KR20090057428A - Lens sheet, surface light source, and liquid crystal display device - Google Patents

Abstract

A prism sheet (4), in which an optical diffusion layer (45) is formed on one face of a transparent substrate (43) and in which a transparent prism array forming layer (44) is attached to the other face, is arranged over a light emitting face (33) of a light guide (3). In the optical diffusion layer (45), optical diffusion materials (452) project from the surface of a transparent resin (451) to form a corrugated face. This corrugated face has a local apex average interval (S) of 50 mum or less and a ten-point average roughness (Rz) of 4 mum or less. The optical diffusion layer (45) has a Haze (Hz) of 50 to 85 %. In the circular area of a radius of 70 mum at an arbitrary position of the optical diffusion layer (45), the optical diffusion materials (452) coagulate in the transparent resin (451), to form at most three secondary particles (453) having a longer diameter of 30 mum or more. The difference between the refractive index (N1) of the transparent resin and the refractive index (N2) of the optical diffusion materials is 0.03 to 0.06.

Description

Lens sheet, surface light source device and liquid crystal display device {LENS SHEET, SURFACE LIGHT SOURCE, AND LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display device, a surface light source device used as a backlight of the liquid crystal display device, and a lens sheet constituting the surface light source device. In particular, the present invention relates to a lens sheet, a surface light source device, and a liquid crystal display device in which reduction of the sparking phenomenon called speckle and sparkling in image display of a liquid crystal display device is intended.

Background Art In recent years, color liquid crystal display devices have been widely used in various fields as image display means such as portable notebook personal computers, desktop personal computer monitors, portable televisions, or video integrated televisions. The liquid crystal display element (liquid crystal panel) used by this liquid crystal display device does not emit light by itself, but functions as an optical shutter. In this way, in order to improve the image display performance of a liquid crystal display device, arranging a surface light source device called a backlight behind a liquid crystal panel, and illuminating a liquid crystal panel from the back by the light emitted from the surface light source device, It is usually done.

Such a backlight is, for example, as described in Japanese Patent Application Laid-Open No. 2-84618 (Patent Document 1) or Japanese Utility Model Publication No. 3-69184 (Patent Document 2), and a fluorescent tube and a light guide as a primary light source. A sieve, a reflective sheet, a prism sheet as an optical deflecting element, and the like. Among these, the prism sheet is disposed on the light exit surface of the light guide to improve the optical efficiency of the backlight and to improve the brightness. For example, a cross-sectional isosceles having a vertex angle of 60 ° to 100 ° on one surface of the light transmissive sheet. It is a lens sheet formed by arranging triangular prism rows in parallel at a pitch of 50 µm.

As a prism sheet, it describes in Unexamined-Japanese-Patent No. 6-324205 (patent document 3), Unexamined-Japanese-Patent No. 10-160914 (patent document 4), and Unexamined-Japanese-Patent No. 2000-353413 (patent document 5). As described above, it is proposed to form a surface structure having a light diffusion function on the surface opposite to the surface on which the prism rows are formed so as to have a function of the light diffusion sheet or the light diffusion film. In the prism sheet of Patent Document 3, by forming a projection group having a light diffusing function and having a height equal to or greater than the wavelength of the light source light and 100 µm or less, the luminance of the surface light source device and the luminance gap are reduced. In the prism sheet of patent document 4, the light diffusion layer of a coating type, an embossing type, or a sandblast type is formed, and the brightness improvement and viewing angle enlargement of a surface light source device are aimed at. In the prism sheet of patent document 5, brightness improvement and viewing angle enlargement are aimed at by apply | coating light-diffusion fine particle layers, such as transparent beads.

(Patent Document 1) Japanese Unexamined Patent Publication No. 2-84618

(Patent Document 2) Japanese Utility Model Publication No. Hei 3-69184

(Patent Document 3) Japanese Unexamined Patent Publication No. 6-324205

(Patent Document 4) Japanese Unexamined Patent Application Publication No. 10-160914

(Patent Document 5) Japanese Unexamined Patent Publication No. 2000-353413

(Initiation of invention)

(Tasks to be solved by the invention)

As a function of the surface structure which has the light-diffusion function of the above prism sheet, the following is mentioned.

(1) adjusting the desired brightness and viewing angle by diffusing light by each projection to express a desired haze;

(2) suppressing a phenomenon called sticking that causes interference fringes due to partial closeness of a light diffusing sheet or a liquid crystal panel positioned on an upper surface of the prism sheet (a surface opposite to the prism row forming surface);

(3) The so-called defect concealment which reduces the visibility of the surface structure defect of a prism row, or reduces the visibility of surface structure defects, such as the mat structure and lens array arrangement formed in the light exit surface of the light guide body, or the opposite back surface.

The defect concealment is of increased importance especially when a high brightness light source is used as the primary light source.

When the surface structure having the light diffusing function is formed on the surface opposite to the prism row forming surface of the prism sheet, the highly directional light emitted from the light guide and reflected internally by the prism row of the prism sheet has the light diffusing function. Interfering with the surface structure, there is a case that a sparking phenomenon called speckle or sparkling, in which fine particles and unevenness of the surface of the coating film are very shiny, may occur. In this case, since the display image becomes very hard to see, it is strongly demanded to solve this glare phenomenon recently. Patent Documents 3 to 5 do not suggest a technical problem of eliminating or reducing such a glare phenomenon.

On the other hand, also in the liquid crystal panel located in the foremost view from the observation side in a liquid crystal display device, in order to suppress the fall of display image quality by the external light sources, such as a fluorescent lamp, to the surface of the observation side of a liquid crystal panel. The surface structure which has the light-diffusion function as mentioned above may be formed in some cases. Moreover, in order to suppress the sticking phenomenon mentioned above, the surface structure which has the above-mentioned light-diffusion function may be formed also in the surface on the light-incidence side of a liquid crystal panel. The surface structure which has the light-diffusion function of these front and back may generate | occur | produce a flashing phenomenon for the same reason as the case of the surface structure which has the light-diffusion function formed in the prism sheet. In this case, since the display image becomes very hard to see, it is strongly required to solve this glare phenomenon.

In order to suppress the flashing phenomenon resulting from the surface structure which has the light-diffusion function mentioned above, it is conceivable to improve light-diffusion property by increasing the quantity of the microparticles | fine-particles added to the coating film which forms a surface structure. Thereby, although the glare phenomenon can be reduced to some extent, there exists a difficulty that the brightness | luminance of a surface light source device or a liquid crystal display device will fall significantly.

Then, an object of this invention is to reduce the glare phenomenon in a liquid crystal display device, without causing the drastic fall of the brightness | luminance of a surface light source device or a liquid crystal display device.

(Means to solve the task)

According to the present invention, in order to solve the above problems, a plurality of lens rows are formed in parallel on the first surface of the sheet-shaped translucent member having a first surface and a second surface, and the second surface is an uneven surface. The uneven surface is provided with a lens sheet characterized in that the locally calculated mean spacing S is 50 µm or less, and the ten point average roughness Rz is 4 µm or less.

In one aspect of the present invention, the sheet-like light transmissive member is formed by attaching a light diffusing layer to one surface of the light transmissive substrate, the light diffusing layer comprising a light transmissive light diffusing material in the light transmissive resin, and the uneven surface is It is formed by protruding the light diffusing material from the surface of the translucent resin. In one embodiment of the present invention, the light diffusion layer has a haze Hz of 50 to 85%. In one form of this invention, the said light-diffusion material is 1-8 micrometers in weight average particle diameter D1. In one aspect of the present invention, the number of secondary particles having a diameter of 30 μm or more, formed by agglomeration of a plurality of the light diffusing materials in the light transmitting resin, in a circular region having a radius of 70 μm at any position of the light diffusing layer is 3 or less. to be. In one aspect of the present invention, the difference between the refractive index N1 of the translucent resin and the refractive index N2 of the light diffusing material is 0.03 to 0.06.

In addition, according to the present invention, in order to solve the above problems, a primary light source, a light guide in which light generated from the primary light source is introduced and guided and emitted, and the lens disposed so that the light emitted from the light guide is incident. And a light guide having a light incidence cross section through which light generated from the primary light source is incident and a light exit face through which the guided light is emitted, wherein the primary light source is adjacent to the light incidence cross section of the light guide. And the lens sheet is disposed such that the first surface faces the light exit surface of the light guide member.

