JP2010026436A - Lens sheet, surface light source device and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a lens sheet that has no decrease in luminance of a back light, hardly has a lens sheet surface electrostatically charged, and prevents a decrease in defect concealment, a product defect due to sticking of dust, dirt, etc., and electric charge, and deterioration in outward appearance; a surface light source device using the lens sheet; and a liquid crystal display device. <P>SOLUTION: The lens sheet 50 has a translucent base having a translucent resin intermediate layer on both surfaces, a lens layer formed on one surface of the translucent base, and a light diffusion layer formed on the other surface of the translucent base, wherein the resin intermediate layer on the side of the light diffusion layer is subjected to an antistatic treatment. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lens sheet, a surface light source device, and a liquid crystal display device.

Liquid crystal display devices are widely used in various fields such as notebook computers and mobile phones, and as the amount of information processing increases and the needs diversify, the liquid crystal display devices are becoming larger and more precise. Yes. In general, a liquid crystal display device includes a backlight unit (surface light source device) and a liquid crystal display surface (liquid crystal panel). As the surface light source device, there are a direct type device in which a light source is arranged directly below a liquid crystal display surface and an edge light type device in which a light source is arranged on a side surface of a light guide. From the viewpoint of downsizing liquid crystal display devices, an edge light type is often used.
In a liquid crystal display device using an edge light type surface light source device, light is incident on the side surface of the light guide from the light source, and the surface facing the liquid crystal panel of the light guide is emitted and emitted to the liquid crystal display surface. , Make surface emission. In such a liquid crystal display device, a lens sheet is used to concentrate and emit light from a surface light source in a specific direction in order to more efficiently use light obtained from the light source.
In such a lens sheet, a lens layer such as a prism array is formed on one surface, and the light is aligned in a certain direction by the lens layer. Then, light is diffused within a viewing angle range according to the application of the liquid crystal display device by a light diffusion layer provided on the surface opposite to the lens layer.

As such a lens sheet, a plastic material having excellent transparency such as polycarbonate resin and acrylic resin is generally used because of its good moldability. However, these plastic materials have a high insulating property exceeding 10 ¹⁵ Ωcm in volume resistivity and exceeding 10 ¹⁵ Ω / □ (ohm square) in surface resistivity. In each process of assembling the light, assembling the liquid crystal display device, etc., charging was likely to occur due to contact with the human body or other insulators. The charged lens sheet absorbs surrounding dust, dust, and dirt during the assembly process of the backlight and closes the opening of the liquid crystal, which causes a decrease in backlight brightness and deterioration in appearance quality. It was.
In addition, when the surface on the light diffusion layer side of the lens sheet is charged, light and dark spots are generated on the screen due to partial adhesion with the liquid crystal panel, or when the surface on the lens layer side is charged, As a result, partial sticking (which may be described as sticking or wet-out) may cause a sticking phenomenon that causes a decrease in luminance or deterioration in appearance quality due to bright and dark spots, interference fringes, or the like.
In order to solve such problems, there has been reported an invention that prevents the lens layer side surface of the lens sheet from being charged by applying an antistatic treatment to the lens surface formed on the lens layer (for example, Patent Document 1). ).
JP-A-8-286004

However, the lens sheet is required to further improve the antistatic effect, and the above-described technique is still insufficient. For example, in the process of distributing and storing the lens sheet, the lens sheet is protected on both sides by a protective film made of plastic. If the antistatic performance of the lens sheet is insufficient, the surface of the lens sheet on the light diffusion layer side and the protective film are in close contact with each other, and there is a problem that the removal operation of the protective film becomes complicated and the working efficiency is lowered. . Therefore, improvement for suppressing adhesion between the lens sheet and the protective film is strongly demanded.
By incorporating a large amount of an antistatic agent in the light diffusion layer or the lens layer of the lens sheet, the antistatic performance can be improved. However, the antistatic agent contained in the light diffusion layer or the lens layer is transferred to a protective film, or transferred to another member such as a liquid crystal panel or a light guide, so that There is a case where an adverse effect occurs, the antistatic performance of the lens sheet is lowered, or the performance varies depending on the location. Furthermore, under a constant temperature and humidity environment, a phenomenon called bleed-out in which the antistatic agent oozes out to the outermost layer may occur, the performance of the light diffusion layer and the lens layer may deteriorate, and the luminance of the backlight may decrease. there were. In addition, when an antistatic layer is provided on the surface of the light diffusing layer or the surface of the lens layer, the performance of the light diffusing layer or the lens layer may deteriorate due to the same cause, or the luminance of the backlight may be lowered. .
Therefore, in the present invention, by imparting good antistatic performance to the lens sheet, it is difficult for the lens sheet surface to be charged, product defects due to adhesion of dust, dust, dust, etc. to the lens sheet surface, deterioration of appearance quality. An object of the present invention is to provide a lens sheet, a surface light source device using the lens sheet, and a liquid crystal display device that do not cause adverse effects on other members and are not accompanied by a decrease in luminance of the backlight.

  As a result of intensive studies by the present inventors, in order to impart antistatic performance to the light diffusion layer side or the lens layer side of the lens sheet, an antistatic agent is contained in the light diffusion layer or the lens layer, Rather than providing an antistatic layer on the surface of the diffusion layer or the surface of the lens layer, antistatic treatment is applied to the resin intermediate layer on the light diffusion layer side or the lens layer side of the lens sheet. The present invention has been completed by discovering that the adverse effect on the member is minimized, sufficient performance and antistatic performance with little deterioration are provided.

  That is, the first gist of the present invention is a translucent substrate having a translucent resin intermediate layer on both surfaces, a lens layer formed on one surface of the translucent substrate, and the translucent group. And a light diffusion layer formed on the other surface of the material, and the resin intermediate layer on the light diffusion layer side is subjected to an antistatic treatment, and is a lens sheet.

  The second gist of the present invention is the lens sheet, wherein the resin intermediate layer on the lens layer side of the lens sheet is subjected to antistatic treatment.

  The third gist of the present invention is the lens sheet, wherein the resin intermediate layer of the lens sheet is subjected to antistatic treatment by containing a cationic antistatic agent.

  According to a fourth aspect of the present invention, there is provided a light source, a light guide having at least one light incident surface facing the light source, a light emitting surface substantially orthogonal to the light incident surface, and light of the light guide. It is a surface light source device characterized by having the lens sheet with the lens layer disposed so as to face the exit surface.

  According to a fifth aspect of the present invention, there is provided a liquid crystal display device comprising the surface light source device.

