JP2007225922A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device capable of suppressing the generation of a circular irregularity and suppressing the deterioration of a display performance. <P>SOLUTION: The image display device is provided with a panel comprising: a substrate made of glass or resin; a surface side stacked body disposed on the visible side of the substrate; and a back side stacked body disposed on the back side of the substrate, wherein, in the whole area in a circle of radius 10 cm around the intersection of diagonal lines of the panel, a distance between the back side optical member and the backlight side optical member adjacent to the back side stacked body is at least 2 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display device such as a thin display, and more particularly to an image display device useful as a liquid crystal display device used for a monitor for a personal computer, a television, or the like.

  Since liquid crystal display devices have various advantages such as low voltage and low power consumption, and can be reduced in size and thickness, they are being developed for monitors for personal computers and portable devices and for television applications. Along with this, the enlargement of the screen is progressing.

In addition, the liquid crystal display device is becoming thinner as a whole image display device at the same time as the screen is enlarged. Thinning of the image display device is achieved by configuring the image display device with a panel having a thin glass or resin substrate. However, when such a liquid crystal panel is exposed to high temperature and high humidity and a black screen is displayed, a “circle unevenness” phenomenon occurs in which light leaks in an annular shape to the panel (screen). It has become.
At this time, when the panel is observed, the panel is warped. When observed from the front side (viewing side) of the image display device, the center portion of the panel is dented and the edge portion is warped to the front side.

  The warping of the panel described above occurs on the observation side and its back side (hereinafter, the back side may be simply referred to as “back side” relative to the observation side) with respect to a glass or resin substrate that does not naturally warp. The laminated members expand and contract due to heating, moisture absorption, moisture release, etc., causing expansion and contraction differences between the observation side and the back side, and the balance of the force between the front and back of the image display device is lost. It is what happens. In a normal image display device, the surface on the observation side of the panel is open, whereas the back surface is incorporated in a housing and is in a semi-sealed state. For this reason, it is considered that there is a difference in the amount of heating, moisture absorption and moisture release between the front side laminated body and the back side laminated body sandwiching the substrate, and the difference is caused in the expansion and contraction, which causes warpage.

  Taking a liquid crystal display device as an example, the liquid crystal display device includes a polarizing plate that creates polarized light on both sides of a liquid crystal cell in which liquid crystal is sealed in a glass substrate, and a retardation plate, an antireflection film, and a brightness enhancement film as necessary. Are stacked together, and the outer peripheral part is fixed with a fixed frame made of a metal plate called stainless steel called “bezel” to form a liquid crystal module, and this liquid crystal module is assembled and housed in a housing together with other components. Manufactured.

  When the power of the liquid crystal display device is turned on, a difference in temperature and humidity may occur between the front side (viewing side) and the backlight side of the device due to the temperature rising by the backlight. In this case, the temperature and humidity conditions to which the front side laminate including the polarizing plate and the back side laminate on the backlight side are exposed with the liquid crystal cell as the boundary are different, and each laminate has a difference between these conditions. It seems to be affected. When the panel is warped, not only the edge portions or four corners of the panel come into contact with the housing, but also a display performance problem occurs due to close contact with the backlight installed on the back surface. Furthermore, when a black display screen is used, a “corner unevenness” phenomenon in which the four corners of the panel (screen) leak light unevenly may cause a very large problem in display performance.

In order to improve the warpage of the panel due to environmental changes, in Patent Document 1, a polarizing plate made of a polarizer with a protective film is provided on both sides of the liquid crystal cell, and a brightness enhancement film is laminated on the polarizing plate on the back side. The film thicknesses of the protective film used for the front-side polarizing plate and the protective film used for the back-side polarizing plate are changed. However, when the thickness of the protective film on the viewing side of the laminate provided on the front side is reduced, there has been a problem that the optical performance is likely to deteriorate due to the deterioration of the polarizer due to humidity.
JP 2003-149634 A

  When the panel is exposed to high temperature and high humidity and then removed under normal temperature and humidity, light leakage (hereinafter sometimes referred to as “circle unevenness”) occurs on the panel (screen) in a black display screen. There is. It is an object of the present invention to provide an image display device that suppresses the occurrence of “circle unevenness” and suppresses a decrease in display performance.