Moreover, according to this invention, it solves the said subject and consists of the liquid crystal panel arrange | positioned so that the light which light-emitted from the said 2nd surface of the said lens sheet of the said surface light source device and this surface light source device may inject, and this liquid crystal panel The liquid crystal display device is provided with the incident surface which the light which light-emitted from the 2nd surface of the said lens sheet enters, and the observation surface on the opposite side.

In one embodiment of the present invention, the observation surface is a nonglare surface, and the gloss value G1 of 60 degrees is 25 or more. In one aspect of the present invention, the observation surface is a glare surface, and the gloss value G1 of 60 degrees is 90 or more. In one embodiment of the present invention, the incident surface is a non-glare surface, and the ratio G1 / G2 of the 60 degree gloss value G1 of the observation surface to the 60 degree gloss value G2 of the incident surface is 1 or more. In one aspect of the present invention, the ten-point average roughness Rz of the observation surface is 2 μm or less.

In one aspect of the present invention, there is provided a light diffusion sheet disposed between the lens sheet and the liquid crystal panel so that light emitted from the second surface of the lens sheet is incident, and the light diffusion sheet has at least one surface. This uneven surface is formed, and the locally calculated average spacing S of the uneven surface is 50 µm or less, and the ten-point average roughness Rz is 4 µm or less. In one embodiment of the present invention, the light diffusing sheet is formed by attaching a light diffusing functional layer to one surface of the light transmissive substrate, and the light diffusing functional layer contains a light transmissive light diffusing material in the translucent resin. The surface is formed by the light diffusing material protruding from the surface of the translucent resin. In one embodiment of the present invention, the light diffusing functional layer has a haze Hz of 20 to 70%. In one form of this invention, the light-diffusion material of the said uneven surface is 1-8 micrometers in weight average particle diameter D1.

(Effects of the Invention)

According to the present invention as described above, both of the locally calculated average spacing S and the ten-point average roughness Rz of the uneven surface of the lens sheet are each within a predetermined range, resulting in a significant decrease in the luminance of the surface light source device or the liquid crystal display device. The glare phenomenon in a liquid crystal display device can be reduced without doing it.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an embodiment of a prism sheet, which is an embodiment of a lens sheet according to the present invention, and a surface light source device according to the present invention using the prism sheet, and an embodiment of a liquid crystal display device using the surface light source device. It is a typical perspective view shown.

FIG. 2 is a schematic partial sectional view of FIG. 1. FIG.

3 is a schematic partial enlarged cross-sectional view of a prism sheet and a light guide.

4 is a schematic plan view of secondary particles.

It is a schematic diagram for demonstrating the manufacturing method of a prism sheet.

6 is a schematic perspective view showing a roll type used for producing a prism sheet.

It is a typical exploded perspective view which shows the roll type used for manufacture of a prism sheet.

8 is an optical micrograph of the light diffusing layer.

9 is an optical micrograph of a light diffusing layer.

10 is an optical micrograph of the light diffusing layer.

11 is an optical micrograph of a light diffusing layer.

12 is an optical micrograph of a light diffusing layer.

Explanation of symbols for the main parts of the drawings

1: primary light source 2: light source reflector

3: light guide 31: light incident cross section

32: side cross-section 33: light exit surface

34: back side 4: prism sheet

41: light incident surface 411: prism heat

411a, 411b: prism face 42: light exit face

43: transparent substrate 44: prism row forming layer

45 light diffusing layer 451 light-transmissive resin

452 light diffusing material 453 secondary particles

5: light reflecting element 7: mold member (roll type)

8 liquid crystal panel 81 incident surface

82: observation surface 9: transparent substrate

10 active energy ray curable composition 11 pressure mechanism

12: resin tank 13: nozzle

14 active energy ray irradiation device 15 thin plate-like member

16: cylindrical shape roll 18: shape transfer surface

28: NIP Roll

(The best mode for carrying out the invention)

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an embodiment of a prism sheet, which is an embodiment of a lens sheet according to the present invention, and a surface light source device according to the present invention using the prism sheet, and a liquid crystal display device according to the present invention using the surface light source device. It is a typical perspective view which shows one Embodiment, and FIG. 2 is its typical partial cross section. In the present embodiment, the surface light source device includes a light guide 3 having at least one side cross section as a light incidence end face 31, and having one surface substantially orthogonal to this as a light exit face 33, The linear primary light source 1 disposed opposite the light incident end face 31 of the light guide 3 and covered with the light source reflector 2, and the light deflecting element disposed on the light exit surface of the light guide 3; And a light reflecting element 5 disposed opposite to the back surface 34 on the opposite side to the light exit surface 33 of the light guide 3. In addition, in this embodiment, the liquid crystal display device includes the liquid crystal panel (liquid crystal display element) 8 arrange | positioned on the light output surface 42 of the prism sheet 4 of a surface light source device.

The light guide 3 is arrange | positioned in parallel with XY surface, and has the rectangular plate shape as a whole. The light guide 3 has four side cross-sections, and at least one side cross-section of a pair of side cross-sections parallel to a YZ plane is made into the light incident cross section 31. As shown in FIG. The light incident end face 31 is disposed to face the primary light source 1, and the light generated from the primary light source 1 is incident on the light incident end face 31 and introduced into the light guide 3. In the present invention, for example, the light source may be disposed opposite to another side end surface such as the side end surface 32 on the opposite side to the light incident end surface 31.

Two main surfaces substantially orthogonal to the light incident end face 31 of the light guide 3 are located substantially parallel to the XY plane, respectively, and one surface (the upper surface in the drawing) becomes the light exit surface 33. By providing a directional light output mechanism consisting of a rough surface or a lens row to the light exit surface 33, the light incident from the light incident end surface 31 is guided in the light guide 3 and the light exit surface ( The light having directivity is emitted from the light incident end surface 31 and the plane (XZ plane) orthogonal to the light exit surface 33 from 33. The angle which the direction (peak light) of the peak of the emission light intensity distribution in this XZ surface distribution makes with the light emission surface 33 is made into (alpha). The angle α is, for example, 10 to 40 degrees, and the full width at half maximum of the emitted light intensity distribution is, for example, 10 to 40 degrees.

The roughness and lens array formed on the surface of the light guide 3 are such that the average inclination angle θa according to ISO4287 / 1-1984 is in the range of 0.5 to 15 degrees. It is preferable at the point which aims at. 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. It is preferable that this average inclination-angle (theta) a sets an optimum range according to ratio (L / d) of the thickness d of the light guide 3, and the length L of the direction in which incident light propagates. That is, when using L / d about 20-200 as the light guide 3, it is preferable to make average inclination-angle (theta) a into 0.5-7.5 degree, More preferably, it is the range of 1-5 degree, More preferably, Is in the range of 1.5 to 4 degrees. In addition, when using L / d about 20 or less as the light guide 3, it is preferable to set average inclination-angle (theta) a to 7-12 degrees, More preferably, it is the range of 8-11 degrees.

According to ISO4287 / 1-1984, the average inclination angle θa of the rough surface formed on the light guide 3 is obtained by measuring the rough surface shape using a stylus type surface roughness meter and setting the coordinates in the measurement direction to x. x) from the following equations (1) and (2)

Can be obtained using Here, L is a measurement length and (DELTA) a is a tangent of average inclination-angle (theta) a.

Moreover, as the light guide 3, it is preferable that the light emission rate exists in 0.5 to 5% of range, More preferably, it is 1 to 3% of range. By setting the light emission rate to 0.5% or more, the amount of light emitted from the light guide 3 increases, and there is a tendency that sufficient luminance can be obtained. In addition, by setting the light emission rate to 5% or less, the emission of a large amount of light in the vicinity of the primary light source 1 is prevented, and the attenuation of the emitted light in the X direction in the light exit surface 33 is reduced, and the light is reduced. There is a tendency that the balance of luminance on the exit surface 33 is improved. Thus, by setting the light output ratio of the light guide 3 to 0.5 to 5%, the angle of the peak light in the output light intensity distribution (in the XZ plane) of the light emitted from the light exit surface is 50 with respect to the normal of the light exit surface. In the range of ˜80 degrees, a light guide having high directivity emitting characteristics with a half value full width of the emitted light intensity distribution (in the XZ surface) at the XZ plane perpendicular to both the light incident cross section and the light exit surface is 10 to 40 degrees. It is possible to emit from (3), and the emission direction can be efficiently deflected to the prism sheet 4, so that a surface light source device having high luminance can be provided.

