JP5301127B2 - LCD module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display module with which the viewing angle is widened without lowering the luminance, and which has a simplicity and low-cost. <P>SOLUTION: The liquid crystal display module has a rectangular shape and includes: a liquid crystal display element comprising a liquid crystal cell interposed between a pair of polarizing plates; and a backlight which is a surface light source and is superposed and disposed on the rear side of the liquid crystal display element, wherein an angle of a transmission axis direction of the rear side polarizing plate is &plusmn;(1/4)&pi;, and it includes a viewing angle widening sheet which is superposed and disposed between the liquid crystal display element and the backlight and which has an optically anisotropic base film composed of a resin, wherein an angle of a crystal axis direction of the base film is in the range of &plusmn;(1/8)&pi; centered on a value &epsi; represented by &epsi;=(1/8)&pi;V-(3/8)&pi; in the case (I) in which the angle of the transmission axis direction is -(1/4)&pi;, and by &epsi;=-(1/8)&pi;V(3/8)&pi; in the case (II) in which the angle of the transmission axis direction is +(1/4)&pi;. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a liquid crystal display module used for a liquid crystal television, a liquid crystal display for a computer, and the like, and more particularly to a liquid crystal display module having viewing angle characteristics, in particular, luminance uniformity corresponding to the viewing angle.

  Liquid crystal display modules (LCDs) are widely used as flat panel displays taking advantage of their features such as thinness, light weight, and low power consumption, and their uses are for information displays such as mobile phones, personal digital assistants (PDAs), personal computers, and televisions. It is expanding year by year as a device.

  As shown in FIG. 12, a conventional general liquid crystal display module has a structure in which a liquid crystal display element 51, various optical sheets 52, and a backlight 53 are superposed in this order from the front surface side to the back surface side. The liquid crystal display element 51 has a structure in which a liquid crystal cell 56 is sandwiched between a pair of polarizing plates 54 and 55, and various display modes such as TN have been proposed. The backlight 53 illuminates the liquid crystal display element 51 from the back side, and forms such as an edge light type and a direct type are widespread. The various optical sheets 52 are superimposed between the liquid crystal display element 51 and the backlight 53, and in order to make the light emitted from the surface of the backlight 53 enter the entire surface of the liquid crystal display element 51 efficiently and uniformly, the normal direction A light diffusion sheet, a prism sheet, and the like having optical functions such as refraction to the side and diffusion are provided.

  In recent years, the characteristics required for liquid crystal display modules vary depending on the application, but they are bright (higher brightness), easier to see (wider viewing angle), energy saving, thinner and lighter, etc. The demand for wide viewing angle is increasing. The viewing angle is the angle of the line of sight with respect to the normal of the screen within the range where practical contrast can be obtained. In the liquid crystal display module, the fluctuation of the transmittance and the reverse phenomenon occur as the angle of viewing the screen increases, and the original image is good There is an inconvenience that cannot be reproduced.

  In the conventional liquid crystal display module, as a technique for widening the viewing angle, (a) a technique that employs a display mode having excellent viewing angle characteristics such as the IPS method (lateral electric field mode driving method) for the liquid crystal display element 51 (for example, JP, 7-134301, A, etc.), (b) Technology which laminates an optical phase difference compensation film between polarizing plates 54 and 55 and liquid crystal cell 56 (for example, refer to JP, 2-91612, etc.), (C) A technique of laminating an optical array body such as a microlens array on the surface side of the liquid crystal display element 51 (see, for example, Japanese Patent Laid-Open No. 10-48628) has been developed.

The improvement of the display mode such as the IPS method (a) has disadvantages such as a complicated manufacturing process and increased power consumption. In the optical retardation compensation film (b), the modulation generated in the TN liquid crystal layer cannot be completely compensated, and a sufficient viewing angle cannot be obtained. Since the technique of laminating the optical array body of (c) above diffuses outgoing light rays that form an image, the image clarity, fine density, and the like may be reduced. In addition, the techniques (a) to (c) described above cause an increase in manufacturing cost, which is contrary to the social demand for lower prices.
JP-A-7-134301 JP-A-2-91612 Japanese Patent Laid-Open No. 10-48628

  The present invention has been made in view of these disadvantages, and an object of the present invention is to provide a liquid crystal display module that can promote a wide viewing angle while suppressing a decrease in luminance, and has a simple structure and low cost. Is.

  The inventor pays attention to the crystal axis direction of the optical sheet (optical film) provided between the liquid crystal display element and the backlight and the balance between the crystal axis direction and the haze value, and the crystal axis of the optical sheet. As a result of diligent examination of the influence of the direction and haze value on the viewing angle characteristics, a rectangular liquid crystal display module in which the angle with respect to the short side of the transmission axis direction of the back-side polarizing plate of the liquid crystal display element is ± (1/4) π In this case, it was found that the viewing angle characteristics are improved when the crystal axis direction and the haze value of the optical sheet are in a specific range.

As a result, the invention made to solve the above problems is
A liquid crystal display element having a liquid crystal cell sandwiched between a pair of polarizing plates;
A backlight of a surface light source superimposed on the back side of the liquid crystal display element,
A square liquid crystal display module in which an angle of the transmission axis direction of the back side polarizing plate of the liquid crystal display element with respect to the short side direction of the back side polarizing plate is ± (1/4) π,
It has a viewing angle widening sheet stacked between the liquid crystal display element and the backlight,
This viewing angle expansion sheet is a resin base film having optical anisotropy, and
Having a light diffusion layer laminated on one surface of the base film,
The light diffusing layer has a plurality of light diffusing agents and its binder, and is formed by coating a composition in which the light diffusing agent is mixed with a polymer composition constituting the binder,
The angle with respect to the short side direction of the back-side polarizing plate in the crystal axis direction of the base film is within a range of ± (1/16) π around the numerical value ε represented by (I) or (II) below. Features.
(I) When the transmission axis direction angle is − (1/4) π, ε = (1/8) π∨− (3/8) π
(II) When the transmission axis direction angle is + (1/4) π, ε = − (1/8) π∨ (3/8) π
The liquid crystal display module includes a viewing angle widening sheet between a liquid crystal display element and a backlight, the viewing angle widening sheet has a resin base film having optical anisotropy, and the crystal of the base film By making the angle with respect to the short side direction of the back side polarizing plate in the axial direction within the range of ± (1/16) π centered on the numerical value ε calculated by the above formulas (I) and (II) The viewing angle can be expanded while suppressing the decrease in the image quality. Therefore, the liquid crystal display module has a simple structure in which a viewing angle widening sheet is overlapped between the liquid crystal display element and the backlight, and promotes the wide viewing angle and the high brightness demanded by society today. Cost reduction, energy saving, and reduction in thickness and weight can be promoted.

In the liquid crystal display module, the angle with respect to the short-side direction of the fast axis direction in the crystal axis direction of the base film is ± (1/16) π around the numerical value ε represented by the following (III) or (IV) It is preferable to be within the range.
(III) When the transmission axis direction angle is-(1/4) π, ε = (1/8) π
(IV) When the transmission axis direction angle is + (1/4) π, ε = − (1/8) π
As described above, when the angle with respect to the short side direction of the fast axis direction is determined with the numerical value ε shown in (III) or (IV) as a center, the fast axis direction of the viewing angle widening sheet is used as a reference. Viewing angle can be further promoted.

  The viewing angle widening sheet may be placed directly below the back surface of the liquid crystal display element. As described above, the wide viewing angle can be effectively promoted by laminating the viewing angle widening sheet directly under the liquid crystal display element.

  The viewing angle widening sheet may have an optical function layer laminated on one surface of the base film. An optical sheet having various optical function layers (for example, a light diffusing sheet, a microlens sheet, a prism sheet, and the like) is generally provided between the liquid crystal display element and the backlight, and thus is generally provided as such means. By using the base film having the above-mentioned viewing angle widening function as the base film of the optical sheet, it is possible to widen the viewing angle without adding a new optical sheet. Reduction in thickness and weight can be promoted.

  Examples of the optical functional layer include (a) one having a plurality of light diffusing agents and its binder (light diffusing layer of a light diffusing sheet), and (b) one having a minute concavo-convex shape having refractive properties (for example, a prism). A prism portion layer of a sheet, a microlens array layer of a microlens sheet, and the like. Since such light diffusion sheets and prism sheets are usually used in liquid crystal display modules, the above-mentioned wide viewing angle can be achieved without incurring an increase in the number of optical sheets, and consequently, high brightness and low cost. , Energy saving, and reduction in thickness and weight can be promoted.

  The haze value of the viewing angle widening sheet on which the optical functional layer is laminated is preferably 10% or more and 44% or less or 80% or more. Thus, by making the haze value of a viewing angle expansion sheet into the above-mentioned range, the above-mentioned wide viewing angle can be effectively promoted, and higher luminance can be further promoted.

