WO2007129609A1

WO2007129609A1 - Liquid crystal display element having prism sheet, and liquid crystal display device using the liquid crystal display element

Info

Publication number: WO2007129609A1
Application number: PCT/JP2007/059180
Authority: WO
Inventors: Tomoyoshi Yamashita; Yuji Nishinaka
Original assignee: Mitsubishi Rayon Co., Ltd.
Priority date: 2006-05-02
Filing date: 2007-04-27
Publication date: 2007-11-15
Also published as: JPWO2007129609A1; TW200745682A

Abstract

A light outputting surface (42) of a prism sheet (4) is bonded on a light inputting side of a liquid crystal display element (8) by a bonding material (86). A light inputting surface (41) of the prism sheet (4) is used as a prism row forming surface. The prism row forming surface (41) is formed by arranging a plurality of prism rows to extend substantially parallel to each other. The prism row forming surface (41) has a roughened section which extends along the prism rows between the adjacent prism rows. The surface of the roughened section is rougher than the prism surface of the prism row. Light emitted from a primary light source (1) is introduced into a light guiding body (3) through a light inputting end surface (31). Light guided in the light guiding body (3) is outputted from a light outputting surface (33) and is permitted to enter the light inputting surface (41) of the prism sheet (4).

Description

Specification

Liquid crystal display element with prism sheet and liquid crystal display device using the same

[0001] The present invention relates to a liquid crystal display element used in combination with a backlight (surface light source device). Furthermore, this invention relates to the liquid crystal display device which combines a liquid crystal display element and a backlight.

Background art

A liquid crystal display device is basically composed of a backlight and a liquid crystal display element. As the backlight, an edge light type is often used from the viewpoint of making the liquid crystal display device compact. Conventionally, as an edge light type backlight, at least one end surface of a rectangular plate-shaped light guide is used as a light incident end surface, and a linear shape such as a straight tube fluorescent lamp is formed along the light incident end surface. Alternatively, a rod-shaped primary light source is disposed, and light emitted from the primary light source is introduced into the light guide from the light incident end surface of the light guide, and is one of the two main surfaces of the light guide. What is emitted from the light exit surface is widely used.

[0003] In such a backlight, light emitted in an oblique direction from the light exit surface of the light guide is guided by light from the light guide in a plane orthogonal to both the light incident end surface and the light exit surface of the light guide. An optical deflecting element is used to deflect toward the exit surface normal. The light deflection element is typically a prism sheet. In this prism sheet, one surface is a flat surface and the other surface is a prism row forming surface. The prism array forming surface is formed by arranging a large number of prism arrays in parallel with each other at a predetermined pitch.

[0004] In order to meet the recent demand for high-definition image display, the characteristics required for a surface light source device for a liquid crystal display device include a high light intensity and a light guide for exhibiting a required optical function. The surface structure such as the mat structure and the lens array arrangement structure formed mainly on the light emitting surface of the body or on the back surface on the opposite side may be difficult to see.

[0005] In order to increase the brightness, the prism row forming surface of the prism sheet of the surface light source device is disposed so as to face the light guide (that is, the prism row forming surface is disposed on the light guide light emitting surface). The light incident surface on which light from the light enters. However, as a prism sheet, opposite to the light entrance surface When a general light emitting surface on the side is a smooth plane, the surface structural force S of the light guide may be visually recognized. Therefore, as described in Japanese Patent Laid-Open No. 6-324205 (Patent Document 1) and Japanese Patent Laid-Open No. 7-151909 (Patent Document 2), the prism sheet has a surface opposite to the prism array forming surface. It is conceivable to apply a technique for providing a fine uneven shape to make it difficult to visually recognize the surface structure of the light guide while maintaining high luminance.

Patent Document 1: JP-A-6-324205

Patent Document 2: JP-A-7-151909

Disclosure of the invention

Problems to be solved by the invention

[0006] Further, in the surface light source device, there is a problem that uneven luminance due to the prism sheet is easily recognized as a high-intensity light source is used as a primary light source. In other words, if there is a defect due to a defect in the die for manufacturing the prism sheet, brightness unevenness may be visually recognized due to a defective form of the prism sheet based on the defect. In addition, an adhesive protective sheet is affixed to protect the prism array forming surface after the prism sheet is manufactured. After the adhesive protective sheet is peeled off when manufacturing the surface light source device, the adhesive of the protective sheet adheres to the top of the prism array. When it remains, brightness unevenness may be visually recognized due to this adhesive residue adhesive.

[0007] It is desirable to conceal the optical defects such as the luminance unevenness caused by the prism sheet without using the light diffusion sheet, if the surface structure of the light guide is as described above.

[0008] In view of the above technical problems, the present invention provides a liquid crystal display device capable of concealing optical defects while suppressing a decrease in luminance with almost no increase in cost, and a liquid crystal display element used therefor The purpose is to provide.

Means for solving the problem

[0009] According to the present invention, as a solution to the above problems,

A liquid crystal display element used in combination with a surface light source device,

A first surface of a prism sheet is bonded to a side of the liquid crystal display element on which light emitted from the surface light source device is incident, and a second surface opposite to the first surface of the prism sheet is a prism array. The prism array forming surface has a plurality of prism arrays substantially parallel to each other. It is formed by arranging so as to extend to

The prism row forming surface has a roughened portion extending along the prism row between the prism rows adjacent to each other, and a surface of the roughened portion is formed by a prism surface of the prism row. There is provided a liquid crystal display element with a prism sheet, characterized in that the degree of roughening is large.

[0010] In one aspect of the present invention, the roughening section has an arrangement pitch of 0.

It has a width of 04 times to 0.5 times.

In one aspect of the present invention as described above, the first surface of the prism sheet is bonded to the liquid crystal display element on the side on which light generated by the surface light source device is incident by a bonding material. In one embodiment of the present invention, the bonding material is an adhesive or a self-adsorbing resin. In one aspect of the present invention, the prism rows are arranged concentrically.

[0012] Furthermore, according to the present invention, as a solution to the above problems,

Comprising: a primary light source; a light guide that is guided and guided by light emitted from the primary light source; and the liquid crystal display element with the prism sheet,

The light guide includes a light incident end surface on which light emitted from the primary light source enters and a light exit surface from which the guided light exits, and the primary light source includes a light incident end surface of the light guide. The liquid crystal display element with a prism sheet is disposed such that the prism row forming surface of the prism sheet faces the light emitting surface of the light guide. A liquid crystal display device,

Is provided.

The invention's effect

[0013] According to the liquid crystal display element with a prism sheet and the liquid crystal display device of the present invention as described above, the prism row forming surface of the prism sheet is a rough surface extending along the prism row between adjacent prism rows. Since the liquid crystal display device is configured by using the liquid crystal display element to which the prism sheet is bonded, based on the light diffusion in the roughened surface portion, it is based on the defects of the prism sheet manufacturing mold. Luminance unevenness caused by defective form of prism sheet, prism array after peeling of the adhesive protective sheet based on the adhesion of the adhesive protective sheet The effect of improving the luminance unevenness caused by the residual adhesion of the protective sheet pressure sensitive adhesive, that is, the effect of concealing optical defects, is obtained, and the decrease in luminance is small.

Brief Description of Drawings

1] A schematic partially cutaway perspective view showing one embodiment of a liquid crystal display device using a liquid crystal display element with a prism sheet according to the present invention.

2] A schematic partial cross-sectional view of the liquid crystal display device of FIG.

3] A schematic partial enlarged sectional view of the prism sheet of the liquid crystal display device of FIG.

4] It is a diagram schematically showing the state of light deflection by the prism sheet.

FIG. 5] A schematic cross-sectional view for explaining the production of a mold member for manufacturing a prism sheet.

6] It is a schematic diagram for explaining shaping of the synthetic resin sheet in the manufacture of the prism sheet.

FIG. 7 is a schematic perspective view showing a roll mold used in the manufacture of a prism sheet. FIG. 8 is a schematic exploded perspective view showing a roll mold used in the manufacture of a prism sheet.

FIG. 9 is a diagram showing the luminance distribution of the surface light source.

FIG. 10 is a diagram showing the luminance distribution of the surface light source.

11] A schematic partial enlarged cross-sectional view of one embodiment of a prism sheet constituting a liquid crystal display element with a prism sheet according to the present invention.

12] FIG. 12 is a schematic partial enlarged bottom view of the prism sheet of FIG.

[13] FIG. 13 is a schematic diagram showing a cross-sectional shape of a valley portion of the prism sheet of FIG.