The “circle unevenness” occurs when the liquid crystal display device is left for a certain period of time under high temperature and high humidity, then taken out at room temperature and normal humidity, and the backlight is turned on for several hours. As a result of investigations to clarify the cause, the inventors of the present invention have found that “circle unevenness” occurs by the following mechanism.
1) When the liquid crystal display device is left under high humidity, both the front side laminate and the back side laminate member absorb moisture. After that, when the backlight of the liquid crystal display device is lit at room temperature and normal humidity, Dehumidification easily occurs and shrinks from the front side laminate of the panel that is open to the outside, but the back side laminate is surrounded by a case etc. so that dehumidification is delayed compared to the front side laminate. Because of this, contraction is delayed. As a result, the balance of shrinkage between the front side laminate and the back side laminate is lost, and the panel warps in the concave direction when viewed from the front side.
2) The panel comes into circular contact with the member on the backlight side due to the generated warpage of the panel. In other words, the back side laminate has a circular portion in contact with the backlight side member. In this case, dehumidification from the non-contact portion is relatively easy, and therefore shrinkage occurs in that region. However, the circular contact portion is difficult to dehumidify because air hardly flows, and shrinkage hardly occurs. That is, since a difference in contraction force occurs between the contact portion and the non-contact portion of the back side laminate with the backlight side member, a phase difference occurs in the back side laminate, and circle unevenness occurs.

Further analysis based on the above mechanism revealed that the curvature radius of the panel warp was about 800 cm. Therefore, in order to prevent the back-side laminate of the panel from coming into contact with the backlight-side member adjacent thereto, the back-side laminate and the above-described laminate are formed in all regions within a circle having a radius of 10 cm centered on the intersection of the diagonal lines of the panel. It was clarified that by making the distance between the optical member on the backlight side adjacent to the back side laminate 2 mm or more, contact between the panel and the optical member on the backlight side can be prevented, and the occurrence of “circle unevenness” can be suppressed.
More specifically, if the curvature radius of the backlight side member is set to 750 cm or less, even if the panel is warped, the back side laminate of the panel does not come into contact with the adjacent backlight side member, and circle unevenness occurs. It was found that can be prevented.

Specifically, the above-described problems can be solved by the following means.
(Aspect 1)
An image display device comprising a substrate made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a panel having a back side laminate provided on the back side of the substrate, the diagonal line of the panel An image display device, wherein the distance between the back-side laminate and the backlight-side optical member adjacent to the back-side laminate is 2 mm or more in all regions within a circle having a radius of 10 cm centering on the intersection.
(Aspect 2)
An image display device comprising a panel made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a panel having a back side laminate provided on the back side of the substrate, the back side laminate An image display device characterized in that a backlight side optical member provided adjacent to is warped in a concave state when viewed from the viewing side and has a radius of curvature of 750 cm or less.
(Aspect 3)
3. The image display device according to aspect 1 or 2, wherein a long side of the panel is 40 cm to 350 cm.
(Aspect 4)
The image according to any one of aspects 1 to 3, wherein the front-side laminate and the substrate are laminated via an adhesive layer, and the thickness of the adhesive layer is 30 μm to 100 μm. Display device.
(Aspect 5)
The image display device according to any one of aspects 1 to 4, wherein a surface of the panel on the viewing side is open, and a back side of the panel is closed by a housing.
(Aspect 6)
The image display device according to any one of aspects 1 to 5, wherein the substrate is a liquid crystal cell, and the back-side laminate includes an optical compensation film.
(Aspect 7) The front-side laminate includes a viewing-side protective film provided on the viewing side and a substrate-side protecting film provided on the substrate side, and includes at least the viewing-side protecting film and the substrate-side protecting film. 7. The image display device according to aspect 6, wherein one is made of cellulose acylate.
(Aspect 8)
8. The image display device according to any one of aspects 1 to 7, using a VA liquid crystal display mode or an IPS liquid crystal display mode.
(Aspect 9)
The image display device according to any one of aspects 1 to 8, wherein a TN mode or OCB mode liquid crystal display mode is used.

