JPH10148825A - Production of liquid crystal display device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the generation of air bubbles in the liquid crystals of a liquid crystal display device for which flexible transparent substrates are used and to reduce the production cost of this liquid crystal display device. SOLUTION: A liquid crystal panel is manufactured by joining a pair of the flexible transparent substrates 1a, 1b to each other so as to form a cell gap and injecting the liquid crystals L into this cell gap. Polarizing plates 7 having gas barrier layers are adhered to the surfaces of the flexible transparent substrates 1a, 1b after the manufacture of such liquid crystal panel. These polarizing plates 7 are added to the liquid crystal panel only when the liquid crystal panel in the sate not adhered with the polarizing plates 7 is a non- defective article. Since the polarizing plates 7 including the gas barrier layers are costly, the non-inclusion of such polarizing plates 7 in the defective liquid crystal panel at the time of discarding this panel is extremely advantageous for the reduction of the cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing a liquid crystal device which displays visible information such as characters by modulating light by controlling the orientation of liquid crystal. In particular, the present invention relates to a method of manufacturing a liquid crystal device in which a flexible transparent substrate such as a plastic film is used as a transparent substrate sandwiching liquid crystal. Further, the present invention relates to a liquid crystal display device manufactured by using the manufacturing method.

[0002]

2. Description of the Related Art In recent years, liquid crystal devices have been widely used as means for displaying visible information in electronic devices such as computers and electronic organizers. This liquid crystal device generally forms a liquid crystal panel by enclosing liquid crystal in a gap formed between a pair of transparent substrates, a so-called cell gap, and connects a liquid crystal driving IC to the liquid crystal panel.
Further, the liquid crystal panel is configured by attaching auxiliary components such as a backlight and a casing.

[0003] The pair of transparent substrates may be formed of a material that does not bend, such as glass, or may be formed of a flexible material, such as a plastic film. The one using a plastic film as the transparent substrate has many advantages such as being hard to break, being thin, being light, being able to be formed into various shapes, and the like.

However, since the flexible transparent substrate has a property of easily transmitting gas, when the flexible transparent substrate is used as a transparent substrate of a liquid crystal display device, the gas enters the liquid crystal through the flexible transparent substrate. Penetrates, resulting in the generation of bubbles inside the liquid crystal. In order to prevent the gas from entering, a technique of providing a gas barrier layer on a flexible transparent substrate has been proposed. For example, JP-A-61-41122 and JP-A-61-69029
JP, JP-A-2-304417 and JP-A-6-304
Such a technique is disclosed in each publication of 234186.

[0005]

The technique disclosed in each of the above publications is to form a gas barrier layer from the beginning on the surface of a flexible transparent substrate by using a sputtering method or another well-known film forming method. It is. In manufacturing a liquid crystal display device, a well-known liquid crystal manufacturing process is performed using a pair of flexible transparent substrates having the gas barrier layer to manufacture the liquid crystal display device.

However, in a manufacturing process of a liquid crystal display device using a flexible transparent substrate, generally, a liquid crystal display device finally obtained in order to perform advanced quality control may be determined to be defective. . This defective product is often discarded as it is. Further, on the other hand, SiO _X, which is generally used as a gas barrier layer, a resin material such as PVA (polyvinyl alcohol) is a flexible transparent substrate substrate PC (polycarbonate), PAr (polyacrylate), PES (poly It is very expensive compared to resins such as ether sulfone).

As described above, conventionally, a liquid crystal display device was manufactured using a flexible transparent substrate on which a gas barrier layer had been formed in advance, so that the finally obtained liquid crystal display device was inspected. When it is determined that the gas barrier layer is defective and discarded, the gas barrier layer is discarded together with the defective liquid crystal display device even if the gas barrier layer itself has no problem. As mentioned above, this gas barrier layer is very expensive, and simply discarding it has led to unnecessarily high costs.

