JP2012133063A - Optical sheet and image display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet having a contrast improvement layer or the like, being configured to prevent depression from occurring in an adhesive layer or the like due to foreign matter between sheets wound around or stacked one upon another, resulting in image distortion, and provide an image display device including the optical sheet.SOLUTION: As a light beam control layer for an optical body part 4 formed of a base material layer 1 and a light beam control layer 2, the optical sheet 10 has a contrast improvement layer 3 in which a light transmission part 3a and a light absorption part 3b are alternately arranged. One side of the optical body part has an adhesive layer 6 and a release film 7, and the other side of it has a protective film 5. The relation between the product ETs of the elastic modulus Es and thickness Ts of the release film and the product ETp of the elastic modulus Ep and thickness Tp of the projective film is set to ETp≤ETs. Further, in order to prevent depression of the contrast improvement layer, the addition ΣETi of the products of the elastic moduli Ei and thicknesses Ti of corresponding layers up to the contrast improvement layer of the projective film side is set to ΣETi>ETs. The image display device has the optical sheet.

Description

  The present invention provides an optical sheet provided with a light control layer such as a contrast enhancement layer that is disposed on the viewer side of a display panel and suppresses a decrease in image contrast due to external light in a bright room environment, and the optical sheet. The present invention relates to the image display device used. More specifically, an optical sheet that has improved the problem that the adhesive layer is recessed due to foreign matter that has entered between the sheets when the sheets are rolled up, stacked, or stacked, and the image appears to be distorted after pasting the display panel is used. The present invention relates to an image display apparatus.

Currently, various flat display type display panels such as a plasma display panel, a liquid crystal panel, and an EL (electroluminescent) panel are widespread, and various image display devices such as a television, an electronic signboard, and a monitor display using these display panels. Has been put to practical use. And the optical sheet provided with the optical function according to the request | requirement is arrange | positioned at the observer side of a display panel. For example, when observing a display image in a bright room environment, external light such as fluorescent light or sunlight is incident on the display panel, so that the image contrast in the bright room, that is, the bright room contrast does not decrease. A contrast enhancing sheet is known. An optical sheet called a contrast-enhancement sheet has a light control structure in which light absorbing portions made of a columnar object such as a wedge-shaped cross section are arranged in a stripe shape in a transparent resin layer in the sheet surface direction ( Patent Document 1).
The contrast enhancement layer having such a light control structure is a transparent portion between the arranged dark light absorbing portions, and allows image light from the display to pass through the viewer, while the light absorbing portion is mainly inclined to the display screen. The bright room contrast is improved by absorbing the external light entering.

  Further, as in Patent Document 1, the optical sheet is usually provided with an adhesive layer for attachment on the display panel side. Further, a protective film for temporarily protecting the surface is often laminated on the surface on the opposite viewer side.

JP 2009-80153 A

By the way, the optical sheet is usually manufactured as a belt-like sheet, and then cut into a sheet having a size matching the shape of the display panel to be applied. Accordingly, the optical sheet is stored and transported in a state in which the sheets are stacked, such as a roll (roll) as a belt-like sheet or a state in which a large number of sheet sheets are stacked. At this time, if foreign matter such as surrounding dust enters between the stacked optical sheets, the adhesive layer will be recessed at the foreign material part, and the recess will remain after pasting on the display panel, and the image will appear distorted There was a problem that occurred.
Also, the contrast improving layer is inevitably thick in order to exhibit its optical function, so it is better to reduce the hardness from the viewpoint of preventing curling of the optical sheet. As in the case, dents are likely to occur.
In addition, although the foreign material is manufactured in a clean environment, it is a fiber of clothes, a protein derived from a person, or a raw material of an optical sheet, etc. present in the manufacturing environment. Also, in the raw material of the optical sheet, polyethylene terephthalate of the base material layer, polypropylene film of the protective film, ultraviolet curable resin of the contrast improving layer, carbon black-containing acrylic resin particles in the light absorbing portion, etc., generated when the sheet is cut It is. Most of such foreign matters have a size of about 0.2 to 0.5 mm, which causes a problem.

  That is, the problem of the present invention is that an optical sheet having a light control layer such as a contrast enhancement layer disposed on the viewer side of the display panel is adhered to the display panel due to foreign matter mixed between the optical sheets during winding or stacking. This is to prevent the occurrence of the dent in the generated pressure-sensitive adhesive layer that causes a problem that the image looks distorted after the combination. Moreover, it is providing the image display apparatus provided with such an optical sheet.

Therefore, in the present invention, an optical sheet having the following configuration and an image display apparatus using the optical sheet are provided.
(1) In the optical sheet that is arranged on the viewer side from the display panel and controls the light incident from the display panel to be emitted to the viewer side,
A contrast improving layer is provided as the light control layer of the optical main body portion comprising a base material layer and a light control layer laminated on the base material layer,
The contrast enhancement layer has a light transmission part arranged along the sheet surface so as to transmit light, and a light absorption part arranged so as to absorb light between the light transmission parts,
A pressure-sensitive adhesive layer and a release film are sequentially laminated on one surface of the optical main body, and a peelable protective film is laminated on the other surface,
An optical sheet in which the product ETp of the elastic modulus Ep and the thickness Tp of the protective film is equal to or less than the product ETs and ETp ≦ ETs with respect to the product ETs of the elastic modulus Es and the thickness Ts of the release film.

(2) Contrast including the protective film on the protective film side of the optical sheet that becomes the opposing surface of the release film when the optical sheets are superimposed on the product ETs of the elastic modulus Es and the thickness Ts of the release film The optical sheet according to (1), wherein the sum ΣETi of the product ETi of the elastic modulus Ei and the thickness Ti of each layer including the contrast enhancement layer up to the enhancement layer is large and ΣETi> ETs.
(3) The optical sheet according to (1) or (2), wherein the pressure-sensitive adhesive layer also serves as an optical functional layer having one or more functions of near infrared absorption, neon light absorption, and color correction.
(4) The optical sheet according to any one of (1) to (3), wherein the optical sheet is wound up.
(5) The optical sheet according to any one of (1) to (3), wherein a plurality of single-sheets are stacked.

(6) An image display device in which the optical sheet of any one of (1) to (5) is bonded to the surface on the viewer side of the plasma display panel with an adhesive layer.