  ADVANTAGE OF THE INVENTION According to this invention, the image display apparatus which suppressed generation | occurrence | production of a circle nonuniformity and suppressed the display performance can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

  The image display device of the present invention will be described in detail below. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Configuration of image display device)
An image display device of the present invention comprises a panel comprising a substrate made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a back side laminate provided on the back side of the substrate, And an optical member provided adjacent to the back side laminate.
Moreover, the said front side laminated body and back side laminated body contain a polarizer. The polarizer of the front side laminate can be provided with a viewing side protective film on the viewing side and a substrate side protecting film on the substrate side. Moreover, it is preferable that at least one of the viewing-side protective film and the substrate-side protective film is made of cellulose acylate.
Similarly, the back side laminate polarizer may be provided with a backlight side protective film on the backlight side and a substrate side protective film on the substrate side. Moreover, it is preferable that at least one of the backlight side protective film and the substrate side protective film is made of cellulose acylate.
Furthermore, the image display device of the present invention preferably includes a backlight. A well-known backlight can be used as appropriate.

The panel which comprises the image display apparatus of this invention may be provided with the other optical film and the functional layer as needed. The panel is preferably installed in the image display apparatus so that the surface on the viewing side is open and the back surface is closed by the housing.
Moreover, it has the structure where various optical members, such as a brightness improvement film and a light-diffusion sheet, were laminated | stacked between the panel and the backlight as needed.

  A configuration example of the image display apparatus of the present invention is shown in FIG. In FIG. 1, the image display device of the present invention is configured by incorporating a panel 1 and a backlight side optical member 9 into a housing 8, and the surface of the panel 1 on the viewing side (above the paper surface) is open, The back side (backlight side below the paper surface) is sealed with a housing 8.

The panel 1 is composed of a front side laminate 2, a substrate 6, and a back side laminate 7, and the front side laminate 2 is composed of a viewing side protective film 3, a polarizer 4, and a substrate side protective film 5. ing. An optical member 9 composed of, for example, a brightness enhancement film, a brightness enhancement film, a light diffusion sheet, a light diffusion plate, a prism sheet, or the like is laminated between the panel 1 and the backlight.
The size of the panel 1 is not particularly limited, but the long side is preferably 40 cm to 350 cm, more preferably 45 cm to 300 cm, and particularly preferably 50 cm to 250 cm.

  In the “liquid crystal display device” of the present invention, polarizing plates (front-side laminate and back-side laminate) are arranged on both sides of a liquid crystal cell serving as a substrate, and a retardation film, an antireflection film, a brightness enhancement film, etc., as necessary. It has a structure in which various optical elements are laminated. In the case of a liquid crystal display device, the substrate as used in the present invention corresponds to a liquid crystal cell, and each laminate corresponds to various optical elements such as a polarizing plate, a retardation film, and an antireflection film.

  In general, a liquid crystal display device is a liquid crystal module in which the outer periphery of the liquid crystal panel is fixed with a fixed frame made of a metal plate such as stainless steel called a “bezel”, and the liquid crystal module is assembled and housed in a casing together with other components. Manufactured. Also in the present invention, the outer peripheral portion of the panel can be fixed with a fixing frame such as a bezel and used in the same configuration.

(Backlight side optical member adjacent to the back side laminate)
The “backlight side optical member adjacent to the back side laminated body” is an optical member adjacent to the back side laminated body and located on the backlight side. Here, the term “adjacent installation” means that it is installed next to each other, and the two do not necessarily have to be in direct contact with each other. Specifically, it is a brightness enhancement film, a brightness enhancement film, a light diffusion sheet, a light diffusion plate, a prism sheet, and the like. In order to prevent contact with the light side member, the backlight side optical member adjacent to the back side optical member and the back side laminated body in all regions within a circle having a radius of 10 cm centered on the intersection of the diagonal lines of the panel The distance is set to 2 mm or more.