  The viewing angle widening sheet is preferably laminated on the other surface of the base film and has a sticking prevention layer in which beads are dispersed in a binder. Thus, by providing the anti-sticking layer on the surface opposite to the optical function layer in the viewing angle widening sheet, sticking between the viewing angle widening sheet and the prism sheet or the like disposed on the back side is prevented, and the luminance is uniform. The quality such as sex can be improved.

  An edge light type backlight may be used as the backlight, and the lamp of the edge light type backlight may be disposed in parallel with the long side direction. Thus, by making the lamp direction of the edge light type backlight parallel to the long side direction (perpendicular to the short side direction), the above wide viewing angle by the viewing angle widening sheet can be effectively functioned. . This is presumably because the edge light type backlight has relatively large polarization characteristics in the direction parallel to the light and in the vertical direction.

  In the liquid crystal display module, when another optical sheet is provided between the liquid crystal display element and the backlight, a low retardation film may be used as a base film of the other optical sheet. A liquid crystal display module is generally equipped with a plurality of optical sheets such as a light diffusion sheet and a prism sheet. When a plurality of optical sheets are provided in this manner, only the base film of a specific optical sheet is provided with the above-described viewing angle expansion function, and the other optical sheets are prevented from changing the polarization direction of transmitted light. Thus, optimization and controllability of the viewing angle expansion function can be promoted.

  The other optical sheet may be a prism sheet, and the ridge line direction of the prism sheet may be orthogonal to the short side direction. In this way, the prism sheet whose ridge line direction is orthogonal to the short side direction is overlapped between the liquid crystal display element and the backlight, thereby effectively promoting the above wide viewing angle, particularly in the long side direction. In addition, higher brightness can be promoted.

  The “viewing angle widening sheet” is a concept including a case of only a base film. “An angle with respect to the short side direction” is an angle on a plane viewed from the surface side, and the short side direction is 0, clockwise is +, and counterclockwise is − (1/2) π˜ An angle of + (1/2) π is meant. “Unit of value indicating angle” is in radians unless otherwise specified. “Surface side” means the viewing side of the display of the liquid crystal display module or when incorporated in the liquid crystal display module. The “back side” means the side opposite to the “front side”. A “low retardation film” is a film having an absolute value of retardation value Re of 60 nm or less. “Retardation value Re” means that the fast axis direction and the slow axis direction orthogonal to the crystal axis direction on the plane of the base film surface are the x direction and the y direction, and the thickness of the base film is d, x The refractive index in the direction and the y direction is nx and ny (nx ≠ ny), and is a value calculated by Re = (ny−nx) d. The concept of “each angle to be defined”, “parallel” and “orthogonal” is allowed within about ± 5 ° of a strict angle.

  As described above, the liquid crystal display module of the present invention has a wide viewing angle, which is demanded by society today, by the viewing angle widening function of the viewing angle widening sheet that is overlapped between the liquid crystal display element and the backlight. As a result, it is possible to promote higher luminance, energy saving, and thinner and lighter weight.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is a schematic perspective view showing a liquid crystal display module according to an embodiment of the present invention, and FIGS. 2A and 2B are transmission axis directions (angle is −) of a back-side polarizing plate in the liquid crystal display module of FIG. (1/4) π) and a schematic plan view for explaining the relationship in the crystal axis direction of the substrate film, FIGS. 3 (a) and 3 (b) are transmissions of the back side polarizing plate in the liquid crystal display module of FIG. FIG. 4 is a schematic plan view for explaining the relationship between the axial direction (when the angle is + (1/4) π) and the crystal axis direction of the base film, and FIG. 4 is a liquid crystal display according to a different form from the liquid crystal display module of FIG. FIG. 5, FIG. 6 and FIG. 7 are schematic cross-sectional views showing a viewing angle widening sheet according to a different form from the viewing angle widening sheet provided in the liquid crystal display module of FIG.

  The liquid crystal display module 1 in FIG. 1 includes a liquid crystal display element 2, a viewing angle widening sheet 3, and a backlight 4. The liquid crystal display element 2, the viewing angle widening sheet 3, and the backlight 4 (light exit surface) have substantially the same and rectangular planar shape, and are superposed in this order from the front surface side to the back surface side.

  The liquid crystal display element 2 includes a front surface side polarizing plate 5 and a back surface side polarizing plate 6 which are disposed substantially in parallel and at a predetermined interval, and a liquid crystal cell 7 sandwiched therebetween. The polarizing plates 5 and 6 are not particularly limited, and in general, polarizers such as iodine polarizers, dye polarizers, and polyene polarizers, and two transparent protective films disposed on both sides thereof. Consists of The front-side polarizing plate 5 and the back-side polarizing plate 6 are arranged so that their transmission axis directions are orthogonal to each other.

  The liquid crystal cell 7 has a function of controlling the amount of transmitted light, and various known ones are employed. The liquid crystal cell 7 is generally a laminated structure including a substrate, a color filter, a counter electrode, a liquid crystal layer, a pixel electrode, a substrate, and the like. A transparent conductive film such as ITO is used for the pixel electrode. As the display mode of the liquid crystal cell 7, currently proposed, for example, TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), Bumper Otc Olyptic Crystal (B). , STN (Super Twisted Nematic), VA (Vertically Aligned), HAN (Hybrid Aligned Nematic), and the like.

  The backlight 4 is an edge light type (also referred to as a side light type) surface light source device, and illuminates the liquid crystal display element 2 from the back side. Specifically, the backlight 4 is a rectangular plate-shaped light guide plate 8 having a substantially wedge-shaped cross-sectional shape in which one end surface (light incident surface) corresponding to the long side is thick and the opposite end surface is thin. A linear lamp 9 disposed along the light incident surface, a reflection sheet (not shown) disposed on the back surface side of the light guide plate 8, a side of the lamp 9 (light incident surface side of the light guide plate 8) A reflector (not shown) disposed so as to surround the light incident surface of the light guide plate 8, a light reflecting film deposited on the opposite end surface of the light incident surface of the light guide plate 8, an upper opening casing for housing these components, and the like. The light beam emitted from the lamp 9 is emitted from the entire surface of the light guide plate 8. Therefore, in the backlight 4, the direction of the lamp 9 is parallel to the long side direction (perpendicular to the short side direction). In addition, in order to raise the outgoing light beam to the normal direction side, a prism light guide plate in which triangular prism-shaped prism portions are formed on the back surface as the light guide plate 8 and are formed perpendicular to the lamp 9 is used on the back surface side. There has also been proposed a backlight 4 having a configuration in which an inverted prism sheet in which triangular prism-shaped prism portions are formed in parallel and in parallel with the lamp 9 is superimposed on the surface side of the light guide plate 8.

  The viewing angle enlarging sheet 3 is an optical sheet having a function of enlarging a viewing angle at which a good image can be formed, and specifically includes a base film 10.

  The base film 10 is a resin film formed in a square shape. As a material for forming the base film 10, a transparent, particularly colorless and transparent synthetic resin is used. The synthetic resin is not particularly limited, and examples thereof include polyethylene terephthalate, polyethylene naphthalate, acrylic resin, polycarbonate, polystyrene, polyolefin, cellulose acetate, and weather resistant vinyl chloride. Among them, as the base film 10, polyethylene terephthalate or polycarbonate having high transparency and strength and easy birefringence control is preferable, and polyethylene terephthalate with improved bending performance is particularly preferable.

  The thickness (average thickness) of the base film 10 is not particularly limited, but is preferably 10 μm or more and 250 μm or less, particularly preferably 20 μm or more and 188 μm or less. When the thickness of the base film 10 is less than the above range, inconveniences such as curling easily occur during processing and handling become difficult. On the contrary, if the thickness of the base film 10 exceeds the above range, the luminance of the liquid crystal display module 1 may be lowered, and the thickness of the liquid crystal display module 1 is increased, which is contrary to the demand for thinning. It also becomes.

  The base film 10 has optical anisotropy, and specifically has birefringence with a different refractive index in the planar direction. It is considered that the base film 10 exhibits the function of expanding the viewing angle by converting the polarization component of the transmitted light into the intended direction due to the birefringence.

  The base film 10 has a crystal axis direction optimized for widening the viewing angle. The angle of the optimized base film 10 in the crystal axis direction (x, y) includes two patterns shown in FIGS. 2 and 3 corresponding to the angle of the transmission axis direction m of the back-side polarizing plate 6.