(1) According to the optical sheet of the present invention, the adhesive layer is prevented from being dented through the release film by foreign matter mixed between the upper and lower optical sheets during winding and stacking, and the optical sheet is attached to the display panel. When combined, it is possible to prevent the occurrence of a problem that the image looks distorted due to the depression of the adhesive layer.
Furthermore, by setting the sum ΣETi of the product ETi for each layer including these from the protective film to the contrast enhancement layer, and ETs of the release film, ΣETi> ETs,
It is possible to prevent the contrast improving layer from being recessed through the protective film, and to prevent the occurrence of a problem that the image looks distorted by the recess of the contrast improving layer when the optical sheet is bonded to the display panel.
(2) According to the image display device of the present invention, since the optical sheet is used as the optical sheet disposed on the observer side, the above-described effects can be obtained. As a result, an image display device in which a defect in which an image looks distorted due to the depression of the pressure-sensitive adhesive layer or the depression of the contrast enhancement layer is improved is obtained.

Sectional drawing which illustrates one form of the optical sheet by this invention. Sectional drawing which shows another form example (it has another optical function layer in an optical main-body part) of the optical sheet by this invention. Sectional drawing which shows another form example (The layer structure of an optical main-body part is upside down) of the optical sheet by this invention. 1 is a cross-sectional view showing an example of an image display device according to the present invention. Sectional drawing which illustrates some of the other example shapes of a light absorption part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are conceptual diagrams, and the scale relationships, aspect ratios, and the like of components may be exaggerated.

[A] Optical Sheet First, FIG. 1 is a cross-sectional view showing an embodiment of an optical sheet according to the present invention. An optical sheet 10 shown in FIG. 1 has an optical main body 4 composed of a base material layer 1 and a light beam control layer 2 laminated on the base material layer 1. The light control layer 2 has a contrast enhancement layer 3. The contrast enhancement layer 3 includes a light transmission part 3a arranged along the sheet surface so as to transmit light, and a light absorption part 3b arranged so as to absorb light between the light transmission parts 3a.
Furthermore, a peelable protective film 5 is laminated on one surface of the optical main body 4 (in the embodiment shown in the figure, the surface above the drawing, specifically, the surface of the contrast enhancement layer 3 as the light control layer 2). Has been. Further, the pressure-sensitive adhesive layer 6 and the release film 7 are sequentially laminated on the other surface of the optical main body 4 (in the embodiment shown in the drawing, the surface below the drawing, specifically, the surface of the base material layer 1). .

  In the embodiment shown in the figure, the light transmitting portion 3a is thicker than the light absorbing portion 3b and equal to the thickness of the contrast improving layer 3, and the portion of the light absorbing portion 3b on the base material layer 1 side is also light. It is a transmission part 3a. In addition, the base material layer 1 and the light transmission part 3a are comprised from a transparent material.

Moreover, in the present invention, attention is paid to the magnitude relationship between the product of the elastic modulus Es and the thickness Ts of the release film 7 as ETs and the product of the elastic modulus Ep and the thickness Tp of the protective film 5 as ETp.
The product ETp related to the protective film 5 is less than the product ETs compared to the product ETs related to the release film 7, that is, ETp ≦ ETs.
The elastic modulus is a compression elastic modulus, and may be a value measured by a commercially available elastic modulus measuring device, for example. The unit is arbitrary as long as it is the same unit for the layers to be compared, but [MPa] is adopted here.
In addition, the thickness may be arbitrarily set to the same unit for the layers to be compared, but [μm] is adopted here.
Therefore, the unit of the product ETp and the product ETs is [MPa · μm] here.

  In this way, by defining the relationship between the physical properties of the release film 7 and the protective film 5, when the optical sheets are overlaid, such as during winding or stacking, between the upper and lower optical sheets 10. Due to the mixed foreign matter, the pressure-sensitive adhesive layer 6 is hardly recessed. As a result, when the optical sheet 10 is bonded to the display panel, it is possible to prevent the occurrence of a problem that the image looks distorted due to the dent.

Further, for the product ETi of the elastic modulus Ei and thickness Ti of each layer on the protective film 5 side, the elastic modulus Ei and thickness Ti for each layer including the contrast improving layer 3 up to the contrast improving layer 3 including the protective film 5 It is also preferable to pay attention to the product ETi. Then, ΣETi, which is the sum of the products ETi, is larger than the product ETs related to the release film 7, and ΣETi> ETs. For example, in the case of the optical sheet 10 illustrated in FIG. 1, the layers targeted for ΣETi are two layers of the protective film 5 and the contrast improving layer 3.
In addition, i is an integer of 1 or more, and the protective film 5 side may be number 1, and the number 2 and number 3 may be numbered toward the inner side of the optical sheet 10, but this may be reversed. In Figure 1, the thickness Tp of the protective film 5 is in T _1, the thickness Tc of the contrast enhancing layer 3 is T _2.

Thus, by defining the relationship between the release film 7 and the sum ΣETi of the product of the elastic modulus and thickness for each layer up to the contrast enhancing layer 3 on the protective film 5 side, the contrast enhancing layer 3 It is also possible to prevent the occurrence of defects due to dents due to foreign matter. Further, the presence of the protective film 5 can prevent blocking when the optical sheet 10 is overlaid.
Furthermore, if the sum of products ΣETi> product ETs is set, dents in the contrast enhancement layer 3 can be prevented.
However, even if ΣETi> product ETs, the depression of the pressure-sensitive adhesive layer 6 cannot be prevented unless ETp ≦ ETs.

  As described above, the release film 7 that protects the pressure-sensitive adhesive layer 6 is in contact with the protective film 5 that forms the opposing surface when the optical sheets 10 are overlaid. Moreover, the foreign material which enters between optical sheets is pinched | interposed into the peeling film 7 and the protective film 5, and has pressed both films. And the film with the weaker resistance with respect to each pressing of the peeling film 7 and the protective film 5 should dent preferentially by a foreign material. Therefore, as an index of resistance to compression, resistance can be expected when the thickness is larger in addition to the compression elastic modulus. Therefore, paying attention to the product of the compression elastic modulus and the thickness, it has been found that by defining the size relationship between the respective products of the release film 7 and the protective film 5, it is possible to prevent the occurrence of dents in the adhesive layer 6. The present invention has been reached.

  In addition, even if a foreign material adheres on the protective film 5 side of the optical sheet 10, the adhered foreign material itself is removed together with the protective film 5 when the protective film 5 is peeled off. Moreover, even if a foreign material adheres to the release film 7 side of the other surface, the attached foreign matter itself is removed together with the release film 7 when the release film 7 is removed. No problem arises.

  Hereinafter, the constituent layers of the optical sheet will be further described in detail. First, the optical sheet 10 includes an optical main body part 4, a protective film 5 laminated on one surface of the optical main body part 4, and an adhesive layer 6 and a release film 7 laminated on the other surface. Have at least.