The distance between the back side optical member and the back side optical member adjacent to the back side laminate is preferably 2 mm to 10 mm in terms of preventing the occurrence of uneven circles and reducing the thickness of the display device. It is more preferable that
Specifically, the curvature radius of the backlight side member is preferably set to 750 cm or less. By doing so, even when the panel is warped, the back side laminate of the panel does not come into contact with the member on the backlight side adjacent thereto, and the occurrence of circle unevenness can be prevented.
The curvature radius on the backlight side is preferably 400 cm to 750 cm, more preferably 500 cm to 750 cm, from the viewpoint of preventing the occurrence of circle unevenness and reducing the thickness of the display device.

  As described above, the distance between the back side optical member and the backlight side optical member adjacent to the back side laminated body is set to 2 mm or more in all regions within a circle having a radius of 10 cm centering on the intersection of the diagonal lines of the panel. As a practical means, a backlight side optical member (such as a light diffusing plate) having the above-mentioned radius of curvature is used, or a spacer or the like is provided in a portion holding the backlight side optical member adjacent to the panel and the back side laminate. For example. The spacer here refers to the back side in all regions within a circle having a radius of 10 cm centered on the intersection of the diagonal lines of the panel by being inserted between the back side laminated body and the optical member on the backlight side adjacent thereto. A member that can make the distance between the optical member and the optical member on the backlight side adjacent to the back side laminated body 2 mm or more, and a member made of a material such as metal or plastic can be used as a preferable spacer.

(substrate)
The substrate constituting the image display device of the present invention is made of glass or resin (plastic). The glass or resin may contain an additive. The substrate may hold components other than glass or resin. The “substrate” in the present invention is preferably a plate for holding a liquid crystal layer.

  As said board | substrate, the glass and resin normally used for the liquid crystal cell use can be employ | adopted as a component, for example. When a liquid crystal cell is used as the substrate, the liquid crystal can be sealed between cell substrates made of glass or resin. Moreover, a transparent conductive film can be provided on both surfaces of the liquid crystal cell, and a color filter can be provided on the front side (viewing side) of the transparent conductive film. From the viewpoint of reducing the thickness of the liquid crystal display device, the thickness of the substrate is preferably 1 mm or less, more preferably 0.7 mm or less, and most preferably 0.5 mm or less. There is no particular limitation on the size of the substrate, and when the area of the substrate is large, the liquid crystal panel is likely to warp. Therefore, the present invention is particularly effective in a large-screen liquid crystal display device.

  Here, as a material that can be used for the resin substrate, the material is not particularly limited as long as it has transparency and mechanical strength, and all conventionally known materials can be used. Examples of the resin that can be used for the resin substrate include thermoplastic resins such as polycarbonate, polyarylate, polyethersulfone, polyester, polysulfone, polymethylmethacrylate, polyetherimide, and polyamide, epoxy resin, Examples thereof include thermosetting resins such as saturated polyester, polydiallyl phthalate, and polyisobornyl methacrylate. 1 type, or 2 or more types can be used for this resin, and it can also be used as a copolymer and a mixture with another component.

(Front side laminate and back side laminate)
Next, the front side laminated body and the back side laminated body in the present invention will be described. The front laminated body and the back laminated body preferably include at least a polarizer and function as a polarizing plate.

  In the present invention, the type of polarizing plate (front side laminate and back side laminate) is not particularly limited as long as it does not impair the effects of the present invention. For example, a polyvinyl alcohol (PVA) film has dichroism. An absorptive polarizing plate formed by bonding a polarizer that has been dyed with iodine or a dichroic dye, stretched, oriented, cross-linked and dried, and a protective film such as a triacetyl cellulose (TAC) film. It can be preferably used. The polarizer is preferably excellent in light transmittance and degree of polarization. The light transmittance of the front side laminate and the back side laminate is preferably 30% to 50%, more preferably 35% to 50%, and most preferably 40% to 50%. The polarization degree of the front side laminate and the back side laminate is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. When the transmittance is 30% or less or the degree of polarization is 90% or less, the brightness and contrast of the image display device may be low, and the display quality may deteriorate. The thickness of the polarizer is preferably 1 to 50 μm, more preferably 1 to 30 μm, and most preferably 8 to 25 μm.