As shown in FIG. 2, when the angle β with respect to the short side direction (“vertical direction” in the figure) of the transmission axis direction m of the back-side polarizing plate 6 is − (1/4) π, the crystal axis direction of the base film 10 The angle α with respect to the short side direction of (x, y) is within a range of ± (1/16) π with the numerical value ε shown in (I) below as the center. Specifically, the angle α in the crystal axis direction (x, y) of the base film 10 is (1/16) π or more (3/16) π or less or − (7/16) π or more − (5 / 16) π or less.
(I) ε = (1/8) π∨− (3/8) π [∨ is a symbol indicating “or”]
In this case, in particular, the angle α with respect to the short side direction of the fast axis direction x in the crystal axis direction (x, y) of the base film 10 is ± (1 / 16) Within the range of π is preferred. As described above, the fast axis direction x of the crystal axis directions of the viewing angle expansion sheet 3 is used as a reference, and the angle α of the fast axis direction x with respect to the short side direction is determined around the numerical value ε shown in the following (III). Then, the above-mentioned wide viewing angle can be further promoted.
(III) ε = (1/8) π
On the other hand, as shown in FIG. 3, when the angle β with respect to the short side direction of the transmission axis direction m of the back-side polarizing plate 6 is (1/4) π, the base film 10 has a short crystal axis direction (x, y). The angle α with respect to the side direction is within a range of ± (1/16) π around the numerical value ε shown in (II) below. Specifically, the angle α in the crystal axis direction (x, y) of the base film 10 is − (3/16) π or more and − (1/16) π or less or (5/16) π or more (7 / 16) π or less.
(II) ε = − (1/8) π∨ (3/8) π [∨ is a symbol indicating “or”]
In this case, in particular, the angle α with respect to the short side direction of the fast axis direction x in the crystal axis direction (x, y) of the base film 10 is ± (1/16) centered on the numerical value ε shown in (IV) below. ) Is preferably within the range of π. As described above, the fast axis direction x of the crystal axis directions of the viewing angle expansion sheet 3 is used as a reference, and the angle α of the fast axis direction x with respect to the short side direction is determined around the numerical value ε shown in (IV) below. Then, the above-mentioned wide viewing angle can be further promoted.
(IV) ε = − (1/8) π
The method for producing the base film 10 is not particularly limited as long as the crystal axis angle α can be controlled within the above numerical range. For example, the crystal axis angle α of the base film 10 can be adjusted by adjusting the drawing force and temperature in the uniaxial drawing process such as polyethylene terephthalate, and the adjustment of the drawing position and the drawing angle in the punching process of the biaxially drawn film. The range can be controlled.

  The liquid crystal display module 1 includes a viewing angle widening sheet 3 between the liquid crystal display element 2 and the backlight 4, and the viewing angle widening sheet 3 includes a resin base film 10 having optical anisotropy, By setting the angle α of the base film 10 with respect to the short side direction in the crystal axis direction within the predetermined range, the viewing angle can be expanded while suppressing a decrease in luminance. Therefore, the liquid crystal display module 1 has a simple structure in which the viewing angle widening sheet 3 is overlapped between the liquid crystal display element 2 and the backlight 4, and widening the viewing angle and increasing the brightness that are socially required today. As a result, cost reduction, energy saving, and reduction in thickness and weight can be promoted. In addition, the liquid crystal display module 1 can effectively promote the above wide viewing angle by stacking the viewing angle widening sheet 3 directly below the liquid crystal display element 2. This is because the edge-light type backlight 4 has relatively large polarization characteristics in the direction parallel to and perpendicular to the lamp 9, and the polarization component of the transmitted light is set to a predetermined direction depending on the specific crystal axis direction of the base film 10. Presumed to convert.

  The liquid crystal display module 11 of FIG. 4 includes a liquid crystal display element 2, a viewing angle widening sheet 3, a prism sheet 12, and a backlight 4 in this order from the surface side. The liquid crystal display element 2, the viewing angle widening sheet 3, and the backlight 4 are the same as the liquid crystal display module 1 of FIG.

  The prism sheet 12 includes a base material layer 13 and a large number of triangular prisms 14 formed on the surface of the base material layer 13. The large number of prism portions 14 are arranged in parallel, equally spaced and densely, and the ridge line direction of the prism portions 14 is parallel to the long side direction (perpendicular to the short side direction) and parallel to the direction of the lamp 9 of the backlight 4. It is.

  As a material for forming the prism sheet 12, the same synthetic resin as that of the base film 10 is used. The manufacturing method of the prism sheet 12 is not particularly limited, and the base material layer 13 and the prism portion 14 may be integrally formed or may be separately formed. In addition, as the base material layer 13, it is good to use a low retardation film. Thus, by using a low retardation film as the base material layer 13 of the prism sheet 12, it is possible to prevent the viewing angle widening function of the viewing angle widening sheet 3 as described above from being hindered.

  Similar to the liquid crystal display module 1, the liquid crystal display module 11 has a viewing angle, in particular, a long viewing angle while maintaining luminance by the viewing angle widening function of the viewing angle widening sheet 3 provided between the liquid crystal display element 2 and the backlight 4. The viewing angle parallel to the side direction can be enlarged. Further, the liquid crystal display module 11 exhibits a peak in the substantially normal direction of the light beam emitted from the backlight 4 by the refraction action of the prism portion 14 of the prism sheet 12 provided between the liquid crystal display element 2 and the backlight 4. The front brightness can be improved. Therefore, the liquid crystal display module 11 promotes both high brightness and wide viewing angle by combining the refraction action in the normal direction by the prism sheet 12 and the viewing angle widening function by the viewing angle widening sheet 3. be able to.

  In the liquid crystal display modules 1 and 11, in addition to the viewing angle widening sheet 3 (in the case of the liquid crystal display module 11, the viewing angle widening sheet 3 and the prism sheet 12) between the liquid crystal display element 2 and the backlight 4, light diffusion Other optical sheets such as a sheet, a microlens sheet, and a prism sheet can be provided. A low retardation film may be used as the base film of the other optical sheet. Thus, by using a low retardation film as a base film of another optical sheet and preventing the other optical sheet from changing the polarization direction of the transmitted light, the viewing angle widening function by the above-mentioned viewing angle widening sheet 3 can be achieved. Inhibition can be prevented.

  The liquid crystal display modules 1 and 11 can include the viewing angle widening sheet 21 of FIG. 5 instead of the viewing angle widening sheet 3. The viewing angle widening sheet 21 is a light diffusing sheet having a light diffusing function for diffusing transmitted light (specifically, a directional diffusing function for condensing light in the normal direction while diffusing). Specifically, the viewing angle widening sheet 21 includes a base film 10 and an optical functional layer (light diffusion layer) 22 laminated on the surface of the base film 10.

  The optical functional layer 22 includes a plurality of light diffusing agents 23 disposed substantially uniformly on the surface of the base film 10, and a binder 24 that fixes the plurality of light diffusing agents 23. The plurality of light diffusing agents 23 are coated with a binder 24. As described above, the plurality of light diffusing agents 23 contained in the optical functional layer 22 can uniformly diffuse the light beam that passes through the optical functional layer 22 from the back side to the front side. Further, fine irregularities are formed substantially uniformly on the surface of the optical functional layer 22 by the plurality of light diffusing agents 23. Thus, the light can be diffused better by the lens-like refractive action of fine irregularities formed on the surface of the viewing angle widening sheet 21. In addition, the average thickness of the optical function layer 22 is not particularly limited, but is set to, for example, about 1 μm or more and 30 μm or less.

  The light diffusing agent 23 is a particle having a property of diffusing light, and is roughly classified into an inorganic filler and an organic filler. As the inorganic filler, for example, silica, aluminum hydroxide, aluminum oxide, zinc oxide, barium sulfide, magnesium silicate, or a mixture thereof can be used. As the organic filler material, for example, acrylic resin, acrylonitrile resin, polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile, polyamide, and the like can be used. Among them, an acrylic resin having high transparency is preferable, and polymethyl methacrylate (PMMA) is particularly preferable.

  The shape of the light diffusing agent 23 is not particularly limited, and examples thereof include a spherical shape, a spindle shape, a needle shape, a rod shape, a cubic shape, a plate shape, a scale shape, and a fiber shape, and are particularly excellent in light diffusibility. Spherical beads are preferred.

  The lower limit of the average particle diameter of the light diffusing agent 23 is preferably 1 μm, particularly 2 μm, and more preferably 5 μm. On the other hand, the upper limit of the average particle diameter of the light diffusing agent 23 is preferably 50 μm, particularly 20 μm, and more preferably 15 μm. When the average particle diameter of the light diffusing agent 23 is less than the above range, the unevenness of the surface of the optical functional layer 22 formed by the light diffusing agent 23 becomes small, and the light diffusing property necessary for the light diffusing sheet may not be satisfied. . On the other hand, if the average particle diameter of the light diffusing agent 23 exceeds the above range, the thickness of the viewing angle widening sheet 21 increases and uniform diffusion becomes difficult.