<Optical body section>
The optical main body 4 is a part exclusively responsible for the optical function as the optical sheet 10, and is composed of the base material layer 1 and the light beam control layer 2.

[Base material layer]
A transparent material is used for the base material layer 1. The base material layer 1 is further preferably flexible in view of suitability for production in a roll-to-roll system. The base material layer 1 is not particularly limited as long as it is a material having such transparency and preferably flexibility, and a known material can be appropriately employed. A typical example of the base material layer 1 is a resin film. The resin is, for example, a polyester resin such as polyethylene terephthalate, a polyolefin resin such as a cycloolefin polymer, a cellulose resin such as triacetyl cellulose, an acrylic resin, or a polycarbonate resin. These resins are used in the form of films, sheets, and plates. Note that “film”, “sheet”, and “plate” are generally roughly distinguished by thickness, but in the present invention, they are merely different in name, and there is no particular distinction in meaning. In addition, the thickness of the base material layer 1 is 25-300 micrometers, for example.

(Light control layer)
The light beam control layer 2 is a layer that performs one or more light beam control operations such as reflection, transmission, absorption, diffusion, or change of polarization state on the light beam incident on the optical sheet 10. Here, the target light rays include ultraviolet rays and infrared rays in addition to visible rays. In particular, when it is arranged on the viewer side of the display panel, it is visible light among these that affects the image to be viewed, such as image distortion due to the depression of the adhesive layer 6.
As such a light control layer 2, various optical functional layers such as a contrast enhancement layer are used according to the control purpose. The light control layer 2 in this embodiment includes the contrast enhancement layer 3 as an essential layer.
Therefore, first, the contrast improving layer 3 will be described, and then optical function layers other than the contrast improving layer 3 will be described.

[Contrast improvement layer]
The contrast enhancement layer 3 has a light transmission part 3a and a light absorption part 3b. Such a contrast enhancement layer 3 is conventionally known, and can be formed by a conventionally known material and formation method.

(Light transmission part)
The light transmission part 3a is a transparent optical element that enters image light from the display panel from one layer surface and emits it to the other layer surface. And the light transmission part 3a is alternately arranged with the light absorption part 3b in the direction along the sheet | seat surface of the optical sheet 10. FIG.
In addition, the light transmission part 3a normally occupies the main (over 50%) part of the volume of the contrast improving layer 3.

  The light transmission part 3a is made of a transparent material. As the transparent material, a resin material is preferably used because it can be flexible from the viewpoint of preventing curling of the optical sheet 10 and can be easily formed. The resin material may be a thermoplastic resin such as an acrylic resin or a polycarbonate resin, but is preferably a curable resin from the viewpoint of solvent resistance and rapid solidification, such as ultraviolet rays and electron beams. It is preferable to use an ionizing radiation curable resin that cures at a high temperature. Examples of the ionizing radiation curable resin include acrylate-based, epoxy-based, and polyester-based resins. In addition, the thickness of the light transmission part 3a is about 10-200 micrometers, for example.

As described above, the thickness of the light transmission portion 3a is usually about the same as or more than that of the base material layer 1, and is relatively thick with respect to, for example, a hard coat layer of about several tens of micrometers at most. For this reason, when a curable resin such as an ionizing radiation curable resin is used, the optical sheet is likely to curl due to the generation of internal stress due to curing shrinkage during formation. In this respect, the resin used for the light transmitting portion 3a is preferably a curable resin having flexibility capable of dispersing stress. For example, in the case of an ionizing radiation curable resin, an acrylate resin is a urethane. A urethane acrylate resin having a bond is one kind of preferable resin.
If the light transmitting portion 3a is flexible as described above, conventionally, as described above, the foreign matter mixed between the sheets at the time of optical sheet superposition tends to cause a problem that the contrast improving layer 3 is recessed. However, as described above, by setting the sum of products ΣETi> product ETs, it is possible to prevent the occurrence of dents in the contrast enhancement layer 3.
Note that the contrast improving layer 3 made of the resin having such flexibility and made of the light transmitting portion 3a (and the light absorbing portion 3b) has a compressive elastic modulus of, for example, 1000 MPa or less.

(Light absorption part)
In the present embodiment, the light absorbing portion 3b is a columnar optical element having a wedge shape that tapers toward the base layer 1 side. A number of light absorbing portions 3b are arranged in parallel to each other in a direction parallel to the sheet surface of the optical sheet 10 and in a direction perpendicular to the extending direction. The extending direction of the light absorbing portion 3b is perpendicular to the paper surface in FIG. Further, the wedge shape of the main cut surface of the light absorbing portion 3b in the present embodiment is a trapezoidal shape, and is also an arrangement in which the upper base of the narrow width faces the base material layer 1 side. Further, since the wedge shape is a trapezoid, each hypotenuse is composed of a single straight line.

  The “main cut surface shape” is a columnar light absorbing portion of the “longitudinal cross section” which is a cross section including the normal N standing on the sheet surface of the optical sheet 10 (or the layer surface of the contrast improving layer 3). It means a cross-sectional shape at a “main cut surface” defined as a cross section orthogonal to the extending direction of 3b.

  Further, the extending direction of the columnar light absorbing portion 3b is often the horizontal direction of the display panel because external light usually has a large amount of component light from the vertical direction when the display panel is observed. However, it may be inclined from the horizontal direction in order to prevent the occurrence of moire with the array pixels of the display panel.

  In addition, the magnitude | size of the light absorption part 3b and its arrangement pitch are set suitably according to a required characteristic. For example, when the thickness is different between the upper and lower sides in the thickness direction of the contrast enhancement layer 3, the width of the wide side is 5 to 50 μm, the width of the narrow side is 2 to 50 μm, and the height Is 10 to 200 μm, the side surface inclination angle is 0 to 15 °, and the arrangement pitch is 10 to 200 μm.

The light absorbing portion 3b can be formed of a light absorbing dark color material. As the dark material, either an organic material or an inorganic material may be used. For example, a resin composition such as paint (or ink) in which a light-absorbing color material such as carbon black or aniline black is contained in a resin binder is used as the dark color material. Note that the dark representative color is black, but may have chromatic colors such as low brightness brownish brown, amber, rosin, and dark green as long as the image display color is not adversely affected.
The resin binder may be a thermoplastic resin such as an acrylic resin or a polycarbonate resin. However, from the viewpoint of rapid solidification, a curable resin, preferably an ionization that is cured by ultraviolet rays, electron beams, or the like. It is preferable to use a radiation curable resin. Examples of the ionizing radiation curable resin include acrylate-based, epoxy-based, and polyester-based resins.
Similarly to the light transmitting portion 3a, the light absorbing portion 3b may be made of a flexible resin in terms of preventing curling of the optical sheet. The resin having flexibility is the same as that of the light transmitting portion 3a.