14] A schematic partially cutaway perspective view showing one embodiment of a liquid crystal display device using a liquid crystal display element with a prism sheet according to the present invention.

15] It is a schematic diagram of a mold member manufacturing apparatus used in Examples.

16] This is a magnified photograph of the cross section of the transfer surface portion of the prism row and valley portion of the mold member blank obtained in the example.

FIG. 17 is a cross-sectional enlarged view of the transfer surface portion of the prism row and the valley portion of the mold member obtained in the example. Is true.

Explanation of symbols

1 Primary light source

2 Hikarihara reflector

3 Light guide

31 Light incident end face

32 Side end face

33 Light exit surface

34 Back side

4 Prism sheet

41 Incident surface

411 prism row

411a, 411b Prism surface

412 Roughening part

2 Light emitting surface

3 Transparent substrate

4 Prism section

5 Light reflecting element

8 Liquid crystal display elements

81, 82 Translucent substrate

3 LCD

4 pixel electrode

5 Transparent electrode

6 Bonding material

1 'type material

11a ', 411b' first region 11a ", 411b" first region 12 'second region 412 "second area

BP blast particles

7 type material (roll type)

9 Transparent substrate

10 Active energy ray-curable composition

11 Pressure mechanism

12 Resin tank

13 nozzles

14 Active energy ray irradiation equipment

15 Thin plate member

16 Cylindrical roll

18 Shape transfer surface

28 Niplo

412A Tanibe

413 Prism row edge

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic partially cutaway perspective view showing one embodiment of a liquid crystal display device using a liquid crystal display element with a prism sheet according to the present invention, and FIG. 2 is a schematic partial sectional view thereof. The liquid crystal display device of this embodiment includes an edge light type surface light source device and a liquid crystal display element with a prism sheet.

As shown in the drawing, the edge light type surface light source device includes at least one side end face as a light incident end face 31 and one light guide face 3 having a light exit face 33 as one surface substantially orthogonal thereto. The linear primary light source 1 disposed opposite to the light incident end surface 31 of the light guide 3 and covered with the light source reflector 2 and the back surface 34 of the light guide 3 opposite to the light exit surface 33 The light reflecting element 5 is disposed to face each other.

The light guide 3 is disposed in parallel with the XY plane and has a rectangular plate shape as a whole. The light guide 3 has four side end faces, of which a small number of the pair of side end faces parallel to the YZ plane. At least one side end face is a light incident end face 31. The light incident end face 31 is arranged to face the primary light source 1, and light emitted from the primary light source 1 enters the light incident end face 31 and is introduced into the light guide 3. In the present invention, for example, the light source may be disposed opposite to another side end face such as the side end face 32 opposite to the light incident end face 31.

[0020] The two main surfaces that are substantially orthogonal to the light incident end surface 31 of the light guide 3 are respectively positioned substantially parallel to the XY plane, and one of the surfaces (the upper surface in the figure) is the light emitting surface 33. Become. By providing the light emitting surface 33 with a directional light emitting mechanism including a rough surface, the light incident from the light incident surface 31 is guided through the light guide 3 while the light incident from the light incident surface 31 is guided through the light incident surface 31. In addition, light having directivity is emitted in a plane (XZ plane) orthogonal to the light exit surface 33. The peak direction (peak light) of the emitted light intensity distribution in this XZ in-plane distribution is the angle formed by the light emitting surface 33. The angle is, for example, 10 to 40 degrees, and the full width at half maximum of the emitted light luminous intensity distribution is, for example, 10 to 40 degrees.

[0021] The rough surface or lens array formed on the surface of the light guide 3 should have an average inclination angle Θ a in the range of 0.5 to 15 degrees according to IS04287 / 1-1984. It is preferable from the viewpoint of improving the uniformity of the luminance in the interior. The average inclination angle Θa is more preferably in the range of 1 to 12 degrees, and more preferably in the range of 1.5 to 11 degrees. The average inclination angle Θa is preferably set to an optimum range by the ratio (L / d) of the thickness (d) of the light guide 3 and the length (L) in the direction in which the incident light propagates. . That is, when using a light guide 3 having an L / d of about 20 to 200, it is preferable to set the average inclination angle Θ a to 0.5 to 7.5 degrees, and more preferably: Is in the range of -5 degrees, more preferably in the range of 1.5-4 degrees. In addition, when a light guide 3 having L / d of about 20 or less is used, it is preferable to set the average inclination angle Θ a to 7 to 12 degrees S, more preferably 8 to 11 degrees. Range.

[0022] The average inclination angle Θ a of the rough surface formed on the light guide 3 is measured according to IS04287Z1-1984 using a stylus type surface roughness meter, and the coordinate in the measurement direction is X From the obtained gradient function f (X), the following equations (1) and (2)

A a = (l / L) ί ^L

o I (d / dx) f (x) I dx (1)

Θ a = tan ^_1 (A a). (2)

Can be obtained using Where L is the measurement length and Δa is the positive value of the average tilt angle Θa It is close.

[0023] Further, the light guide 3 preferably has a light emission rate in the range of 0.5 to 5%, more preferably in the range of 1 to 3%. By setting the light emission rate to 0.5% or more, the amount of light emitted from the light guide 3 is increased and sufficient luminance tends to be obtained. In addition, by setting the light emission rate to 5% or less, emission of a large amount of light in the vicinity of the primary light source 1 is prevented, and attenuation of the emitted light in the X direction within the light emission surface 33 is reduced. The luminance uniformity on surface 33 tends to improve. Thus, by setting the light emission rate of the light guide 3 to 0.5 to 5%, the angle of the peak light in the emission light intensity distribution (in the XZ plane) of the light emitted from the light emission surface becomes the light emission. The full width at half maximum of the emitted light intensity distribution (in the XZ plane) in the XZ plane that is in the range of 50 to 80 degrees with respect to the normal of the surface and is perpendicular to both the light incident end face and the light emitting face is 10 to 40 degrees. Light with such highly directional emission characteristics can be emitted from the light guide 3, and the emission direction can be efficiently deflected by the prism sheet 4 bonded to the liquid crystal display element 8. A surface light source having high power and brightness can be provided.

In the present invention, the light emission rate from the light guide 3 is defined as follows. From the light intensity (I) of the emitted light at the edge on the light incident end surface 31 side of the light emitting surface 33 and the edge on the light incident end surface 31 side

0

The relationship with the emitted light intensity (I) at the distance L is given by the following equation (3), where d is the thickness of the light guide 3 (dimension in the Z direction):

1 = 1/100) [l— / 100)] ^{L / d} … (3)

0

Satisfying such a relationship. Here, the constant α is the light output rate, and the light guide 3 per unit length (length corresponding to the light guide thickness d) in the X direction orthogonal to the light incident end surface 31 on the light output surface 33 It is a ratio (percentage:%) at which light is emitted from the light source. This light emission rate _α is obtained from the gradient by plotting the relationship between the logarithm of the light intensity of the light emitted from the light exit surface 23 on the vertical axis and (L / d) on the horizontal axis. be able to.

In the present invention, instead of forming the light emitting mechanism on the light emitting surface 33 as described above, or in combination with this, the light diffusing fine particles are mixed and dispersed inside the light guide. A neutral light emitting mechanism may be provided.

[0026] In addition, the back surface 34, which is the main surface to which no directional light emitting mechanism is provided, controls the directivity on a surface (YZ surface) parallel to the primary light source 1 of the light emitted from the light guide 3. For the light incident end A prism array forming surface is formed by arranging a number of prism arrays 1J extending in a direction crossing the surface 31, more specifically in a direction substantially perpendicular to the light incident end surface 31 (X direction). The prism row on the rear surface 34 of the light guide 3 can have an arrangement pitch in the range of 10 to 100 μm, preferably 30 to 60 111, for example. Further, the prism array on the back surface 34 of the light guide 3 can have an apex angle in the range of 85 to 110 degrees, for example. This is because by setting the apex angle within this range, the light emitted from the light guide 3 can be condensed appropriately, and the luminance as a surface light source device can be improved. The angle is more preferably in the range of 90 to 100 degrees.

The light guide 3 is not limited to the shape shown in FIG. 1, but can have various shapes such as a light incident end face having a thick shape and a wedge shape.