  According to the present invention, the lens sheet surface is less likely to be charged by imparting good antistatic performance to the lens sheet, and product defects and appearance quality deterioration due to adhesion of dust, dust, dust, etc. to the lens sheet surface. Can be prevented, and adverse effects on other members can be minimized to provide a lens sheet that does not cause a decrease in luminance of the backlight, a surface light source device using the lens sheet, and a liquid crystal display device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a liquid crystal display device 10 using a lens sheet 50 of the present invention. FIG. 2 is a partial cross-sectional view showing an example of the lens sheet 50 of the present invention. In FIG. 1, the reflection sheet 30, the light guide 40, the lens sheet 50, and the liquid crystal panel 60 are illustrated separately from each other, but in actuality, they are in close contact with each other.

As shown in FIG. 1, the liquid crystal display device 10 includes a surface light source device 100 including a light source 20, a light source reflection sheet 22, a reflection sheet 30, a light guide 40, and a lens sheet 50, and a liquid crystal panel 60. It is configured.
The light source 20 is disposed such that the irradiation surface thereof faces the light incident surface 42 of the light guide 40, and the light source reflection sheet 22 is disposed so as to cover other than the irradiation surface of the light source 20. The reflection sheet 30 is disposed on the surface 44 side of the light guide 40. The lens sheet 50 is disposed so that the surface 52 on which the lens layer is formed faces the light emitting surface 46 of the light guide 40.
The liquid crystal panel 60 is disposed so that the incident surface 62 opposite to the observation surface 64 faces the surface 54 of the lens sheet 50.

(Lens sheet)
The lens sheet 50 will be described with reference to FIG. As shown in FIG. 2, the lens sheet 50 is provided with a light diffusion layer 55 on one surface of a translucent substrate 59 having a light diffusion layer side resin intermediate layer 56 and a lens layer side resin intermediate layer 58. Yes. Further, a lens layer 51 in which a plurality of lens rows 53 are formed in parallel at regular intervals is provided on the other surface of the translucent substrate 59. The surface of the light diffusion layer 55 forms the surface 54, and the surface of the lens layer 51 forms the surface 52.

<Translucent substrate>
In the translucent substrate 59, the light diffusion layer side resin intermediate layer 56 is formed on one surface of the substrate layer 57, and the lens layer side resin intermediate layer 58 is formed on the other surface.
<Base material layer>
Although it does not specifically limit as the base material layer 57, The thing which permeate | transmits active energy rays, such as an ultraviolet-ray and an electron beam, is preferable, As such a thing, a flexible glass plate etc. can also be used, For example, a polycrystal Acrylic resins such as methyl methacrylate, polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, cellulose resins such as diacetylcellulose and triacetylcellulose, styrene resins such as polystyrene and acrylonitrile / styrene copolymers, polyethylene, polypropylene , Polyolefins having a cyclic or norbornene structure, olefin resins such as ethylene / propylene copolymers, polyamide resins such as nylon and aromatic polyamide, vinyl chloride resins, polymethacrylate. Film made of a resin such as Ruimido resin sheet, it is possible to use a plate or the like.
The base material layer 57 may have a single layer structure or a multilayer structure of two or more layers.

<Resin intermediate layer>
The light diffusion layer side resin intermediate layer 56 is provided in order to improve the adhesion between the translucent substrate 59 and the light diffusion layer 55. The lens layer side resin intermediate layer 58 is provided to improve the adhesion between the translucent substrate 59 and the lens layer 51.
The material of the light diffusion layer side resin intermediate layer 56 and the lens layer side resin intermediate layer 58 is not particularly limited as long as it is a translucent resin. For example, the light diffusion layer side resin intermediate layer 56 and the lens layer side resin intermediate layer 58 are made of polyester resin, acrylic resin, urethane resin, or the like. Is mentioned.

  The light diffusion layer side resin intermediate layer 56 is subjected to antistatic treatment. The antistatic treatment applied to the light diffusion layer side resin intermediate layer 56 is, for example, formed by applying the light diffusion layer side resin intermediate layer 56 using a resin material containing an antistatic agent. Can be mentioned. Further, before the light diffusion layer side resin intermediate layer 56 is coated with a resin material serving as a binder containing an antistatic agent, an antistatic treatment may be performed by plating or vapor deposition of a metal or a metal compound. . The light diffusion layer-side resin intermediate layer 56 is applied by in-line coating (hereinafter referred to as in-line) in which the resin intermediate layer is coated and surface-treated in the production line simultaneously with the formation of the base material layer 57. A light diffusion layer-side resin intermediate layer subjected to an antistatic treatment may be formed, and is preferable from the viewpoint of efficiency because it can be formed simultaneously with the production of the base material layer 57. Contrary to in-line, when the film formation of the base material layer and the coating of the resin intermediate layer are performed separately, it is particularly indicated as offline.

Antistatic agents include anionic, cationic, amphoteric, non-ionic, such as alkyl metal salts of sulfonic acids, phosphonium salts of sulfonic acids, alkyl sulfonates, alkyl sulfate esters, alkyl phosphate esters, and quaternary ammonium salts. Various ionic antistatic agents, resins having them in the backbone such as main chain and side chain, and polymers comprising these resins; polyethylene oxide, polyether ester amide, polyether amide imide, ethylene oxide / shrimp halohydrin copolymer , Polyether-based polymer antistatic agents such as methoxypolyethylene glycol (meth) acrylate copolymer; fatty acid ester compounds; carbon-based fillers such as carbon and graphite; indium tin compounds (ITO), silver, silver-copper Alloy, nickel, platinum, gold, ruthenium Metallic fillers and the like; may be mentioned fillers such as inorganic, such as kaolin.
Since many anionic antistatic agents are often acidic, they are difficult to handle and may adversely affect the production line. In addition, nonionic antistatic agents generally tend to have poor performance. On the other hand, among the cationic antistatic agents preferably used in the present invention, the resin having a quaternary ammonium moiety exhibits performance when added in a small amount, and is relatively inexpensive and easily available. It is advantageous in terms of handling and is excellent in terms of handling.

  These antistatic agents can be used alone or in combination of two or more. Among the antistatic agents as described above, when using particles such as metals, metal compounds, fillers, etc., use particles having a particle size that is small enough not to decrease the translucency of the lens sheet 10. Is preferred.