  The lower limit of the amount of the light diffusing agent 23 (the amount in terms of solid content relative to 100 parts of the base polymer in the polymer composition that is the forming material of the binder 24) is preferably 10 parts, particularly 20 parts, and more preferably 50 parts. The upper limit of this amount is preferably 500 parts, particularly 300 parts, and more preferably 200 parts. This is because if the blending amount of the light diffusing agent 23 is less than the above range, the light diffusing property becomes insufficient. On the other hand, if the blending amount of the light diffusing agent 23 exceeds the above range, the light diffusing agent 23 is fixed. It is because the effect to do falls. In the case of the so-called upward light diffusion sheet disposed on the surface side of the prism sheet, high light diffusibility is not required, so the amount of the light diffusing agent 23 is 10 parts or more and 40 parts or less, particularly 10 parts. The amount is preferably 30 parts or less.

  The binder 24 is formed by crosslinking and curing a polymer composition containing a base polymer. The light diffusing agent 23 is arranged and fixed on the surface of the base film 10 by the binder 24 at a substantially equal density. In addition to the base polymer, the polymer composition for forming the binder 24 includes, for example, a fine inorganic filler, a curing agent, an antistatic agent, a plasticizer, a dispersant, various leveling agents, an ultraviolet absorber, and an antioxidant. , Viscosity modifiers, lubricants, light stabilizers and the like may be appropriately blended.

  The base polymer is not particularly limited, and examples thereof include acrylic resins, polyurethanes, polyesters, fluorine resins, silicone resins, polyamideimides, epoxy resins, ultraviolet curable resins, and the like. Can be used singly or in combination of two or more. In particular, the base polymer is preferably a polyol that has high processability and can easily form the optical functional layer 22 by means such as coating. In addition, the base polymer itself used for the binder 24 is preferably transparent from the viewpoint of increasing light transmittance, and is particularly preferably colorless and transparent.

  As said polyol, the polyester polyol or the acrylic polyol obtained by superposing | polymerizing the monomer component containing a hydroxyl-containing unsaturated monomer, and having a (meth) acryl unit etc. is preferable. The binder 24 having such a polyester polyol or acrylic polyol as a base polymer has high weather resistance, and can suppress yellowing of the optical functional layer 22. In addition, any one of this polyester polyol and acrylic polyol may be used, and both may be used.

  The number of hydroxyl groups in the polyester polyol and acrylic polyol is not particularly limited as long as it is 2 or more per molecule, but if the hydroxyl value in the solid content is 10 or less, the number of crosslinking points decreases, and the solvent resistance , Film properties such as water resistance, heat resistance and surface hardness tend to decrease.

  A fine inorganic filler may be contained in the polymer composition forming the binder 24. Thus, by including a fine inorganic filler in the binder 24, the heat resistance of the optical functional layer 22 and thus the viewing angle widening sheet 21 is improved. The inorganic material constituting the fine inorganic filler is not particularly limited, and an inorganic oxide is preferable. Inorganic oxides are defined as various oxygen-containing metal compounds in which a metal element mainly forms a three-dimensional network through bonds with oxygen atoms. As the metal element constituting the inorganic oxide, for example, an element selected from Groups 2 to 6 of the Periodic Table of Elements is preferable, and an element selected from Groups 3 to 5 of the Periodic Table of Elements is more preferable. In particular, an element selected from Si, Al, Ti, and Zr is preferable, and colloidal silica in which the metal element is Si is most preferable as a fine inorganic filler in terms of heat resistance improvement effect and uniform dispersibility. The shape of the fine inorganic filler may be any particle shape such as a spherical shape, a needle shape, a plate shape, a scale shape, and a crushed shape, and is not particularly limited.

  The lower limit of the average particle size of the fine inorganic filler is preferably 5 nm, and particularly preferably 10 nm. On the other hand, the upper limit of the average particle size of the fine inorganic filler is preferably 50 nm, particularly preferably 25 nm. This is because if the average particle size of the fine inorganic filler is less than the above range, the surface energy of the fine inorganic filler becomes high and aggregation or the like is likely to occur. Conversely, if the average particle size exceeds the above range, This is because it becomes cloudy under the influence of a short wavelength, and the transparency of the viewing angle widening sheet 21 cannot be maintained completely.

  The lower limit of the amount of the fine inorganic filler based on 100 parts of the base polymer (the amount of only the inorganic component) is preferably 5 parts, particularly preferably 50 parts in terms of solid content. On the other hand, the upper limit of the amount of the fine inorganic filler is preferably 500 parts, more preferably 200 parts, and particularly preferably 100 parts. This is because if the blending amount of the fine inorganic filler is less than the above range, the heat resistance of the viewing angle widening sheet 21 may not be sufficiently expressed. Conversely, the blending amount is within the above range. If it exceeds, blending into the polymer composition becomes difficult, and the light transmittance of the optical functional layer 22 may be lowered.

  As the fine inorganic filler, one having an organic polymer fixed on its surface may be used. As described above, by using the organic polymer-fixed fine inorganic filler, the dispersibility in the binder 24 and the affinity with the binder 24 can be improved. The organic polymer is not particularly limited with respect to its molecular weight, shape, composition, presence or absence of a functional group, and any organic polymer can be used. Moreover, about the shape of an organic polymer, the thing of arbitrary shapes, such as a linear form, a branched form, and a crosslinked structure, can be used.

  The fine inorganic filler may contain an organic polymer in the fine particles. As a result, moderate softness and toughness can be imparted to the inorganic material that is the core of the fine inorganic filler.

  As the organic polymer, one containing an alkoxy group may be used, and the content is preferably 0.01 mmol or more and 50 mmol or less per 1 g of the fine inorganic filler on which the organic polymer is fixed. Such an alkoxy group can improve the affinity with the matrix resin constituting the binder 24 and the dispersibility in the binder 24.

  The alkoxy group represents an RO group bonded to a metal element that forms a fine particle skeleton. R is an alkyl group which may be substituted, and the RO groups in the fine particles may be the same or different. Specific examples of R include methyl, ethyl, n-propyl, isopropyl, n-butyl and the like. It is preferable to use the same metal alkoxy group as the metal constituting the fine inorganic filler. When the fine inorganic filler is colloidal silica, it is preferable to use an alkoxy group having silicon as a metal.

  The content of the organic polymer in the fine inorganic filler to which the organic polymer is fixed is not particularly limited, but is preferably 0.5% by mass or more and 50% by mass or less based on the fine inorganic filler.

  A polyfunctional isocyanate compound, melamine compound and amino having at least two functional groups capable of reacting with a hydroxyl group in the polymer composition constituting the binder 24 are used as the organic polymer fixed to the fine inorganic filler. It is good to contain the at least 1 sort (s) chosen from plast resin. As a result, the fine inorganic filler and the matrix resin of the binder 24 are bonded in a crosslinked structure, and the storage stability, stain resistance, flexibility, weather resistance, storage stability, etc. are improved, and the resulting film is further obtained. It becomes glossy.

  The base polymer is preferably a polyol having a cycloalkyl group. Thus, by introducing a cycloalkyl group into the polyol as the base polymer constituting the binder 24, the hydrophobicity of the binder 24, such as water repellency and water resistance, is increased, and the said property under high temperature and high humidity conditions. The bending resistance, dimensional stability, etc. of the viewing angle expansion sheet 21 are improved. Further, the basic properties of the coating film such as weather resistance, hardness, feeling of holding, and solvent resistance of the optical functional layer 22 are improved. Furthermore, the affinity with the fine inorganic filler having the organic polymer fixed on the surface and the uniform dispersibility of the fine inorganic filler are further improved.

  The cycloalkyl group is not particularly limited, and examples thereof include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cycloundecyl group, a cyclododecyl group, a cyclotridecyl group, Examples thereof include a cyclotetradecyl group, a cyclopentadecyl group, a cyclohexadecyl group, a cycloheptadecyl group, and a cyclooctadecyl group.

  The polyol having a cycloalkyl group can be obtained by copolymerizing a polymerizable unsaturated monomer having a cycloalkyl group. The polymerizable unsaturated monomer having a cycloalkyl group is a polymerizable unsaturated monomer having at least one cycloalkyl group in the molecule. The polymerizable unsaturated monomer is not particularly limited, and examples thereof include cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, and cyclododecyl (meth) acrylate.

  Moreover, it is good to contain isocyanate as a hardening | curing agent in a polymer composition. Thus, by containing an isocyanate hardening | curing agent in a polymer composition, it becomes a much stronger crosslinked structure, and the film physical property of the optical function layer 22 further improves. As this isocyanate, the same substance as the polyfunctional isocyanate compound is used. Of these, aliphatic isocyanates that prevent yellowing of the coating are preferred.