  Moreover, it is preferable to use the same kind of resin as the light transmitting portion 3a as the resin of the light absorbing portion 3b from the viewpoint of adhesion between the light absorbing portion 3b and the light transmitting portion 3a. For example, if an acrylate ionizing radiation curable resin is used for the light transmission part 3a, it is preferable to use the same acrylate ionizing radiation curable resin.

(Method of forming light transmitting portion and light absorbing portion)
The light transmitting portion 3a and the light absorbing portion 3b can be formed by a conventionally known method for forming the contrast improving layer 3.
For example, a hot pressing method in which a heated mold is pressed against a thermoplastic resin layer, a casting method in which a thermoplastic resin composition is injected into a mold and solidified, an injection molding method, and an ionizing radiation curable resin composition are molded. A 2P method (photopolymer method) or the like that is injected into the mold (inside) and cured with ionizing radiation can be used. Among these molding methods, the 2P method is more preferable in terms of excellent productivity. In the 2P method, a cylindrical (cylindrical) mold can be used to continuously form a belt-like sheet or the like. If the base material layer 1 is used as the belt-like sheet, a light transmitting portion 3a laminated on the base material layer 1 and a concave portion having an uneven shape opposite to the light absorbing portion 3b are formed on the surface on the light transmitting portion 3a side. it can. The light absorbing portion 3b can be formed by filling the inside of the concave portion with a dark color material such as an ionizing radiation curable resin composition and solidifying it.

[Optical function layer]
As the light control layer 2, in addition to the above-described contrast improving layer 3, various conventionally known optical functional layers in an optical sheet for a display panel can be appropriately employed. For example, as an optical functional layer, a near-infrared absorbing layer that absorbs near-infrared rays, an ultraviolet-absorbing layer that absorbs ultraviolet rays, or a neon light absorption that absorbs neon light from a plasma display panel body that provides a visual effect. A specific light transmission layer that is a wavelength filter layer having a function of suppressing the transmission of light of a predetermined wavelength and transmitting the remaining light of a predetermined wavelength, such as a layer, a color correction function for correcting a display image to a desired color tone, There is an antireflection layer (any of antiglare, antireflection, antiglare and antireflection) usually provided on the outermost layer.
For example, the anti-reflection / hard coat layer 8 as in the embodiment shown in FIG. Since the antireflection / hard coat layer 8 is a layer provided in the outermost layer among the optical functional layers, in the form shown in the figure, the surface of the base material layer 1 (upward in the drawing) which becomes the outermost layer after the protective film 5 is peeled off. They are stacked.
Moreover, about the layer which does not need to be made into the outermost layer among optical function layers, the adhesive layer 6 of the contrast improvement layer 3 between the base material layer 1 and the contrast improvement layer 3 other than the position used as an outermost layer, for example. Layered positions, such as sides, are arbitrary.

  The contrast enhancement layer 3 is also a kind of optical functional layer. However, in the present invention, which is also effective for preventing dents in the contrast enhancement layer 3, the contrast enhancement layer is an essential layer. The other optical functional layers excluded from the contrast enhancement layer 3 are referred to as “optical functional layers”, and the “optical functional layer” and the “contrast enhancement layer” together are referred to as “light control layers”. ing.

  Each layer of the optical function layer may be a single layer that also serves a plurality of functions. Further, the near-infrared absorbing layer, the ultraviolet absorbing layer, the neon light absorbing layer, the specific light transmitting layer, and the like may be used also as the light transmitting portion 3a in the base material layer 1, the adhesive layer 6, or the contrast improving layer 3. it can.

[Vertical relationship between the base material layer and the light control layer]
In the form illustrated in FIG. 1, the layered vertical relationship between the base material layer 1 and the light control layer 2 in the optical main body 4 is such that the light control layer 2 is located above the base material layer 1. Yes, the protective film 5 was an example laminated on the surface of the light control layer 2 located above the drawing.
However, for example, like the optical sheet 10 of the embodiment shown in FIG. 3, the layer relationship between the base material layer 1 and the light control layer 2 is upside down, and the protective film 5 is against the surface of the base material layer 1. It may be in the form of stacked layers. The configuration of FIG. 3 is an example in which the optical main body 4 is turned upside down with respect to the configuration of the optical sheet 10 of FIG.

"Protective film"
As the protective film 5, various conventionally known protective films can be basically used as the optical sheet, and usually a transparent resin film whose one surface is subjected to weak adhesion treatment is used. Examples of such a resin film resin include polyester resins such as polyethylene terephthalate, and polyolefin resins such as polyethylene and polypropylene. At that time, as described above, a product having a predetermined relationship between the product of the elastic modulus and the thickness is selected. In addition, the thickness of the protective film 5 is set from the range of 20-100 micrometers, for example. The thinner the thickness, the smaller the product ETp, and the more effective the depression of the pressure-sensitive adhesive layer 6. However, on the other hand, it is counter-effective for the dent of the contrast improving layer 3, and therefore it is preferable to set the thickness in consideration of these.

<Adhesive layer>
The pressure-sensitive adhesive layer 6 is not particularly limited as long as it is transparent, but more preferably, the pressure-sensitive adhesive layer 6 can be peeled even after bonding, that is, has removability.

As a pressure-sensitive adhesive for forming a pressure-sensitive adhesive layer with or without such removability, a known pressure-sensitive adhesive may be used as appropriate. For example, an acrylic adhesive, a silicone adhesive, a polyester adhesive, a rubber adhesive, and the like.
In addition, although the thickness of an adhesive layer is about 15-50 micrometers normally, since adhesive force will become weak when too thin, and it will become high cost when too thick, More preferably, it is about 20-30 micrometers.

<Release film>
For the release film 7, a known resin film such as a polyethylene terephthalate film or a polypropylene film whose surface is release-treated with silicone or the like can be suitably used.
In addition, the thickness of the peeling film 7 is set in the range of 20-100 micrometers, for example. The thicker one is more effective for the depression of the pressure-sensitive adhesive layer 6 in that the product ETs can be increased. However, on the other hand, it is counter-effective for the dent of the contrast improving layer 3, and therefore it is preferable to set the thickness in consideration of these.

《Other constituent layers》
The optical sheet 10 may include other constituent layers in addition to the above-described layers. For example, it is the following non-optical functional layer.