The present invention has been made in view of the above problems in a conventional method of manufacturing a liquid crystal display device,
An object of a liquid crystal display device using a flexible transparent substrate is to reliably prevent bubbles from being generated in liquid crystal and to reduce the manufacturing cost of the liquid crystal display device.

[0009]

According to a first method of manufacturing a liquid crystal display device according to the present invention, a substrate bonding step of bonding a pair of flexible transparent substrates to each other so as to form a cell gap; A liquid crystal display step of injecting liquid crystal into the liquid crystal display device, wherein after the liquid crystal injection step, a polarizing plate having a gas barrier layer is provided on at least one of the pair of flexible transparent substrates. It is characterized by bonding.

[0010] In the above configuration, "gas barrier layer" is, for example, PVA (polyvinyl alcohol), and organic substances such as EVA (ethylene vinyl alcohol) or the like, can be formed by an inorganic material such as such as SiO _X, and the like. As is well known, a “polarizing plate” is an optical member having a function of transmitting only a specific polarized light component to incident light. For example, as shown in FIG. 5, iodine (I ₂ ) Is formed by melting and mixing PVA.
And a surface layer 12 laminated on both sides of the main layer 11
And is formed. These surface layers 12 are made of, for example, triacetyl cellulose (= 3 cellulose acetate: T
AC). The method for providing the gas barrier layer on the polarizing plate is not limited to a specific method, for example,
Processing such as vapor deposition and adhesion can be adopted.

A polarizing plate having a gas barrier layer is bonded to a pair of flexible transparent substrates constituting a liquid crystal panel. Here, “adhesion” refers to permanently bonding a plurality of substances, and is a process different from “adhesion”. The adhesive that can be used is not limited to a specific type, but may be, for example, an epoxy-based, acrylic-based, urethane-based, silicon-based, or various other adhesives. These have high molecular density or lattice density and have a gas barrier function. On the other hand, the adhesive is a binder for temporarily binding a plurality of substances, and is a binder capable of moving the substances to each other after the binding. This adhesive has a low molecular density or lattice density and does not have a gas barrier function, such as silicon rubber.

According to the method of manufacturing a liquid crystal display device described above,
Since the polarizing plate having the gas barrier layer is provided on the flexible transparent substrate, gas can be prevented from entering the liquid crystal through the flexible transparent substrate, and as a result, bubbles are generated in the liquid crystal. Can be prevented. Further, since the gas barrier layer is not formed on the flexible transparent substrate from the beginning, but is added to the flexible transparent substrate together with the polarizing plate, the following operation and effect can be obtained. That is, in a manufacturing process of a liquid crystal display device using a flexible transparent substrate, generally, a liquid crystal display device finally obtained for performing advanced quality control may be determined to be defective and discarded. . In this case, if a gas barrier layer is formed on the flexible transparent substrate from the beginning, when a defect occurs in any part of the liquid crystal display device, the gas barrier layer can be used even when there is no problem with the gas barrier layer itself. Are discarded together with the liquid crystal display device. Since the gas barrier layer is very expensive, it is very uneconomical to discard it meaninglessly.

On the other hand, as in the present invention, after the liquid crystal injection step is completed and the main part of the liquid crystal display device is completed, the gas barrier layer may be added to the flexible transparent substrate together with the polarizing plate later. When the liquid crystal display device is defective, only the liquid crystal display device not including the gas barrier layer is discarded, and the expensive gas barrier layer does not have to be discarded. Therefore, cost reduction can be achieved without wasting expenses.

Next, in a second method for manufacturing a liquid crystal display device according to the present invention, a substrate bonding step of bonding a pair of flexible transparent substrates to each other so as to form a cell gap; In a method for manufacturing a liquid crystal display device having a liquid crystal injecting step of injecting, a polarizing plate is bonded to at least one of the pair of flexible transparent substrates after the liquid crystal injecting step, and then, It is characterized by bonding a gas barrier film. The difference between the second manufacturing method and the first manufacturing method is that the gas barrier layer is not formed in advance with the polarizing plate but is prepared separately from each other, and the main components of the liquid crystal display device are prepared. After the part is completed, the polarizing plate and the gas barrier film are sequentially bonded and laminated.

