JPH0675701A - Production of liquid crystal display device - Google Patents

Abstract

(57) [Abstract] [Purpose] An air layer does not exist even as bubbles between the transparent protective plate and the liquid crystal display panel, and there is little loss of light reflection at the interface between them, resulting in excellent visibility and high technology. To obtain a method for manufacturing a liquid crystal display device which can be mass-produced efficiently without need and which is hard to be damaged and which can be handwritten. [Structure] When a transparent protective plate (1) is provided on the viewing side of a liquid crystal display panel (4) to manufacture a handwriting-type liquid crystal display device equipped with a tablet plate (3), the liquid crystal display panel and the transparent protective plate are combined. A method for producing a liquid crystal display device, which comprises an adhesive sheet (2) made of a transparent adhesive resin and having a buffering property, and an ultraviolet polymerizable liquid is interposed at the adhesive interface to perform an adhesive treatment by ultraviolet irradiation. [Effect] It is possible to mass-produce a liquid crystal display device capable of handwriting with excellent visibility by a simple bonding operation using an adhesive sheet method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device capable of handwriting input in which a liquid crystal display panel and a transparent protective plate are adhered while preventing bubbles from being generated, and the reflection loss is small and the visibility is excellent. Regarding

[0002]

2. Description of the Related Art As shown in FIG. 3, a tablet plate 3 for detecting an input position is arranged on a liquid crystal display panel 4 so that characters, patterns and the like can be manually input, and the input contents are displayed on a liquid crystal display. There has been proposed a liquid crystal display device that displays on a display panel.

In such a liquid crystal display device, the liquid crystal display panel 4 is visually recognized in order to prevent the liquid crystal display panel from being locally pressured by the writing pressure at the time of handwriting input through an input pen or the like and thus deteriorating the display quality. The transparent protective plate 1 is arranged on the side. Therefore, handwriting is input through the transparent protective plate 1, and therefore the transparent protective plate 1 is arranged with a gap from the liquid crystal display panel 4.

Conventionally, as a method of manufacturing the above liquid crystal display device capable of handwriting input, a method of simply disposing the transparent protective plate 1 on the viewing side of the liquid crystal display panel 4 via a frame spacer or the like has been known. Therefore, as shown in FIG. 3, an air layer is present in the gap between the transparent protective plate and the liquid crystal display panel, and there is a problem that the reflection loss of light at the interface between them is large and the visibility of the display panel is poor. There is also a proposal to reduce the reflection loss by applying an antireflection film to the reflective surface of a transparent protective plate or a liquid crystal display panel, but the antireflection film requires a high level of technology for its application, and requires a lot of labor for many hours. In addition to being poor in mass productivity, it is easily damaged and easily damaged during assembly of the liquid crystal display device.

[0005]

DISCLOSURE OF THE INVENTION The present invention prevents the presence of an air layer as bubbles even between the transparent protective plate and the liquid crystal display panel, and reduces the reflection loss of light at the interface between them, thereby making it possible to see visually. The object is to develop a manufacturing method of a liquid crystal display device which is excellent in productivity, can be mass-produced efficiently without requiring advanced technology, and is less likely to be damaged, and capable of handwriting input.

[0006]

According to the present invention, a transparent protective plate is provided on the viewing side of a liquid crystal display panel to manufacture a handwritten liquid crystal display device equipped with a tablet plate. A method for producing a liquid crystal display device, characterized in that the adhesive treatment is carried out by irradiating ultraviolet rays through a buffering adhesive sheet made of a transparent adhesive resin and having an ultraviolet polymerizable liquid at the adhesive interface. Is provided.

[0007]

[Function] The transparent protective plate and the liquid crystal are protected by a method that does not require advanced technology, has excellent work efficiency, and is less likely to be damaged by the method of performing the adhesion processing through the buffer adhesive sheet made of a transparent adhesive resin. A reflection loss of light at the interface of the display panel can be significantly reduced, and a handwritten liquid crystal display device having excellent visibility and mass productivity can be obtained. In that case, by adopting a method in which a UV-polymerizable liquid is interposed at the bonding interface and the bonding treatment is performed by UV irradiation, it is possible to prevent bubbles from being mixed in and prevent visibility from being hindered.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is to manufacture a handwritten liquid crystal display device equipped with a tablet plate having a transparent protective plate adhered to the viewing side of a liquid crystal display panel via an adhesive sheet. Therefore, the liquid crystal display device according to the present invention includes at least the liquid crystal display panel, the tablet plate that enables handwriting input, and the transparent protective plate. Examples thereof are shown in FIGS. 1 and 2. 1 is a transparent protective plate, 2 is an adhesive layer, 3 is a tablet plate,
Reference numeral 4 is a liquid crystal display panel in which a polarizing plate 41 is adhered to the liquid crystal display cell 42, and 5 is an illumination system including a reflection plate and a backlight system.