  In particular, when a polyol is used as the base polymer, one or more of hexamethylene diisocyanate, isofurone diisocyanate and xylene diisocyanate may be mixed and used as a curing agent to be blended in the polymer composition. When these curing agents are used, the curing reaction rate of the polymer composition is increased. Therefore, even if a cationic agent that contributes to the dispersion stability of the fine inorganic filler is used as the antistatic agent, the cationic antistatic agent is used. Can sufficiently compensate for a decrease in the curing reaction rate. Moreover, the improvement in the curing reaction rate of such a polymer composition contributes to the uniform dispersibility of the fine inorganic filler in the binder. As a result, the viewing angle widening sheet 21 can remarkably suppress bending and yellowing due to heat, ultraviolet rays, and the like.

  Moreover, it is good to contain a ultraviolet absorber in the said polymer composition. In this way, by forming the binder 24 from the polymer composition containing the ultraviolet absorber, the viewing angle expansion sheet 21 is provided with an ultraviolet ray cutting function, and a small amount of ultraviolet rays emitted from the lamp of the backlight unit are cut, The destruction of the liquid crystal layer due to ultraviolet rays can be prevented.

  The ultraviolet absorber is not particularly limited as long as it is a compound that absorbs ultraviolet rays and can be efficiently converted into thermal energy, and is stable to light, and a known one can be used. . Among them, salicylic acid-based UV absorbers, benzophenone-based UV absorbers, benzotriazole-based UV absorbers, and cyano have a high UV-absorbing function, good compatibility with the above-mentioned base polymer, and exist stably in the base polymer. An acrylate ultraviolet absorber is preferable, and one or more selected from these groups may be used. Further, as the ultraviolet absorber, a polymer having an ultraviolet absorbing group in a molecular chain (for example, “Udable UV” series of Nippon Shokubai Co., Ltd.) is also preferably used. By using a polymer having an ultraviolet absorbing group in the molecular chain, the binder 24 is highly compatible with the main polymer, and deterioration of the ultraviolet absorbing function due to bleeding out of the ultraviolet absorbent can be prevented. A polymer having an ultraviolet absorbing group in the molecular chain may be used as the base polymer of the binder 24. Further, it is possible to use the polymer to which the ultraviolet absorbing group is bonded as the base polymer of the binder 24, and further to contain an ultraviolet absorber in the base polymer, so that the ultraviolet absorbing function can be further improved.

  The lower limit of the content of the ultraviolet absorber relative to the base polymer of the binder 24 is preferably 0.1% by mass, particularly 1% by mass, and more preferably 3% by mass, and the upper limit of the content of the ultraviolet absorber is 10% by mass. In particular, 8% by mass, and further 5% by mass are preferable. This is because, if the mass ratio of the ultraviolet absorber to the base polymer is smaller than the lower limit, the ultraviolet absorption function of the viewing angle widening sheet 21 cannot be effectively achieved. This is because if the mass ratio exceeds the above upper limit, the base polymer is adversely affected and the strength and durability of the binder 24 are lowered.

  It is also possible to use an ultraviolet stabilizer (including a base polymer in which an ultraviolet stabilizing group is bonded to a molecular chain) instead of the ultraviolet absorbent or together with the ultraviolet absorbent. By this ultraviolet stabilizer, radicals generated by ultraviolet rays, active oxygen and the like are inactivated, and ultraviolet stability, weather resistance and the like can be improved. As this ultraviolet stabilizer, a hindered amine ultraviolet stabilizer having high stability against ultraviolet rays is preferably used. In addition, the combined use of an ultraviolet absorber and an ultraviolet stabilizer significantly improves deterioration prevention and weather resistance due to ultraviolet rays.

  Furthermore, an antistatic agent may be kneaded in the polymer composition. By forming the binder 24 from the polymer composition kneaded with the antistatic agent in this way, the antistatic effect is exerted on the viewing angle widening sheet 21, and it is difficult to suck dust or to overlap with the prism sheet or the like. It is possible to prevent inconveniences caused by electrostatic charging such as. Further, when the surface is coated with an antistatic agent, the surface becomes sticky or contaminated. However, such an adverse effect is reduced by kneading into the polymer composition. Such an antistatic agent is not particularly limited. For example, anionic antistatic agents such as alkyl sulfates and alkyl phosphates, cationic antistatic agents such as quaternary ammonium salts and imidazoline compounds, and polyethylene glycol-based agents. Nonionic antistatic agents such as polyoxyethylene sorbitan monostearic acid ester and ethanolamides, and high molecular antistatic agents such as polyacrylic acid are used. Among these, a cationic antistatic agent having a relatively large antistatic effect is preferable, and an antistatic effect is exhibited by addition of a small amount.

  Next, a method for manufacturing the viewing angle widening sheet 21 will be described. The manufacturing method of the said viewing angle expansion sheet | seat 21 is (a) The process of manufacturing the composition for optical function layers by mixing the light-diffusion agent 23 with the polymer composition which comprises the binder 24, (b) Optical function layer And the step of forming the optical functional layer 22 by laminating the composition for use on the surface of the base film 10 and curing it. The means for laminating the optical functional layer composition on the base film 10 is not particularly limited. For example, a bar coater, blade coater, spin coater, roll coater, gravure coater, flow coater, spray, screen printing. The coating using etc. is employ | adopted.

  The viewing angle enlarging sheet 21 has a high light diffusion function (direction) due to reflection and refraction at the interface of the light diffusing agent 23 contained in the optical function layer 22 and refraction at fine irregularities formed on the surface of the optical function layer 22. Sex diffusion function). Moreover, the said viewing angle expansion sheet 21 has the said viewing angle expansion function by the base film 10 which has a predetermined crystal-axis direction similarly to the said viewing angle expansion sheet 3. FIG. Therefore, the liquid crystal display module including the viewing angle widening sheet 21 promotes both high brightness and wide viewing angle by combining the light diffusion function by the optical functional layer 22 and the viewing angle widening function by the base film 10. can do. Since the light diffusion sheet is usually used in a liquid crystal display module, the liquid crystal display module using the viewing angle widening sheet 21 has the above-described viewing angle widening function without causing an increase in the number of installed optical sheets. As a result, high brightness, low cost, energy saving, and thin and light weight can be promoted.

  The haze value of the viewing angle widening sheet 21 is preferably 10% or more and 44% or less or 80% or more from the viewpoint of wide viewing angle. In addition to this wide viewing angle, 10% or more is considered. 44% or less is preferable, and 25% or more and 35% or less is particularly preferable. By setting the haze value of the viewing angle enlarging sheet 21 in the above range, the viewing angle enlarging function is remarkably increased, and the front luminance is also increased. In addition, the “haze value” in the present specification is a value measured according to JIS-K-7105.

  The liquid crystal display modules 1 and 11 can include the viewing angle widening sheet 31 of FIG. 6 instead of the viewing angle widening sheet 3. The viewing angle expanding sheet 31 is a light diffusing sheet having a light diffusing function for diffusing transmitted light (specifically, a directional diffusing function for condensing in the normal direction side while diffusing). Specifically, the viewing angle widening sheet 31 is laminated on the base film 10, the optical functional layer (light diffusion layer) 22 laminated on the surface of the base film 10, and the back surface of the base film 10. And an anti-sticking layer 32. Since this base film 10 is the same as the viewing angle widening sheet 3 and the optical function layer 22 is the same as the viewing angle widening sheet 21, the same number is given and the description is omitted.

  The anti-sticking layer 32 includes a plurality of beads 33 that are scattered on the back surface of the base film 10 and a binder 34 that fixes the plurality of beads 33. The binder 34 is also formed by crosslinking and curing the same polymer composition as the binder 24 of the optical function layer 22. The material of the beads 33 is the same as that of the light diffusing agent 23 of the optical function layer 22. The thickness of the anti-sticking layer 32 (the thickness of the binder 34 portion where the beads 33 are not present) is not particularly limited, but is, for example, about 1 μm to 10 μm.

  The amount of the beads 33 is relatively small, and the beads 33 are dispersed in the binder 34 so as to be separated from each other. Further, a convex portion is formed on the lower surface of the viewing angle widening sheet 31 at the bead 33 portion. Therefore, when the viewing angle widening sheet 31 is laminated on the light guide plate or the like, the protruding bead 33 portion contacts the surface of the light guide plate or the like, and the entire back surface of the viewing angle widening sheet 31 does not contact the light guide plate or the like. As a result, sticking between the viewing angle widening sheet 31 and the light guide plate or the like is prevented, and uneven brightness on the screen of the liquid crystal display module is suppressed.