In the present invention, the light emission rate from the light guide 3 is defined as follows. The light intensity I _O of the outgoing light at the end on the light incident end face 31 side of the light exit face 33 and the outgoing light intensity I at the position L at a distance L from the end on the light incidence end face 31 side. The relation is that when the thickness (Z direction dimension) of the light guide 3 is d, following formula (3)

Satisfies the relationship Here, the constant α is the light exit 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 face 31 on the light exit surface 33. The rate at which light is emitted from (%). This light emission rate? Can be obtained from its inclination by taking the number of light intensities of the emitted light from the light exit surface 23 on the vertical axis, taking (L / d) on the horizontal axis, and plotting these relationships.

In addition, in the present invention, instead of or in combination with forming the light output mechanism on the light output surface 33 as described above, even if the directional light output mechanism is provided by mixing and dispersing the light diffusing fine particles in the light guide body. good.

Moreover, the back surface 34 which is the main surface to which the directional light output mechanism is not provided, in order to control the directivity in the surface (YZ surface) parallel to the primary light source 1 of the outgoing light from the light guide 3, In the direction crossing the incident end surface 31, more specifically, it is a prism row forming surface which arranged the several prism row extended in the direction (X direction) substantially perpendicular to the light incident end surface 31. As shown in FIG. The prism array of the back surface 34 of this light guide 3 can make array pitch into the range of 10-100 micrometers, for example, Preferably it is 30-60 micrometers. In addition, the prism row of the back surface 34 of this light guide 3 can make a vertex angle into the range of 85-110 degree, for example. This is because by setting the vertex angle to this range, the light emitted from the light guide 3 can be properly focused, and the luminance as the surface light source device can be improved, and the vertex angle is more preferably in the range of 90 to 100 degrees. .

As the light guide 3, it is not limited to the shape as shown in FIG. 1, A thing with various shapes, such as a thick wedge shape, can be used for the light incident cross section.

The light guide 3 can be comprised with the synthetic resin with high light transmittance. As such a synthetic resin, methacryl resin, acrylic resin, polycarbonate resin, polyester resin, and vinyl chloride resin can be illustrated. In particular, methacryl resin is excellent in being excellent in the height of light transmittance, heat resistance, a mechanical characteristic, and moldability. As such methacryl resin, it is resin which has methyl methacrylate as a main component, and it is preferable that methyl methacrylate is 80 weight% or more. In forming the surface structure such as the rough surface of the light guide 3, the surface structure such as the prism heat, or the lenticular lens train, the transparent synthetic resin plate is formed by hot pressing using a mold member having a desired surface structure. It may be sufficient, and shape may be given simultaneously with shaping | molding by screen printing, extrusion molding, injection molding, etc. Moreover, a structural surface can also be formed using heat or photocurable resin. Moreover, the rough surface which consists of active-energy-ray-curable resin on the surface of transparent base materials, such as a transparent film or sheet which consists of polyester resin, acrylic resin, polycarbonate resin, vinyl chloride resin, polymethacrylimide resin, etc. The structure may also form a lens array arrangement, and such a sheet may be integrally bonded onto a separate transparent substrate by a method such as bonding or fusion. As active energy ray hardening type resin, a polyfunctional (meth) acryl compound, a vinyl compound, (meth) acrylic acid ester, an allyl compound, the metal salt of (meth) acrylic acid, etc. can be used.

The prism sheet 4 is disposed on the light exit surface 33 of the light guide 3. The prism sheet 4 is made of a sheet-like translucent member, and the two main surfaces, the first surface 41 and the second surface 42, are arranged in parallel with each other as a whole, and are respectively located in parallel with the XY plane. . The first surface 41 (the main surface located opposite to the light exit surface 33 of the light guide 3), which is one main surface, is the light incident surface, and the other main surface 42 is the light exit surface. . The light incident surface 41 is a prism row forming surface in which prism rows extending in a plurality of Y directions are arranged in parallel with each other. The light exit surface 42 is an uneven surface.

3, the typical partial enlarged sectional view of the prism sheet 4 and the light guide 3 is shown. The prism sheet 4 consists of a translucent base 43, the translucent prism row forming layer 44 which is a transparent lens row forming layer, and the light-diffusion layer 45. As shown in FIG. These light-transmitting base 43, the prism heat forming layer 44, and the light-diffusion layer 45 comprise the sheet-like light transmissive member. A prism row 411 is formed on the lower surface of the prism row forming layer 44, and the lower surface forms a light incident surface 41. In addition, the upper surface of the light diffusion layer 45 forms the light exit surface 42.

It is preferable that the material of the light-transmitting base 43 transmits active energy rays such as ultraviolet rays and electron beams, and although such a flexible glass plate can be used, polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, poly Acrylic resins such as methyl methacrylate, cellulose resins such as diacetyl cellulose and triacetyl cellulose, styrene resins such as polystyrene and acrylonitrile styrene copolymer, polyethylene, polypropylene, cyclic to norbornene structures Transparent resin sheet | seats and films, such as polyolefin resin, such as polyolefin which has polyolefin and ethylene copolymer, polyamide resin, such as nylon and aromatic polyamide, polycarbonate resin, vinyl chloride resin, and polymethacrylimide resin This is preferred. As for the thickness of the translucent base 43, 10-500 micrometers is preferable from a viewpoint of workability, such as strength and handleability, 20-400 micrometers is more preferable, and its 30-300 micrometers are especially preferable. Moreover, in order to improve the adhesiveness of the prism heat forming layer 44 which consists of active-energy-ray-curing resin, and the translucent base 43 to the translucent base 43, it is preferable that the adhesive improvement process, such as an anchor coating process, was given to the surface. Do.

The upper surface of the prism row forming layer 44 is a flat surface, and is joined to the lower surface of the translucent base 43. The lower surface of the prism row forming layer 44, that is, the light incident surface 41, is a prism row forming surface, and a plurality of prism rows 411 extending in the Y direction are arranged in parallel with each other. The thickness of the prism row forming layer 44 is 10-500 micrometers, for example. The arrangement pitch P of the prism rows 411 is, for example, 10 µm to 500 µm.

The prism row 411 is composed of two prism faces 411a and 411b. These prism surfaces may be optically smooth surfaces (mirror surfaces) or may be rough surfaces. In this invention, it is preferable to make a prism surface a mirror surface from the point which maintains desired optical characteristic by a prism sheet. It is preferable to set the vertex angle (theta) of the prism row 411 in 40-150 degrees. Generally, in the backlight of a liquid crystal display device, when arranging a prism sheet so that a prism row forming surface may face a liquid crystal panel, the vertex angle of prism row will be about 80-100 degree, Preferably it is 85-95 degree Range. On the other hand, when the prism sheet 4 is arranged such that the prism row forming surface faces the light guide 3 as in the above embodiment, the vertex angle θ of the prism row 411 is in a range of about 40 to 75 °, and is preferable. Preferably in the range of 45-70 °.

The prism heat forming layer 44 is made of, for example, an active energy ray curable resin, and preferably has a high refractive index in view of improving the brightness of the surface light source device, and specifically, the refractive index is 1.55 or more, More preferably 1.6 or more. The active energy ray-curing resin for forming the prism heat forming layer 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, and polyester (meth) acryl (Meth) acrylate type resins, such as a rate, an epoxy (meth) acrylate, and a urethane (meth) acrylate, etc. are mentioned. Especially, (meth) acrylate type resin is especially preferable from a viewpoint of the optical characteristic. As an active energy ray curable composition used for such a cured resin, it is a polyacrylate and / or a polymethacrylate (henceforth a polyvalent (meth) acrylate), a monoacrylate, and / from a viewpoint of handleability, curability, etc. Or it is preferable to have monomethacrylate (it describes as a mono (meth) acrylate hereafter), and the photoinitiator by an active energy ray as a main component. Representative polyvalent (meth) acrylates include polyol poly (meth) acrylates, polyester poly (meth) acrylates, epoxy poly (meth) acrylates, urethane poly (meth) acrylates, and the like. These are used individually or as a mixture of 2 or more types. Moreover, as mono (meth) acrylate, the mono (meth) acrylic acid ester of monoalcohol, the mono (meth) acrylic acid ester of polyol, etc. are mentioned.