As is clear from the figure, the tablet plate 3
Can be arranged on either the front side or the back side of the liquid crystal display panel 4 on the viewing side. In the present invention, a handwriting inputtable liquid crystal display device having an appropriate structure is formed by a manufacturing process such as an appropriate assembly sequence, etc., except that a transparent protective plate is adhered to the viewing side of the liquid crystal display panel by a predetermined method. can do. Therefore, in the case of the structure having the tablet plate 3 on the front side of the liquid crystal display panel 4 on the viewing side, the tablet plate 3 and the transparent protective plate 1 are bonded together via the adhesive sheet (2). The order of formation is arbitrary.

Further, the liquid crystal display panel and the transparent protective plate may be appropriately formed. Generally, a liquid crystal display panel is formed by arranging polarizing plates on both sides or one side of a liquid crystal display cell in which liquid crystal is controlled by an appropriate driving method. The transparent protective plate is formed of a glass plate, various resin plates, or the like.

In the present invention, the liquid crystal display panel and the transparent protective plate disposed on the viewing side thereof are adhered to each other through a buffering adhesive sheet made of a transparent adhesive resin and bonded to the liquid crystal display panel. It is carried out by irradiating ultraviolet rays with an ultraviolet polymerizable liquid being interposed at least at one of the interfaces between the sheet and the transparent protective plate.

As the visco-adhesive resin forming the adhesive sheet, a transparent and buffering resin having a small difference in refractive index between the liquid crystal display panel to be adhered and the transparent protective plate is used. The transparency of the tacky adhesive resin or the adhesive layer made of the adhesive resin is JIS K from the viewpoint of light transmittance.
5 or less, especially 2 based on the Haze value according to 6714
The following are preferred.

Further, from the viewpoint of protecting the liquid crystal display panel from the writing pressure at the time of handwriting input, 0.01 to 5 mm, especially 0.02 to
When the adhesive layer has a thickness of 3 mm, it is preferable that the liquid crystal display panel has a cushioning property so that the writing pressure does not locally deform.
Further, the difference in refractive index between the two objects to be adhered is preferably 0.2 or less with respect to each surface layer of the liquid crystal display panel and the transparent protective plate, which are objects of adhesion, from the viewpoint of reducing reflection loss at the interface.

Examples of the tacky-adhesive resin which can be preferably used in the present invention include an acrylic polymer containing an acrylic monomer having an acrylic group or a methacrylic group as a component, and a silicone-based adhesive polymer based on a polyorganosiloxane skeleton. can give.

Specific examples of the acrylic polymer include acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, pentyl acrylate, isopentyl acrylate, acrylic acid. Hexyl, heptyl acrylate, octyl acrylate, isooctyl acrylate, nonyl acrylate, isononyl acrylate, decanyl acrylate, isodecanyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate,
Butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decanyl methacrylate,
Examples thereof include alkyl esters of acrylic acid or methacrylic acid such as isodecanyl methacrylate, and those obtained by subjecting a part of the alkyl group substituted with a hydroxyl group as a main component to a polymerization treatment. The polymerization treatment can be appropriately performed, but in general, an addition polymerization method such as a solution polymerization method, a photopolymerization method using electron beams or ultraviolet rays, and a combination method thereof is adopted.

As a specific example of the above-mentioned silicone-based adhesive polymer, a silicone-based polymer having a polyorganosiloxane as a skeleton is used as a main component, and a hydrolyzable polymer such as an acetoxy group, an alkoxy group or a ketoxime group is added to the main component. Examples thereof include a composition containing a functional silane compound, a crosslinkable siloxane compound having three or more reactive groups such as silanol groups, and the like.

The adhesive sheet is prepared by spreading a tacky adhesive resin as a solution with a solvent or the like on the separator, if necessary.
It may be formed by an appropriate method such as a method in which a separator is further arranged on the spread layer to form a sheet. The separator can be obtained by, for example, a method of surface-treating thin leaves such as a film with a release agent.

In addition, the liquid crystal display panel and the transparent protective plate are adhered to each other through an adhesive sheet by, for example, sticking the adhesive sheet to one of the liquid crystal display panel and the transparent protective plate by peeling off one of the separators and using a roll laminator or the like. After that, the remaining separator is peeled off, and an ultraviolet polymerizable liquid is applied to the surface of the liquid crystal display panel or the other side of the transparent protective plate by applying an appropriate method such as a dropping method, a spray method, or a coating method, and the ultraviolet ray is irradiated on it. It can be performed according to the method.