[Non-optical functional layer]
The non-optical functional layer is a layer not exclusively responsible for the optical function, for example, an electromagnetic wave shielding layer that shields electromagnetic waves from the display panel, a surface protective layer or a hard coat layer that protects the surface, an antistatic layer, a pollution prevention layer, An impact-resistant layer, a barrier layer that prevents mass transfer between two layers, an adhesive layer (including a pressure-sensitive adhesive layer) that adheres the two layers, and the like. Further, the layer position of the non-optical functional layer may be provided as appropriate depending on the purpose. In addition to the outside of the optical main body 4, it may be inside.
Each layer of the non-optical functional layer may be a single layer and also have a plurality of functions. Further, the non-optical functional layer may also be used as the optical functional layer and the contrast improving layer 3. For example, the anti-reflection / hard coat layer 8 in the optical sheet 10 of FIG.

[B] Image Display Device The image display device according to the present invention is a surface of the plasma display panel 9 on the side of the viewer V, like the image display device 20 shown in the embodiment of FIG. The display device is directly attached to the adhesive layer 6.

  In addition to the plasma display panel 9 and the optical filter 10, the image display device 20 includes a display driving circuit, wiring for connecting the driving circuit and the display panel, a chassis or frame that integrates them into a panel module, Depending on the application of the image display device, for example, in the case of a television receiver, various known components such as various input / output components such as a tuner, a housing (cabinet) for storing these components, and the like can be provided. These other components are not particularly limited, and depend on the application.

  By using the image display device 20 having such a configuration, the effect based on the optical sheet 10 described above can be obtained. As a result, it is possible to prevent an image from appearing to be distorted due to the depression of the pressure-sensitive adhesive layer 6 caused by the optical sheet 10 and the depression of the contrast enhancement layer 3 and to display an image with high quality.

[C] Deformation In addition, the optical sheet 10 and the image display device 20 using the same according to the present invention are within the scope not departing from the gist of the present invention, other layers, members, components, etc. other than those described above. May be included. Further, the above-described constituent elements may be modified other than the above.

For example, the main cutting plane shape of the light absorbing portion 3b is a trapezoidal shape with four sides formed by straight lines in the embodiment illustrated in FIG. 1 and has a wedge shape, but may have other shapes. For example, as shown in FIG. 5A, a quadrangular shape whose slope is parallel to the normal line N and perpendicular to the optical sheet surface may be used. The main cut surface shape may be a triangular shape (including an isosceles triangular shape), a pentagonal shape, a hexagonal shape, or the like. Alternatively, a trapezoidal shape, a triangular shape or the like, or one of the hypotenuses may be a polygonal or curved shape (a convex shape or a concave shape toward the outside of the light absorbing portion 3b).
Further, the base layer 1 side (lower side in FIG. 1) of the light absorbing portion 3b is a smooth continuous curve having no cusp in a convex shape toward the outside of the light absorbing portion 3b as shown in FIG. 5B. There may be.
In this way, by adjusting the main cut surface shape of the light absorbing portion 3b, the viewing angle can be adjusted by adjusting the traveling direction of the image light from the display panel, and the amount of light absorption with respect to various angle components of external light can be adjusted. Can be adjusted.

  In addition, the contrast enhancement layer 3 may have an effect of improving the bright room contrast. In addition to this, it is possible to emit the image light by narrowing the viewing angle in a specific direction such as the front direction, and pay attention only to this function. Then, it may have a function as a peep prevention filter.

In the embodiment illustrated in FIG. 1, the surface of the light absorbing portion 3b opposite to the base material layer 1 (upward in the drawing) is at the same level as the surface Pa of the light transmitting portion 3a. With respect to the surface Pa of the part 3a, the entire surface or a part of the surface 3a may be recessed or swollen.
For example, in the light absorbing portion 3b illustrated in FIG. 5C, the connection portion with the light transmitting portion 3a is at the same level as the light transmitting portion 3a, but the central portion in the width direction is on the surface Pa of the light transmitting portion 3a. This is an example of a shape having a recess 3bu that is recessed.
In addition, in order to make the surface Pa on the opposite side to the base material layer 1 side of the light absorbing portion 3b into a shape that is recessed from the surface of the light transmitting portion 3a, for example, the following is formed. can do. First, a dark color material such as an ionizing radiation curable resin composition that shrinks in volume when solidified by addition of a solvent or the like inside a concave portion having an uneven shape opposite to the light absorbing portion 3b formed between the light transmitting portions 3a. Can be filled and solidified by a wiping method or the like, and the light-absorbing portion 3b can be formed in which the dark material is contracted in volume during solidification and the surface is recessed and exposed.
By using the light absorbing portion 3b having the dent 3bu in this way, the surface area of the surface on the dent 3bu side is increased, and the adhesive layer 6 (see FIG. 2) on the dent 3bu side is correspondingly increased. The contact area with the layer increases, and the interlayer adhesion can be improved.

[D] Applications The optical sheet according to the present invention is suitably used for applications arranged on the viewer side of various display panels in an image display device. The display panel is, for example, a plasma display panel, a liquid crystal panel, an EL (electroluminescence) panel, or the like, and among them, the plasma display panel is one of suitable panels.
An image display device provided with such an optical sheet on the observer side such as a plasma display panel is a television receiver, measuring device or instrument, office device, medical device, computer device, telephone, electronic signboard, amusement device. It is suitable as an image display device such as a digital photo frame.

  Hereinafter, the present invention will be described in detail with reference to Examples, Comparative Examples, and Reference Examples.

Example 1
As Example 1, an optical sheet 10 as shown in FIG. 1 was produced as follows.

(1) Production of cylindrical mold A mold for molding the contrast enhancement layer 3 was produced. The mold was plated with copper, and the copper-plated portion was cut into a groove corresponding to the light transmitting portion 3a with a diamond tool. The groove pitch at the time of cutting was 45 μm. The groove has a trapezoidal shape with a depth of 85 μm, a groove bottom width of 35 μm, and a groove width of 41 μm on the surface of the mold. After cutting, chrome plating was applied.

(2) Preparation of resin composition for forming light transmission part 40.0 parts by mass of bisphenol A-ethylene oxide 2-mole adduct and 15.0 parts by mass of isophorone diisocyanate were added bismuth tri (2-ethylhexanoate) as a urethanization catalyst. ) (2-ethylhexanoic acid 50% solution) 0.02 parts by mass is added and reacted at 80 ° C. for 5 hours, then 5.0 parts by mass of 2-hydroxyethyl acrylate is added and reacted at 80 ° C. for 5 hours. An ionizing radiation curable urethane acrylate prepolymer was obtained. 60.0 parts by mass of the urethane acrylate-based prepolymer, 15.0 parts by mass of phenoxyethyl acrylate (molecular weight 192) as an ionizing radiation curable monomer, and diacrylate (molecular weight 512) 25 of bisphenol A ethylene oxide 4 mol adduct 0.0 part by mass, 0.05 parts by mass of a phosphoric acid ester (monoester / diester = molar ratio 1/1) of tetradecanol-ethylene oxide 10 mol adduct as a mold release agent, and 15 mol addition of stearylamine ethylene oxide 0.05 parts by weight of the product, and 1 part by weight of 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure (registered trademark) 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator, A resin composition for forming a light transmission part was obtained.