  When an antistatic agent is added to the light diffusion layer side resin intermediate layer 56, the amount of the antistatic agent depends on the material of the light diffusion layer 55 formed on the base layer 57 and the light diffusion layer side resin intermediate layer 56. Since the solid content composition of the intermediate layer fluctuates, the amount of the antistatic agent also fluctuates accordingly, and is not particularly limited. However, the light diffusion layer side resin intermediate layer 56 has a solid content composition of 1 to 80% by mass. It is preferable to add. If it is less than 1% by mass, the antistatic performance on the surface 54 of the light diffusion layer 55 tends to be insufficient, and if it exceeds 80% by mass, other components blended in the light diffusion layer side resin intermediate layer 56. There is a tendency that the adhesion ratio between the translucent substrate 59 and the light diffusion layer 55 is lowered.

  The thickness of the light diffusion layer side resin intermediate layer 56 is not particularly limited, but in the case of in-line coating, it is preferably in the range of 0.01 to 1 μm. In the case of offline coating, there is no particular limitation. If the thickness of the in-line light diffusion layer side resin intermediate layer 56 is less than 0.01 μm, antistatic performance and easy adhesion tend to be difficult to develop. Although improved, there is a tendency that a phenomenon called blocking in which the films are in close contact with each other during the production of the translucent substrate 59 tends to occur.

In addition to the light diffusing layer side resin intermediate layer 56, it is preferable that the lens layer side resin intermediate layer 58 is also subjected to antistatic treatment. The lens layer side resin intermediate layer 58 may be the same as the light diffusion layer side resin intermediate layer 56.
By applying the antistatic treatment to the lens layer side resin intermediate layer 58 as well, the sticking phenomenon between the surface 52 of the lens layer 51 and the light emitting surface 46 of the light guide 40 can be suppressed. The sticking phenomenon may or may not occur depending on the processed shape of the light emitting surface 46 of the light guide 40.

  The light diffusion layer side resin intermediate layer 56 is not limited to a single layer structure including only a layer subjected to antistatic treatment, and may be a multilayer structure including two or more layers. Examples of the layers other than the layer subjected to the antistatic treatment include, for example, light diffusion characteristics, light collection characteristics, viewing angle characteristics, specific wavelength cut characteristics, color temperature conversion characteristics, phase compensation characteristics, polarization characteristics, glare prevention characteristics, etc. Various characteristics can be provided. Similarly, the lens layer-side resin intermediate layer 58 is not limited to a single layer structure including only a layer subjected to antistatic treatment, and may be a multilayer structure including two or more layers. Examples of the layers other than the layer subjected to the antistatic treatment include, for example, light diffusion characteristics, light collection characteristics, viewing angle characteristics, specific wavelength cut characteristics, color temperature conversion characteristics, phase compensation characteristics, polarization characteristics, glare prevention characteristics, etc. Various characteristics can be provided.

  Although the thickness of the translucent base material 59 is not specifically limited, For example, 10-500 micrometers is preferable, 15-400 micrometers is more preferable, and 20-300 micrometers is especially preferable from viewpoints of a market request | requirement, intensity | strength, and handleability.

<Light diffusion layer>
The shape of the surface 54 of the light diffusion layer 55 may be a smooth surface or may have irregularities. From the viewpoint of reducing adhesion with the incident surface 62 of the liquid crystal panel 60 and preventing damage due to pressing or vibration, it is preferable to form an uneven surface.

  The light diffusion layer 55 can be used without particular limitation as long as it has high translucency and has desired heat resistance, scratch resistance, elasticity, and the like. Examples of such translucent resins include polyamide resins, polyurethane resins, polyester resins, acrylic resins, and other thermoplastic resins, thermosetting resins, active energy ray curable resins (ionizing radiation curable resins), and the like. Among them, the use of an acrylic resin having a high transmittance is particularly preferable. As the acrylic resin, polymers such as hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, and acrylic acid are preferable. In particular, an acrylic polyol containing hydroxyalkyl (meth) acrylate as a monomer unit is dissolved in a solvent such as toluene or methyl ethyl ketone, and an isocyanate bifunctional monomer or an oligomerized isocyanate compound such as isocyanurate or melamine An acrylic resin obtained by mixing with a cross-linking agent, coating, and curing is preferable in terms of strength and adhesion to a translucent substrate. Moreover, from a heat resistant viewpoint, the thing whose glass transition point is 60 degreeC or more is preferable.

The light diffusing layer 55 can contain and add a light diffusing material, a leveling agent, a thixotropic agent, a slip agent, an antifoaming agent, an antistatic agent, an ultraviolet absorber, and the like as necessary.
In particular, the surface 54 can be easily formed into an uneven shape by adding a light diffusing material. The light diffusing material can be used regardless of whether it is organic or inorganic. Examples of the inorganic particles include glass, silica, talc, barium sulfate and the like. Examples of organic particles include cross-linked organic fine particles such as polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, and melamine, fine particles of silicone resin, acrylic rubber, butadiene, styrene-butadiene, acrylonitrile-butadiene-styrene (ABS). ) And the like, and silicone rubber.
The shape of the light diffusing material can be appropriately selected and used regardless of the shape such as a sphere, an indeterminate shape, a bowl shape, a spheroid, or a needle shape.

The light diffusing material preferably has a particle diameter of 0.01 to 10 μm in 1% by volume or more, preferably 10% by volume or more of the light diffusing material. The light diffusing material has a tendency to increase the effect of preventing the glare phenomenon of the screen called speckle or sparkling as the particle diameter is small. However, if there are many particles having a particle diameter exceeding 10 μm, the above-mentioned glare phenomenon. This is not preferable because the effect of preventing the reduction tends to be low.
The particle size in the present invention is a value calculated from the particle size distribution measured by various particle size distribution measuring devices. Examples of the particle size distribution measuring apparatus include COULTER MULTISIZER manufactured by Beckman Coulter.

  The thickness of the light diffusion layer 55 is preferably in the range of 1 to 15 μm, more preferably in the range of 1 to 13 μm, and particularly preferably in the range of 1 to 10 μm. When the thickness is less than 1 μm, the concealing property is lowered, and there is a tendency that the defect of the mold for manufacturing the prism sheet is easily seen or the defect of the light guide body 40 is easily seen. This is not preferable because it tends to occur.