In the above description, the UV-polymerizable liquid is for increasing the adhesion at the adhesive interface between the adhesive sheet and the liquid crystal display panel or the transparent protective plate to prevent bubbles from entering. Therefore, the UV-polymerizable liquid is allowed to intervene in at least one of the adhesive interfaces of the liquid crystal display panel, the adhesive sheet and the transparent protective plate, and optionally in all the interfaces. The method of interposing is arbitrary, such as a method of applying an ultraviolet-polymerizable liquid to a liquid crystal display panel or a transparent protective plate, or a method of applying it to an adhesive sheet. To improve the adhesion at the adhesive interface, a solvent with good volatility may be added to improve the wettability.

The UV-polymerizable liquid to be interposed is, for example, an addition-polymerizable ester-based monomer or oligomer having two or more acrylic groups or methacrylic groups, and a photopolymerization initiator which generates radicals or the like upon irradiation with ultraviolet rays. It is possible to use an appropriate liquid exhibiting ultraviolet polymerizability such as a mixed solution, and it is preferable to use a liquid which can complete the reaction rapidly and cure.

Example 1 A polarizing film (NPF-F1205D manufactured by Nitto Denko Corp.) is formed on one surface of a transparent glass plate (180 mm × 250 mm) having a thickness of 1.1 mm.
U) is adhered on top of the adhesive sheet with a thickness of 200 μm, one of the separators is peeled off and pressure-bonded via a roll laminator, then the remaining separator is peeled off to expose the adhesive sheet surface and UV-polymerizable surface. Liquid of 1.1 mm is laid on the transparent glass plates having a thickness of 1.1 mm to adhere them to each other, and the UV-polymerizable liquid layer is spread in a thin layer on the entire interface between the adhesive sheet and the glass plate, and ultraviolet rays are applied by a high pressure mercury lamp. Is irradiated with 200 mJ / cm ² to cure the development of the UV-polymerizable thin layer, and a glass transparent protective plate is bonded onto a glass plate for forming a liquid crystal display panel via a polarizing film and a transparent adhesive layer. A laminated body was obtained.

In the above, the adhesive sheet was prepared by dissolving 95 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid and 0.2 parts by weight of benzoyl peroxide in 300 parts by weight of toluene and stirring at about 60 ° C. for 6 hours. The reaction is performed to obtain a tacky acrylic polymer solution, and 0.5 part by weight of an isocyanate crosslinking agent is added to 100 parts by weight of the acrylic polymer, and the mixture is spread on a polyester separator by a reverse roll coating method. It is formed by further applying a polyester separator and heating and drying it.

The UV-polymerizable liquid consists of an acrylic ester monomer solution prepared by mixing and dissolving 100 parts by weight of trimethylolpropane triacrylate and 3 parts by weight of 1-hydroxycyclohexyl phenyl ketone.

Comparative Example A laminated body was obtained in the same manner as in Example 1 except that the ultraviolet ray-polymerizable liquid was not used and the ultraviolet ray was not irradiated.

In the above, in the laminated body obtained in Example 1, no air bubbles were observed at each adhesive interface inside, and each layer was firmly adhered and was excellent in visibility. However, in the laminated body obtained in the comparative example, a large number of bubbles, which are sufficiently visible even when mixed at the internal adhesive interface, were mixed and the visibility was poor.

[0026]

According to the present invention, the transparent protective plate and the liquid crystal display panel can be laminated without the inclusion of air bubbles by a simple and efficient operation, which is an adhesive sheet-type bonding process, and which is less likely to cause damage. It is possible to mass-produce a liquid crystal display device capable of handwriting input which has little light reflection loss and excellent visibility.

[Brief description of drawings]

FIG. 1 is a sectional view of an example.

FIG. 2 is a sectional view of another embodiment.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

 1: Transparent protective plate 2: Adhesive layer 3: Tablet plate 4: Liquid crystal display panel

Claims (1)

[Claims] 1. When manufacturing a liquid crystal display device equipped with a transparent protective plate on the viewing side of the liquid crystal display panel and equipped with a tablet plate, the liquid crystal display panel and the transparent protective plate are made of a transparent adhesive resin. A method for manufacturing a liquid crystal display device, comprising: performing a bonding treatment by irradiating ultraviolet rays through an adhesive sheet having a buffering property consisting of, and having an ultraviolet polymerizable liquid interposed at the bonding interface.