  Next, a method for manufacturing the viewing angle widening sheet 31 will be described. The manufacturing method of the said viewing angle expansion sheet 31 is that the optical functional layer 22 is formed by the same method as the said viewing angle expansion sheet 21, and also (c) mixing the bead 33 with the polymer composition which comprises the binder 34. And (d) laminating the anti-sticking layer composition on the back surface of the base film 10 and curing the anti-sticking layer composition. As a means for laminating the anti-sticking layer composition on the base film 10, the same laminating means as the optical functional layer 22 is employed.

  The viewing angle widening sheet 31 is similar to the viewing angle widening sheet 21, without causing an increase in the number of installed optical sheets, and a light diffusion function by the optical functional layer 22 and a viewing angle widening function by the base film 10. In combination, the liquid crystal display module can be increased in brightness and wide viewing angle, and in addition, cost reduction, energy saving, and reduction in thickness and weight can be promoted. Further, the viewing angle widening sheet 31 is prevented from sticking to the light guide plate or the like by the anti-sticking layer 32, so that the luminance unevenness of the screen of the liquid crystal display module is suppressed, and thus contributes to the wide viewing angle of the liquid crystal display module. To do.

  The liquid crystal display modules 1 and 11 can include the viewing angle widening sheet 41 of FIG. 7 instead of the viewing angle widening sheet 3. The viewing angle widening sheet 41 is a so-called microlens sheet having optical functions such as high condensing, refraction in the normal direction side, and diffusion. The viewing angle widening sheet 41 includes a base film 10 and an optical functional layer 42 laminated on the surface of the base film 10. Since the base film 10 of the viewing angle widening sheet 41 is the same as the viewing angle widening sheet 3, the same number is assigned and the description is omitted.

  The optical functional layer 42 includes a sheet-like portion 43 laminated on the surface of the base film 10 and a microlens array 44 formed on the surface of the sheet-like portion 43. Note that the optical functional layer 42 can be configured by only the microlens array 44 without the sheet-like portion 43. That is, the microlens array 44 can be directly formed on the surface of the base film 10.

  The optical functional layer 42 is made of a synthetic resin that is transparent, particularly colorless and transparent, because it is necessary to transmit light. Examples of the synthetic resin used for the optical functional layer 42 include polyethylene terephthalate, polyethylene naphthalate, acrylic resin, polycarbonate, polystyrene, polyolefin, cellulose acetate, weather resistant vinyl chloride, and active energy ray curable resin. Among these, radiation curable resins such as ultraviolet curable resins and electron beam curable resins excellent in moldability of the microlens array 44 and polyethylene terephthalate excellent in transparency and strength are particularly preferable. In addition to the above synthetic resin, for example, a filler, a plasticizer, a stabilizer, a deterioration inhibitor, a dispersant, and the like may be blended in the optical function layer 42.

  The microlens array 44 is composed of a large number of microlenses 45. The microlens 45 has a hemispherical shape (including a shape that approximates a hemisphere) and protrudes from the surface of the base film 10. Note that the microlens 45 is not limited to the hemispherical convex lens, and may be a microlens of a hemispherical concave lens. The microlens of the hemispherical concave lens also has the same excellent optical function as the microlens 45.

  The microlenses 45 are relatively densely and geometrically disposed on the surface of the base film 10. Specifically, the microlenses 45 are arranged in an equilateral triangular lattice pattern on the surface of the base film 10. Therefore, the pitch (P) and the inter-lens distance (S) of the microlenses 45 are all constant. With this arrangement pattern, the microlenses 45 can be arranged most densely. The arrangement pattern of the microlenses 45 is not limited to the regular triangular lattice pattern that can be densely packed, and for example, a square lattice pattern or a random pattern is also possible. According to this random pattern, the occurrence of moire is reduced when the viewing angle widening sheet 41 is overlapped with another optical member.

  The lower limit of the diameter (D) of the microlens 45 is preferably 10 μm, particularly 100 μm, and more particularly 200 μm. On the other hand, the upper limit of the diameter (D) of the microlens 45 is preferably 1000 μm, particularly preferably 700 μm. When the diameter (D) of the microlens 45 is smaller than 10 μm, the influence of diffraction becomes large, optical performance and color separation tend to occur, and quality is deteriorated. On the other hand, if the diameter (D) of the microlens 45 exceeds 1000 μm, the thickness is likely to increase and luminance unevenness is likely to occur, leading to a reduction in quality. In addition, by setting the diameter (D) of the microlens 45 to 100 μm or more, the number of microlenses 45 per unit area is reduced. As a result, it is easy to increase the area of the viewing angle expansion sheet 41 that is a microlens sheet, The technical and cost burden during production is reduced.

  The lower limit of the surface roughness (Ra) of the microlens 45 is preferably 0.01 μm and particularly preferably 0.03 μm. On the other hand, the upper limit of the surface roughness (Ra) of the microlens 45 is preferably 0.1 μm, and particularly preferably 0.07 μm. Thus, by setting the surface roughness (Ra) of the microlens 45 to be equal to or higher than the above lower limit, the moldability of the microlens array 44 of the viewing angle widening sheet 41 is facilitated, and technical and cost in terms of manufacturing. The burden is reduced. On the other hand, by making the surface roughness (Ra) of the microlens 45 less than the above upper limit, light scattering on the surface of the microlens 45 is reduced. As a result, the condensing function by the microlens 45 and the normal direction side are reduced. The refraction function is enhanced, and high brightness in the front direction is achieved due to such a good optical function.

  The lower limit of the height ratio (H / R) of the height (H) of the microlens 45 to the radius of curvature (R) is preferably 5/8, and particularly preferably 3/4. On the other hand, the upper limit of the height ratio (H / R) is preferably 1. In this way, by setting the height ratio (H / R) of the microlens 45 within the above range, the lens-like refraction action of the microlens 45 is effectively achieved, and the light such as the condensing of the viewing angle expansion sheet 41 is optically effective. Function is greatly improved.

  The upper limit of the distance ratio (S / D) to the diameter (D) of the inter-lens distance (S; PD) of the microlens 45 is preferably 1/2, and particularly preferably 1/5. In this way, by setting the inter-lens distance (S) of the microlens 45 to be equal to or less than the above upper limit, the flat portion that does not contribute to the optical function is reduced, and the optical function such as condensing of the viewing angle expanding sheet 41 is remarkably improved. To be improved.

  As a minimum of the filling rate of micro lens 45, 40% is preferred and 60% is especially preferred. In this way, by setting the filling rate of the microlenses 45 to be equal to or higher than the lower limit, the area occupied by the microlenses 45 on the surface of the viewing angle widening sheet 41 is increased, and the optical functions such as light collection of the viewing angle widening sheet 41 are achieved. Greatly improved.

  The numerical ranges of the height ratio (H / R), the spacing ratio (S / D), and the filling rate described above are derived based on luminance analysis simulation by non-sequential ray tracing using the Monte Carlo method. .

  The lower limit of the refractive index of the material constituting the optical function layer 42 is preferably 1.3, and particularly preferably 1.45. On the other hand, the upper limit of the refractive index of this material is preferably 1.8, and particularly preferably 1.6. Among these ranges, the refractive index of the material constituting the optical functional layer 42 is most preferably 1.5. Thus, by making the refractive index of the material constituting the optical functional layer 42 in the above range, the lens-like refraction action in the microlens 45 is effectively achieved, and the viewing angle widening sheet 41 is optically focused and the like. Function is further enhanced.

The manufacturing method of the viewing angle widening sheet 41 is not particularly limited as long as the above structure can be formed, and various methods are employed. As a manufacturing method of the viewing angle expansion sheet 41, specifically,
(A) A method of forming the viewing angle widening sheet 41 by laminating the synthetic resin and the base film 10 in this order on a sheet mold having an inverted shape on the surface of the microlens array 44 and peeling the sheet mold;
(B) A method of transferring the shape by reheating the sheeted resin and pressing between the metal plate and the mold having the inverted shape of the surface of the microlens array 44 together with the base film 10;
(C) An extruded sheet molding method in which a molten resin and the base film 10 are passed through a nip between a roll mold having a reverse shape of the surface of the microlens array 44 on the peripheral surface and another roll, and the shape is transferred.
(D) An ultraviolet curable resin is applied to the substrate film 10, and the shape is transferred to an uncured ultraviolet curable resin by pressing against a sheet mold, a mold or a roll mold having the same inverted shape as described above, and ultraviolet rays To cure the UV curable resin by applying
(E) An uncured ultraviolet curable resin is filled and applied to a mold or roll mold having the same inverted shape as above, pressed by the base film 10 and leveled, and irradiated with ultraviolet rays to cure the ultraviolet curable resin. How to
(F) A method of injecting or discharging uncured (liquid) ultraviolet curable resin or the like from a fine nozzle so as to form the microlens 45 on the base film 10 and curing the resin.
(G) There is a method of using an electron beam curable resin instead of an ultraviolet curable resin.