On the other hand, the light diffusing layer 45 is formed by containing a plurality of light-transmitting light diffusing materials (light diffusing particles) 452 in the light-transmitting resin 451, and from the surface of the light-transmitting resin 451 forming a layer, As the 452 protrudes, the surface of the light diffusion layer 45 is formed with an uneven surface.

The formation method of the light-diffusion layer 45 is not specifically limited, A suitable system can be employ | adopted. For example, the translucent resin 451 is dissolved in a solvent, and a necessary amount of light diffusing material is added thereto to prepare a dope (paint). The dope is coated on the surface of the light transmissive substrate 43 and dried to form irregularities on the surface by the light diffusing material. The shape of the unevenness can be easily adjusted according to the content of the translucent resin in the dope, the coating amount and the weight average particle diameter of the light diffusing material. In order to express the required haze, the height of the unevenness can be appropriately adjusted. Moreover, the shape of the unevenness | corrugation formed is derived from the shape of a light-diffusion material, and, for example, when a spherical light-diffusion material is used, it becomes a shape like an aggregate of a fine concave and convex lens. Moreover, when the height of the unevenness is too high, the angle formed with respect to the surface of the light transmissive substrate 43 on a part of the surface of the light diffusion layer 45 tends to exceed the critical angle of incident light from the light transmissive substrate. In this case, the light is totally reflected at a part of the emission surface of the light diffusing layer 45 to become lost light, thereby lowering the luminance of the surface light source device. For this reason, it is preferable to make the height of the unevenness | corrugation of the light-diffusion layer 45 into the height which does not produce steep inclination of the surface which generate | occur | produces the total reflection as mentioned above. At the time of coating, it is preferable to set so that the average thickness of the coating film after solvent drying may be less than 1.5 times the weight average particle diameter D1 of the light-diffusion material to be used. By setting it in this way, overlap of the light-diffusion material in the thickness direction of a coating film can be prevented, and glare can be suppressed.

As a solvent used for preparation of dope, general solvents, such as toluene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, isopropyl alcohol, ethanol, are mentioned. As a coating method of dope, the coating method using gravure coating, lip coating, comma coating, etc. are mentioned.

As the transparent resin 451, the light diffusing material 452 can be dispersed, and any resin can be used without particular limitation as long as it is a resin having transparency having sufficient strength. Examples of such light-transmissive resins include thermoplastic resins such as polyamide-based resins, polyurethane-based resins, polyester-based resins, and acrylic resins, thermosetting resins, active energy ray-curable resins (ionizing radiation-curable resins), and the like. It is preferable to select appropriately in consideration of adhesiveness with the base material 43 and the light diffusing material 452.

In addition, the light-transmitting resin 451 can contain and contain a leveling agent, a thixotropic agent, an antistatic agent, an ultraviolet absorber, and the like. Especially, by containing a leveling agent, aggregation of a light-diffusion material can be suppressed and the unevenness by a light-diffusion material can be formed easily.

Examples of the light diffusing material 452 include inorganic fine particles such as silica, alumina, and glass, crosslinked organic fine particles such as polymethyl methacrylate, polystyrene, polyurethane, acryl-styrene copolymer, benzoguanamine and melamine, and silicone type. Fine particles etc. can be selected suitably and used. Moreover, you may use together 2 or more types of light-diffusion materials according to the objective. As the light diffusing material, any of spherical, irregular, spheroidal, and the like can be used without limitation, but is preferably spherical from the viewpoint of improving scratch resistance of irregularities. When forming the light-diffusion layer 45 which has an uneven surface by coating, as the light-diffusion material 452, since the bridge | crosslinking organic microparticles | fine-particles near specific gravity are close to the solvent which can melt | dissolve a translucent resin, there is little settling in dope (paint). It is preferably used.

The difference between the refractive index N2 of the light diffusing material 452 and the refractive index N1 of the light transmissive resin 451 suppresses internal scattering according to the difference in refractive index at the interface between the light diffusing material 452 and the light transmissive resin 451 as much as possible to reduce the transmittance. In order to improve and to improve the brightness | luminance of a surface light source device, 0.03-0.10 are preferable, 0.04-0.09 are more preferable, 0.05-0.08 are especially preferable.

It is preferable that content of the light-diffusion material 452 in the light-diffusion layer 45 is 15-35 wt% with respect to the translucent resin 451, in order to make the haze of the light-diffusion layer 45 50-85%. When the content of the light diffusing material 452 is less than 15 wt%, the haze to the light diffusing layer 45 is lower than 50%, the viewing angle of the surface light source device tends to decrease, and the content of the light diffusing material 452 is increased. When the amount is more than 30 wt%, the haze tends to exceed 85% and the luminance tends to decrease. More preferably, the haze of the light-diffusion layer 45 is 60 to 85%.

1-8 micrometers is preferable, as for the weight average particle diameter D1 of the light-diffusion material 452, 1-6 micrometers is more preferable, 1-5 micrometers is especially preferable. When the weight average particle diameter D1 of the light diffusing material 452 is smaller than 1 μm, light rays passing through the light diffusing layer 45 may be colored to lower the color temperature of the surface light source device or to reduce defect concealment. When the weight average particle diameter D1 of the light diffusing material 452 is larger than 8 µm, the light diffusing material 452 aggregates and there is a tendency that the sparking phenomenon is strongly generated.

As for the uneven surface of the light diffusion layer 45, the locally calculated average interval S of unevenness prescribed in JIS B 0601-1994 needs to be 50 µm or less, and preferably 45 µm or less. In addition, the locally calculated average interval S is preferably 5 µm or more. In addition, the uneven surface of the light diffusion layer 45 is formed so that the ten point average roughness Rz prescribed | regulated to JIS B0601-1994 may be 4 micrometers or less, More preferably, it is formed so that it may be 3 micrometers or less, More preferably, 2 It is formed so that it may be micrometer or less. It is particularly important to suppress the agglomeration phenomenon by forming the uneven surface of the light diffusing layer 45 by suppressing the aggregation of the light diffusing material. Ten-point average roughness Rz, Preferably it is formed so that it may become 0.5 micrometer or more, More preferably, it is formed so that it may become 1 micrometer or more. It is preferable to form the uneven surface of the light diffusing layer 45 in this way from the viewpoint of obtaining good light diffusibility and defect concealment.

Moreover, it is preferable that the uneven surface of the light-diffusion layer 45 is formed so that the average space | interval (average length of an outline curve element) Sm of unevenness prescribed | regulated to JIS B0601-1994 may be 160 micrometers or less, and 120 micrometers or less It is preferable, 100 micrometers or less are more preferable, and 80 micrometers or less are especially preferable.

A plurality of fine particles such as the light diffusing material 452 may aggregate and aggregate in the coating liquid to form secondary particles 453. This agglomeration is caused by the difference in affinity according to the difference between the SP value (solubility parameter) of the light diffusing material 452, the light transmitting resin 451 and the solvent, the surface potential of the light diffusing material 452, and the viscosity of the dope during coating. And the length of the leveling time (time from coating to drying), the presence or absence of a leveling agent, and the like. The range of 30-120 mPa * S is preferable, and, as for the viscosity of dope, 40-80 mPa * S is more preferable. The average spacing Sm of the uneven surface becomes large when aggregation in the coating film inner direction becomes significant. In addition, the ten-point average roughness Rz of the uneven surface becomes large when aggregation in the coating film thickness direction becomes remarkable.

Moreover, in the circular area | region of 70 micrometers of radius of arbitrary positions of the light-diffusion layer 45, the number of the secondary particle 453 of 30 micrometers or more of long diameter is three or less, Preferably it is two or less, More preferably, it is one or less. It is preferable to suppress the glare phenomenon. More preferably, in the circular region having a radius of 70 µm at any position of the light diffusion layer 45, the number of secondary particles 453 having a long diameter of 20 µm or more is three or less, preferably two or less, and more preferably It is one or less. As shown in the plan view in FIG. 4, the planar shape of the secondary particles 453 formed by the aggregation of the plurality of light diffusing materials 452 is generally not circular. Thus, the size of the secondary particles 453 is represented by the long diameter D.