<Lens layer>
The material of the lens layer 51 is not particularly limited. For example, the lens layer 51 is made of an active energy ray curable resin and has a refractive index of about 1.48 to 1.6. The active energy ray curable resin is not particularly limited as long as it is cured with active energy rays such as ultraviolet rays and electron beams. For example, polyesters, epoxy resins, polyester (meth) acrylates, epoxy ( Examples include (meth) acrylate resins such as (meth) acrylate and urethane (meth) acrylate. Among these, (meth) acrylate resins are particularly preferable from the viewpoint of optical characteristics and the like. The active energy ray-curable composition used for such a cured resin is a polyfunctional acrylate and / or a polyfunctional methacrylate (hereinafter referred to as polyfunctional (meth) acrylate) in terms of handleability and curability. , Monoacrylate and / or monomethacrylate (hereinafter referred to as mono (meth) acrylate), and a photopolymerization initiator by active energy rays are preferred. Typical polyfunctional (meth) acrylates include polyol poly (meth) acrylate, polyester poly (meth) acrylate, epoxy poly (meth) acrylate, urethane poly (meth) acrylate, and the like. These are used alone or as a mixture of two or more. Examples of mono (meth) acrylates include mono (meth) acrylates of monoalcohols and mono (meth) acrylates of polyols.

The lens array 53 formed in the lens layer 51 is not limited to a substantially triangular prism as shown in FIG. 2, and can be determined according to the application. For example, a cylindrical lens, a lenticular lens, a polygonal pyramid, a conical lens, etc. can be mentioned.
For example, when the lens array 53 is a prism whose cross-sectional shape parallel to the XZ plane (FIG. 1) is substantially triangular, the apex angle of the prism is not particularly limited, but is preferably in the range of about 25 to 120 °. Preferably it is the range of 30-115 degrees. These prism surfaces may be optically sufficiently smooth surfaces (mirror surfaces) or rough surfaces. In the present invention, the prism surface is preferably a mirror surface from the viewpoint of maintaining desired optical characteristics of the lens sheet.
Moreover, although the pitch which arrange | positions a prism is not specifically limited, 1-500 micrometers is preferable and it is more preferable to set it as 5-100 micrometers.

  The thickness of the lens layer 51 is not particularly limited, and is preferably determined according to the shape or the like of the formed lens array 53, and is preferably determined in the range of, for example, 5 to 80 μm. If it is less than 5 μm, the function of aligning light in a certain direction tends to be poor, and if it exceeds 80 μm, the antistatic performance tends not to be exhibited, which is not preferable.

The antistatic performance on the surface 54 of the light diffusing layer 55 of the lens sheet 50 and the surface 52 of the lens layer 51 includes a frictional charge attenuation measuring instrument (conforming to JIS L 1094: 1997) and a friction cloth (conforming to JIS L 0803). Using, in a 23 ± 5 ° C, 50 ± 10% RH environment, the measurement of the frictional voltage after 40 to 60 reciprocating frictions is taken as one measurement, and 3 measurements are repeated intermittently without any charge removal. In order to exhibit good antistatic performance, it is indicated by each frictional band voltage at the time of being in the range of −5 kV to 5 kV. Such a frictional voltage is achieved by combining the antistatic treatment method of the light diffusion layer side resin intermediate layer 56 and the lens layer side resin intermediate layer 58 described above, and the kind and amount of the antistatic agent to be added. be able to.
In addition, as a triboelectric charge decay measuring device, EST-8 etc. by Intec Co., Ltd. can be used.
In addition, it is important to improve the reproducibility of the measurement result that the lens sheet 50 is conditioned in advance at 23 ± 5 ° C. and 50 ± 10% RH for 24 hours or more.

(Light source and reflection sheet for light source)
The light source 20 is not particularly limited, and can be determined according to the desired surface light source device 100 and the liquid crystal display device 10. For example, it is possible to use a line light source in which a fluorescent lamp or a generation source is located at a distance.
The light source reflection sheet 22 that covers the light source 20 is not particularly limited as long as the loss of light from the light source 20 can be reduced and led to the light guide 40, and a plastic film or a diffusion material having a metal-deposited reflection layer on the surface. A contained plastic film or the like can be used.

(Reflective sheet)
The reflection sheet 30 is not particularly limited as long as it reflects the light emitted from the surface 44 of the light guide 40 and enters the light guide 40 again. Examples thereof include polyethylene terephthalate (PET), polycarbonate, polystyrene, and polyolefin. Of these, polyethylene terephthalate is preferable. Moreover, it is preferable that the reflection sheet 30 is a white sheet containing a pigment. Examples of the pigment include titanium oxide, barium sulfate, calcium carbonate, and magnesium carbonate. Instead of the reflective sheet 30, a reflective layer may be formed on the surface 44 of the light guide 40 by metal vapor deposition or the like.
The thickness of the reflection sheet 30 is not specifically limited, For example, it is preferable to determine in the range of 30-300 micrometers.

(Light guide)
The light guide 40 can be composed of a highly transparent synthetic resin. Examples of such synthetic resins include methacrylic resins, acrylic resins, polycarbonate resins, polyolefin resins having a cyclic or norbornene structure, polyester resins, and vinyl chloride resins. In particular, methacrylic resins are optimal because of their high light transmittance, heat resistance, mechanical properties, and molding processability. As such a methacrylic resin, it is resin which has methyl methacrylate as a main component, and the thing whose methyl methacrylate is 80 mass% or more is preferable.

(LCD panel)
The liquid crystal panel 60 is not particularly limited, and any of an active matrix driving TFT liquid crystal display element and a simple matrix driving STN liquid crystal display element can be used. In the TFT type liquid crystal display element, various active elements such as polysilicon, amorphous silicon, metal insulator, and metal can be used as the element.

(Production method)
Below, an example of the manufacturing method of the lens sheet 50, the surface light source device 100, and the liquid crystal display device 10 is demonstrated.
Although the manufacturing method of the lens sheet 50 is not specifically limited, For example, it can manufacture as follows. First, a resin intermediate layer coating solution to which an antistatic agent is added is applied to both surfaces of the base material layer 57 to form a light diffusion layer side resin intermediate layer 56 and a lens layer side resin intermediate layer 58. Then, a light diffusion layer 55 is formed on the light diffusion layer side resin intermediate layer 56 by applying a light diffusion layer coating liquid containing a light-transmitting resin and an additive such as a light diffusion material. Next, the lens sheet 50 can be manufactured by forming the lens layer 51 with an active energy ray curable resin or the like on the lens layer side resin intermediate layer 58.