[0028] The light guide 3 can be made of a synthetic resin having a high light transmittance. Examples of such synthetic resin include methacrylic resin, acrylic resin, polycarbonate resin, polyester resin, and chlorinated resin. In particular, methacrylic resins are optimal because of their high light transmittance, heat resistance, mechanical properties, and moldability. Such a methacrylic resin is a resin mainly composed of methyl methacrylate, and preferably has a methyl methacrylate content of 80% by weight or more. When forming a surface structure such as a rough surface of the light guide 3 and a surface structure such as a prism array or a lenticular lens array, the transparent synthetic resin plate is hot-pressed using a mold member having a desired surface structure. Or may be formed simultaneously with molding by screen printing, extrusion molding, injection molding, or the like. The structural surface can also be formed using heat or a photo-curable resin. Furthermore, an active energy line curable resin is applied on the surface of a transparent substrate such as a polyester film, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polymethacrylimide resin, or a transparent substrate. A rough surface structure or a lens array arrangement structure may be formed, and such a sheet may be bonded and integrated on a separate transparent substrate by a method such as adhesion or fusion. As the active energy ray-curable resin, it is possible to use polyfunctional (meth) acrylic compounds, vinyl compounds, (meth) acrylic acid esters, aryl compounds, (meth) acrylic acid metal salts, and the like.

[0029] The primary light source 1 is a linear light source extending in the Y direction. A light lamp or a cold cathode tube can be used. In this case, as shown in FIG. 1, the primary light source 1 may be further installed on the opposite side end surface as needed, not only when it is installed facing one side end surface of the light guide 3. You can also.

The light source reflector 2 guides the light from the primary light source 1 to the light guide 3 with little loss. For example, a plastic film having a metal-deposited reflective layer on the surface can be used as the material. As shown in the drawing, the light source reflector 2 is rubbed from the outer surface of the edge of the light reflecting element 5 to the edge of the light emitting surface of the light guide 3 through the outer surface of the primary light source 1. A reflection member similar to the light source reflector 2 can be attached to the side end face other than the light incident end face 31 of the light guide 3.

[0031] As the light reflecting element 5, for example, a plastic sheet having a metal-deposited reflecting layer on the surface can be used. In the present invention, it is also possible to use a light reflecting layer or the like formed on the back surface 34 of the light guide 3 by metal vapor deposition or the like instead of the reflecting sheet as the light reflecting element 5.

On the other hand, as the liquid crystal display element 8, a well-known transmissive liquid crystal display element can be used without particular limitation. As this transmissive liquid crystal display element, for example, a liquid crystal 83 is interposed between two translucent substrates 81, 82 made of a glass sheet or a synthetic resin sheet arranged in parallel with each other, and formed on the lower surface of the substrate 82. An example of performing image display by applying a voltage according to an image signal between the transparent electrode 85 and a required one of the pixel electrodes 84 formed on the upper surface of the substrate 81 is exemplified. Furthermore, it may include a color filter for color display, a pair of polarizing plates as a polarizer and an analyzer, and other known appropriate functional members.

The liquid crystal display element 8 is disposed above the light emitting surface 33 of the light guide 3. In this embodiment, the light exit surface (first surface) of the prism sheet 4 as a light deflecting element on the side (lower side in the figure) on which light emitted from the surface light source device of the liquid crystal display element 8 is incident 42 Are joined. This joining is performed by a joining material 86. The bonding material 86 is not particularly limited as long as it has translucency. For example, an adhesive or a self-adsorbing resin is preferable. Adhesives include UV curable adhesives and those commonly known as pressure sensitive adhesives, and it has excellent heat resistance, electrical insulation, and chemical resistance. Use corn adhesive (main component is polydimethylsiloxane), transparent acrylic adhesive with excellent weather resistance (for example, main component is polybutyl acrylate, polyoctyl acrylate), resin with thermoplasticity at relatively low temperature Hot melt type adhesives (for example, those based on ethylene / vinyl acetate copolymer) are effective. Self-adsorbing resin

It is a detachable bonding material and is a soft resin that has the property of sticking to a smooth surface. Examples of the self-adsorbing resin include a soft silicon resin (rubber) using a material having a low glass transition temperature, a soft acrylic crosslinkable resin, and a soft polyethylene resin. When a self-adsorbing resin is used as the bonding material, it can be detached and repaired easily during assembly. The light incident surface (second surface) 41 opposite to the light exit surface 42 of the prism sheet 4 is a prism row forming surface formed by arranging a plurality of prism rows so as to extend substantially parallel to each other. ing. Thereby, the liquid crystal display element 8 with the prism sheet 4 is formed.

In addition, the prism sheet 4 constitutes a surface light source that emits light along the direction of the normal direction of the light guide surface of the light guide, together with the primary light source 1 and the light guide 3, in terms of optical function. However, in the present invention, the prism sheet 4 is joined and integrated with the liquid crystal display element 8 to form a liquid crystal display element with a prism sheet. Therefore, in this specification, for the sake of convenience, the members constituting the surface light source as described above are used. A surface light source device is referred to as a surface light source device excluding the prism sheet.

Hereinafter, the prism sheet 4 will be described in detail.

The prism sheet 4 is disposed above the light emitting surface 33 of the light guide 3. The two principal surfaces 41 and 42 of the prism sheet 4 are arranged in parallel with each other as a whole, and are located parallel to the XY plane as a whole. One of the main surfaces 41, 42 (the main surface located on the light emitting surface 33 side of the light guide 3) is a light incident surface 41, and the other is a light emitting surface 42. The light exit surface 42 is a flat surface parallel to the light exit surface 33 of the light guide 3. The light incident surface 41 is a prism row forming surface in which a large number of prisms IJ411 extending in the Y direction are arranged in parallel to each other.

FIG. 3 shows a schematic partial enlarged cross-sectional view of the prism sheet 4. The prism sheet 4 can be composed of a transparent base material 43 and a prism portion 44. In this case, the upper surface of the transparent substrate 43 forms the light exit surface 42, and the lower surface of the prism portion 44 forms the light incident surface 41. [0038] The transparent substrate 43 is preferably made of a material that transmits active energy rays such as ultraviolet rays and electron beams. As such, a flexible glass plate or the like can be used. A transparent resin sheet or film such as a resin, an acrylic resin, a polycarbonate resin, a salt vinyl resin, or a polymetalinoleimide resin is preferable. In particular, polymethylmetatalylate having a refractive index lower than the refractive index of the prism portion 44 and low surface reflectance, a mixture of polymethyl acrylate and polyvinylidene fluoride resin, polycarbonate resin, polyethylene terephthalate, etc. What consists of a polyester-type resin is preferable. The thickness of the transparent substrate 43 is, for example, about 50 μm to 500 μm. The transparent base material 43 has its surface subjected to an adhesion improvement treatment such as an anchor coat treatment in order to improve the adhesion between the prism portion 44 made of an active energy line curable resin and the transparent base material 43. Is preferred.

The upper surface of the prism portion 44 is a flat surface, and is joined to the lower surface of the transparent base material 43. The lower surface of the prism portion 44, that is, the light incident surface 41 is a prism row forming surface, and a plurality of prisms 1J41 1 extending in the Y direction are arranged in parallel with each other and between adjacent prism rows. And a roughened surface 412 extending in the Y direction along the prism row. The thickness of the prism portion 44 is, for example, 10 to 500 μΐη. The arrangement pitch P of the prism array 41 1 is, for example, 10 μm to 500 μm.

[0040] The prism row 41 1 has two prism surfaces 41 la and 41 lb force. These prism surfaces may be optically sufficiently smooth surfaces (mirror surfaces), or may be rough surfaces having a roughening degree smaller than the surface of the roughening portion 412. In the present invention, the prism surface is preferably a mirror surface from the viewpoint of maintaining desired optical characteristics by the prism sheet. In this case, the region near the roughened portion of the prism surface may be roughened. The degree of roughening indicates the degree of roughening, and can be expressed by, for example, centerline average roughness Ra or ten-point average roughness. The apex angle Θ of the prism array 41 1 is preferably in the range of 40 to 150 °. In general, in the backlight of a liquid crystal display device, when the prism sheet is arranged so that the prism array forming surface is on the liquid crystal panel side, the apex angle Θ of the prism array is in the range of about 80 to 100 °. Yes, preferably in the range of 85-95 °. On the other hand, when the prism sheet 4 is arranged so that the prism row forming surface is on the light guide 3 side as in the above embodiment, the apex angle Θ of the prism row 41 1 is in the range of about 40 to 75 °. Preferably in the range of 45-70 ° . In the present application, as described later, a surface having an irregular cross-sectional shape is also referred to as a rough surface.