  The polarizers of the front side laminate and the back side laminate are a viewing side protective film provided on the viewing side, or a backlight side protective film provided on the backlight side, and a substrate side protective film provided on the substrate side. Can have. Moreover, it is preferable that at least one of the visual recognition side protective film and the substrate side protective film is made of cellulose acylate.

  In the present invention, the adhesive treatment between the polarizer and each protective film is not particularly limited. For example, an adhesive made of a vinyl alcohol polymer, boric acid, borax, glutaraldehyde, melamine, or oxalic acid. It can be carried out via an adhesive comprising at least a water-soluble cross-linking agent of a vinyl alcohol polymer. In particular, it is preferable to use a polyvinyl alcohol-based adhesive because it has the best adhesion to the polyvinyl alcohol-based film. Such an adhesive layer can be formed as a coating / drying layer of an aqueous solution, but other additives and a catalyst such as an acid can be blended as necessary when preparing the aqueous solution.

  As a material for forming each protective film, a polymer excellent in optical performance transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable. Examples include polycarbonate polymers, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymers such as polymethyl methacrylate, and styrene polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin). Polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers , Polyether ether ketone polymers, polyphenylene sulfide polymers, vinylidene chloride polymers, vinyl alcohol polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or polymers mixed with the above polymers Take as an example. Further, each protective film used in the present invention can be formed as a cured layer of an acrylic, urethane, acrylic urethane, epoxy, silicone, or other ultraviolet curable or thermosetting resin.

  In the present invention, a thermoplastic norbornene resin can be preferably used as a material for forming each protective film. Examples of the thermoplastic norbornene-based resin include ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., and ARTON manufactured by JSR Corporation.

  In addition, as a material for forming each protective film, a cellulose polymer such as cellulose acylate typified by triacetylcellulose, which has been used as a transparent protective film for polarizing plates, which has excellent bonding properties with a polarizer. Can also be preferably used.

  Each protective film used in the present invention may be formed by thermally melting a thermoplastic polymer resin, or may be formed by solution film formation (solvent casting method) from a solution in which a polymer is uniformly dissolved. Good. In the case of hot melt film formation, various additives (for example, a compound that reduces optical anisotropy, a wavelength dispersion adjusting agent, an ultraviolet ray preventing agent, a plasticizer, a deterioration preventing agent, fine particles, an optical property adjusting agent, etc.) are heated. It can be added at the time of melting. On the other hand, when the protective film is prepared from a solution, the polymer solution (hereinafter referred to as “dope”) includes various additives (for example, compounds that reduce optical anisotropy) depending on the application in each preparation step. , A wavelength dispersion adjusting agent, an ultraviolet ray preventing agent, a plasticizer, a deterioration preventing agent, fine particles, an optical property adjusting agent, and the like). The additive may be added at any stage in the dope preparation process or at the end of the dope preparation process.

  An optical compensation film may be used as necessary for the protective film (substrate-side protective film) on the liquid crystal cell side of the polarizer. The optical compensation film generally refers to an optical material that compensates a viewing angle in an oblique direction of a liquid crystal display device, and is synonymous with a retardation plate, an optical compensation sheet, and the like. The optical compensation film may be an integral type in which the protective film itself of the polarizing plate has optical performance, for example, a triacetyl cellulose acylate film having optical compensation performance to form a protective film for a polarizer. For example, a triacetyl cellulose film may be coated with a discotic liquid crystal and then integrated with a polarizing plate.

  In particular, when the substrate is a liquid crystal cell, the back side laminate preferably includes an optical compensation film. The optical compensation film of the back side laminate may be of a type that is integrated with the same polarizing plate as that described for the front side laminate, or may be a laminate of a plurality of sheets. As the optical compensation film to be bonded, a polymer film is mainly preferably used. For example, bi-directional stretching such as a birefringent polymer film stretched biaxially in the plane direction, or a tilted orientation polymer film with a controlled refractive index in the thickness direction stretched uniaxially in the plane direction and stretched in the thickness direction A film or the like is used. Furthermore, an inclined alignment film is also used. For example, a heat-shrinkable film may be bonded to the polymer film, and the polymer film may be stretched and / or shrunk under the action of the shrinkage force by heating, or the liquid crystal polymer may be obliquely oriented.