The coating method of the resin intermediate layer coating liquid is not particularly limited. For example, existing coating methods such as a screen printing method, a die coating method, a gravure coating method, a spin coating method, a dip coating method, a bar coating method, and a spray coating method. The resin intermediate layer coating solution is applied on the base material layer 57 offline using a method or the like, or the resin intermediate layer coating solution is applied on the base material layer 57 in-line using the same existing coating method. Coating is performed to form a resin intermediate layer on the base material layer 57 to obtain a translucent base material 59.
As a dispersion medium used for the resin intermediate layer coating liquid, it is preferable to select a dispersion medium having good dissolution of the translucent resin, dispersion of the antistatic agent, and the like, depending on the type of the translucent resin and the antistatic agent. Can be determined. Examples thereof include methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, butyl acetate, isopropyl alcohol, ethanol and the like.

  Next, a light transmissive resin and other additives are added to and mixed with the dispersion medium to obtain a light diffusion layer coating solution, and the light diffusion layer coating solution is applied to one surface of the light transmissive substrate 59. Then, the light diffusing layer 55 is formed by curing the translucent resin.

The coating method of the light diffusion layer coating liquid is not particularly limited. For example, the existing coating such as screen printing method, die coating method, gravure coating method, spin coating method, dip coating method, bar coating method, spray coating method, etc. A method can be mentioned.
The coating amount of the light diffusion layer coating solution may be an amount that can obtain the light diffusion layer 55 having a desired thickness, and is preferably about ² to 100 g / m ² , for example.
It does not specifically limit as a method to harden translucent resin, It determines according to the kind of translucent resin. For example, when a thermosetting resin is used, the heat treatment can be performed at 80 to 180 ° C. In order to provide irregularities on the surface 54 of the light diffusion layer 55, irregularities may be formed by hot pressing.

  Next, the lens array 53 is formed on the surface of the translucent substrate 59 opposite to the surface on which the light diffusion layer 55 is formed. The method for forming the lens array 53 is not particularly limited, and an existing method can be used. For example, a known heat press method or a roll-shaped mold in which the shape of the lens array 53 is engraved is filled with an active energy ray-curable resin, and then covered with a translucent substrate 59 via a resin liquid, ultraviolet rays, etc. Is irradiated and cured to continuously manufacture the translucent substrate 59 provided with the lens layer 51, and a resin liquid is poured into a mold corresponding to the shape of the lens array 53, thereby translucent substrate 59. The method of manufacturing the translucent base material 59 in which the lens layer 51 was provided by a batch system by laminating | stacking on is mentioned. In this way, the lens sheet 50 can be obtained.

  Using the lens sheet 50 obtained as described above, the reflective sheet 30, the light guide 40, and the lens sheet 50 are placed in this order as shown in FIG. The surface light source device 100 can be obtained by arranging the reflection sheet 22. Further, the liquid crystal panel 60 is placed so that the surface 54 on the light diffusion layer 55 side of the lens sheet 50 of the surface light source device 100 and the incident surface 62 of the liquid crystal panel 60 face each other. Obtainable.

According to the lens sheet 50 of the present invention, the surface 54 on the light diffusion layer 55 side and the surface on the lens layer 51 side are obtained by applying an antistatic treatment to the light diffusion layer side resin intermediate layer 56 and the lens layer side resin intermediate layer 58. The frictional voltage of 52 can be in the range from -5 kV to 5 kV. By having such characteristics, it is possible to effectively prevent the lens sheet 50 from being in close contact with the liquid crystal panel 60, the light guide 40, and the protective film, and suction of dust, dust, and the like. Further, since the addition of the antistatic agent is performed on the light diffusion layer side resin intermediate layer 56 and the lens layer side resin intermediate layer 58, the light transmissive property and diffusibility of the light diffusion layer 55 and the light transmission property of the lens layer 51 The antistatic performance can be imparted without impairing the properties and light collecting properties. For this reason, the adverse effect on other members is minimized, the brightness of the backlight is not reduced, the surface of the lens sheet 50 is hardly charged, the defect concealing property is improved, and dust, dust, dust, etc. are attached. Defects and deterioration of appearance quality can be prevented. In addition, an antistatic effect equal to or higher than that can be obtained by using a smaller amount of the antistatic agent than performing the antistatic treatment on the light diffusion layer 55 and the lens layer 51.
In the present invention, the antistatic treatment is not directly performed on the light diffusion layer 55 and the lens layer 51. For this reason, the antistatic agent etc. which are contained in the light-diffusion layer 55 or the lens layer 51 are transferred to a protective film or transferred to other members such as a liquid crystal panel or a light guide, thereby preventing the antistatic. It is possible to obtain an antistatic effect without causing deterioration in performance, occurrence of performance spots due to the location of the lens sheet 50, and adverse effects on other members.

Hereinafter, the present invention will be described more specifically with reference to examples.
(Manufacture of light diffusion layer coating solution A)
In a 2 L separable flask of a polymerization reaction vessel, 106 parts by mass of toluene, 71 parts by mass of methyl ethyl ketone (MEK), 69 parts by mass of methyl methacrylate (MMA), 25 parts by mass of ethyl acrylate, 5 parts by mass of 2-hydroxyethyl methacrylate, methacrylic acid One part by mass was weighed, and bubbling with nitrogen was performed for 30 minutes while stirring with a stirring blade. Thereafter, 0.45 part by mass of 2,2-azobisisobutyronitrile as a radical polymerization initiator was added, and then the reaction vessel was heated to 90 ° C. and kept in that state for 5 hours. Further, 1 part by mass of 2,2-azobisisobutyronitrile was added and the reaction vessel was kept for 4 hours, and then cooled to room temperature to complete the reaction, whereby an acrylic resin A solution was obtained.

  The molecular weight of the acrylic resin A is MW = 75,100, the hydroxyl value is 21.6 mgKOH / g, the acid value is 2.1 mgKOH / g, Tg is 61 ° C., and the heating residue of the acrylic resin A solution is 36.0% by mass. there were.

  To 209 parts by mass of the acrylic resin A solution, silicone resin fine particles having a refractive index of 1.42, an average particle diameter of 3.0 μm, and a true specific gravity of 1.32 (trade name; Tospearl, manufactured by GE Toshiba Silicone Co., Ltd.) 130) Acrylic resin fine particles having a refractive index of 1.49, an average particle diameter of 3.0 μm, and a true specific gravity of 1.20 as a second light diffusing material (trade name; XX-57B, manufactured by Sekisui Plastics Co., Ltd.) ) 6.7 parts by mass, 5.8 parts by mass of Duranate TPA-100 manufactured by Asahi Kasei Chemicals Co., Ltd. as a crosslinking agent, 53.0 parts by mass of MEK as an additional solvent, and 79.5 parts by mass of toluene are weighed in a container and stirred with a stirring blade. By stirring, a light diffusion layer coating liquid A for forming a light diffusion layer in which the light diffusion material was uniformly dispersed was produced.