In the above-mentioned embodiment, the light-diffusion layer 45 is formed by application | coating of the dope containing the translucent resin 451 and the light-diffusion material 452, and the light-diffusion layer 45 is according to the addition amount of the light-diffusion material 452. The haze can be easily adjusted, and the performance such as brightness and viewing angle of the surface light source device can be easily adjusted, which is suitable.

However, in this invention, it is also possible to form the light-diffusion layer which has an uneven surface by other methods. For example, an uneven surface can be formed by roughening the surface of the light-transmitting substrate in advance using chemical etching, sand blasting, embossing roll, or the like. In addition, a coating film made of a translucent resin may be coated on the light-transmissive substrate separately, and the concave-convex structure may be applied to the surface of the translucent resin film thus formed by using a transfer method using a mold or the like. Two or more types of the above methods may be combined to form a concave-convex surface having different concave-convex structures.

As mentioned above, although the prism sheet 4 had the prism row forming layer 44 separately from the translucent base 43, it demonstrated, In this invention, the translucent base 43 and the prism row forming layer 44 are common members. It can be made of. That is, the prism heat can be formed on the surface of the translucent base 43. In this case, the translucent base 43 can be comprised with the synthetic resin with high light transmittance. As such a synthetic resin, methacryl resin, acrylic resin, polycarbonate resin, polyester resin, and vinyl chloride resin can be illustrated. In particular, methacryl resin is excellent in the height of light transmittance, heat resistance, a mechanical characteristic, and moldability, and is optimal. As such methacryl resin, it is resin which has methyl methacrylate as a main component, and it is preferable that methyl methacrylate is 80 weight% or more.

3, the state of the optical deflection in the XZ plane by the prism sheet 4 is shown typically. In this figure, an example of the advancing direction of the peak light (light corresponding to the peak of the emitted light distribution) from the light guide 3 in the XZ plane is shown. Most of the peak light which is inclined at an angle α from the light exit surface 33 of the light guide 3 is incident on the first prism surface 411a of the prism row 411, and is almost caused by the second prism surface 411b. It is totally internally reflected and progresses to the direction of the normal line of the light exiting surface 42, and is diffused and radiate | emitted mainly by the surface of the uneven structure of the light-diffusion layer 45. In addition, in the YZ plane, the prism heat of the light guide body 34 as described above is also acted, and the luminance in the direction of the normal line of the light exit surface 42 can be sufficiently improved in a wide range.

In addition, the shape of the prism surfaces 411a and 411b of the prism row 411 of the prism sheet 4 is not limited to a single plane, For example, it can be set as cross-sectional convex polygon shape or convex curved surface shape, It is possible to achieve higher luminance and narrower field of view.

In the prism sheet 4, the prism for the desired shape is precisely produced to obtain stable optical performance, and for the purpose of restraining abrasion and deformation of the prism column head portions at the time of assembly work or use of the light source device, You may form a tap part flat part or a tap part curved part in the row part of a row. In this case, it is preferable to set the width | variety of a part of a flat part of a top part, or a part of a curved part of a top part to be 3 micrometers or less from a viewpoint which suppresses generation | occurrence | production of the luminance nonuniformity pattern by the fall of the brightness as a surface light source device, or sticking phenomenon, Preferably the width | variety of a nipple partial flat part or a nipple partial curved part is 2 micrometers or less, More preferably, it is 1 micrometer or less.

The formation of the prism rows as described above is performed by using a mold member having a shape transfer surface for transferring the light incident surface 41 formed of the prism heat forming surface having the prism rows 411 to form the shaping of the surface of the synthetic resin sheet. This can be achieved by doing.

FIG. 5: is a schematic diagram which shows embodiment of formation of the prism row in a prism sheet.

In FIG. 5, the code | symbol 7 is a die member (roll type) formed by forming the shape transfer surface which transfer-forms the light incident surface 41 in the cylindrical outer peripheral surface. This roll die 7 can be made of metals such as aluminum, brass, and steel. 6 is a schematic perspective view of the roll die 7. The shape transfer surface 18 is formed in the outer peripheral surface of the cylindrical roll 16. As shown in FIG. 7 is a schematic exploded perspective view illustrating a modification of the roll die 7. In this modification, the thin mold-shaped member 15 is wound around and fixed to the outer circumferential surface of the cylindrical roll 16. This thin plate-shaped member 15 is formed with the shape transfer surface in the outer surface.

As shown in FIG. 5, the translucent substrate 9 and 43 are supplied to the roll die 7 along its outer circumferential surface, that is, the shape transfer surface, and the roll die 7 and the translucent substrate 9 are provided. In between, the active energy ray curable composition 10 is continuously supplied from the resin tank 12 through the nozzle 13. On the outer side of the translucent base 9, the NIP roll 28 for uniformizing the thickness of the supplied active energy ray curable composition 10 is provided. As the NIP roll 28, a metal roll, a rubber roll, etc. are used. In addition, in order to make the thickness of the active energy ray-curable composition 10 uniform, it is preferable to process it with high precision with respect to the roundness, surface roughness, etc. of the NIP roll 28, In the case of a rubber roll, rubber hardness is 60 degrees It is preferable that it is a high hardness of the above. This NIP roll 28 needs to adjust the thickness of the active energy ray curable composition 10 correctly, and is operated by the pressure mechanism 11. As this pressure mechanism 11, a hydraulic cylinder, a pneumatic cylinder, various screw mechanisms, etc. can be used, but a pneumatic cylinder is preferable from a viewpoint of the simplicity of a mechanism. The air pressure is controlled by a pressure regulating valve or the like.

In order to make the thickness of the prism part obtained, the active energy ray curable composition 10 supplied between the roll mold 7 and the translucent base material 9 is preferable to hold | maintain with a fixed viscosity. It is preferable to make a viscosity range into the viscosity of the range of 20-3000 mPa * S generally, More preferably, it is the range of 100-1000 mPa * S. By setting the viscosity of the active energy ray-curable composition 10 to 20 mPa · S or more, it is unnecessary to set the NIP pressure very low or to make the molding speed extremely fast in order to make the thickness of the prism portion constant. When the NIP pressure is made very low, there is a tendency that the stable operation of the pressure mechanism 11 cannot be performed, and the thickness of the prism portion is not constant. In addition, when the molding speed is made extremely high, there is a tendency that the irradiation amount of the active energy ray is insufficient and the curing of the active energy ray curable composition is insufficient. 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 spread to the details of the roll-shaped shape transfer surface structure, and accurate transfer of the lens shape is difficult. It is easy to produce defects due to breakage or mixing of bubbles, or to bring about a deterioration in productivity due to an extreme decrease in molding speed. For this reason, in order to hold | maintain the viscosity of the active-energy-ray-curable composition 10 uniformly, it is possible to control temperature of the curable composition 10, such as a sheath heater and a warm water jacket in the exterior or inside of the resin tank 12. It is preferable to provide a heat source facility.

After supplying the active energy ray curable composition 10 between the roll mold 7 and the light transmissive substrate 9, the active energy ray curable composition 10 is formed between the roll die 7 and the light transmissive substrate 9. In the sandwiched state, the active energy ray is irradiated from the active energy ray irradiation device 14 through the light-transmitting substrate 9 to polymerize and harden the active energy ray curable composition 10, and the shape transfer surface formed in the roll mold 7 Performs transcription. As the active energy ray irradiation device 14, a chemical lamp for chemical reaction, a low pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, a visible light halogen lamp and the like are used. As an irradiation amount of an active energy ray, it is preferable to set it as about the accumulation energy of the wavelength of 200-600 nm becoming 0.1-50 J / cm <2>. Moreover, as irradiation atmosphere of an active energy ray, you may be in air and may be in inert gas atmosphere, such as nitrogen and argon. Next, the prism sheet which consists of the translucent base materials 9 and 43 and the prism heat forming layer 44 formed from active energy ray hardening resin is mold-released from the roll type | mold 7.

Returning to FIG. 1, the primary light source 1 is a linear light source extending in the Y direction, and as the primary light source 1, for example, a fluorescent lamp or a cold cathode tube can be used. In this case, as shown in FIG. 1, the primary light source 1 may be provided not only in the case where it is provided opposite to one side end surface of the light guide 3, but also in the side end surface on the opposite side as necessary.