  When the optical compensation film is provided on the back side laminate, the refractive index anisotropy is small in the protective film (substrate side protective film) on the liquid crystal cell side of the polarizer of the front side laminate (not different in the surface direction or thickness direction). ) A protective film may be used.

  The thickness of the viewing side protective film, the backlight side protective film and the substrate side protective film is preferably 20 μm to 150 μm, and more preferably 30 μm to 130 μm.

  A hard coat film, an antireflection film, an antiglare film, or the like may be appropriately provided on the surface on the viewing side of the polarizer by bonding or surface treatment. The hard coat film or the hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizer, for example, a cured film excellent in hardness, slipperiness, etc. by an appropriate ultraviolet curable resin such as a silicone type, It can be formed by a method of adding to the surface of the transparent protective film. The anti-reflection film or anti-reflection treatment (anti-reflection) is applied for the purpose of preventing the reflection of external light on the polarizing plate surface, and the anti-glare film or anti-glare treatment (anti-glare) is the surface of the panel (screen). Therefore, it is intended to prevent the outside light from being reflected and hindering the viewing of the transmitted light from the panel. These functions provide a fine uneven structure on the surface of the protective film by an appropriate method such as a roughening method such as a sand blasting method or an embossing method, or a method of coating a coating liquid containing transparent fine particles. Can be formed.

(Adhesive)
In the liquid crystal display device of the present invention, when the front-side and back-side laminates are bonded to a substrate, it is generally adhered using a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive. These pressure-sensitive adhesive layers can be formed of an appropriate pressure-sensitive adhesive such as an acrylic type. From the viewpoints of preventing foaming and peeling phenomena due to moisture absorption, and reducing optical characteristics due to differences in thermal expansion, etc., an adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  In the liquid crystal display device of the present invention, the thickness of the pressure-sensitive adhesive layer used when the front and back side laminates are bonded to the substrate is preferably 30 μm to 100 μm, more preferably 33 μm to 70 μm, and still more preferably 34 μm to 50 μm.

  As the material for the pressure-sensitive adhesive, pressure-sensitive pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, polyether-based pressure-sensitive adhesives, and polyester-based pressure-sensitive adhesives are preferable.

  In the case of an acrylic pressure-sensitive adhesive, monomers used in the acrylic polymer that is the base polymer include various (meth) acrylic acid esters (here, “(meth) acrylic acid ester” means acrylic acid esters and methacrylic acid esters). This is a general term for acid esters, and the following compound names with (meth) have the same meaning. Specific examples of such (meth) acrylic acid esters include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and phenyl (meth) acrylate. Etc., and these can be used alone or in combination. Moreover, in order to provide polarity to the obtained acrylic polymer, a small amount of (meth) acrylic acid can be used instead of a part of the (meth) acrylic acid ester. Furthermore, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide and the like may be used in combination as the crosslinkable monomer. Furthermore, if desired, other copolymerizable monomers such as vinyl acetate and styrene may be used in combination as long as the adhesive properties of the (meth) acrylic acid ester polymer are not impaired.

  Examples of the base polymer of the rubber adhesive include natural rubber, isoprene rubber, styrene-butadiene rubber, recycled rubber, polyisobutylene rubber, styrene-isoprene-styrene rubber, styrene-butadiene-styrene rubber, and the like. Is mentioned.

  Examples of the base polymer of the silicone pressure-sensitive adhesive include dimethylpolysiloxane and diphenylpolysiloxane.

  Examples of the base polymer of the polyether-based pressure-sensitive adhesive include polyvinyl ethyl ether, polyvinyl butyl ether, and polyvinyl isobutyl ether.

  The pressure-sensitive adhesive used in the present invention can be prepared, for example, by blending the base polymer (a) with a compound (b) having a molecular weight of 100,000 or less. The ratio (mass ratio) of (a) :( b) is more preferably 90: 10-20: 80.