  The light diffusion layer coating liquid A has a total solid content of 28% by mass, the addition amount of the light diffusion material to the total solid content is 21.7% by mass, and the addition ratio of the first and second light diffusion materials is the first light. The diffusion material is 70% by mass, the second light diffusion material is 30% by mass, the ratio of MEK to toluene is 40% by mass of MEK, 60% by mass of toluene, and the ratio of the solid content of the acrylic resin A to the crosslinking agent is The solid content of the acrylic resin A is 92.8% by mass, and the crosslinking agent is 7.2% by mass.

(Production of antistatic agent A)
A separable flask was charged with 188 parts by mass of dimethylaminopropylmethacrylamide and 228 parts by mass of methanol, and then 2.4 parts by mass of 2,2-azobis (2,4-dimethylvaleronitrile) and 2.4 of n-octyl mercaptan. Mass parts, 384 parts by mass of methanol, and 485 parts by mass of polyethylene glycol (23) monomethacrylate monomethyl ether (the number in parentheses is the number of polyethylene glycol units) were added and polymerized at 60 ° C. in a nitrogen atmosphere for 6 hours.
Next, while stirring, a mixture of 39.3 parts by mass of concentrated hydrochloric acid and 41.3 parts by mass of methanol was added dropwise so that the internal temperature was 15 ° C. or less. To obtain an antistatic agent A having antistatic performance.

(Manufacture of resin intermediate layer coating solution A)
To a separable flask, 95 parts by mass of dimethyl terephthalate, 95 parts by mass of dimethyl isophthalate, 35 parts by mass of ethylene glycol, 145 parts by mass of neopentyl glycol, 0.1 part by mass of zinc acetate and 0.1 part by mass of antimony trioxide were added, 180 Transesterification was carried out at 3 ° C for 3 hours. Next, 6.0 parts by mass of 5-sodium isophthalic acid was added, esterified at 240 ° C. for 90 minutes, and then polymerized to obtain a solution B.

  6.7 parts by mass of a 30% aqueous dispersion of the solution B, 20% aqueous solution of a self-crosslinking polyurethane resin containing an isocyanate group protected with sodium bisulfite (Elastotron H-3, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 40 parts by weight, 0.5 parts by weight of an elastolone catalyst (Cat 64), 47.8 parts by weight of water and 5 parts by weight of isopropyl alcohol are mixed, and further 1% by weight of anionic surfactant in a total weight ratio, colloidal silica particles (Snowtex OL, manufactured by Nissan Chemical Industries, Ltd.) was added at a solid content ratio of 5% by mass to obtain a resin intermediate layer coating solution A having no antistatic performance and only easy adhesion.

(Production of resin intermediate layer coating solution B)
70 parts by mass of the above-mentioned resin intermediate layer coating liquid A and 30 parts by mass of the antistatic agent A are mixed and stirred for 90 minutes, thereby providing a resin intermediate layer coating having antistatic performance and easy adhesion. Liquid B was obtained.

(Manufacture of light diffusion layer coating solution B)
80 parts by mass of the light diffusion layer coating liquid A and 20 parts by mass of the antistatic agent A were mixed and stirred for 90 minutes to obtain a light diffusion layer coating liquid B having antistatic performance.

Example 1
As a base material layer, a resin intermediate layer coating solution B is applied to one surface of a PET film having a thickness of 100 μm (T600-100, manufactured by Mitsubishi Plastics Co., Ltd.), and a resin intermediate layer coating solution A is applied to the other surface. Was applied to obtain a translucent substrate A. The light diffusion layer coating solution A is applied to the coating surface side of the resin intermediate layer coating solution B of the translucent substrate A using a reverse gravure coating method so that the average thickness after solvent drying is 5 μm. And dried. Thereby, the laminated body A which has a light-diffusion layer on the coating surface of the resin intermediate | middle layer coating liquid B of the said translucent base material A was obtained.

A shape transfer surface having a shape corresponding to the shape of the prism row forming surface was formed on the surface of three types of JIS brass thin plates having a thickness of 1.0 mm and 400 mm × 690 mm to obtain a mold member. Here, the target prism array forming surface has a shape in which a large number of prism arrays having a pitch P = 50 μm and an apex angle θ = 65 ° are arranged in parallel.
Next, a stainless steel cylindrical roll having a diameter of 220 mm and a length of 450 mm was prepared, and a mold member was wound around and fixed to the outer peripheral surface to obtain a roll-shaped mold (roll mold). Between the roll mold and the rubber roll, the laminate A was supplied along the roll mold so that the surface opposite to the side where the light diffusion layer was formed was the mold roll side. Then, the laminate A was nipped between the rubber roll and the roll mold by a pneumatic cylinder connected to the rubber roll.
On the other hand, an ultraviolet curable composition having the following composition was adjusted to a viscosity of 300 mPa · S / 25 ° C.
-Phenoxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd., Biscoat # 192): 50 parts by mass-Bisphenol A-diepoxy-acrylate (Kyoeisha Oil Chemical Co., Ltd., Epoxy ester 3000A): 50 parts by mass-2-Hydroxy-2- Methyl-1-phenyl-propan-1-one (Ciba Geigy, Darocur 1173): 1.5 parts by mass

  This ultraviolet curable composition was supplied to the surface of the translucent substrate A that was nipped into a roll mold by a rubber roll, on the side opposite to the surface provided with the light diffusion layer. While rotating the roll mold, in a state where the ultraviolet curable composition is sandwiched between the roll mold and the translucent substrate, ultraviolet rays are irradiated from an ultraviolet irradiation device to polymerize and cure the ultraviolet curable composition. The prism row pattern on the shape transfer surface of the mold was transferred. Then, it released from the roll type | mold and obtained the lens sheet A which has a light-diffusion layer and a lens layer.

(Example 2)
The resin intermediate layer coating liquid B was applied to both surfaces of the base material layer used in Example 1 by the same method as in Example 1 to obtain a translucent base material B. Next, a light diffusing layer was formed on one surface of the translucent substrate B by the same method as in Example 1 to obtain a laminate B. Next, a lens layer was formed on the other surface of the laminate B by the same method as in Example 1 to obtain a lens sheet B.