  In addition, as a manufacturing method of the mold (mold) having the inverted shape of the microlens array 44, for example, a spot-like three-dimensional pattern is formed on a base material using a photoresist material, and the three-dimensional pattern is curved by heating and fluidizing. Thus, a microlens array model can be manufactured, and a metal layer can be laminated on the surface of the microlens array model by an electroforming method, and the metal layer can be peeled off. In addition, as a method for producing the microlens array model, the method described in (f) above can be adopted.

  According to the manufacturing method, the microlens array 44 having an arbitrary shape is easily and reliably formed. Accordingly, the diameter (D), height ratio (H / R), spacing ratio (S / D), filling rate, etc. of the microlens 45 constituting the microlens array 44 are easily and reliably adjusted, and as a result, the field of view The optical function of the corner enlargement sheet 41 is easily and reliably controlled.

  The viewing angle widening sheet 41 has optical functions such as high condensing, refraction in the normal direction side, and diffusion by the microlens array 44, and the optical functions can be easily and reliably controlled. Moreover, the said viewing angle expansion sheet 21 has the said viewing angle expansion function by the base film 10 which has a predetermined crystal-axis direction similarly to the said viewing angle expansion sheet 3. FIG. Therefore, the liquid crystal display module including the viewing angle widening sheet 41 has a high luminance and a wide viewing angle due to the light diffusion function such as diffusion by the optical functional layer 42 and the viewing angle widening function by the base film 10. Can be promoted together. The haze value of the viewing angle widening sheet 41 is preferably 10% or more and 44% or less, particularly 25% or more and 35% or less, similar to the viewing angle widening sheet 21, and widening the viewing angle and increasing the brightness. It can be further promoted.

  Here, the “microlens” means a microlens having a partially spherical interface, and includes, for example, a hemispherical convex lens and a hemispherical concave lens. “Diameter (D)” means the diameter of the base or aperture of the microlens. “Height (H)” is the vertical distance from the base surface of the microlens to the top when the microlens is a convex lens, and the vertical distance from the opening surface of the microlens to the bottom when the microlens is a concave lens. Means distance. “Distance between lenses” means the shortest distance between a pair of adjacent microlenses. “Filling rate” means the area ratio of microlenses per unit area in the surface projection shape. The “regular triangle lattice pattern” means a pattern in which the surface is divided into equilateral triangles having the same shape and a microlens is arranged at each vertex of the equilateral triangle.

  The liquid crystal display module of the present invention is not limited to the above embodiment. For example, the optical function layer of the viewing angle widening sheet is not limited to the light diffusion layer of FIG. 5 or the microlens array of FIG. 7, and for example, a plurality of triangular prisms arranged in stripes, a cylindrical lens unit It can be configured from a minute concavo-convex shape having refraction properties such as. In other words, for example, the base film 10 can be used as a base film such as a prism sheet or a lens sheet, and the prism sheet or the like can be configured to exhibit a viewing angle expansion function. In addition, the viewing angle widening sheet provided in the liquid crystal display module may be laminated with other layers such as an ultraviolet absorber layer and a top coat layer.

  The liquid crystal display module is not limited to the above-described edge light type backlight, and a direct type backlight can also be adopted, and a viewing angle widening function is achieved by a viewing angle widening sheet.

The microlens that constitutes the microlens array may be formed in an elliptical partial shape with the major axis in the normal direction. In this way, according to the microlens having the elliptical partial shape with the major axis directed in the normal direction, the spherical aberration and hence the loss of light is reduced, and the condensing function to the front side with respect to the transmitted light, the diffusion function, Optical functions such as a function of changing the angle toward the normal direction are enhanced. The flatness ratio (R _L / R _S ) of the major axis radius (R _L ) to the minor axis radius (R _S ) of this elliptical surface is 1.05 or more in order to effectively reduce the spherical aberration of the microlens. 1.7 or less is preferable.

  The microlens constituting the microlens array may be formed in an elliptical partial shape whose major axis is positioned substantially parallel to a predetermined plane direction. Thus, according to the microlens having an elliptical partial shape whose major axis is positioned substantially parallel to the predetermined plane direction, the optical function has anisotropy, specifically, the major axis of the microlens The optical function in the direction perpendicular to the major axis is greater than the optical function in the direction parallel to the axis.

  Regarding the ultraviolet absorber and the antistatic agent, it is possible to replace the means contained in the binder 24 of the optical functional layer 22 described above, or to laminate an ultraviolet absorber layer or an antistatic agent layer together with the means. It is also possible to contain an ultraviolet absorber or an antistatic agent in the binder 34 or the base film 10 of the prevention layer 32. Also by these means, the ultraviolet ray absorbing function or the antistatic function is exhibited in the viewing angle widening sheet.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, this invention is not interpreted limitedly based on description of this Example.

<Viewing angle characteristic evaluation experiment by crystal axis angle when angle of transmission axis direction of back side polarizing plate is-(1/4) π>
The polyethylene terephthalate is removed from the original biaxially stretched material at different positions, and the angle of the crystal axis direction (fast axis direction) with respect to the short side direction is changed from-(1/2) π to + (1/2) π (1 / 16) Making a square base film changed by π, applying a polymer composition containing transparent resin beads on the surface of these base films, and curing them, a field of view having a haze value of 30% A corner enlargement sheet was created.

  A liquid crystal display element having a TN liquid crystal cell sandwiched between a pair of polarizing plates, a prism sheet overlaid on the back surface of the liquid crystal display element, and a light diffusion sheet overlaid on the back surface of the prism sheet; And an edge-light type backlight similar to that shown in FIG. 1 superimposed on the back surface of the light diffusion sheet, and the angle of the back-side polarizing plate of the liquid crystal display element with respect to the short side direction is − (1 / 4) Using a square liquid crystal display module of π, the respective viewing angle widening sheets were laminated between the liquid crystal display element and the prism sheet, and the luminance uniformity ratio at a predetermined viewing angle was measured. The results are shown in Table 1 below and FIG.

The luminance uniformity ratio of the predetermined viewing angle is the B. of TCO'03FPD. 2.3.4 “Luminance uniformity-angular dependency”. Specifically, the luminance uniformity ratio of the predetermined viewing angle this time is a luminance meter placed on the normal passing through the center point of the screen, and the short side direction axis (vertical axis) passing through the center point of the screen is the center the luminance meter was ± 30 ° rotation as, P _L point of the screen from the position (point from the left end of the screen in terms of the long-side direction through the center point of the screen (horizontal) 1/10 center of the long side length) and P _R points brightness (point from the right edge of the screen in terms of the long-side direction through the center point of the screen of the tenth central long side distance) was measured, the ratio of minimum luminance L _min of the maximum luminance L _max (L _max / L _min ).

  As shown in Table 1 and FIG. 8, in the liquid crystal display module having an angle of − (1/4) π with respect to the short side direction of the transmission axis direction of the back side polarizing plate, the crystal axis of the base film of the viewing angle expansion sheet When the angle of the direction with respect to the short side direction is 0 or more and (1/4) π or less, or − (1/2) π or more and − (1/4) π or less, the luminance uniformity ratio of the predetermined viewing angle is 1.5. The wide viewing angle is achieved as follows. In particular, the angle with respect to the short side direction of the crystal axis direction of the base film of the viewing angle expansion sheet is (1/16) π or more (3/16) π or less or − (7/16) π or more − (5/16) In the case of π or less, the luminance uniformity ratio of the predetermined viewing angle becomes 1.4 or less, and the wide viewing angle is further promoted. Further, in the case where the angle with respect to the short side direction in the fast axis direction is 0 or more (1/4) π or less in the crystal axis direction of the base film, − (1/2) π or more − (1/4). ) A wider viewing angle is slightly enhanced than the case of π or less. Therefore, the validity of the range of the angle with respect to the short side direction of the crystal axis direction of the base film of the viewing angle expansion sheet specified by the present invention as described above has been demonstrated.

<Viewing angle characteristic evaluation experiment by crystal axis angle when angle of transmission axis direction of back side polarizing plate is + (1/4) π>
A liquid crystal display element having a configuration similar to that of the liquid crystal display module, using a rectangular liquid crystal display module having an angle of + (1/4) π with respect to the short side direction of the transmission axis direction of the back side polarizing plate of the liquid crystal display element. The respective viewing angle widening sheets were laminated between the prism sheet and the luminance uniformity ratio at a predetermined viewing angle. The results are shown in Table 2 below and FIG.