The light source reflector 2 guides the light of the primary light source 1 to the light guide 3 with little loss. As the material, for example, a plastic film having a metal vapor deposition reflective layer on its surface can be used. As shown, the light source reflector 2 avoids the prism sheet 4 and passes through the outer surface of the primary light source 1 from the outer surface of the end portion of the light reflecting element 5 to the light exit surface of the light guide 3. It is wound around the end part. On the other hand, the light source reflector 2 can also be wound from the outer surface of the end portion of the light reflection element 5 to the light emitting surface end portion of the prism sheet 4 past the outer surface of the primary light source 1. It is also possible to attach a reflecting member such as the light source reflector 2 to the side cross section other than the light incident end face 31 of the light guide 3.

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

The light emitting surface (prism sheet 4) of the surface light source device including the primary light source 1, the light source reflector 2, the light guide 3, the prism sheet 4, and the light reflecting element 5 as described above. By arrange | positioning the transmissive liquid crystal panel (liquid crystal display element) 8 on the light output surface 42, the liquid crystal display device which made the surface light source device of this invention into a backlight is comprised. The liquid crystal display device is observed by an observer from above.

Light emitted from the light exit surface 42 of the prism sheet 4 of the surface light source device enters the incident surface 81 of the liquid crystal panel 8, receives modulation according to the image information signal, and observes the observation surface 82. Exit from Observation surface 82 is a surface having a non-glare function of 60 degrees gloss value (JIS Z 8741) G1 of 25 or more, more preferably 30 or more, particularly preferably 35 or more (surface subjected to gloss removal treatment or antiglare treatment) ) Is preferable in that it has an antiglare function and suppresses the glare. In addition, it is preferable from the viewpoint of anti-glare that a 60 degree glossiness value G1 is a glare surface (surface which is not subjected to a glossiness removal process or an antiglare process) of 90 or more. In addition, from the viewpoint of glare prevention, the incident surface 81 becomes a non-glare surface, and the ratio G1 / G2 of the 60 degree gloss value G1 of the observation surface 82 with respect to the 60 degree gloss value G2 is 1 or more, more Preferably it is 1.2 or more, Especially preferably, it is 1.4 or more. In addition, it is preferable that ten point average roughness Rz of the observation surface 82 is 2 micrometers or less from a viewpoint of glare prevention.

In the present embodiment, in particular, the light diffusing layer 45 of the prism sheet 4 has the characteristics as described above, so that the luminance of the surface light source device or the liquid crystal display device is not significantly reduced. The glare phenomenon in this can be reduced.

In the above embodiment, a prism sheet having a prism row is used as the lens sheet having a lens row, but in the present invention, other lens rows, for example, a lenticular lens having a lenticular lens row or the like can be used.

In the above embodiment, in particular, when the locally calculated average interval S of the unevenness of the uneven surface of the light diffusing layer 45 is 50 μm or less, the light diffusing layer 45 of the prism sheet exhibits a sufficient light diffusing function. The arrangement of separate light diffusing sheets is unnecessary. However, in the present invention, in particular, when the locally calculated average interval S of the unevenness of the uneven surface of the light diffusing layer 45 exceeds 50 µm, the flash in the liquid crystal display device is used by using a separate light diffusing sheet in combination. The brightness can be improved by further improving the light diffusivity while reducing the phenomenon.

The separate light-diffusion sheet used together is arrange | positioned between a prism sheet and a liquid crystal panel so that the light radiate | emitted from the 2nd surface of a prism sheet may inject. At least one surface of the light diffusion sheet has an uneven surface, and the locally calculated average spacing S of the uneven surface is 50 µm or less, preferably 45 µm or less, and the ten-point average roughness Rz is 4 µm or less. Preferably it is 3 micrometers or less, More preferably, it is 2 micrometers or less. It is especially important to form the uneven surface in this way in order to suppress the glare phenomenon.

As a light-diffusion sheet, what forms a light-diffusion functional layer on one surface of a translucent base material is illustrated. Here, the light-diffusion functional layer is formed by containing a light-transmissive light diffusing material in the light-transmissive resin, and the uneven surface is formed by the light-diffusion material protruding from the surface of the light-transmissive resin. As the light transmitting resin and the light diffusing material, those similar to those in the light diffusing layer of the prism sheet can be used. Haze Hz of a light-diffusion functional layer becomes like this. Preferably it is 20 to 70%, More preferably, it is 25 to 65%, More preferably, it is 30 to 60%. This is because when the haze Hz is 20% or less, the viewing angle decreases or the glare becomes strong, and when the haze Hz exceeds 70%, the luminance decreases.

It is preferable that weight average particle diameter D1 is 1-8 micrometers, It is more preferable that it is 1-6 micrometers, and, as for the light-diffusion material of an uneven surface, it is especially preferable that it is 1-5 micrometers. When the weight average particle diameter D1 of this light-diffusion material is smaller than 1 micrometer, the light ray which passed the light-diffusion functional layer may be colored, and the color temperature of a surface light source device may be reduced, or defect concealability may fall, and light-diffusion may be carried out. If the weight average particle diameter D1 of the ash is larger than 8 µm, the glazing phenomenon tends to occur strongly.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

The prism sheet, surface light source device, and liquid crystal display device which were demonstrated with reference to FIGS. 1-3 were produced as follows.

As a light-transmitting base material 43, a PET film (Toyo Spin Co., Ltd. product, brand name A4300) of thickness 188 micrometers was used. A mixed solvent of MEK (methyl ethyl ketone) and toluene (mixing ratio of 50 wt%) using a polyester resin having a refractive index of 1.55 (trade name: Byron # 200) as a light transmitting resin (binder resin) constituting the light diffusion layer. The coating solution was prepared by dissolving so that the concentration of Byron # 200 became 26wt%. As the light diffusing material, PMMA crosslinked fine particles having a refractive index of 1.49 and a weight average particle diameter of 3.2 μm were added to the coating solution so as to be 19.7 wt% with respect to the translucent resin, and stirred and mixed to form a coating solution containing the light diffusing material ( Viscosity: 50 mPa * S) was prepared.

Using the gravure coating method, the coating liquid was coated on the PET film so as to have an average thickness of 5 탆 after solvent drying at a line speed of 15 m / min, and dried. Thereby, the light-diffusion layer which has an uneven structure based on a light-diffusion material, ie, an uneven surface, was formed in one surface of PET film. The light diffusing layer was attached to the light diffusing layer using a haze meter (manufactured by Nippon Denshoku Co., Ltd., brand name NDH2000) such that the light diffusing layer was directed toward the light receiver side, and total light transmittance (JIS K 7316) Tt and haze (JIS K 7136) Haze Was measured. As a result, the total light transmittance was 92.6% and the haze was 64.7%. In addition, the locally calculated average spacing S, average spacing Sm, and ten-point average roughness Rz of the unevenness of the uneven surface of the light diffusing layer were measured under the following conditions using a surface roughness meter (manufactured by Tokyo Precision Co., Ltd., product name SURFCOM 1500DX-3DF). (JIS B 0601-1994).

ㆍ Measurement type: roughness measurement

ㆍ Measurement Length: 5.0㎜

ㆍ Cut Off Type: 2RC (Phase Ratio Compensation)

ㆍ Slant Correction: Least Squared Straight Line Correction

Cutoff Wavelength: 0.8mm

ㆍ Measurement Magnification: × 20K

ㆍ Measurement Speed: 0.15㎜ / s

ㆍ Tip tip radius: 1㎛

As a result, the locally calculated average interval S was 27.0 µm, the average interval Sm was 38.3 µm, and the ten-point average roughness Rz was 1.8 µm. In addition, the aggregation state of the light-diffusion material in the light-diffusion layer was observed by the transmitted light at 500 times the magnification using the optical microscope (Olympus company make, brand name MX61L). As a result, the number of the secondary particles of 30 micrometers or more of long diameter in the circular area | region of 70 micrometers of radius of arbitrary positions of the surface of a light-diffusion layer was at most one. The optical micrograph of this light-diffusion layer is shown in FIG. In FIG. 8, the rectangular edge of 100 micrometers of short sides and 150 micrometers of long sides is shown for the dimension reference (the same in the following micrograph).

The shape transfer surface of the shape corresponding to the shape of the prism row formation surface was formed in the surface of three types of JIS brass thin sheets of thickness 1.0mm and 400mm x 690mm, and the mold member was obtained. Here, as for the shape of the prism row formation surface made into the objective, many prism rows 411 of pitch P = 50 micrometer and vertex angle (theta) = 65 degrees were arrange | positioned in parallel.