According to this manufacturing method, the generation of bubbles due to gas intrusion can be prevented, and the manufacturing cost can be reduced, for the same reason as described above.

In the first and second manufacturing methods of the liquid crystal display device, the flexible transparent substrate is made of, for example, PC (polycarbonate), PAr (polyacrylate), PES.
(Polyethersulfone) or the like, and can be formed only with an inexpensive resin. Although these materials do not have a gas barrier function, in the present invention, a polarizing plate or a gas barrier film having a gas barrier layer is separately bonded to a flexible transparent substrate, so that a liquid crystal display device as a final product has no problem as expected. It will have a gas barrier function.

However, when it is necessary to ensure the completeness of the gas barrier function, a gas barrier layer may be formed in advance on both the front and back surfaces of the main layer such as PC constituting the flexible transparent substrate. In this case, the gas barrier layer results in a multilayer structure. However, from the viewpoint of cost reduction, it is desirable that the flexible transparent substrate is formed only by an inexpensive PC or the like.

Next, a liquid crystal display device according to the present invention is a liquid crystal display device manufactured by using the above-described first manufacturing method or the second manufacturing method. In particular,
This is a liquid crystal display device manufactured by manufacturing a main portion of the liquid crystal display device by a substrate bonding step and a liquid crystal injecting step, and then separately bonding a polarizing plate or a gas barrier film having a gas barrier layer to the main portion.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment of a method for manufacturing a liquid crystal display device according to the present invention will be described with reference to FIG. First, flexible transparent substrates 1a and 1b are prepared. These flexible transparent substrates are formed as a single-layer structure of any one of, for example, PC, PAr or PES. These materials are relatively inexpensive materials having no gas barrier function.

Next, both flexible transparent substrates 1a and 1
a transparent electrode layer of ITO (Indium Tin Oxide) is formed on one surface of the substrate b by using a sputtering method or other well-known methods, and is further patterned by using a photolithographic method or the like to form transparent electrodes 2a and 2b. Form. Then, the transparent electrodes 2a of both flexible transparent substrates 1a and 1b
And 2b, an alignment film 3 is formed, and a rubbing process is performed on each alignment film.

Thereafter, a bead-shaped spacer 4 is dispersed on one of the flexible transparent substrates 1a and 1b,
Further, a thermosetting or thermoplastic sealing material 6 is printed on the other substrate. Then, the flexible transparent substrates 1a and 1b, which have completed the above-described processes, are respectively replaced with the transparent electrodes 2a and 2b.
Are bonded so as to face each other, and the sealing material 6 is further cured, whereby a liquid crystal panel containing no liquid crystal in the cell gap, a so-called empty panel, is formed. Then, the liquid crystal L is injected into the cell gap using a well-known vacuum injection method or the like, and the liquid crystal injection port is sealed, thereby completing the main part of the liquid crystal panel, that is, the liquid crystal display device.

When the above steps are completed, various inspections are performed on the liquid crystal panel, and a liquid crystal panel that does not satisfy predetermined characteristics is discarded as a defective product. For a good liquid crystal panel that satisfies predetermined characteristics, the polarizing plate 7 is bonded to the outer surfaces of the flexible transparent substrates 1a and 1b. As the adhesive, a normal adhesive having gas barrier properties, for example, an epoxy-based adhesive is used. The polarizing plate 7 is formed by laminating a gas barrier layer 9 on one surface of the main body 8 as shown in FIG. The main body 8 is formed by forming the surface layer 12 on both the front and back surfaces of the main body layer 11. In addition,
The main layer 11 is formed of, for example, polyvinyl alcohol (PVA) in which iodine (I ₂ ) is dissolved and mixed. The surface layer 12 is formed of, for example, triacetyl cellulose (TAC). Gas barrier layer 9, for example, be formed by depositing or adhering the PVA, EVA or SiO _X like.