(Comparative Example 1)
A resin intermediate layer coating solution A was applied to both surfaces of the base material layer used in Example 1 by the same method as in Example 1 to obtain a translucent base material C. Next, a light diffusing layer was formed on one surface of the translucent substrate C by the same method as in Example 1 to obtain a laminate C. Next, a lens layer was formed on the other surface of the laminate C by the same method as in Example 1, and a lens sheet C was obtained.

(Comparative Example 2)
Using the light-transmitting substrate C obtained in Comparative Example 1, a light diffusion layer is formed on one surface by applying the light diffusion layer coating solution B in the same manner as in Example 1 to form a laminate. D was obtained. Next, a lens layer was formed on the other surface of the laminate D by the same method as in Example 1 to obtain a lens sheet D.

(Evaluation methods)
<Friction band voltage>
The lens sheet was preconditioned for 24 hours in an environment of 23 ° C. and 50% RH before measurement. After neutralizing the humidity-adjusted lens sheet, in a 23 ° C., 50% RH environment, using a frictional charge attenuation measuring instrument conforming to JIS L 1094: 1997 and a friction cloth conforming to JIS L 0803 to the test surface 40 times of reciprocating friction and then measuring the friction band voltage of the same test surface as one measurement, repeating the measurement three times without removing the static electricity, and measuring each friction band voltage did. The frictional voltage obtained in the first measurement is the frictional voltage, the frictional voltage obtained in the first and second measurements is the frictional voltage 2, and the frictional voltage obtained in the third measurement is the frictional voltage 3. To do.
Table 1 shows the results of each frictional voltage 3 when the test surface is on the light diffusion layer side and the lens layer side of the lens sheet.

<Panel sticking test>
The lens sheet was preconditioned for 24 hours in an environment of 23 ° C. and 50% RH before measurement. Electricity was removed from the humidity-adjusted lens sheet, four types of liquid crystal panels (described later), an adhesive roll (manufactured by KSM Superclean Ltd.) which is a member for forcibly charging the lens sheet, and a SUS plate having a smooth surface. Next, in an environment of 23 ° C. and 50% RH, the lens sheet was placed on the smooth surface of the SUS plate so that the evaluation surface faced the upper surface. Next, 100 times of reciprocating friction is performed on the evaluation surface using an adhesive roll to charge the lens sheet, and the evaluation surface side of the charged lens sheet is brought into contact with the light incident surface side of the liquid crystal panel to be stuck. Whether or not it occurred was evaluated, and a series of these evaluations were performed for each of the four types of liquid crystal panels.
In addition, when the light incident surface side of the liquid crystal panel and the evaluation surface side of the lens sheet were brought into contact with each other, whether or not the lens sheet was stuck between the liquid crystal panels was evaluated as follows.

<Evaluation criteria for panel sticking test>
○: No sticking phenomenon occurs.
X: A sticking phenomenon occurs.

Moreover, since the liquid crystal panel has different specifications depending on the surface treatment of the polarizing film on the outermost layer on the light incident surface side, the following four types of liquid crystal panels were evaluated.
-Glare panel (number of pixels is XGA, size is 15.4W, light incident surface is glare treated product)
・ Non-glare panel (number of pixels is XGA, size is 15.4W, light incident surface is non-glare treated product)
・ TAC panel (number of pixels is XGA, size is 15.4W, light incident surface is TAC (cellulose triacetate) film processed product)
・ APCF panel (number of pixels is XGA, size is 15.4W, light incident surface is DBEF treated product)
Table 1 shows the evaluation results of the panel sticking test when the evaluation surface is on the light diffusion layer side and the lens layer side of the lens sheet.

<Paper sticking test>
The lens sheet was preconditioned for 24 hours in an environment of 23 ° C. and 50% RH before measurement. Electricity was removed from a humidity-adjusted lens sheet, a piece of paper (diameter 6 mm, circular), an adhesive roll (manufactured by KSM Superclean Ltd.) that is a member for forcibly charging the lens sheet, and a SUS plate having a smooth surface. Next, in an environment of 23 ° C. and 50% RH, the lens sheet was placed on the smooth surface of the SUS plate so that the evaluation surface faced the upper surface. Next, the lens sheet is charged by performing reciprocating friction 100 times on the evaluation surface using an adhesive roll, and the evaluation surface side of the charged lens sheet is brought close to or in contact with a piece of paper to determine whether sticking occurs. Was evaluated.
In addition, the proximity approached the lens sheet to a distance of 10 mm from the paper piece, and the contact was evaluated as follows as to whether or not sticking occurred when the lens sheet was brought into contact with the paper piece.

<Evaluation criteria for paper sticking test>
○: No sticking phenomenon occurs.
X: A sticking phenomenon occurs.
Table 2 shows the evaluation results of the paper piece sticking test when the evaluation surface is on the light diffusion layer side and the lens layer side of the lens sheet.

<Light guide sticking test (sticking test, wet-out test)>
The lens sheet was preconditioned for 24 hours in an environment of 23 ° C. and 50% RH before measurement. The lens sheet, the light guide (ten-point average roughness Rz 0.82 μm, size 14.1 W), and an adhesive roll (manufactured by KSM Superclean Ltd.), which is a member for forcibly charging the lens sheet, were removed. Next, in an environment of 23 ° C. and 50% RH, the lens sheet is arranged so that the lens layer faces the light exit surface of the light guide, and then the light diffusion layer side of the lens sheet is used with an adhesive roll. Twice reciprocating friction was performed to cause sticking between the light guide and the lens sheet, and the sticking condition was evaluated.
In addition, about evaluation, it was evaluated as follows whether sticking (sticking, wet out) occurred.

<Evaluation criteria for light guide sticking test (sticking test, wet-out test)>
○: No sticking or very weak.
(Triangle | delta): Sticking exists moderately.
X: Sticking strongly exists.
Table 2 shows the evaluation results of the light guide sticking test (sticking test, wet-out test).

<Constant temperature and humidity test>
After the protective film of the lens sheet was peeled off, the charge was removed, and the lens sheet was left in an environment of 60 ° C. and 95% RH for 1000 hours. Next, the difference in appearance between the lens sheet and the lens sheet that had been left in a room temperature environment for 1000 hours was evaluated after removing the protective film in the same manner.
In addition, about evaluation, the difference in the external appearance of the lens sheet left still under 60 degreeC and 95% RH environment and the lens sheet left still under normal temperature environment was evaluated as follows.

<Evaluation criteria for constant temperature and humidity test>
○: No difference in appearance quality.
Δ: Slight difference in appearance quality.
X: A large difference occurred in the appearance product.
Table 2 shows the evaluation results of the constant temperature and humidity test.