(3) Preparation of Base Material Layer As the base material layer 1, a 100 μm thick polyethylene terephthalate film (trade name: A4300, manufactured by Toyobo Co., Ltd.) was prepared.

(4) Formation of a light transmission part While inserting and conveying the base material layer 1 of said (3) between the shaping | molding die produced by said (1), and a nip roll, the resin composition of said (2) is made into a base material. The resin composition was supplied onto the layer 1 and filled between the base material layer 1 and the mold by a pressing force between the mold and the nip roll. Thereafter, the resin composition was cured by irradiating with 800 mJ / cm ² of ultraviolet light from the base material layer 1 side, and then the light cured on the base material layer 1 together with the base material layer 1 from the mold with a peeling roll. The transmissive part 3a was released, and an intermediate sheet member having a contrast enhancing layer 3 having a thickness of 100 μm on the base material layer 1 was produced.
In addition, the compression elastic modulus of the light transmission part 3a of this intermediate sheet member was 800 MPa. The elastic modulus was measured by applying a load to the micro indenter using a compression micro hardness tester (FISCHERSCOPE (registered trademark) HM2000, manufactured by Fusher Instruments Co., Ltd.) and unloading it. The measurement conditions are a load force of 100 mN, a load speed of 4 μm / 10 s, and a holding time of 60 s.

(5) Preparation of resin composition for forming light absorbing portion As ionizing radiation curable prepolymer, oxirane, 2,2 ′-[(1-methylethylidene) bis (4,1-phenyleneoxymethylene)] bis-, Homopolymer, 20.0 parts by mass of di-2-propenoate, and 20.0 parts by mass of 2-phenoxyethyl acrylate as reactive diluent monomer, 20.0 parts by mass of α-acryloyl-ω-phenoxy poly (oxyethylene) , And 2- {2- [2- (acryloyloxy) (methyl) ethoxy] (methyl) ethoxy} (methyl) ethyl acrylate 13.0 parts by mass and 25% carbon black as a light absorbing colorant 20.0 parts by mass of acrylic crosslinked fine particles (manufactured by Ganz Kasei Co., Ltd.) having an average particle size of 4.0 μm and 1-hydroxysilane as a photopolymerization initiator Rohexyl phenyl ketone (trade name: Irgacure (registered trademark) 184, Ciba Specialty Chemicals Co., Ltd.) 7.0 parts by mass was mixed and homogenized to obtain a resin composition for forming a light absorption part. .

(6) Formation of light absorbing portion The resin composition obtained in (5) above is supplied onto the intermediate sheet member prepared in (4) above, and the light of the intermediate sheet member is obtained by a wiping method using a doctor blade. While filling the substantially V-shaped groove formed on the surface of the transmission part 3a, the excess resin composition was scraped off. Thereafter, an intermediate optical sheet member in which the resin composition is cured by irradiating an ultraviolet ray of 800 mJ / cm ^{2 with} a high-pressure mercury lamp to form a light absorbing portion 3b, and the contrast improving layer 3 is formed on the base material layer 1. Got.

(7) Lamination | stacking of protective film Next, the protective film 5 of 40 micrometers in thickness which consists of a transparent polypropylene film was laminated | stacked with respect to the surface of the contrast improvement layer 3 of the said intermediate | middle optical sheet.

(8) Adjustment of pressure-sensitive adhesive composition 80.0 parts by mass of butyl acrylate, 10.0 parts by mass of γ-methacryloxypropyltrimethoxysilane, 10.0 parts by mass of acetoacetoxyethyl acrylate, 10.0 parts by mass of triethylene glycol dimercaptan Part, 0.3 part by weight of azobisisobutyronitrile, and 100.0 parts by weight of toluene were reacted in a nitrogen gas stream at 80 ° C. for 8 hours, diluted with toluene, and silane having a solid content of 40%. A coupling agent solution was obtained.
Thereafter, 94.0 parts by mass of butyl acrylate, 5.0 parts by mass of acrylic acid, 1.0 part by mass of 2-hydroxyethyl acrylate, 0.1 part by mass of azobisisobutyronitrile and 100.0 parts by mass of ethyl acetate were stirred. The mixture was reacted at 70 ° C. for 8 hours in a nitrogen gas stream and diluted with ethyl acetate to obtain a copolymer solution having a solid content of 20%.
The solid content of the silane coupling agent solution is 0.4 parts by mass with respect to the solid content of 100.0 parts by mass of the copolymer solution, and polyisocyanate (Coronate (registered trademark) L, Japan) as a crosslinking agent. 0.2 mass parts of the solid content of Polyurethane Industry Co., Ltd. was added and mixed to obtain an adhesive composition.

(9) Formation of pressure-sensitive adhesive layer Next, the above-mentioned pressure-sensitive adhesive composition was applied to a release film 7 (trade name: E7007, manufactured by Toyobo Co., Ltd., thickness 38 μm), dried, and re-peelable at a thickness of 25 μm. A second release film (trade name: E7006, manufactured by Toyobo Co., Ltd., thickness 38 μm) was further bonded to form a non-carrier pressure-sensitive adhesive film.
The 2nd peeling film of this non-carrier adhesive film was peeled, and it bonded on the surface of the base material layer 1 of the intermediate | middle optical sheet member obtained by said (6).

(10) Production of optical sheet as single sheet The belt-shaped optical sheet 10 is an optical sheet having a width of 1550 mm and a thickness of 303 μm, and is wound by winding a length of 600 m around a 6-inch core (core). A roll of the optical sheet 10 in the obtained state was produced. At this time, the wound diameter of the optical sheet was 515 mm, and the weight was 392 kg.
After 120 hours had passed in the roll state, this roll was unwound, and a rectangular sheet of 1123 × 637 mm was cut out by punching with a bias angle of 4.5 degrees in the sheet flow direction. The weight of one sheet was 263 g. One hundred optical sheets 10 in a single sheet state were stacked, and the stacked optical sheets 10 having a content weight of 26.3 kg were packed with a plastic packing material.