  The compound (b) having a molecular weight of 100,000 or less preferably has a good compatibility when blended with the base polymer (a), is optically transparent, and has a glass transition point (Tg) of 30 ° C. or higher. For example, it is the same polymer as the base polymer having a mass average molecular weight of 100,000 or less, and a monomer component using many components having a high Tg such as methyl (meth) acrylate.

  The pressure-sensitive adhesive used in the present invention can contain a crosslinking agent. Examples of the crosslinking agent include polyisocyanate compounds, polyamine compounds, melamine resins, urea resins, and epoxy resins.

  Furthermore, for the pressure-sensitive adhesive used in the present invention, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, and the like are appropriately used as necessary without departing from the object of the present invention. Can do. As these additives, conventionally known ones can be appropriately selected and used.

  The method for forming the pressure-sensitive adhesive layer is not particularly limited. For example, conventionally known methods such as a method of applying and drying a pressure-sensitive adhesive solution and a method of transferring the pressure-sensitive adhesive layer using a release sheet provided with a pressure-sensitive adhesive layer can be mentioned.

(Size of each layer)
The size of each layer used in the image display device is equal to the size of the panel (screen). Although depending on the panel size of the image display device, the length of the long side is preferably 10 cm to 500 cm from the viewpoint of practical size and manufacturing. More preferably, it is 20 cm-450 cm, More preferably, it is 30 cm-400 cm, Most preferably, it is 40 cm-350 cm. There is no particular limitation on the size, but the larger the area, the greater the warpage of the liquid crystal panel. Therefore, the present invention is particularly effective when used in a large-screen liquid crystal display device.

(Image display device)
The image display device of the present invention can be achieved by using liquid crystal cells in various display modes. Display modes include IPS (In-Plane Switching), VA (Vertical Aligned), TN (Twisted Nematic), OCB (Optically Compensated Bend), STN (Super Twisted Nematic), ECB (Electrically Controlled Birefringence), FLC (Ferroelectric Liquid Crystal). ), AFLC (Anti-ferroelectric Liquid Crystal), and HAN (Hybrid Aligned Nematic) have been proposed. There has also been proposed a display mode in which the display mode is orientation-divided.

  The image display device of the present invention preferably uses a VA mode or IPS mode liquid crystal display mode, or a TN mode or OCB mode liquid crystal display mode.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(1) Preparation of protective film 100 parts by mass of cellulose acetate having an acetyl substitution degree of 2.86, 10 parts by mass of triphenyl phosphate (TPP), 400 parts by mass of methylene chloride (first solvent), 60 parts by mass of methanol (second solvent) Each part was put into a mixing tank and dissolved by stirring to prepare a cellulose acetate solution. This cellulose acetate solution was filtered, cast onto a metal support, held in a tenter zone at 100 ° C. and conveyed, and then dried by passing through a 130 ° C. drying zone for 30 minutes, whereby a transparent film sample 101 was produced. The resulting transparent film 101 had a residual solvent amount of 0.2% or less and a film thickness of 80 μm. In addition, the above-mentioned degree of acetyl substitution indicates a ratio in which the hydrogen atoms of hydroxyl groups at the 2nd, 3rd and 5th positions of cellulose are substituted with acetyl groups, and all of the 2nd, 3rd and 5th positions. When the hydrogen atom of the hydroxyl group is substituted with an acetyl group, the degree of acetyl substitution is 3.
The transparent film sample 101 was immersed in a 1.5 mol / L aqueous sodium hydroxide solution at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing tub, and neutralized using the 0.1 mol / L sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. Thus, the surface of each transparent film sample was surface-treated.

(2) Production of panel (production of iodine-based polarizing plate)
A roll-shaped polyvinyl alcohol film (manufactured by Kuraray Co., Ltd.) having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer having a thickness of 25 μm.
The surface-treated transparent film sample 101 is bonded as a protective film on both surfaces of a 25 μm-thick polarizer using a polyvinyl alcohol-based adhesive, and iodine-based polarized light on the front side (viewing side) and the back side (backlight side) A plate was made.
Next, in a VA type liquid crystal cell having a horizontal long side of 40 cm and a vertical short side of 32 cm using a glass substrate having a thickness of 0.5 mm, the direction of the absorption axis of the polarizer of the polarizing plate is parallel to the long side direction of the panel. Thus, on the back side of the VA type liquid crystal cell, each of the polarizing plates was 27 μm thick acrylic adhesive (Sanlitz Co., Ltd.) so that the polarizer absorption axis of the polarizing plate was perpendicular to the absorption axis of the polarizing plate on the front side. To make a liquid crystal panel.