[0041] It is preferable that the width W of the roughened portion 412 is 0.04 times to 0.5 times the arrangement pitch P of the prism row 411. It is 0.08 times to 0.3 times. Is more preferably 0.1 times to 0.2 times. This is because if the width W of the roughened portion 412 is within the range of 0.04 to 0.5 times the arrangement pitch P, the desired observation direction range based on the light diffusion in the roughened portion 412 This is because the effect of concentrating the light amount and the effect of improving the brightness unevenness can be obtained, and the reduction of the light deflection effect toward the normal light exit surface of the light guide by the prism IJ411 can be reduced. The surface roughness of the roughened portion 412 is preferably 0.3 to 2 xm in terms of the center line average roughness Ra, more preferably 0.4 to 1.7 m. The average roughness Rz is preferably 1 to 3 μm, and more preferably 1.3 to 2.7 zm. These roughness values are measured according to JIS B0601-199 4 based on the surface shape of 100 μm along the extending direction of the roughened portion at the center of the roughened portion 412 (that is, the bottom of the valley). It is obtained.

The two prism surfaces 41 la and 41 lb of the prism array 411 may be rough surfaces having a roughening degree smaller than the surface of the roughening part 412. The roughness of the prism surfaces 41 la and 41 lb is preferably less than 0 · 3 μΐη at the centerline average roughness Ra, more preferably 0 · 1 / im or less, and a 10-point average The roughness Rz is preferably less than 1 μm, more preferably 0.5 / im or less. These roughness values are obtained based on the surface shape of the unit length (100 / im) along the extending direction of the prism surfaces 41 la and 41 lb. By making the surface roughness of the prism surfaces 411a and 411b smaller than that of the surface of the rough surface portion 412, light diffusion on the prism surfaces 41 la and 41 lb is reduced, and light from the light guide by the prism array 411 is obtained. It is possible to reduce the deterioration of the light deflection action toward the exit surface normal.

[0043] The surface shape of the roughened portion 412 or the prism surface 41 la, 41 lb of the prism array 411 is measured using, for example, an ultra-deep shape measuring microscope (for example, VK-8500 manufactured by Keyence Corporation) ]).

[0044] The entire shape of the XZ cross section excluding the shape based on the fine structure of the roughened portion 412 (or the shape based on the fine structure is averaged and connected by a smooth line) is as shown in FIG. A concave curve is formed downward. Alternatively, the overall shape of the XZ cross section of the roughened portion 412 may be a planar shape parallel to the XY plane. In the present invention, the roughened portion and the prism surface are distinguished from each other by the degree of roughening, and the portion having a large degree of roughening is called a roughened portion, which is a mirror surface or roughened surface. The small part of the degree is the prism surface.

[0046] The prism portion 44 is made of, for example, an active energy ray-curable resin and preferably has a high refractive index from the viewpoint of improving the luminance of the surface light source device. 1. 55 or more, more preferably 1.6 or more. The active energy ray curable resin for forming the prism portion 44 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, etc. And (meth) acrylate resins such as polyester (meth) acrylate, epoxy (meth) acrylate and urethane (meth) acrylate. Among these, (meth) acrylate resins are particularly preferable from the viewpoint of optical properties and the like. The active energy ray-curable composition used for such a cured resin includes a polyfunctional acrylate and / or a polyfunctional metatalylate (hereinafter referred to as a polyvalent (meta)) in terms of handling property, properties and curability. It is preferable to use as a main component a monoacrylate and / or monomethacrylate (hereinafter referred to as mono (meth) acrylate) and a photopolymerization initiator by active energy rays. Typical polyfunctional (meth) acrylates include polyol poly (meth) acrylate, polyester poly (meth) acrylate, epoxy poly (meth) acrylate, urethane poly (meth) acrylate. These are used alone or as a mixture of two or more. Examples of mono (meth) acrylate include mono (meth) acrylates of monoalcohol, mono (meth) acrylates of polyol, and the like.

As described above, the prism sheet 4 is described as including the transparent base material 43 and the prism portion 44. However, in the present invention, the prism sheet 4 may be composed of a single material. In this case, the prism sheet 4 can be made of a synthetic resin having a high light transmittance. Examples of such a synthetic resin include methacrylic resin, acrylic resin, polycarbonate resin, polyester resin, and salt resin resin. In particular, methacrylic resin is optimal because of its high light transmittance, heat resistance, mechanical properties, and molding cacheability. Such a methacrylic resin is a resin containing methyl methacrylate as a main component, and methyl methacrylate is preferably 80% by weight or more. FIG. 4 schematically shows how the prism sheet 4 deflects light in the XZ plane. This figure shows an example of the traveling direction of peak light (light corresponding to the peak of the outgoing light distribution) from the light guide 3 in the XZ plane. Most of the peak light obliquely emitted at an angle α from the light emitting surface 33 of the light guide 3 is incident on the first prism surface 41 la of the prism 歹 Ij411 and is almost entirely in the inner surface by the second prism surface 411b. The light is reflected and emitted in the direction of the normal of the light exit surface 42. A part of the peak light is incident on the first prism surface 41 la of the prism IJ411, diffused by the roughening unit 412 and emitted from the light exit surface 42. This light diffusion is also done in the YZ plane. Further, part of the light other than the peak light is directly incident on the roughened portion 412 and diffused. Based on such light diffusion in the roughened portion 412, an effect of concentrating the amount of light in a desired observation direction range and an excellent effect of improving luminance unevenness can be obtained. In addition, in the YZ plane, there is the action of the prism row on the back surface 34 of the light guide as described above, so that the luminance in the normal direction of the light exit surface 42 can be sufficiently improved in a wide range.

Note that the shape of the prism surfaces 41 la and 41 lb of the prism row 411 of the prism sheet 4 is not limited to a single flat surface, and can be, for example, a convex polygonal shape or a convex curved surface shape. Further, it is possible to further increase the brightness and narrow the visual field.

[0050] In the prism sheet 4, the desired prism array shape is accurately manufactured to obtain stable optical performance, and the purpose of suppressing wear and deformation of the top of the prism array during assembly work and use of the light source device Thus, a top flat portion or a top curved surface portion may be formed at the top of the prism row. In this case, the width of the top flat portion or the top curved surface portion should be 3 / m or less. It is preferable from the viewpoint of suppressing the occurrence of uneven brightness patterns due to sticking phenomenon as the brightness of the liquid crystal display device is reduced. More preferably, the width of the top flat portion or the top curved surface portion is 2 μm or less, and more preferably 1 μm or less.

The prism sheet 4 as described above is synthesized using a mold member having a shape transfer surface that transfers and forms a light incident surface 41 including a prism row forming surface having a prism row 411 and a roughened portion 412. Manufacturing power S can be achieved by shaping the surface of the resin sheet. The production of this mold part will be described with reference to FIG.

[0052] First, as shown in FIG. 5 (a), the first regions 411a ", 411b" having a shape corresponding to the prism surfaces 41la, 411b of the prism row 411 and the roughened portion 412 are substantially the same. Corresponding shape A mold member 41 ′ having a shape transfer surface composed of the second region 412 ″ is produced. Here, the shape of the second region 412 ″ substantially corresponds to the roughened portion 412 ”will be described later. This means that the shape corresponding to the roughened portion 412 can be obtained by blasting. For example, the shape of the second region 412 "can be a shape formed by extending the shape (for example, a plane) of the first region 41la", 41lb "as it is.

Next, blasting is performed on the shape transfer surface of the mold member 41 ′, so that the second region 4 12 ″ is roughened and has a shape corresponding to the roughened portion 412. Such a blasting process is performed such that the blast particles are not substantially sprayed to the first regions 41 la ″ and 411b ″ of the mold member 41 ′ and are sprayed only to the second regions 412 ″. Specifically, for example, blasting is performed using blast particles having a size (particle size) that does not enter the depth of the recess of the mold member 41 ′. When the blast particles are sprayed from above with respect to the cross section shown in Fig. 5 (b), depending on the apex angle Θ and pitch P of the prism row, blast particles BP within an appropriate particle size range should be used. Yo! For example, when the prism apex angle Θ force is ¾0 to 75 degrees, it is preferable to use a particle having a particle diameter of 0.3 times pitch P or more. When the particle size of the blast particle BP is too large, the degree of roughening becomes small. Therefore, the particle size is preferably about 5 times the pitch P at the maximum. The particle size of the blast particle BP is more preferably 1 to 4 times the pitch P, and still more preferably 2 to 3 times the pitch P. The blast pressure can be set as appropriate according to the material and particle size of the blast particles to be used, the material of the mold member 41 ′, etc. By performing the blasting process as described above for an appropriate time, it corresponds to the first regions 41 la ′ and 411b ′ having a shape corresponding to the prism row and the roughened portion as shown in FIG. A mold member 41 ′ having a shape transfer surface composed of the shape second region 412 ′ is obtained.