Example 2
Optical sheet as in Example 1, except that the release film 7 was changed from 38 μm to 25 μm and the protective film 5 was the same thickness and the material was changed from polypropylene to polyethylene in Example 1. Was made.

Example 3
An optical sheet was produced in the same manner as in Example 1 except that the protective film 5 was changed from 40 μm to 38 μm in thickness and the material was changed from polypropylene to polyethylene terephthalate.

Example 4
In Example 1, the vertical relationship of the optical main body 4 is reversed, and the adhesive layer 6 is provided on the contrast improving layer 3 side and the protective film 5 is provided on the base material layer 1 side. Thus, an optical sheet was produced.

Example 5
In Example 1, the upper and lower relations of the optical body part 4 are reversed, the pressure-sensitive adhesive layer 6 is provided on the contrast improving layer 3 side, the protective film 5 is provided on the base material layer 1 side, and the protective film 5 has the same thickness. An optical sheet was produced in the same manner as in Example 1 except that the material was changed from polypropylene to polyethylene.

Example 6
In Example 1, the optical body part 4 is reversed in the vertical relationship, and the pressure-sensitive adhesive layer 6 is provided on the contrast improving layer 3 side, the protective film 5 is provided on the base material layer 1 side, and the protective film 5 is further reduced in thickness from 40 μm. An optical sheet was produced in the same manner as in Example 1 except that the material was changed to 38 μm and the material was changed from polypropylene to polyethylene terephthalate.

Example 7
In Example 4, the base material layer 1 to be formed with the light transmission part 3a was formed as a cured product layer of an ultraviolet curable resin on the surface opposite to the surface on which the light transmission part 3a was formed. An optical sheet was produced in the same manner as in Example 4 except that a polyethylene terephthalate film in which a transparent antireflection / hard coat layer 8 having a thickness of 10 μm was previously provided was used (see FIG. 2).
The antireflection / hard coat layer 8 was formed by coating a fluorine-containing low refractive index layer on a coating film obtained by curing an ultraviolet curable resin.

Example 8
In Example 5, a transparent antireflection / hard coat layer having a thickness of 10 μm is formed on the surface opposite to the surface on which the light transmitting portion 3a is formed as the base material layer 1 to be formed with the light transmitting portion 3a. An optical sheet was prepared in the same manner as in Example 5 except that the same polyethylene terephthalate film as that used in Example 7 was used.

Example 9
In Example 6, a transparent antireflection / hard coat layer having a thickness of 10 μm is formed on the surface opposite to the surface on which the light transmitting portion 3a is formed as the base material layer 1 to be formed with the light transmitting portion 3a. An optical sheet was prepared in the same manner as in Example 6 except that the same polyethylene terephthalate film as that used in Example 7 was used.

<< Comparative Example 1 >>
In Example 1, an optical sheet was produced in the same manner as in Example 1 except that the lamination of the protective film 5 was omitted.

<< Comparative Example 2 >>
In Example 4, an optical sheet was produced in the same manner as in Example 4 except that the lamination of the protective film 5 was omitted.
In addition, this optical sheet corresponds to the layer structure in which the upper and lower sides of the optical main body 4 are reversed in Comparative Example 1.

<< Comparative Example 3 >>
In Example 1, the polyethylene terephthalate film of the base material layer 1 was changed from 100 μm to 50 μm, and the contrast improving layer 3 was also changed from 100 μm to 50 μm (in addition, the light transmission part 3a and the light absorption part 3b). Example 1 except that the thickness was also halved and a mold with the light absorbing portion 3b halved was used), the release film was changed from 38 μm to 75 μm, and the protective film 5 was not laminated. Similarly, an optical sheet was produced.

<< Comparative Example 4 >>
In Comparative Example 3, an optical sheet was prepared in the same manner as in Example 3 except that the optical main body 4 was turned upside down and the adhesive layer 6 and the release film 7 were laminated on the surface of the contrast enhancement layer 3. .

<< Comparative Example 5 >>
In Example 3, an optical sheet was prepared in the same manner as in Example 3 except that the release film 7 was changed from 38 μm to 25 μm in thickness.

<< Comparative Example 6 >>
In Example 6, an optical sheet was prepared in the same manner as in Example 6 except that the release film 7 was changed from 38 μm to 25 μm.

<< Comparative Example 7 >>
In Example 9, an optical sheet was produced in the same manner as Example 9 except that the release film 7 was changed from 38 μm to 25 μm.

<Performance evaluation>
After 120 hours have passed after packing the optical product loaded with 100 optical sheets, the packaging is opened, the optical sheets are taken out one by one, the appearance is visually confirmed, and the dent ("adhesion dent" generated in the adhesive layer 6 is checked. )). Moreover, the presence or absence of generation | occurrence | production of the depression ("functional layer depression") which arises in the contrast improvement layer 3, and the unintentional adhesion | attachment (blocking) between the upper and lower optical sheets when taking out an optical sheet one by one was also confirmed.
Adhesion dents were evaluated based on the size of a 10 cm square optical sheet. Adhesion dents did not occur or were acceptable even if they occurred (◎, ○, Δ in Table 1), unacceptable adhesion dents occurred. The material was NG (X mark in Table 1).
The breakdown of OK is that immediately after the optical sheet loaded in a single sheet is released from the stack and there is no dent larger than 0.5 mm ² including the contour of the dent, the optical sheet loaded in a single sheet is released from the stack. It is alleviated over time, and no dent larger than 0.5 mm ² including the contour of the dent is produced, and the optical sheet loaded in a single sheet is released from the stack and relaxed over time, from 0.5 mm ² A case where the number of dents less than 2.0 mm ² was 1 to 3 was indicated as Δ.
There also sheet stacking the optical sheet released from loading by relaxing over time, 0.5 mm ² greater than 2.0 mm ² below the recess 4 or more, or 2.0 mm ² or more indentations or one The material was NG (X mark in Table 1).
In addition, the case where the “functional layer dent” in which the contrast enhancement layer 3 was recessed did not occur was determined to be OK (◯ mark in Table 1), and the result was determined to be NG (X mark in Table 1).
Moreover, the thing in which blocking did not arise was made OK (circle mark in Table 1), and the thing which produced was made NG (* mark in Table 1) impossible.
The “adhesion dent” and the “functional layer dent” are not the presence or absence of distortion of the image after being directly bonded to the display panel, but the optical sheet alone is placed on the black sheet, and the ceiling fluorescent lamp 2500 lx The reflected light was observed, and the size of the dent was visually evaluated from the distortion of the reflected fluorescent lamp.

    Table 1 summarizes the layer configurations, elastic modulus / size specifications, and evaluation results of Examples and Comparative Examples.