From the results of the frictional band voltage in Table 1, the lens sheets of Examples 1 and 2 were subjected to antistatic treatment only on the light diffusion layer side resin intermediate layer, or on both the light diffusion layer side resin intermediate layer and the lens layer side resin intermediate layer. As a result, the frictional voltage on both surfaces of the lens sheet could be kept within the range of -5 kV to 5 kV. In Comparative Example 2 in which the light diffusion layer was subjected to antistatic treatment, the frictional voltage on both surfaces of the lens sheet could be kept within the range of -5 kV to 5 kV. On the other hand, since the lens sheet of Comparative Example 1 was not subjected to antistatic treatment on any of the light diffusion layer side resin intermediate layer, the lens layer side resin intermediate layer, and the light diffusion layer, the frictional voltage was within the range of −5 kV to 5 kV. I couldn't stop.
From the results of the panel adhesion test in Table 1, the lens sheets of Examples 1 and 2 were subjected to antistatic treatment only in the light diffusion layer side resin intermediate layer, or both the light diffusion layer side resin intermediate layer and the lens layer side resin intermediate layer. As a result, sticking to the liquid crystal panel could be prevented on both surfaces of the lens sheet. In Comparative Example 2 in which the light diffusion layer was subjected to antistatic treatment, it was possible to prevent sticking to the liquid crystal panel on both surfaces of the lens sheet. On the other hand, since the lens sheet of Comparative Example 1 was not subjected to antistatic treatment on any of the light diffusion layer side resin intermediate layer, the lens layer side resin intermediate layer, and the light diffusion layer, it could not suppress sticking to the liquid crystal panel. It was.

From the results of the paper piece sticking test in Table 2, the lens sheets of Examples 1 and 2 were subjected to antistatic treatment only on the light diffusion layer side resin intermediate layer, or both the light diffusion layer side resin intermediate layer and the lens layer side resin intermediate layer. As a result, it was possible to prevent sticking when a piece of paper approached on both surfaces of the lens sheet. Further, in Comparative Example 2 in which the light diffusion layer was subjected to antistatic treatment, it was possible to prevent sticking when a piece of paper approached on both surfaces of the lens sheet. However, since the lens sheet of Comparative Example 1 was not subjected to antistatic treatment on any of the light diffusion layer side resin intermediate layer, the lens layer side resin intermediate layer, and the light diffusion layer, it suppresses sticking when a piece of paper approaches. It did not lead to.
In addition, since the light diffusion layer side resin intermediate layer and the lens layer side resin intermediate layer were subjected to antistatic treatment, the lens sheet of Example 2 prevents sticking when a piece of paper comes into contact with both surfaces of the lens sheet. I was able to. On the other hand, in Example 1 in which the light diffusion layer side resin intermediate layer was subjected to antistatic treatment and in Comparative Example 2 in which the light diffusion layer was subjected to antistatic treatment, sticking when a piece of paper contacts the light diffusion layer. Although it was possible to prevent, sticking when a piece of paper contacted the lens layer could not be prevented. On the other hand, since the lens sheet of Comparative Example 1 was not subjected to the antistatic treatment on any of the light diffusion layer side resin intermediate layer, the lens layer side resin intermediate layer, and the light diffusion layer, a piece of paper on the light diffusion layer side and the lens layer side. It did not lead to suppression of sticking at the time of contact.

  From the results of the light guide sticking test in Table 2, the lens sheet of Example 2 was attached to the light guide because both the light diffusion layer side resin intermediate layer and the lens layer side resin intermediate layer were subjected to antistatic treatment. Could be prevented. In Example 1 in which the light diffusion layer-side resin intermediate layer was subjected to antistatic treatment and in Comparative Example 2 in which the light diffusion layer was subjected to antistatic treatment, sticking to the light guide could be reduced. On the other hand, since the antistatic treatment was not performed on any of the light diffusion layer side resin intermediate layer, the lens layer side resin intermediate layer, and the light diffusion layer, the lens sheet of Comparative Example 1 suppresses sticking to the light guide. It did not lead to.

  From the results of the constant temperature and humidity test of Table 2, in the lens sheets of Examples 1 and 2, the outermost light diffusion layer is not subjected to antistatic treatment, but the light diffusion layer side resin intermediate or the lens layer side resin intermediate layer Since the antistatic treatment was applied to this, the appearance did not differ and the appearance quality was maintained. In addition, since the lens sheet of Comparative Example 1 was not subjected to antistatic treatment, the appearance did not differ and the appearance quality was maintained. On the other hand, the lens sheet of Comparative Example 2 was not subjected to antistatic treatment on the resin intermediate layer, and was subjected to antistatic treatment by containing a large amount of antistatic agent in the light diffusion layer, resulting in bleed out and deterioration in appearance quality. It came to do.

  From the above, Examples 1 and 2 in which the light diffusion layer side resin intermediate layer or the lens layer side resin intermediate layer was subjected to antistatic treatment, Comparative Example 1 in which the antistatic treatment was not performed, and the light diffusion layer were antistatic. From the comparison with Comparative Example 2 where the treatment was performed, the friction band voltage on the light diffusion layer side in Example 1 and the friction band voltage on the light diffusion layer side and the lens layer side in Example 2 were kept within the range of −5 kV to 5 kV. It was found that sticking of panels and paper pieces was suppressed.

It is a perspective view which shows the liquid crystal display device concerning embodiment of this invention. It is a fragmentary sectional view of the lens sheet concerning the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 20 Light source 40 Light guide 42 Light incident surface 46 Light output surface 50 Lens sheet 51 Lens layer 55 Light diffusion layer 56 Light diffusion layer side resin intermediate layer 58 Lens layer side resin intermediate layer 59 Translucent base material

Claims (5)

  A translucent substrate having a translucent resin intermediate layer on both sides, a lens layer formed on one side of the translucent substrate, and a light diffusion formed on the other side of the translucent substrate And a resin intermediate layer on the light diffusion layer side is subjected to antistatic treatment.   The lens sheet according to claim 1, wherein the resin intermediate layer on the lens layer side is subjected to an antistatic treatment.   The lens sheet according to claim 1, wherein the resin intermediate layer is subjected to an antistatic treatment by containing a cationic antistatic agent.   A light source having a light source, at least one light incident surface facing the light source, a light emitting surface substantially orthogonal to the light incident surface, and the lens layer facing the light emitting surface of the light guide A surface light source device having the lens sheet according to any one of claims 1 to 3. A liquid crystal display device comprising the surface light source device according to claim 4.

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