[0054] In the blasting process, as shown in Fig. 5 (c), the direction of spraying of the blast particles BP can be made oblique. In this case, it is possible to use blast particles having a small particle size, in which the blast pressure is easily controlled, as compared with the case of FIG. 5 (b). In addition, by appropriately setting the blast particle spraying angle, the width of the second region 412 ′ having a shape corresponding to the roughened portion can be appropriately set.

[0055] In the above description, the prism surfaces 411a and 41 lb of the prism 歹 Ij411 are optically sufficiently flat. A smooth surface is shown, and the first region 41 la ", 41 lb" of the mold member 41 'has already been formed into a shape corresponding to the prism surfaces 411a, 41 lb before blasting. This area is almost unaffected by blasting. However, the blast particles may include those having a flat shape, and the influence of the blast treatment may reach the first region 41 la ", 411b". In such a case, the first regions 411a "and 41 lb" are slightly roughened by blasting to form the first regions 41 la 'and 41 lb. That is, the prism surfaces 411a and 41 lb of the prism row 411 are slightly roughened to a roughening degree smaller than the surface of the roughened portion 412.

On the other hand, the prism surfaces 41 la and 411b of the prism array 411 may be intentionally roughened to a roughening degree smaller than the surface of the roughened portion 412. In this case, the first regions 41 la "and 41 lb" of the mold member 41 'are formed in a shape substantially corresponding to the prism surfaces 41 la and 41 lb before blasting. Here, with respect to the shape of the first region 411a ", 41 lb", the shape "corresponds substantially to the prism surfaces 41 la, 411b" means that the shape corresponding to the prism surfaces 41 la, 41 lb is obtained by blasting. It refers to such a shape. Then, in addition to roughening the second region 412 "by the blasting process (first blasting process) as described above, the second blasting process for spraying blasting particles having a smaller particle size is performed. Thus, the first region 41 la ", 411b" is roughened, and the shape corresponding to the prism surfaces 41 la, 41 lb of the prism array 411 is formed, and the second region 412 "is roughened by the roughened portion 412. It becomes the shape corresponding to. The particle size of the blast particles used for the second blasting process can be, for example, 0.1 to 0.5 times the arrangement pitch P of the prism rows.

A prism sheet can be obtained by performing synthetic resin molding using the mold member produced as described above and the mold member having a planar shape transfer surface. That is, by using the mold member produced as described above and shaping the surface of the synthetic resin sheet, a prism sheet having a required prism array forming surface can be obtained. The surface of the synthetic resin sheet can be shaped by hot pressing, extrusion molding, injection molding or the like.

FIG. 6 is a schematic view showing another embodiment of shaping a synthetic resin sheet.

In FIG. 6, reference numeral 7 denotes a mold member (roll mold) in which a shape transfer surface equivalent to the mold member 41 ′ is formed on a cylindrical outer peripheral surface. This roll type 7 is made of metal such as anorium, brass, steel, etc. It can be powerful. FIG. 7 is a schematic perspective view of the roll mold 7. A shape transfer surface 18 is formed on the outer peripheral surface of the cylindrical tool 16. The blasting process as described above for forming the shape transfer surface 18 can be performed with high accuracy and good productivity while rotating the roll mold. FIG. 8 is a schematic exploded perspective view showing a modified example of the roll mold 7. In this modification, a thin plate-shaped mold member 15 is wound around and fixed to the outer peripheral surface of the cylindrical roll 16. The thin plate-shaped mold member 15 is equivalent to the mold member 41 ′, and a shape transfer surface is formed on the outer surface. The blasting process as described above for forming the shape transfer surface can be performed on the flat thin plate-shaped mold member 15, but the mold member 15 is wound around and fixed to the outer peripheral surface of the cylindrical roll 16. It can be performed with high accuracy by rotating the roll mold after forming the roll mold.

[0060] As shown in FIG. 6, a transparent substrate 9 is supplied along the outer peripheral surface, that is, the shape transfer surface, to the Ronole mold 7, and the mold 7 and the transparent substrate 9 In the meantime, the active energy ray-curable composition 10 is continuously supplied from the resin tank 12 through the nozzle 13. On the outside of the transparent substrate 9, an ep roll 28 for making the thickness of the supplied active energy ray-curable composition 10 uniform is installed. As the nip roll 28, a metal roll, a rubber roll or the like is used. Further, in order to make the thickness of the active energy ray-curable composition 10 uniform, it is preferable to use a rubber roll that is highly accurate with respect to the roundness, surface roughness, etc. of the ep roll 28. In this case, a rubber having a high hardness of 60 degrees or more is preferable. The nip roll 28 is required to accurately adjust the thickness of the active energy ray-curable composition 10 and is operated by the pressure mechanism 11. As the pressure mechanism 11, a hydraulic cylinder, a pneumatic cylinder, various screw mechanisms, and the like can be used, but a pneumatic cylinder is preferable from the viewpoint of simplicity of the mechanism. The air pressure is controlled by a pressure regulating valve.

[0061] The active energy ray-curable composition 10 supplied between the roll mold 7 and the transparent substrate 9 is preferably maintained at a constant viscosity in order to keep the thickness of the obtained prism portion constant. Ms. In general, the viscosity range is preferably in the range of 20 to 3000 mPa ′ S, and more preferably in the range of 100 to 1000 mPa ′ S. In order to make the thickness of the prism portion constant by setting the viscosity of the active energy ray-curable composition 10 to 20 mPa 'S or more. In addition, it is not necessary to set the dip pressure very low or to extremely increase the molding speed. If the dip pressure is extremely low, the pressure mechanism 11 tends to be unable to operate stably, and the thickness of the prism portion becomes unstable. Further, when the molding speed is extremely increased, the irradiation amount of the active energy line is insufficient, and the active energy ray-curable composition tends to be insufficiently cured. On the other hand, by setting the viscosity of the active energy ray-curable composition 10 to 3000 mPa'S or less, the curable composition 10 can be sufficiently distributed to the details of the roll-shaped shape transfer surface structure, and the lens shape can be accurately determined. Transfer is difficult, defects due to air bubbles are likely to occur, and productivity is not deteriorated due to an extremely low molding speed. Therefore, in order to keep the viscosity of the active energy ray curable composition 10 constant, a sheathed heater, a hot water jacket, etc. are provided outside or inside the resin tank 12 so that the temperature of the curable composition 10 can be controlled. It is preferable to install a heat source facility.

[0062] After supplying the active energy ray-curable composition 10 between the roll mold 7 and the transparent substrate 9, the active energy ray-curable composition 10 is formed between the mouth mold 7 and the transparent substrate 9. The active energy ray irradiating device 14 irradiates the active energy ray through the transparent base material 9 to polymerize and cure the active energy ray curable composition 10, and the shape transfer formed on the roll mold 7 Transfer the surface. As the active energy ray irradiation device 14, a chemical reaction chemical lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a visible light halogen lamp, or the like is used. The irradiation amount of the active energy ray is preferably such that the integrated energy of the wavelength of 200 to 600 nm is 0.:! To 50 j / cm ² . The irradiation atmosphere of active energy rays may be air or an inert gas atmosphere such as nitrogen or argon. Next, the prism sheet composed of the transparent substrate 9 (the transparent substrate 43) and the prism portion (the prism portion 44) formed of an active energy ray-curable resin is released from the roll die 7.

The present invention includes the surface light source device including the primary light source 1, the light source reflector 2, the light guide 3, and the light reflecting element 5 as described above, and the transmissive liquid crystal display element 8 with the prism sheet 4. A liquid crystal display device is constructed. The liquid crystal display device is observed by an upward force observer in FIG. 1 or FIG. [0064] In the present embodiment, since the prism sheet 4 has the above-described characteristics, the luminance unevenness in the liquid crystal display device is improved, and the force is less reduced in luminance. In particular, in this embodiment, the prism sheet 4 has a mirror surface or a rough surface with a small degree of roughening formed at the top and the vicinity of the prism row 411 that greatly contributes to the light deflection function. The rough surface 412 having a large surface roughness is formed in the portion between adjacent prism rows that contributes little to the The concealment function can also be exhibited well.