In addition, the meanings of the abbreviations, etc. in Table 1 are as follows.
The layer structure is referred to as layer 1, layer 2,... Layer 6 in order from the release film 7 side. For example, in Example 1, it has layers 1 to 5, and the blank layer 6 is I don't have it. The thickness T is the thickness of each layer such as the layers 1 to 6 expressed in this way. The same applies to the elastic modulus E. Further, in Table 1, for example, actual 1 means Example 1, and ratio 1 means Comparative Example 1.

S-PET: The resin of the release film 7 is polyethylene terephthalate.
PSA: adhesive layer 6
CRL: Contrast improving layer 3
B-PET: The resin of the base material layer 1 is polyethylene terephthalate.
P-PP: The resin of the protective film 5 is polypropylene.
P-PE: The protective film 5 resin is polyethylene.
P-PET: The resin of the protective film 5 is polyethylene terephthalate.
AR / HC: hard coat layer 8 also serving as an antireflection layer.

As shown in Table 1, in Examples 1 to 9 satisfying ETp ≦ ETs, “adhesion dents” did not occur and all were OK. At the same time, ΣETi> ETs was satisfied, and the “functional layer recess” in which the contrast enhancement layer 3 was recessed did not occur, and was OK.
On the other hand, in Comparative Example 2 and Comparative Examples 5 to 7 that did not satisfy ETp ≦ ETs, “adhesion dents” were all produced, resulting in NG. In other Comparative Examples 1, 3 and 4, the “adhesion dent” was OK, but ΣETi> ETs was not satisfied, and the “functional layer dent” was generated, resulting in NG. Moreover, since Comparative Example 1, Comparative Example 3 and Comparative Example 4 do not have the protective film 5, there is a risk of foreign matter adhesion or scratches on the surface, and among these, the contrast improving layer 3 is the outermost layer. In Comparative Example 1 and Comparative Example 3, the blocking also occurs.

<< Examples 10 to 12, Comparative Example 8 >>
Moreover, in Example 7, Example 8, Example 9, and Comparative Example 7, those prepared in the same manner except that the pressure-sensitive adhesive layer was formed of the following pressure-sensitive adhesive composition, respectively, Example 10, Example 11, Example 12 and Comparative Example 8 were used.
As a result, the pressure-sensitive adhesive layer became a colored pressure-sensitive adhesive layer that also served as an optical functional layer that shared three functions of a near infrared absorption function, a neon light absorption function, and a color correction function.

(1) Adjustment of pressure-sensitive adhesive composition The following pressure-sensitive adhesive composition was prepared for forming a pressure-sensitive adhesive layer.
Acrylic pressure-sensitive adhesive (pressure-sensitive pressure-sensitive adhesive “Olivein (registered trademark)” BPS6271: trade name, solid content 27%, manufactured by Toyo Ink Mfg. Co., Ltd. 99.7 parts by mass, and curing agent (BXX5627: trade name, Toyo 0.3 parts by mass of Ink Manufacturing Co., Ltd., and 0.05 parts by mass of a phthalocyanine compound (IR12: trade name, manufactured by Nippon Shokubai Co., Ltd.) and a phthalocyanine compound (IR14: trade name) as a near infrared absorber. 0.02 part by mass, manufactured by Nippon Shokubai Co., Ltd., and 0.03 part by mass of diimmonium-based compound (IRG-068: trade name, manufactured by Nippon Shokubai Co., Ltd.). Furthermore, 0.01 part by mass of a neon light absorbing compound (TAP2: trade name, Yamada Chemical Co., Ltd.) was blended. Furthermore, 4 parts by mass of Cyasorb (registered trademark) UV24 (manufactured by Cytec Technology) as an ultraviolet absorber and TINUVIN (registered trademark) 144 (manufactured by Ciba Specialty Chemical Co., Ltd.) as a light stabilizer. 2 parts by mass, 0.1 parts by mass of KAYASET (manufactured by Nippon Kayaku Co., Ltd.) as the toning pigment, and 0.06 of Kunipia (registered trademark) D36 (manufactured by Kunimine Kogyo Co., Ltd.) as the layered clay mineral. 05 parts by mass was blended to obtain a mixture. This mixture was sufficiently stirred to produce a colored pressure-sensitive adhesive composition.

<Performance evaluation>
Examples 10 to 12 and Comparative Example 8 in which the adhesive layers of Examples 7 to 9 and Comparative Example 7 were replaced with colored adhesive layers were also Examples 7 to 9 and The same performance evaluation results as in Comparative Example 7 were obtained.

DESCRIPTION OF SYMBOLS 1 Base material layer 2 Light control layer 3 Contrast improvement layer 3a Light transmission part 3b Light absorption part 3bu Indentation of light absorption part 4 Optical main body part 5 Protective film 6 Adhesive layer 7 Release film 8 Functional layer (Antireflection and anti-glare layer) )
9 Plasma display panel (adherent)
10 optical sheet 20 image display device N normal V observer

Claims (6)

In the optical sheet that is arranged on the viewer side from the display panel and controls the light incident from the display panel to be emitted to the viewer side,
A contrast improving layer is provided as the light control layer of the optical main body portion comprising a base material layer and a light control layer laminated on the base material layer,
The contrast enhancement layer has a light transmission part arranged along the sheet surface so as to transmit light, and a light absorption part arranged so as to absorb light between the light transmission parts,
A pressure-sensitive adhesive layer and a release film are sequentially laminated on one surface of the optical main body, and a peelable protective film is laminated on the other surface,
An optical sheet in which the product ETp of the elastic modulus Ep and the thickness Tp of the protective film is equal to or less than the product ETs and ETp ≦ ETs with respect to the product ETs of the elastic modulus Es and the thickness Ts of the release film.   For the product ETs of the elastic modulus Es and thickness Ts of the release film, up to the contrast improving layer including the protective film on the protective film side of the optical sheet that becomes the opposite surface of the release film when the optical sheets are superimposed 2. The optical sheet according to claim 1, wherein a sum ΣETi of a product ETi of elastic modulus Ei and thickness Ti of each layer including the contrast enhancement layer is large and ΣETi> ETs.   The optical sheet according to claim 1, wherein the pressure-sensitive adhesive layer also serves as an optical functional layer having one or more functions of near infrared absorption, neon light absorption, and color correction.   The optical sheet according to any one of claims 1 to 3, which is in a wound state.   The optical sheet according to any one of claims 1 to 3, wherein a plurality of sheet sheets are stacked. The image display apparatus by which the optical sheet in any one of Claims 1-5 is bonded to the surface by the side of the observer of a plasma display panel with an adhesive layer.

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