Subsequently, a cylindrical roll made of stainless steel having a diameter of 220 mm and a length of 450 mm was prepared, the mold member was wound around the outer peripheral surface thereof, and fixed with a screw to obtain a roll mold. The light-transmissive substrate with the light diffusion layer was supplied between the roll mold 7 and the rubber roll along the roll mold, and the light-transmissive substrate was NIP between the rubber roll and the roll mold by a pneumatic cylinder connected to the rubber roll. .

In addition, the following ultraviolet curable compositions were adjusted to the viscosity of 300 mPa * S / 25 degreeC.

Phenoxyethyl acrylate (Biscote # 192, manufactured by Osaka Organic Chemical Industries, Ltd.): 50 parts by weight

Bisphenol A-diepoxy-acrylate (Epoxy ester 3000A manufactured by Kyoeisha Oil & Chemical Co., Ltd.): 50 parts by weight

2-hydroxy-2-methyl-1-phenyl-propane-1-one (Dalocure 1173 from Chiba-Geigi Co., Ltd.): 1.5 parts by weight

This ultraviolet curable composition was supplied to the surface on the opposite side to the surface provided with the said light-diffusion layer of the translucent base material nipped in roll shape with a rubber roll. While rotating the roll mold, the ultraviolet curable composition was irradiated with ultraviolet rays from the ultraviolet irradiation device in a state sandwiched between the roll mold and the light-transmitting base material, thereby polymerizing and curing the ultraviolet curable composition and transferring the prism heat pattern of the roll-shaped transfer surface. I was. Thereafter, the mold was released from a roll to obtain a prism sheet.

The prism sheet obtained as described above is cut out to a size of 14.1W (wide), and this is shown on the light exit surface of the 14.1W (wide) sized light guide of acrylic resin in which a cold cathode tube is disposed on the side. As shown in the figure, the prism row forming surface was mounted downward, and the other side surface and the back surface were covered with a reflective sheet to obtain a surface light source device. In this surface light source device, the cold cathode tube was turned on, and the normal luminance and the half value angle were measured using a luminance meter (manufactured by Topcon Corporation, trade name BM-7). As a result, the normal luminance was 3160 Hz / m 2, and the half value angle was 18.7 °.

The transmissive liquid crystal panel was mounted on the prism sheet of the surface light source device obtained as mentioned above. This liquid crystal panel has a 60-degree glossiness value G1 of 48.6 on an observation surface (nonglare surface) measured by a glossmeter (Nippon Denshoku Kogyo Co., Ltd., brand name VGS-300A), and 60-degree glossiness of the incident surface (nonglare surface). The value G2 was 31.2, the ratio G1 / G2 was 1.6, the ten-point average roughness Rz of the observation surface was 0.8 µm, and the size was 14.1 W (wide) liquid crystal panel with the pixel count XGA. In this liquid crystal display device, the surface light source device was made to emit light, and a white image was displayed by the liquid crystal panel, and when the glare was observed, there was almost no glare phenomenon and an easy-to-view image quality with a very smooth texture was obtained.

Example 2

30% blended PMMA crosslinked fine particles having a refractive index of 1.49 and a weight average particle diameter of 5.3 mu m in weight ratio were used as the light diffusing material as the light diffusing material, and 20.0 wt% of the light diffusing material in the light transmitting material used in Example 1. The light-diffusion layer was formed like Example 1 except having added and adjusting the coating liquid of viscosity 55mPa * S.

About the obtained light-diffusion layer, the total light transmittance and haze were measured like Example 1. As a result, the total light transmittance was 93.3% and haze was 70.4%. In addition, the locally calculated average spacing S, average spacing Sm, and ten-point average roughness Rz of the unevenness of the uneven surface of the light diffusing layer were measured in the same manner as in Example 1. As a result, the locally calculated average interval S was 27.6 µm, the average interval Sm was 53.9 µm, and the ten-point average roughness Rz was 3.2 µm. In addition, the aggregation state of the light-diffusion material in the light-diffusion layer was observed like Example 1. As a result, the number of the secondary particles of 30 micrometers or more of long diameter in the circular area | region of 70 micrometers of radius of arbitrary positions of the surface of a light-diffusion layer was at most one. The optical micrograph of this light-diffusion layer is shown in FIG.

A prism sheet was formed in the same manner as in Example 1 to obtain a prism sheet, and a surface light source device was manufactured in the same manner as in Example 1 using this prism sheet. In this surface light source device, the normal luminance and the half value angle were measured in the same manner as in Example 1. As a result, the normal luminance was 3058 dl / m 2, and the half value angle was 19.4 °.

Moreover, the liquid crystal display device was produced like Example 1 using this surface light source device. In this liquid crystal display device, when the glare was observed in the same manner as in Example 1, there was almost no glare phenomenon and an easy to see image quality having a very smooth texture was obtained.

Example 3

A transmissive liquid crystal panel was mounted on the prism sheet of the surface light source device produced in the same manner as in Example 1. The liquid crystal panel had a 60 degree glossiness value G1 of 96.9 on the observation surface (glare surface) measured in the same manner as in Example 1, and a 60 degree gloss value G2 of the incident surface (non glare surface) on 31.3, The ratio was 3.1, the ten-point average roughness Rz of the observation surface was 0.02 µm, and the size was 14.1 W (wide) liquid crystal panel with the pixel count XGA. In this liquid crystal display, when the glare was observed in the same manner as in Example 1, there was almost no glare phenomenon and an easy to see image quality having a very smooth texture was obtained.

Comparative Example 1

As the light diffusing material, PMMA crosslinked fine particles having a refractive index of 1.49 and a weight average particle diameter of 7.8 μm were used, and this was added to the coating solution so as to be 25 wt% with respect to the translucent resin (viscosity 71 mPa · S), and the coating line speed was 10 m / min. Except for the above, the light diffusion layer was formed in the same manner as in Example 1.

About the obtained light-diffusion layer, the total light transmittance and haze were measured like Example 1. As a result, the total light transmittance was 94.4% and haze was 79.6%. In addition, the locally calculated average spacing S, average spacing Sm, and ten-point average roughness Rz of the unevenness of the uneven surface of the light diffusing layer were measured in the same manner as in Example 1. As a result, the locally calculated average interval S was 57.4 µm, the average interval Sm was 102.1 µm, and the ten-point average roughness Rz was 7.2 µm. In addition, the aggregation state of the light-diffusion material in the light-diffusion layer was observed like Example 1. As a result, the maximum number of secondary particles having a diameter of 30 µm or more in a circular region having a radius of 70 µm at an arbitrary position on the surface of the light diffusion layer was at most five. The optical micrograph of this light-diffusion layer is shown in FIG.

A prism sheet was formed in the same manner as in Example 1 to obtain a prism sheet, and a surface light source device was manufactured in the same manner as in Example 1 using this prism sheet. In this surface light source device, the normal luminance and the half value angle were measured in the same manner as in Example 1. As a result, the normal luminance was 2621 mW / m 2 and the half value angle was 22.2 degrees.

Moreover, the liquid crystal display device was produced like Example 1 using this surface light source device. In this liquid crystal display, when the flash was observed in the same manner as in Example 1, a very strong flash phenomenon was observed, and only a very difficult image quality was obtained.

Comparative Example 2

As the light diffusing material, PMMA crosslinked fine particles having a refractive index of 1.49 and a weight average particle diameter of 8.0 μm were used, and this was added to the coating solution so as to be 20 wt% with respect to the translucent resin (viscosity 53 mPa · S), and the average thickness after solvent drying was 3 A light diffusing layer was formed in the same manner as in Example 1 except that the coating was performed so as to be 탆.

About the obtained light-diffusion layer, the total light transmittance and haze were measured like Example 1. As a result, the total light transmittance was 85.5% and the haze was 73.4%. In addition, the locally calculated average spacing S, average spacing Sm, and ten-point average roughness Rz of the unevenness of the uneven surface of the light diffusing layer were measured in the same manner as in Example 1. As a result, the locally calculated average interval S was 41.5 µm, the average interval Sm was 63.1 µm, and the ten-point average roughness Rz was 9.9 µm. In addition, the aggregation state of the light-diffusion material in the light-diffusion layer was observed like Example 1. As a result, the number of the secondary particle of 30 micrometers or more of long diameter in the circular area | region of 70 micrometers of radius of arbitrary positions of the surface of a light-diffusion layer was a maximum of four. The optical micrograph of this light-diffusion layer is shown in FIG.