FIG. 11 is a schematic partial enlarged cross-sectional view of one embodiment of a prism sheet constituting the liquid crystal display element with a prism sheet according to the present invention, and FIG. 12 is a schematic partial enlarged bottom view thereof. In these drawings, members or portions having the same functions as in FIGS. 1 to 8 are given the same reference numerals.

[0066] As shown in these drawings, in the prism sheet of the present embodiment, the light incident surface 41, which is the prism row forming surface, extends the plurality of prisms IJ411 in parallel to each other in the Y direction. In the point formed by arranging, it is the same as that of the said embodiment. The prism row forming surface 41 has a trough portion 412A extending in the Y direction between adjacent prisms 1J411. The width WA of the valley 412A is preferably 0.04 times to 0.5 times the arrangement pitch P of the prism rows 411, similarly to the width W of the roughened portion 412 of the above embodiment. It is more preferable that the ratio is 08 times to 0.3 times. It is particularly preferable that the ratio is 0.1 times to 0.2 times. 11 and 12, the ridge line of the prism row 411 is indicated by reference numeral 413.

[0067] The trough portion 412A has an irregular cross-sectional shape. Here, the irregularity is taken for each prism array arrangement pitch P in both the extending direction (Y direction) and the array direction (X direction) of the prism array 411 within an area (domain) of a predetermined size. This means that the pattern of the cross-sectional shape is different between any two regions. The predetermined size of the region may be 500 zm for each of the Y direction and the X direction. If the arrangement pitch P of the prism array 411 is 100 zm, as shown in FIG. 12, the valley 412A existing in each of the X-direction coordinates xl to x5 has a prism array array pin in the X direction. It is arranged continuously for every P. For each of these five continuously arranged valleys 412A, on each surface of the Y-direction coordinates yl to y5 separated by the prism array arrangement pitch P. Take 5 cut sections. That is, in total, 25 cross-sectional shapes with XY coordinates from (xl, yl) to (x5, y5) are taken. When the region having the pattern of 25 cross-sectional shapes is defined as one domain and the patterns of 25 cross-sectional shapes of any two domains are not the same, the valley cross-sectional shape is irregular. That is. Here, with respect to the 25 cross-sectional shapes of each domain, it is preferable that more than half (ie, 13 or more) are different from any other cross-sectional shape, and more preferably all 25 cross-sectional shapes. However, it is different from other cross sections.

Here, the fact that the cross-sectional shapes of the valleys are different means that the differences in the optical functions for reflecting or refracting the incoming light from the light guide 3 as described with reference to FIG. 4 are significant. . For example, in a prism row in which a synthetic resin member is mechanically cut using a cutting tool, when two cross-sectional shapes separated by an arrangement pitch P in the extending direction are taken, the cross-sectional shapes are There is virtually no difference in optical function. On the other hand, the fact that the cross-sectional shapes of the valleys are different means that the shape and optical function are not identical. Figure 13 shows the XZ cross-sectional shape of the valley 412A. In FIG. 13, (a) and (b) show different valley cross-sectional shapes.

[0069] The force described above when the arrangement pitch P of the prism 歹 IJ411 is 100 μm. When the arrangement pitch P of the prism 歹 IJ411 is 50 / im, the total XY coordinates are (xl, yl) To 100 (x 10, ylO). If the region having a pattern of 100 cross-sectional shapes is defined as one domain and the patterns of 100 cross-sectional shapes of any two domains are not the same, the cross-sectional shape of the valley is irregular. It is said. Here, with respect to the 100 cross-sectional shapes of each domain, it is preferable that more than half (ie, 50 or more) cross-sectional shapes are different from any other cross-sectional shape, more preferably all 100 cross-sectional shapes. Is different from any other cross-sectional shape.

[0070] The trough 412A having an irregular cross-sectional shape as described above is blasted with blast particles having an average particle diameter of 0.3 to 5 times the prism row arrangement pitch as described in the above embodiment. A forming member can be formed by shaping the surface of the synthetic resin sheet using a mold member having a shaped transfer surface. 11 to 13 do not mention the fine structure of the valley 412A, but the valley 412A is as described in the above embodiment. It has a fine structure of surface roughness.

When a prism sheet-attached liquid crystal display element and a liquid crystal display device using the same are configured using the prism sheet of this embodiment in the same manner as in the above-described embodiment, the prism array forming surface 41 of the prism sheet is used. By having the valley 412A having an irregular cross-sectional shape, the incoming light of the light guide force is irregularly diffused or reflected, so that it is difficult to visually recognize the surface structure of the light guide. In particular, in the present embodiment, the prism sheet 4 has a mirror surface or a rough surface with a small degree of roughness formed on the top and the vicinity of the prism row 411 that greatly contributes to the light deflection function. The trough 412A having an irregular cross-sectional shape is formed in the portion between adjacent prism rows that has a small contribution to the surface, so that the surface structure of the light guide can be visually confirmed while performing the required light deflection function satisfactorily. The function of concealing optical defects can also be exhibited well.

[0072] According to the present embodiment, a simple means of making only the cross-sectional shape of the valley portion irregular while maintaining the cross-sectional shape of the prism row, that is, adding blasting to the mold member on the manufacturing surface. By simple means, it is possible to conceal optical defects that cause luminance unevenness due to the structure of a light guide or the like that does not cause a decrease in luminance and causes speckles at low cost.

FIG. 14 is a schematic partially cutaway perspective view showing one embodiment of a liquid crystal display device using a liquid crystal display element with a prism sheet according to the present invention. In these drawings, members or portions having the same functions as those in FIGS. 1 to 8 and 11 to 13 are denoted by the same reference numerals.

In this embodiment, a point light source such as a light emitting diode (LED) is used as the primary light source 1. One corner of the rectangular plate-shaped light guide 3 is cut out, and a light incident end face 31 is formed here. The primary light source 1 is disposed so as to face the light incident end face. On the light emitting surface 33 of the light guide, a light emitting mechanism is formed as in the above embodiment.

In the present embodiment, the prism rows 411 formed on the light incident surface 41 of the prism sheet 4 are arranged in parallel concentrically around the corner where the light incident end surface 31 of the light guide 3 is formed. ing. In this specification, the arrangement of such a plurality of prism rows is also substantially parallel to each other. In the present embodiment, the light emitted from the primary light source 1 is a divergent light beam in the plane parallel to the light emitting surface 33 and is incident on the light incident end surface 31 and introduced into the light guide 3. The emitted light travels substantially radially about the primary light source 1 and is also emitted substantially radially when exiting from the light exit surface 33. Since the prism rows 411 on the light incident surface of the prism sheet 4 are concentrically arranged as described above, the light incident on the light incident surface 41 and introduced into the prism sheet 4 is described in the above embodiment. Similarly, the light is deflected in a substantially normal direction of the light guide light emitting surface 33 and emitted from the light emitting surface 42. Also in the present embodiment, irregularly shaped valleys 412A are formed between adjacent ones of the plurality of prisms IJ411 formed on the light incident surface 41 of the prism sheet 4.

In this embodiment, the behavior of light when viewed in a cross-section (cross-section passing through the primary light source) orthogonal to the extending direction of the prism ridge 11 (direction of tangent at each position of the arc) is the above-described embodiment. This is similar to the behavior of light when viewed in a cross section (XZ cross section) perpendicular to the extending direction of the prism row 411. Accordingly, the dimensional relationship between the prism IJ411 and the valley 412A is the same as that of the above embodiment when viewed from these cross sections.

In the above embodiment, the bonding of the prism sheet 4 and the liquid crystal display element 8 by the bonding material 86 is performed over the entire facing surface. However, in the present invention, This bonding may be performed on a part of the opposing surface of the prism sheet 4 and the liquid crystal display element 8. For example, you may adhere | attach by a joining material only in a peripheral part. Furthermore, in the present invention, a method other than bonding using a bonding material may be used for bonding the prism sheet 4 and the liquid crystal display element 8. An example of such a method is holding the pressure at the peripheral portion by the mechanical pressure means.

Example

[0079] Hereinafter, the present invention will be described more specifically with reference to Examples.

