layer 103 is kept uniform, which is different from that of the transparent glass substrate 106 on the opposite side. Liquid crystal driving element layer 1
This means that the distance of 03, that is, the liquid crystal cell gap described above is uniform, which is very effective in improving the image quality.

Further, by using the same material as the transparent glass substrate 102 and the transparent glass substrate 104, it is possible to make the warp of the liquid crystal display device extremely small. In this embodiment as well, AL glass is used as the transparent glass substrate material. (Asahi Glass Co., Ltd.), the warp amount of the liquid crystal display device was almost 0 μm.

(Embodiment 8) Next, an eighth embodiment will be described with reference to FIG. 8, (a) is a plan view of the liquid crystal display device, 201 is a substrate having a liquid crystal driving peripheral circuit and a pixel portion, 202 is a liquid crystal driving horizontal shift register,
Reference numeral 203 is a vertical shift register for driving a liquid crystal, 204 is a pixel area, and 205 is a dummy area having the same pattern as the pixel area.

On the other hand, (b) is a cross-sectional shape taken along line XX 'shown in (a).
Although omitted, it is actually provided. Reference numeral 206 denotes a glass substrate on which a color filter 208, a light blocking layer 207 for blocking light between the color filters, and a common transparent electrode (not shown) for applying a voltage to the liquid crystal layer are provided. There is. Reference numeral 210 is a liquid crystal, and for example, a TN type or the like can be used. 209 is a frame material for forming a liquid crystal cell, 213 is a liquid crystal driving element layer, 211 is a pixel electrode, 2
12 is a TFT. Reference numeral 214 is the Si substrate region described in the above embodiment, 215 is a frame material that can contain the potting material, 216 is a potting material, and 217 is a glass plate. As the frame material, the potting material, etc., those shown in the above-mentioned embodiments etc. can be used.

The feature of this embodiment is that a dummy pixel region is provided on the outer peripheral portion of the effective pixel region, and a liquid crystal cell side frame member 209 and a potting cell side frame member 215 are formed in the dummy pixel region. There is a point. This relationship is formed in the same region across the liquid crystal driving element layer in the figure, but it is not always necessary, and at least the liquid crystal cell frame material and the potting cell frame material are overlapped in the dummy area. If there is an area where

By using this structure, pressure from the top to the bottom is exerted by the frames 209 and 215 through the layer 213, so that unnecessary pressure, stress, strain, etc. are not applied to the layer 213, and it is stable. , The reliability of the display device was improved. Further, as in the above-mentioned embodiment, the volume of the potting material 216 is equal to or smaller than that of the liquid crystal layer 210, so that the thermal expansion of the potting material and the change due to the atmospheric pressure do not deform the liquid crystal cell and the like, and the environmental change. Stable display characteristics have been realized.

(Ninth Embodiment) Next, a ninth embodiment of the present invention will be described with reference to FIG. The same parts as those in the eighth embodiment are designated by the same reference numerals and the description thereof will be omitted. The first difference between this embodiment and the eighth embodiment is that the potting material 2 is used.
The point is that 16 injection ports and sealing ports 221 are provided. If the frame material 215 is first formed, then vacuuming is performed and the potting material is injected, the injection can be performed easily and a good reinforcing material can be obtained without inclusion of bubbles or the like.

A liquid crystal material may be used as the potting material, and if the injection and sealing ports corresponding to 221 are provided in the liquid crystal cell portion and the material of 210 and 216 is injected at the same time, the process is shortened and the cost is reduced. it can.

[0053]

Since the liquid crystal display device of the present invention has the reinforcing structure as described above, not only the durability and reliability are improved, but also the image quality can be improved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method of manufacturing a device of the present invention.

FIG. 2 is a schematic sectional view showing an embodiment of the present invention.

FIG. 3 is a schematic sectional view showing another embodiment of the present invention.

FIG. 4 is a schematic sectional view showing another embodiment of the present invention.

FIG. 5 is a schematic sectional view showing another embodiment of the present invention.

FIG. 6 is a schematic sectional view showing another embodiment of the present invention.

FIG. 7 is a schematic sectional view showing another embodiment of the present invention.

FIG. 8 is a schematic view showing another embodiment of the present invention.

FIG. 9 is a schematic view showing another embodiment of the present invention.

[Explanation of symbols]

 101 fluid material (potting material) 102, 106 transparent substrate 103 liquid crystal drive element layers 104, 108 frame material 105 liquid crystal layer 107 Si substrate 110 transparent beads

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshihiko Fukumoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. A liquid crystal drive element layer is sandwiched between two substrates, a liquid crystal material is provided between one of the substrates and the liquid crystal drive element layer, and another substrate is provided between the liquid crystal drive element layer and the liquid crystal drive element layer. A liquid crystal display device each having a fluid material, wherein the two substrates are transparent substrates, and the volume of the liquid crystal material is equal to or larger than the volume of the fluid material. 2. The liquid crystal driving element layer is formed on a substrate having an opaque region and a transparent region, and a frame member is provided on the opaque region, and the frame member is in contact with the one transparent substrate. The liquid crystal display device according to claim 1, wherein the volume of the fluid material is defined thereby. 3. The liquid crystal display device according to claim 1, wherein a transparent gap material is provided in the fluid material. 4. When the size of the transparent region is L ₁ and the size of the opening on the substrate surface side of the opaque region is L ₂ , the glass plate size x for sealing the fluid material is L ₁ <x <L ₂ . The liquid crystal display device according to claim 2, wherein 5. The thickness d of the fluent material is about 1 when the refractive index of the fluent material is n and the natural number is m. The liquid crystal display device according to claim 1, wherein: 6. The liquid crystal display device according to claim 1, wherein a region having a shape similar to that of the display region is provided on an outer peripheral portion of the display region. 7. The liquid crystal display device according to claim 6, wherein a frame for sealing the liquid crystal material and a frame for sealing the fluid material are provided in a region portion having a shape similar to that of the display region.