(3) Production of Backlight Side Optical Member Using a plate-like acrylic plate (Mitsubishi Rayon Co., Ltd.) having a long side of 40 cm, a short side of 32 cm, and a thickness of 2 mm, it is warped in the long side direction and its curvature An acrylic plate having a radius of 500 cm (sample 1), 750 cm (sample 2), 850 cm (sample 3), 1000 cm (sample 4), and infinite (no warpage) (sample 5) was prepared.
When a panel having the long side of 40 cm and the short side of 32 cm is placed on these acrylic plates, the back side laminate of the panel and the acrylic plate in a region within a circle having a radius of 10 cm centered on the intersection of the diagonal lines of the panel ( The minimum value of the distance to the optical member on the backlight side adjacent to the back side laminate is 3 mm for sample 1, 2 mm for sample 2, 1.76 mm for sample 3, 1.5 mm for sample 4, 5 was 0 mm.

(4) Evaluation by wet heat treatment of liquid crystal display device The panel produced by the method (2) was left in an environment of a temperature of 40 ° C. and a relative humidity of 90% for 4 days.
Thereafter, the acrylic plate prepared in (3) above was placed on the glass plate with the concave surface facing upward, and the panel was further placed thereon, and transferred to an environment having a temperature of 36 ° C. and a relative humidity of 30%.
As a result of placing the panel on the light table and observing it in a dark room, circle unevenness was observed in the panels on the acrylic plates of Sample 3, Sample 4 and Sample 5, but in the panels on the acrylic plates of Sample 1 and Sample 2, Circle unevenness was not observed.

  As described above, in the image display device of the present invention, since the occurrence of circle unevenness is suppressed, it is possible to effectively suppress a decrease in display performance. For this reason, it is possible to maintain excellent display performance even under conditions in which environmental changes are significant. Therefore, the present invention has high industrial applicability.

It is sectional drawing which shows the structural example of the image display apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Panel 2 Front side laminated body 3 View side protective film 4 Polarizer 5 Substrate side protective film 6 Substrate 7 Back side laminated body 8 Case 9 Backlight side optical member

Claims (9)

  An image display device comprising a substrate made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a panel having a back side laminate provided on the back side of the substrate, the diagonal line of the panel An image display device, wherein the distance between the back-side laminate and the backlight-side optical member adjacent to the back-side laminate is 2 mm or more in all regions within a circle having a radius of 10 cm centering on the intersection.   An image display device comprising a panel made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a panel having a back side laminate provided on the back side of the substrate, the back side laminate An image display device characterized in that a backlight side optical member provided adjacent to is warped in a concave state when viewed from the viewing side and has a radius of curvature of 750 cm or less.   The image display device according to claim 1, wherein a long side of the panel is 40 cm to 350 cm.   The said front side laminated body and the said board | substrate are laminated | stacked through the adhesive layer, and the thickness of the said adhesive layer is 30 micrometers-100 micrometers, The any one of Claims 1-3 characterized by the above-mentioned. Image display device.   5. The image display device according to claim 1, wherein a surface on the viewing side of the panel is open, and a back side of the panel is closed with a housing.   The image display device according to claim 1, wherein the substrate is a liquid crystal cell, and the back-side laminate includes an optical compensation film.   The front side laminate has a viewing side protective film provided on the viewing side and a substrate side protecting film provided on the substrate side, and at least one of the viewing side protective film and the substrate side protecting film is a cellulose The image display device according to claim 6, comprising a rate.   The image display device according to claim 1, wherein a VA mode or IPS mode liquid crystal display mode is used.   The image display apparatus according to claim 1, wherein a TN mode or OCB mode liquid crystal display mode is used.

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