[0080] [Example 1]

A shape transfer surface with a shape almost corresponding to the shape of the prism array formation surface as described with reference to Fig. 5 (a) is formed on the surface of three types of thin plates with a thickness of 1 Omm, 400 mm X 690 mm. It was. Here, as shown in FIG. 3, the shape of the target prism array forming surface is that a large number of prism arrays 411 having a pitch P = 50 / im and an apex angle Θ = 65 ° are arranged in parallel. Rough The width of the chamfered portion 412 is W = 20 μΐη. In addition, the shape of the second region 412 "of the shape transfer surface of the mold member shown in Fig. 5 (a) corresponds to an extension of the planar shape of the first regions 411a" and 41 lb ". It is.

[0081] On the shape transfer surface of the mold member, blasting is performed by spraying with blast particles made of glass beads having a center particle diameter of 45 to 75 xm at a nozzle discharge pressure of 0.07 MPa. The shape of the second region 412 ′ as described with respect to (b) was formed. The roughness of the second region was a center line average roughness Ra of 0.5 111 and a 10-point average roughness of 1 ^ of 1.5 μm. Further, the roughness of the first region was such that the center line average roughness Ra was 0 .: m and the 10-point average roughness Rz was 0. The shape transfer surface of the mold member obtained as described above was subjected to electroless nickel plating.

Next, in order to fix the mold member, a stainless steel cylindrical roll having a diameter of 220 mm and a length of 450 mm as shown in FIG. 8 is prepared, and the mold member 15 is wound around the outer peripheral surface thereof with a screw. Fixed to obtain a roll type.

As shown in FIG. 6, an NBR rubber roll 28 having a rubber hardness of 80 ° was disposed so as to be close to the roll mold 7. A polyester film (transparent substrate) 9 having a thickness of 125 μΐη, which is slightly wider than the roll mold 7, is supplied between the roll mold 7 and the rubber roll 28 along the roll mold 7 and connected to the rubber mold 28. The polyester film 9 was nipped between the rubber roll 28 and the roll mold 7 by the pneumatic cylinder 11. The operating pressure of the pneumatic cylinder 11 at this time was 0. IMP a. As the pneumatic cylinder 11, an SMC air cylinder with an air tube diameter of 32 mm was used. Further, an ultraviolet irradiation device 14 was installed below the roll mold 7. The ultraviolet irradiation device 14 has an ultraviolet intensity of 120 W / cm, a capacity of 9.6 kW, a UV irradiation lamp manufactured by Western Quart, a cold mirror type parallel light reflector and a power source. The ultraviolet curable composition 10 was mixed with a refractive index adjusting component, a catalyst, and the like in advance, and charged into the resin tank 12. The resin tank 12 was made of SUS304 at all the portions in contact with the ultraviolet curable composition 10. In addition, it has a hot water jacket layer for controlling the liquid temperature of the ultraviolet curable composition 10, and hot water adjusted to 40 ° C by a temperature controller is supplied to the hot water jacket layer, and the resin tank 12 The liquid temperature of the UV curable composition 10 is 40. C ± 1. C was held. Furthermore, the resin tank 12 is evacuated by a vacuum pump. Thus, bubbles generated at the time of charging were removed.

[0084] The ultraviolet curable composition 10 was as follows, and the viscosity was adjusted to 300 mPa'S / 25 ° C.

[0085] Phenoxetyl Atylate (Biscoat # 192, Osaka Organic Chemical Industry Co., Ltd.): 50 parts by weight

Bisphenol A-diepoxy monoacrylate (Epoxy Cisternol 3000A manufactured by Kyoeisha Yushi Chemical Co., Ltd.): 50 parts by weight

2-Hydroxy_2-Methyl-1- 1-Phenyl-1-Propane-1-one (Ciba Geigy Darocur 1 173): 1.5 parts by weight

[0086] After the inside of the resin tank 12 is returned to normal pressure, the tank is sealed, an air pressure of 0.02 MPa is applied to the resin tank 12, and the valve at the lower part of the resin tank 12 is opened, whereby an ultraviolet curable composition is obtained. 10 was passed through a temperature-controlled pipe and supplied from a supply nozzle 13 which was also temperature-controlled onto a polyester film 9 which was nipped into a roll mold 7 by a rubber roll 28. The supply nozzle 13 used was an AV101 valve manufactured by Iwashita Engineering Co., Ltd., which was equipped with a MN-18-G13 needle. While the roll mold 7 is rotated at a speed of 3.5 m per minute with a 0 · 2kW geared motor (reduction ratio 1/200) manufactured by Mitsubishi Electric, the UV curable composition 10 becomes the roll mold 7 and the polyester film 9 In the state of being sandwiched between the two, the ultraviolet ray irradiation device 14 was irradiated with ultraviolet rays to polymerize and cure the ultraviolet curable composition 10 to transfer the prism row pattern on the shape transfer surface of the roll mold 7. Thereafter, it was released from the roll mold 7 to obtain a prism sheet.

[0087] When the cross section of the obtained prism sheet was confirmed with a scanning electron microscope (JEOL Ltd. SM-840A, 2000 times), the width W of the roughened portion was 20 / im, and the desired configuration was obtained. It turns out that it has. An adhesive protective sheet was attached to the prism row forming surface of this prism sheet.

[0088] Further, after removing the adhesive protective sheet from the obtained prism sheet, the prism row forming surface is directed downward on the light emission surface of the acrylic resin light guide having the cold cathode tube arranged on the side surface. The other side surface and back surface were covered with a reflection sheet, and a surface light source for a 14.1-inch liquid crystal display device was obtained. In this surface light source, the cold cathode tube was turned on and the light emitting surface (light emitting surface of the prism sheet) was observed. As a result, the brightness unevenness is not visually recognized, and it is optically concealed. It was excellent. In this surface light source, the cold-cathode tube was turned on to measure the luminance distribution (distribution in the XZ plane and distribution in the YZ plane) of the light emitting surface. The results are shown in Figs. In the distribution in the XZ plane, the peak luminance value was 2534 cd / m ² , the peak angle was -3.7 degrees, and the half width was 21 degrees. In the distribution in the YZ plane, the peak luminance value was 2377 cd / m ² , the peak angle was −3.0 degrees, and the half-value width was 41 degrees.

[0089] Further, on the light incident side surface of the 14.1 inch liquid crystal display element for notebook computers, as shown in FIGS. 1 and 2, the above prism is formed using a soft silicon resin (rubber) as a bonding material. The light-emitting surface of the sheet was joined. Thereby, a liquid crystal display element with a prism sheet was formed, and a liquid crystal display device was obtained. The cold cathode tube was turned on and the liquid crystal display element was driven, and the white screen displayed on the liquid crystal display element was observed. As a result, the luminance unevenness was not visually recognized and was excellent in optical concealment.

[Example 2]

A prism sheet was obtained by performing the same process as in Example 1 except that the nozzle discharge pressure was set to 0 · 15 MPa in the blasting process on the shape transfer surface of the mold member. As for the roughness of the second region of the die member after the blast treatment, the center line average roughness Ra was 0.8 μΐη and the ten-point average roughness Rz was 2.6 μΐη. The roughness of the first region was such that the center line average roughness Ra was 0.1111 and the ten-point average roughness 1¾ was 0.5 / im. Further, in the obtained prism sheet, the width of the roughened portion was 30 μΐη. Using this prism sheet, a surface light source was obtained in the same manner as in Example 1. With this surface light source, the cold cathode tube was turned on in the same manner as in Example 1 to observe the light emitting surface. As a result, the luminance unevenness was not visually recognized, and the optical concealment was excellent. In this surface light source, the cold cathode tube was turned on and the luminance distribution (distribution in the XZ plane and distribution in the YZ plane) of the light emitting surface was measured. The results are shown in Figs. In the XZ plane distribution, the peak luminance value was 2207 cd / m ² , the peak angle was 9.1 degrees, and the half-value width was 20.5 degrees. In the distribution in the YZ plane, the peak luminance value was 1466 cd / m ² , the peak angle was -4 degrees, and the half width was 42 degrees.

Further, in the same manner as in Example 1, the light emitting surface of the prism sheet was bonded to the light incident side surface of the liquid crystal display element. Thus, a liquid crystal display element with a prism sheet was formed, and a liquid crystal display device was obtained. The cold cathode tube is turned on and the liquid crystal display element is driven, thereby the liquid crystal display element The white screen displayed on the screen was observed. As a result, the luminance unevenness was not visually recognized and was excellent in optical concealment.