As described above, the liquid crystal panel is completed. Thereafter, the liquid crystal display device is completed by attaching auxiliary devices such as a liquid crystal driving IC and a backlight to the liquid crystal panel. With respect to the completed liquid crystal display device, the polarizing plate 7 having the gas barrier layer 9 is provided on the flexible transparent substrates 1a and 1b.
Can be prevented from entering the gas, and as a result, bubbles can be prevented from being generated in the liquid crystal L.

Further, the gas barrier layer 9 is formed on the flexible transparent substrate 1.
The main part of the liquid crystal panel is added to the flexible transparent substrate together with the polarizing plate 7 after the main part of the liquid crystal panel is manufactured, instead of being formed from the beginning on a and 1b. Is not satisfied, only the main part of the liquid crystal panel can be discarded without attaching the polarizing plate 7. Since the polarizing plate 7 including the gas barrier layer 9 is generally expensive, it is not necessary to discard it.
This is extremely advantageous in reducing costs.

(Second Embodiment) As the polarizing plate used in FIG. 1, a polarizing plate 17 having a layer configuration shown in FIG. 4 can be used instead of the polarizing plate 7 having a layer configuration shown in FIG. This polarizing plate 17 differs from the polarizing plate 7 of FIG. 3 in that the gas barrier layers 9 are formed not only on one surface of the main body 8 but also on the front and back surfaces thereof. When the polarizing plate 17 is used, the gas barrier layer 9 has a two-layer structure, so that higher gas barrier properties can be obtained.

(Third Embodiment) A third embodiment of the method for manufacturing a liquid crystal display device according to the present invention will be described with reference to FIG. This embodiment is different from the first embodiment (see FIG. 1) in that a polarizing plate 7 or 17 having a gas barrier layer is bonded to the surfaces of the flexible transparent substrates 1a and 1b instead of having a gas barrier layer. No polarizing plate 27 is attached to the flexible transparent substrate 1a.
1b, and the gas barrier film 19 is further adhered on the polarizing plate 27. That is, in the present embodiment, the polarizing plate and the gas barrier film are bonded as separate elements.

As shown in FIG. 5, the polarizing plate 27 is provided on both the front and back surfaces of the main layer 11 mainly composed of polyvinyl alcohol.
Surface layer 12 formed by triacetyl cellulose
Can be formed. Gas barrier film 19 may be formed by PVA, EVA or SiO _X like.

(Fourth Embodiment) A fourth embodiment of the method for manufacturing a liquid crystal display device according to the present invention will be described with reference to FIG. The fourth embodiment differs from the first embodiment (see FIG. 1) in that the flexible transparent substrates 1a and 1b are changed to other flexible transparent substrates 21a and 21b. While the flexible transparent substrates 1a and 1b used in the first embodiment have a single-layer structure of polycarbonate or the like, the flexible transparent substrates 21a and 21b used in the present embodiment are, as shown in FIG. , A main layer 22, a gas barrier layer 23 and a surface layer 24. The main layer 22 is made of PC, P
Ar, is formed by any one of PES such as gas barrier layer 23 is PVA, it is formed by any one of such EVA or SiO _X, and the surface layer 24 is formed by an epoxy resin or the like. According to this embodiment,
A polarizing plate 7 or 17 having a gas barrier layer is further laminated on the flexible transparent substrates 21a and 21b having a gas barrier layer from the beginning. As a result, since the gas barrier layer has a multilayer structure, a higher gas barrier function can be achieved.