  As shown in Table 2 and FIG. 9, in the liquid crystal display module having an angle of + (1/4) π with respect to the short side direction of the transmission axis direction of the back side polarizing plate, the crystal axis of the base film of the viewing angle widening sheet When the angle of the direction with respect to the short side direction is − (¼) π or more and 0 or less or (1/4) π or more and (1/2) π or less, the luminance uniformity ratio of the predetermined viewing angle is 1.5 or less. Thus, a wide viewing angle has been achieved. In particular, the angle of the viewing angle expansion sheet with respect to the short side direction in the crystal axis direction of the base film is − (3/16) π or more, − (1/16) π or less, or (5/16) π or more (7/16). In the case of π or less, the luminance uniformity ratio of the predetermined viewing angle becomes 1.4 or less, and the wide viewing angle is further promoted. Moreover, the direction when the angle with respect to the short side direction of the fast axis direction in the crystal axis direction of the base film is − (1/4) π or more and 0 or less is (1/4) π or more (1/2). The wide viewing angle is slightly higher than in the case of π or less. Therefore, the validity of the range of the angle with respect to the short side direction of the crystal axis direction of the base film of the viewing angle expansion sheet specified by the present invention as described above has been demonstrated.

<Experimental experiment of relationship between haze value of viewing angle expansion sheet and luminance uniformity ratio of predetermined viewing angle>
A plurality of rectangular base films having a crystal axis direction (fast axis direction) angle of (1/8) π with respect to the short side direction from a biaxially stretched polyethylene terephthalate are prepared, and the surfaces of these base film A polymer composition containing transparent resin beads was applied at different bead contents, and cured to prepare a viewing angle expansion sheet having a haze value of 10% to 95%.

  Using the liquid crystal display module (the angle with respect to the short side direction of the transmission axis direction of the back-side polarizing plate of the liquid crystal display element is − (1/4) π), the haze value is different between the liquid crystal display element and the prism sheet. The respective viewing angle expansion sheets were laminated, and the luminance uniformity ratio and front luminance at a predetermined viewing angle were measured. The results are shown in Table 3 below. FIG. 10 shows the relationship between the haze value and the luminance uniformity ratio of the predetermined viewing angle, and FIG. 11 shows the relationship between the haze value and the front luminance.

As shown in Table 3, FIG. 10 and FIG. 11, when the haze value of the viewing angle expansion sheet is 10% or more and 44% or less, the luminance uniformity ratio of the predetermined viewing angle is 1.5 or less and the front luminance is 460 [ cd / m ² ] or more, and wide viewing angle and high brightness are promoted. In particular, when the haze value of the viewing angle widening sheet is 25% or more and 35% or less, the luminance uniformity ratio at a predetermined viewing angle is 1.4 or less and the front luminance is 470 [cd / m ² ] or more, thereby widening the viewing angle. In addition, higher brightness is further promoted. Further, when the haze value of the viewing angle expansion sheet is 80% or more, the luminance uniformity ratio of the predetermined viewing angle is 1.5 or less, and a wide viewing angle can be achieved, but the haze value is 10% or more and 44. The front luminance is reduced as compared with the case of less than%. Therefore, the validity of the range of the haze value of the viewing angle expansion sheet specified by the present invention as described above has been demonstrated.

  As described above, the liquid crystal display module of the present invention is useful as an information display device such as a mobile phone, a personal digital assistant (PDA), a personal computer, and a television, and is used particularly for an information display device having a relatively large screen. Suitable for

1 is a schematic perspective view showing a liquid crystal display module according to an embodiment of the present invention. (A) And (b) is the model explaining the relationship of the transmission axis direction (when angle is-(1/4) (pi)) of the back surface side polarizing plate in the liquid crystal display module of FIG. 1, and the crystal axis direction of a base film. Plan view (A) And (b) is a model explaining the relationship between the transmission axis direction (when the angle is + (1/4) π) of the back side polarizing plate and the crystal axis direction of the base film in the liquid crystal display module of FIG. Plan view The typical perspective view which shows the liquid crystal display module which concerns on the form different from the liquid crystal display module of FIG. Typical sectional drawing which shows the viewing angle expansion sheet (light-diffusion sheet) which concerns on a different form from the viewing angle expansion sheet with which the liquid crystal display module of FIG. 1 is equipped. Typical sectional drawing which shows the viewing angle expansion sheet (light-diffusion sheet) which concerns on a different form from the viewing angle expansion sheet with which the liquid crystal display module of FIG. 1 is equipped. 1 is a schematic cross-sectional view showing a viewing angle widening sheet (microlens sheet) according to a different form from the viewing angle widening sheet provided in the liquid crystal display module of FIG. The graph which shows the relationship between the crystal-axis angle of the base film in case the angle of the transmission-axis direction of a back surface side polarizing plate is-(1/4) (pi), and the luminance uniformity ratio of a predetermined viewing angle. The graph which shows the relationship between the crystal-axis angle of a base film in case the angle of the transmission-axis direction of a back surface side polarizing plate is + (1/4) (pi), and the luminance uniformity ratio of a predetermined viewing angle. A graph showing the relationship between the haze value of a viewing angle expansion sheet and the luminance uniformity ratio of a predetermined viewing angle A graph showing the relationship between the haze value of the viewing angle expansion sheet and the front luminance Schematic sectional view showing a general liquid crystal display module

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display module 2 Liquid crystal display element 3 Viewing angle expansion sheet 4 Backlight 5 Front surface side polarizing plate 6 Back surface side polarizing plate 7 Liquid crystal cell 8 Light guide plate 9 Lamp 10 Base film 11 Liquid crystal display module 12 Prism sheet 13 Base material layer 14 Prism section 21 Viewing angle expansion sheet 22 Optical function layer 23 Light diffusing agent 24 Binder 31 Viewing angle expansion sheet 32 Sticking prevention layer 33 Bead 34 Binder 41 Viewing angle expansion sheet 42 Optical function layer 43 Sheet-shaped section 44 Microlens array 45 Microlens m Transmission axis direction of the back side polarizing plate α Angle of the crystal axis direction of the base film β Angle of the transmission axis direction of the back side polarizing plate x Fast axis direction of the base film y Slow axis direction of the base film

Claims (9)

A liquid crystal display element having a liquid crystal cell sandwiched between a pair of polarizing plates;
A backlight of a surface light source superimposed on the back side of the liquid crystal display element,
A square liquid crystal display module in which an angle of the transmission axis direction of the back side polarizing plate of the liquid crystal display element with respect to the short side direction of the back side polarizing plate is ± (1/4) π,
It has a viewing angle widening sheet stacked between the liquid crystal display element and the backlight,
This viewing angle expansion sheet is a resin base film having optical anisotropy , and
A light diffusion layer laminated on one surface of the base film ,
The light diffusing layer has a plurality of light diffusing agents and its binder, and is formed by coating a composition in which the light diffusing agent is mixed with a polymer composition constituting the binder,
The angle with respect to the short side direction of the back-side polarizing plate in the crystal axis direction of the base film is within a range of ± (1/16) π around the numerical value ε represented by (I) or (II) below. A featured liquid crystal display module.
(I) When the transmission axis direction angle is − (1/4) π, ε = (1/8) π∨− (3/8) π
(II) When the transmission axis direction angle is + (1/4) π, ε = − (1/8) π∨ (3/8) π The angle with respect to the short side direction of the back-side polarizing plate in the fast axis direction among the crystal axis directions of the base film is ± (1/16) π around the numerical value ε shown in the following (III) or (IV) The liquid crystal display module according to claim 1, which is within a range.
(III) When the transmission axis direction angle is-(1/4) π, ε = (1/8) π
(IV) When the transmission axis direction angle is + (1/4) π, ε = − (1/8) π   The liquid crystal display module according to claim 1, wherein the viewing angle widening sheet is superposed directly below the back surface of the liquid crystal display element.   The liquid crystal display module according to claim 1, wherein the viewing angle expansion sheet has a haze value of 10% to 44% or 80% or more. The liquid crystal display according to any one of claims 1 to 4, wherein the viewing angle widening sheet has a sticking prevention layer laminated on the other surface of the base film and in which beads are dispersed in a binder. module. An edge light type backlight is used as the backlight,
The liquid crystal display module according to claim 1 , wherein the lamp of the edge light type backlight is disposed in parallel with the long side direction. Other optical sheets are provided between the liquid crystal display element and the backlight,
The liquid crystal display module according to any one of claims 1 to 6, wherein a low retardation film is used as a base film of the other optical sheet. The other optical sheet is a prism sheet,
The liquid crystal display module according to claim 7 , wherein the ridge line direction of the prism sheet is orthogonal to the short side direction of the back-side polarizing plate . Particle diameter of the light diffusing agent is 5μm or more 50μm or less, wherein the preceding claims amount of solid equivalent to the substrate polymer 100 parts of the polymer composition being the material for forming the binder is less than 500 parts or more and 10 parts Item 9. The liquid crystal display module according to any one of items 8 to 9 .

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