[0092] [Example 3]

A prism sheet was obtained by carrying out the same steps as in Example 1 except that the blast treatment was performed as follows. That is, in the blasting process for the shape transfer surface of the mold member, after performing the first blasting process using a blast particle made of glass beads having a central particle diameter of 45 to 75 μm and spraying at a nozzle discharge pressure of 0.07 MPa, A second blasting process was performed using blast particles made of glass beads with a central particle size of 10 μm and sprayed at a nozzle discharge pressure of 0. IMPa. The roughness of the second region of the die member after blasting was 0.6111 for the center line average roughness Ra and 1 for the 10-point average roughness 1 ^. As for the roughness of the first region, the center line average roughness Ra was 0.3111 and the ten-point average roughness 1¾ was 0. In the obtained prism sheet, the width of the roughened portion was 23 × m. Using this prism sheet, a surface light source was obtained in the same manner as in Example 1. In this surface light source, the cold cathode tube was turned on in the same manner as in Example 1 to observe the light emitting surface. As a result, the luminance unevenness was not visually recognized and was excellent in optical concealment.

Further, in the same manner as in Example 1, the light emitting surface of the prism sheet was bonded to the light incident side surface of the liquid crystal display element. Thus, a liquid crystal display element with a prism sheet was formed, and a liquid crystal display device was obtained. The cold cathode tube was turned on and the liquid crystal display element was driven, and the white screen displayed on the liquid crystal display element was observed. As a result, the luminance unevenness was not visually recognized and was excellent in optical concealment.

[0094] [Example 4]

Place the prism sheet on the light output surface of the acrylic resin light guide with 4 white LEDs made by Nichia on the side so that the prism array formation surface faces down, and reflect the other side and back surface. Cover with a sheet to obtain a surface light source for a 2.4 inch liquid crystal display element, and on the light incident side surface of the 2.4 inch liquid crystal display element, as shown in FIGS. A liquid crystal display device with a prism sheet was formed in the same manner as in Example 1 except that the light exit surface of the prism sheet was bonded using silicon resin (rubber) to obtain a liquid crystal display device. A white LED is turned on and a liquid crystal display element is driven, and the liquid crystal display element The white screen displayed on the screen was observed. As a result, the luminance unevenness was not visually recognized and was excellent in optical concealment.

[0095] [Comparative Example 1]

A prism sheet was obtained by performing the same process as in Example 1 except that the blasting treatment for the shape transfer surface of the mold member was not performed. The center line average roughness Ra and the ten-point average roughness Rz of the prism row of the obtained prism sheet are the center line average roughness Ra of 0.16 zm and the ten-point average roughness Rz at the top of the prism row. The center line average roughness Ra on the prism surface was 0.05 05 111 and the 10-point average roughness 1 ^ was 0. In this prism sheet, the width of the roughened portion was 0 zm, that is, there was no roughened portion. Using this prism sheet, a surface light source was obtained in the same manner as in Example 1. In this surface light source, the cold cathode tube was turned on in the same manner as in Example 1 and the light emitting surface was observed. As a result, uneven brightness due to defective form of the prism sheet based on defects in the mold for manufacturing the prism sheet and adhesion residue of the protective sheet adhesive on the prism row after the adhesive protective sheet is peeled off due to the application of the adhesive protective sheet. Was visible and the optical hiding was not sufficient. In this surface light source, the cold cathode tube was turned on and the luminance distribution (distribution in the XZ plane and distribution in the YZ plane) was measured. The results are shown in FIG. 9 and FIG. In the XZ plane distribution, the peak luminance value was 2631 cd / m ² , the peak angle was −2.5 degrees, and the half-value width was 20 degrees. In the distribution in the YZ plane, the peak luminance value was 2436 cd / m ² , the peak angle was −2 degrees, and the half-value width was 40 degrees.

Further, in the same manner as in Example 1, the light emitting surface of the prism sheet was bonded to the light incident side surface of the liquid crystal display element. Thus, a liquid crystal display element with a prism sheet was formed, and a liquid crystal display device was obtained. The cold cathode tube was turned on and the liquid crystal display element was driven, and the white screen displayed on the liquid crystal display element was observed. As a result, uneven brightness was visually recognized and the optical concealment was not sufficient.

[0097] [Example 5]

A mold member was produced by an apparatus as shown in FIG.

[0098] That is, a surface of a cylindrical metal roll having a diameter F "of 230 mm and a length B of 500 mm is subjected to a copper plating (not shown) having a thickness of 0.5 mm, and then the copper plating surface is smoothed. Processing and copper plating part A prism shape C with an apex angle of 68 degrees and an array pitch of 50 _β m was continuously formed by cutting with a cutting tool. Thereafter, for the purpose of improving the corrosion resistance of the mold member, an electroless nickel plating film (not shown) was formed with a thickness of 1 μm, and a mold member blank A in which the prism shape was continuously formed was produced. FIG. 16 shows an enlarged cross-sectional photograph of the prism row of this mold member blank A and the transfer surface portion of the trough. The shapes of the transfer surfaces of the prism rows and the valleys were substantially the same for adjacent repeating units.

[0099] The mold member blank A was subjected to a blasting treatment as follows. That is, the mold member blank A was mounted on a device (not shown) that can rotate the mold member blank A installed in the blast box continuously or discontinuously in the circumferential direction. The air blasting device AMD-10 type manufactured by Niche Yu Co., Ltd. was used as the blasting device, and glass beads [trade name J-120] manufactured by Potters Valorutini Co., Ltd. were used as the polishing material. Nozzle D with a tip diameter of 2 mm was used, the discharge pressure was 0. IMPa, and the distance E between the tip of Nozno D and the surface of the die blank A was 450 mm. The movement of the nozzle D during blasting is done by setting the distances F and F 'to 100 mm each in order to suppress the occurrence of spraying irregularities at the start and end of discharge in addition to the effective area B of the mold blank A. In addition, the total travel distance was 700 mm. Blasting is performed while moving the nozzle D at a constant speed of 5m / min to D 'in the direction perpendicular to the cutting direction of the prism row transfer surface formed on the mold blank A (K-K' direction). Carried out. After that, the mold part blank A was rotated in the circumferential direction of the mold part blank A by a circumference of 20 mm (angle of about 10 degrees), and blasting was performed in the K—K ′ direction by the same operation as described above. In the circumferential direction of the mold member blank A, blasting was performed on all parts, that is, the entire outer peripheral surface of the mold member blank A.

FIG. 17 shows an enlarged cross-sectional photograph of the prism row and the trough transfer surface portion of the mold member obtained as described above. The shape of the trough transfer surface (bottom edge in the figure) was substantially different for all adjacent repeat units.

[0101] Using the mold member obtained as described above, a prism sheet was obtained in the same manner as in Example 1. A surface light source was obtained in the same manner as in Example 1 using the obtained prism sheet. As a result of illuminating the surface light source and observing the light-emitting surface, the surface structure of the light guide and prism sheet is visible. Further, luminance unevenness was not visually recognized, and it was excellent in concealing optical defects.

Claims

The scope of the claims

[1] A liquid crystal display element used in combination with a surface light source device,

A first surface of a prism sheet is bonded to a side of the liquid crystal display element on which light emitted from the surface light source device is incident, and a second surface opposite to the first surface of the prism sheet is a prism array. The prism row forming surface is formed by arranging a plurality of prism rows so as to extend substantially parallel to each other,

The prism row forming surface has a roughened portion extending along the prism row between the prism rows adjacent to each other, and a surface of the roughened portion is formed by a prism surface of the prism row. A liquid crystal display element with a prism sheet, characterized in that the degree of roughening is large.

[2] The liquid crystal display element with a prism sheet according to [1], wherein the roughened portion has a width that is 0.04 times to 0.5 times the arrangement pitch of the prism rows.

[3] The first surface of the prism sheet according to claim 1, wherein a first surface of the prism sheet is bonded to a side on which light emitted from the surface light source device of the liquid crystal display element is incident by a bonding material. Liquid crystal display element with prism sheet.

[4] The liquid crystal display element with a prism sheet according to [3], wherein the bonding material is an adhesive or a self-adsorbing resin.

5. The liquid crystal display element with a prism sheet according to claim 1, wherein the prism rows are arranged concentrically.

[6] comprising a primary light source, a light guide that is guided by the light emitted from the primary light source, is guided and emitted, and the liquid crystal display element with a prism sheet according to claim 1.

The light guide includes a light incident end surface on which light emitted from the primary light source enters and a light exit surface from which the guided light exits, and the primary light source includes a light incident end surface of the light guide. The liquid crystal display element with a prism sheet is disposed such that the prism row forming surface of the prism sheet faces the light emitting surface of the light guide. A liquid crystal display device.