A prism sheet was formed in the same manner as in Example 1 to obtain a prism sheet, and a surface light source device was manufactured in the same manner as in Example 1 using this prism sheet. In this surface light source device, the normal luminance and the half value angle were measured in the same manner as in Example 1. As a result, the normal luminance was 2373 dB / m 2, and the half value angle was 22.4 degrees.

Moreover, the liquid crystal display device was produced like Example 1 using this surface light source device. In this liquid crystal display, when the flash was observed in the same manner as in Example 1, a very strong flash phenomenon was observed, and only a very difficult image quality was obtained. In addition, since the total light transmittance was lowered, the normal luminance was lowered to 2373 Pa / m 2, and only a very dark screen could be obtained.

Comparative Example 3

A light diffusing layer was formed in the same manner as in Example 1 except that the light diffusing material was added to the coating liquid so as to be 15wt% based on the light transmitting resin (viscosity 41mPa · S), and the coating was performed so that the average thickness after drying the solvent was 15 μm. .

About the obtained light-diffusion layer, the total light transmittance and haze were measured like Example 1. As a result, the total light transmittance was 95.5% and the haze was 73.9%. In addition, the locally calculated average spacing S, average spacing Sm, and ten-point average roughness Rz of the unevenness of the uneven surface of the light diffusing layer were measured in the same manner as in Example 1. As a result, the locally calculated average interval S was 61.0 µm, the average interval Sm was 149.1 µm, and the ten-point average roughness Rz was 3.4 µm. In addition, the aggregation state of the light-diffusion material in the light-diffusion layer was observed like Example 1. As a result, the number of secondary particles of 30 micrometers or more in long diameter in the circular region of 70 micrometers of radius of arbitrary positions of the surface of a light-diffusion layer was 0 pieces. The optical micrograph of this light-diffusion layer is shown in FIG.

A prism sheet was formed in the same manner as in Example 1 to obtain a prism sheet, and a surface light source device was manufactured in the same manner as in Example 1 using this prism sheet. In this surface light source device, the normal luminance and the half value angle were measured in the same manner as in Example 1. As a result, the normal luminance was 2987 mW / m 2 and the half value angle was 20.4 degrees.

Moreover, the liquid crystal display device was produced like Example 1 using this surface light source device. In this liquid crystal display, when the flash was observed in the same manner as in Example 1, a very strong flash phenomenon was observed, and only a very difficult image quality was obtained.

[Comparative Example 4]

A transmissive liquid crystal panel was mounted on the prism sheet of the surface light source device produced as in Comparative Example 1. This liquid crystal panel had a 60 degree glossiness value G1 of 22.3 on the observation surface (nonglare surface) measured in the same manner as in Example 1, a 60 degree gloss value G2 of the incident surface (nonglare surface) on 29.8, and G1 / G2. The ratio was 0.75, the ten-point average roughness Rz of the observation surface was 2.29 µm, and the size was 14.1 W (wide) liquid crystal panel with the pixel count XGA. In this liquid crystal display device, the flashing was observed in the same manner as in Example 1, so that a stronger flashing phenomenon was observed even in comparison with Comparative Example 1, and only a very difficult image quality was obtained.

Example 4

TF-8 in a mixed solvent (mixing ratio of 50 wt%) of MEK (methyl ethyl ketone) and toluene using an acrylic resin having a refractive index of 1.49 (manufactured by Mitsubishi Rayon, trade name TF-8) as a light transmitting resin constituting the light diffusion layer. The light-diffusion layer was formed like Example 1 except having melt | dissolved so that the density | concentration of might be set to 20 wt%, and the coating liquid of viscosity 60mPa * S was produced.

About the obtained light-diffusion layer, the total light transmittance and haze were measured like Example 1. As a result, the total light transmittance was 95.6% and haze was 80.4%. Since the refractive indexes of the translucent resin and the light diffusing material were the same, a very high total light transmittance could be obtained. In addition, the locally calculated average spacing S, average spacing Sm, and ten-point average roughness Rz of the unevenness of the uneven surface of the light diffusing layer were measured in the same manner as in Example 1. As a result, the locally calculated average interval S was 43.5 µm, the average interval Sm was 53.3 µm, and the ten-point average roughness Rz was 3.9 µm. In addition, the aggregation state of the light-diffusion material in the light-diffusion layer was observed like Example 1. As a result, the number of the secondary particles of 30 micrometers or more of long diameter in the circular area | region of 70 micrometers of radius of arbitrary positions of the surface of a light-diffusion layer was at most one.

A prism sheet was formed in the same manner as in Example 1 to obtain a prism sheet, and a surface light source device was manufactured in the same manner as in Example 1 using this prism sheet. In this surface light source device, the normal luminance and the half value angle were measured in the same manner as in Example 1. As a result, the normal luminance was 2772 mW / m 2 and the half value angle was 21.8 degrees.

Moreover, the liquid crystal display device was produced like Example 1 using this surface light source device. In this liquid crystal display, when the glare was observed in the same manner as in Example 1, there was almost no glare phenomenon and an easy to see image quality with a very smooth texture was obtained.

The results of the above Examples and Comparative Examples are shown in Table 1 below.

Claims (13)

A plurality of lens rows are formed in parallel on the first surface of the sheet-like translucent member having a first surface and a second surface, the second surface is an uneven surface, and the uneven surface is a locally calculated average interval S Is 50 µm or less and the ten-point average roughness Rz is 4 µm or less. The method of claim 1, The sheet-like translucent member is formed by attaching a light diffusing layer to one surface of the light transmissive substrate, and the light diffusing layer contains a light transmissive material in the light transmissive resin, and the uneven surface has the light diffusing material from the surface of the light transmissive resin. It is formed by protruding, The lens sheet characterized by the above-mentioned. The method of claim 2, The light diffusion layer is a lens sheet, characterized in that the haze Hz is 50 ~ 85%. The method of claim 2, The light diffusion material is a lens sheet, characterized in that the weight average particle diameter D1 is 1 ~ 8㎛. The method of claim 2, A lens sheet, characterized in that, in a circular region having a radius of 70 µm at any position of the light diffusing layer, the number of secondary particles having a diameter of 30 µm or more formed by aggregation of a plurality of the light diffusing materials in the translucent resin is 3 or less. The method of claim 2, The difference between the refractive index N1 of the said translucent resin and the refractive index N2 of the said light-diffusion material is 0.03-0.06, The lens sheet characterized by the above-mentioned. A primary light source, a light guide in which light generated from the primary light source is introduced and guided and emitted, and the lens sheet according to claim 1 arranged to receive light emitted from the light guide, The light guide has a light incidence cross section through which light from the primary light source is incident and a light exit face through which the guided light is emitted, and the primary light source is disposed adjacent to the light incidence cross section of the light guide body, The lens sheet is disposed so that the first surface faces the light exit surface of the light guide. Surface light source device characterized in that. It consists of the surface light source device of Claim 7, and the liquid crystal panel arrange | positioned so that the light which light-emitted from the 2nd surface of the said lens sheet of the said surface light source device may inject, The liquid crystal panel having an incident surface on which light emitted from the second surface of the lens sheet is incident and an observation surface on the opposite side thereof; Liquid crystal display device characterized in that. The method of claim 8, The said observation surface is a nonglare surface, and 60 degree glossiness value G1 is 25 or more, The liquid crystal display device characterized by the above-mentioned. The method of claim 8, The observation surface is a glare surface, and a 60 degree glossiness value G1 is 90 or more. The method of claim 8, The incident surface is a non-glare surface, and the ratio G1 / G2 of the 60 degree gloss value G1 of the observation surface to the 60 degree gloss value G2 of the incident surface is 1 or more. The method of claim 8, 10-point average roughness Rz of the said observation surface is 2 micrometers or less, The liquid crystal display device characterized by the above-mentioned. The method of claim 8, And a light diffusing sheet disposed between the lens sheet and the liquid crystal panel so that light emitted from the second surface of the lens sheet is incident, wherein the light diffusing sheet has at least one surface as an uneven surface. The locally calculated average spacing S of the uneven surface is 50 µm or less, and the ten-point average roughness Rz is 4 µm or less.

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