[0029]

According to the method for manufacturing a liquid crystal display device according to the first aspect and the liquid crystal display device according to the fourth aspect, the polarizing plate having the gas barrier layer is provided on the flexible transparent substrate.
Gases can be prevented from entering the liquid crystal through the flexible transparent substrates, and thus, generation of bubbles in the liquid crystal can be prevented.

Also, instead of forming the gas barrier layer on the flexible transparent substrate from the beginning, the gas barrier layer is added to the flexible transparent substrate together with the polarizing plate after the main part of the liquid crystal panel is manufactured. Therefore, when the main portion of the liquid crystal panel does not satisfy the predetermined characteristics, only the main portion can be discarded without attaching a polarizing plate, that is, a gas barrier layer. Since the material of the gas barrier layer is generally expensive, it is very economical to avoid having to discard it.

According to the method of manufacturing a liquid crystal display device according to the second aspect, the gas barrier film is provided on the flexible transparent substrates, so that the gas can enter the liquid crystal through the flexible transparent substrates. Therefore, it is possible to prevent bubbles from being generated in the liquid crystal.

In addition, instead of forming the gas barrier film on the flexible transparent substrate from the beginning, the gas barrier film is added to the flexible transparent substrate after manufacturing the main part of the liquid crystal panel. When the main part of the liquid crystal panel does not satisfy the predetermined characteristics, only the main part of the liquid crystal panel can be discarded without attaching a gas barrier film. Since gas barrier films are generally expensive, it is very economical not to dispose of them.

According to the method of manufacturing a liquid crystal display device according to the third aspect, the main body of the liquid crystal panel is manufactured using an inexpensive flexible transparent resin having no gas barrier function, and the main body is good. Sometimes it is possible, for the first time, to add an expensive gas barrier layer or gas barrier film. By doing so, it is possible to reduce the cost loss when the main body of the liquid crystal panel is defective.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one embodiment of a method for manufacturing a liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view schematically showing another embodiment of the method for manufacturing a liquid crystal display device according to the present invention.

FIG. 3 is a cross-sectional view illustrating a cross-sectional structure of an example of a polarizing plate.

FIG. 4 is a cross-sectional view illustrating a cross-sectional structure of another example of the polarizing plate.

FIG. 5 is a sectional view showing a sectional structure of still another example of the polarizing plate.

FIG. 6 is a cross-sectional view illustrating a cross-sectional structure of an example of a flexible transparent substrate.

[Explanation of symbols]

 1a, 1b Flexible transparent substrate 2a, 2b Transparent electrode 3 Alignment film 6 Sealing material 7 Polarizer 8 Main body of polarizer 9 Gas barrier layer 11 Main layer of polarizer 12 Surface layer of polarizer 17 Polarizer 19 Gas barrier film 21a , 21b Flexible transparent substrate 22 Main layer of transparent substrate 23 Gas barrier layer of transparent substrate 24 Surface layer of transparent substrate 27 Polarizing plate L Liquid crystal

Claims (4)

[Claims] 1. A method of manufacturing a liquid crystal display device, comprising: a substrate bonding step of bonding a pair of flexible transparent substrates to each other to form a cell gap; and a liquid crystal injection step of injecting liquid crystal into the cell gap. After the liquid crystal injecting step, a method for manufacturing a liquid crystal display device, comprising: bonding a polarizing plate having a gas barrier layer to at least one of the pair of flexible transparent substrates. 2. A method of manufacturing a liquid crystal display device, comprising: a substrate bonding step of bonding a pair of flexible transparent substrates to each other so as to form a cell gap; and a liquid crystal injection step of injecting liquid crystal into the cell gap. After the liquid crystal injection step, a polarizing plate is bonded to at least one of the pair of flexible transparent substrates, and then a gas barrier film is bonded to the polarizing plate. . 3. The method for manufacturing a liquid crystal display device according to claim 1, wherein the flexible transparent substrate is formed of a resin having no gas barrier function. 4. A liquid crystal display device manufactured by using the manufacturing method according to claim 1. Description: