JP2002250917A - Front light device having antireflection property and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reflection of the light incident through the back side of a light guide plate without substantially increasing the thickness of the light guide plate and to improve the luminance when the device is viewed from the observation side. SOLUTION: In the liquid crystal display device 100 or the like, the following antireflection film 105 is laminated in the opposite side of a light guide plate 102 with a light source 101 to the observation side, with the light guide plate 102 disposed in the observation side of the display part such as a liquid crystal display part 103 having a reflector 104 on the lower face of the display part. The antireflection film 105 has an antireflection layer which is made of a transparent raw material and is composed of a great number of minute recesses and projections with pitches shorter than the wavelength of the light and the refractive index of which varies in the thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device such as a front light type liquid crystal display device, and more particularly, to a front light device that reflects light reflected from a display side such as a liquid crystal display portion of the front light device. The present invention also relates to a front light device that has been subjected to a process for making light incident effectively.

[0002]

2. Description of the Related Art Liquid crystal display devices have been widely used as display devices in various applications because of their low power consumption, thinness and light weight. In particular,
In most cases, a liquid crystal display is used in a display for a portable small computer such as a handheld or a palmtop, or a mobile phone or other communication terminal. Efforts to reduce size, thickness, or weight continue.

A liquid crystal display portion having a structure in which a liquid crystal layer is sandwiched between glass plates having transparent electrodes does not emit light by itself. As one means for reducing the thickness, there is a movement to make this lighting means a front light type.

FIG. 1 is a view showing a state in which a front light device is applied.
Represents the light guide plate 10 from the observation side (the upper side in FIG. 1).
2. The liquid crystal display unit 103 and the reflection plate 104 are arranged in this order. The light guide plate 102 is formed of a transparent plate-like body, and each ridge line (not necessarily clear in the drawing, the top of the convex portion is a line extending in the direction from the near side to the far side of the paper) on the surface on the observation side. ) Is a parallel prism array formed, and this structure is more compact. However, an inclined surface having a uniform inclination may be formed on the observation surface side. Further, the opposite side of the light guide plate 102 from the observation side is a flat surface. Further, the light guide plate 102
A light source unit 101 is disposed at an end of the light source unit 10.
1 is a rod-like light source 1 such as a cold cathode fluorescent tube or an LED
01a and a reflector 101b that covers the light source and has an opening on the light guide plate 102 side. FIG.
In the embodiment, the light source unit 101 is disposed only at the left end. However, the light source unit 101 may be disposed on both the left and right sides, or may be disposed over the entire circumference of the light guide plate 102.

In a liquid crystal display device having such a front light device, light emitted from the light source unit 101 enters the light guide plate 102 and repeats irregular reflection in the light guide plate 102, and then repeats the light reflection on the liquid crystal display unit 103 side. Idemitsu. Then, the light that has entered the liquid crystal display unit 103 exits on the back surface side of the light guide plate 102 (the lower surface side in FIG. 1), is reflected by the reflection plate 104, passes through the liquid crystal display unit 103 again, and The light enters the light guide plate 102 and exits to the observation side. Since the light emitted from the light source 101 follows such an optical path, it is reflected or refracted at each interface and attenuates. In particular, the light returned from the liquid crystal display 103 is transmitted to the light guide plate 102. At the time of incidence, there is a great need to make this light effectively enter from the back side of the light guide plate 102.

[0006] Conventionally, the light guide plate 102 has been processed to have a matte finish on the front and back sides, or as shown in Japanese Patent Application Laid-Open No. 2000-19330, the surface of the non-observation side of the light guide plate has a rectangular wave-shaped cross section. It is larger than that of the present invention, and is described as having a depth of about 10 μm and a width of about 25 μm as an example.)
Attempts have been made to provide a light guide plate, but all of these processes tend to increase the thickness of the light guide plate, which is contrary to the reduction in weight and thickness. Also, JP-A-2000-275
Japanese Patent No. 637 describes a light control film in which light transmittance is continuously changed in a plane direction of the film. The light control film is a light source disposed at an end of a liquid crystal display. This is for making the light from the unit uniform over the entire surface of the display, and not for making effective use of the incident light from the back side of the light guide plate 102.

[0007]

SUMMARY OF THE INVENTION In the present invention, the reflection of light incident from the back side of the light guide plate is prevented without causing a substantial increase in the thickness of the light guide plate, so that the light guide plate when viewed from the observation side can be prevented. It is an object to improve luminance.

[0008]

Means for Solving the Problems The same applicant as the present invention is disclosed in Japanese Patent Application No.
In 000-74347, an antireflection film having an uneven portion formed with fine unevenness having a pitch equal to or less than the wavelength of light has already been proposed, and this antireflection film is used on the observation side of various display devices. It prevents reflection of external light and makes it possible to view high-luminance images or images.However, when applied to the back of the front light type illumination means, it prevents reflection from the display unit side. As a result, it has been found that the light can be effectively incident, and as a result, the reflected light from the liquid crystal display unit can be effectively used.

A first invention comprises a transparent light guide plate and a light source unit disposed on an end face of the light guide plate and for entering light into the light guide plate, wherein the light guide plate has a uniform inclination on the observation side. The light incident on the light guide plate is reflected and emitted to the non-observation side by having a prism array having parallel ridges. On the non-observation side of the light plate, formed of a transparent material, consisting of countless fine irregularities with a pitch less than the wavelength of light,
The present invention relates to a front light device having antireflection performance, characterized in that an antireflection layer whose refractive index changes in the thickness direction is laminated. According to a second aspect, in the first aspect, the antireflection film in which the antireflection layer including the fine irregularities is laminated on one side of the transparent film, wherein the transparent film side faces the light guide plate side, 2. A front light device having antireflection performance according to claim 1, wherein fine irregularities are formed by being laminated on the light guide plate. The third invention is the first invention
Alternatively, in the second invention, the anti-reflection layer relates to a front light device having anti-reflection performance, wherein the anti-reflection layer is laminated on the light guide plate via an adhesive layer. A fourth invention is characterized in that, in any one of the first to third inventions, the fine unevenness is formed using a mold in which fine unevenness is formed on a photosensitive resin by a laser light interference method. The present invention relates to a front light device having anti-reflection performance. The fifth invention relates to the first to fifth aspects.
In any one of the third inventions, the fine irregularities are formed using a mold in which fine irregularities are formed by an electron beam etching method on a glass substrate or a metal layer on a glass substrate having a metal layer formed on the surface. The present invention relates to a front light device having anti-reflection performance, characterized in that the front light device is characterized in that: A sixth invention relates to a display device, wherein the front light device according to any one of the first to fifth inventions is arranged on a front surface of a display unit. A seventh invention is directed to the display device according to the sixth invention, wherein the display unit is a liquid crystal display unit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, the liquid crystal display device of the present invention has substantially the same structure as that of the conventional liquid crystal display device shown in FIG. The light source unit 101 includes a transparent light guide plate 102 having an anti-reflection film 105 on the lower surface side, a liquid crystal display unit 103, and a reflector plate 104. The light source unit 101 is disposed on an end surface of the light guide plate 102, and the light guide plate 102 The display unit 103 and the reflection plate 104 are arranged so as to be parallel to each other. The display device shown in FIG. 2 is merely an example, and any type of a reflective display unit provided with a reflective display unit and a light guide plate and a lighting device on its observation side. The present invention is also applicable to a device having a front light device.

The light guide plate 102 is formed of a transparent plate-like body, and has a prism array whose ridge lines are parallel to each other on the surface on the observation side (the upper surface in the figure). Is a flat surface. Of course, on the observation side,
An inclined surface having a uniform inclination may be formed.

The light source 101 includes a rod-shaped light source 101a such as a cold cathode fluorescent tube or an LED, and a reflector (reflection plate) 101b which covers the light source 101a and has an opening having a fixed width on the light guide plate 102 side. The opening faces the end surface of the light guide plate 102. The light source unit 1
The position of 01 is not limited only to the left end, and may be arranged on both the left and right sides or the entire circumference.

In the present invention, an antireflection film 105 is laminated on the lower surface of the light guide plate 102, and the antireflection film 105 has irregularities on the lower surface side.
For example, as shown in FIG. 3, on the transparent film 1, formed of a transparent material and having a pitch equal to or less than the wavelength of light, that is, fine irregularities 2 (hereinafter, "fine irregularities having a pitch equal to or less than the wavelength of light"). Is also simply referred to as fine irregularities.). The anti-reflection film shown in FIG. 3 is shown upside down with respect to the anti-reflection film 105 shown in FIG. Light guide plate 102 and antireflection film 1
05 and the transparent film 1 may be appropriately laminated, for example,
It may be performed through a transparent adhesive layer or by a method of mechanically fixing. The former has the advantage that the adhesion is reliable over the entire surface. In the present invention, for the purpose of preventing reflection of the light guide plate 102, as described above,
It is not necessary to have the transparent film 1, and it is sufficient that the transparent film 1 has only a transparent layer 3 formed of a transparent material and having a pitch equal to or less than the wavelength of light, that is, having a large number of fine irregularities 2. The transparent layer 3 may be directly laminated on the light guide plate, or may be laminated via an adhesive layer.

Therefore, the above-mentioned antireflection film 105,
The fine irregularities 2 and the like serving as points will be described below.

As shown in FIG. 3A, the anti-reflection film 105 is composed of, for example, a myriad of fine irregularities 2 having a pitch equal to or less than the wavelength of light on a transparent base film 1 and refracting light in the thickness direction. A transparent layer 3 (functionally an anti-reflection layer) whose rate changes is laminated. The transparent layer 3 is usually a continuous layer connected in the plane direction of the transparent substrate film, but may be composed of a large number of convex portions separated from each other.

As shown in FIG. 3B, the antireflection film 105 is obtained by further laminating a surface layer 4 made of another transparent layer having a different refractive index of light on the uneven portion 2 on the surface of the transparent layer 3. It may be. Although the upper surface of the surface layer 4 is illustrated as being flat in the figure, the upper surface may have a shape conforming to the shape of the uneven portion 2. The surface layer 4 may be formed so that the upper surface thereof is constant at the same height as the top of the uneven portion 2 as shown in the figure, but may be formed higher than the top of the unevenness or formed lower than the top of the unevenness. It could be.

In any of the examples shown in FIGS. 3A and 3B, the transparent base film 1 may be omitted. In addition, in each of FIGS. 3A and 3B and the examples described below, the uneven portions 2 are not limited to those formed on only one surface of the antireflection film 1. The uneven portion 2 may be formed on both surfaces.

The transparent substrate film 1 is preferably one having transparency and smoothness and free of foreign matter.
Those having mechanical strength are preferred for processing and product use reasons. Further, when the heat of the display is transmitted to the antireflection film, a film having heat resistance is preferable.

In general, the transparent substrate film 1 is preferably made of various polyesters represented by cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, polyethylene terephthalate, polyamide, polyimide, polyether sulfone, polysulfone, polypropylene, It is a film of a thermoplastic resin such as polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, or polyurethane.

Of the above, in the case of a photographic film coated with a photographic emulsion, a polyester which is often used is preferred in view of mechanical strength and coating suitability. Cellulose triacetate and the like are preferable in terms of high transparency, no optical anisotropy, and low refractive index. Polycarbonate is preferred in terms of transparency and heat resistance.

Although these thermoplastic resin films are flexible and easy to use, there is no need to bend them even during handling, and when a hard material is desired, a plate-like material such as the above resin plate or glass plate can be used. Can also be used. The thickness is preferably about 8 to 1000 μm, and is preferably 25 to 3 μm.
It is more preferably about 00 μm. In the case of a plate,
This range may be exceeded.

In order to improve the adhesiveness of the transparent substrate film 1 to the layers formed on the upper surface, or the upper and lower surfaces, various kinds of treatments that can be usually performed, that is,
In addition to a physical treatment such as a corona discharge treatment and an oxidation treatment, a primer layer (not shown) may be formed by applying a paint called an anchor agent or a primer in advance.

The transparent layer 3 having the irregularities 2 on which innumerable fine irregularities are formed can be made of a thermoplastic resin or a thermosetting resin, but is made of a cured product of an ionizing radiation-curable resin composition. Is preferred in terms of the production method. The ionizing radiation-curable resin composition has a high abrasion resistance after curing so that the curing rate when forming the uneven portion 2 by the casting method using a mold is high and the surface of the transparent layer 3 is not damaged. Those having properties are preferred. The hardness after curing of the ionizing radiation-curable resin composition is JIS K540.
Those showing a hardness of “H” or more in a pencil hardness test indicated by 0 are more preferable.

The refractive index of light of the transparent layer 3 is preferably low in order to exhibit anti-reflection performance. However, for long-term use as an anti-reflection film, the durability of the surface, especially the abrasion resistance, is low. It is necessary to increase the hardness, so that it is necessary to increase the density to increase the hardness. Therefore, the refractive index of light of the transparent layer 3 is 1.4 to 1.7,
More preferably, it is 1.6 or less.

The ionizing radiation-curable resin composition is obtained by appropriately mixing a prepolymer, an oligomer and / or a monomer having a polymerizable unsaturated bond or an epoxy group in a molecule. Ionizing radiation refers to electromagnetic waves or charged particle beams having energy quanta that can polymerize or crosslink molecules, and usually use ultraviolet rays or electron beams.

Examples of prepolymers and oligomers in the ionizing radiation-curable resin composition include unsaturated polyesters such as condensates of unsaturated dicarboxylic acids and polyhydric alcohols, polyester methacrylates, polyether methacrylates, polyol methacrylates, melamines. Methacrylates such as methacrylate, polyester acrylate,
Examples include acrylates such as epoxy acrylate, urethane acrylate, polyether acrylate, polyol acrylate, and melamine acrylate, and cationic polymerization type epoxy compounds.

Examples of monomers in the ionizing radiation-curable resin composition include styrene monomers such as styrene and α-methylstyrene, methyl acrylate, and acrylic acid-2-
Acrylic esters such as ethylhexyl, methoxyethyl acrylate, butoxyethyl acrylate, butyl acrylate, methoxybutyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methoxyethyl methacrylate, methacrylic acid Methacrylic esters such as ethoxymethyl, phenyl methacrylate and lauryl methacrylate; 2- (N, N-diethylamino) ethyl acrylate; 2- (N, N-dimethylamino) ethyl acrylate; -2 acrylic acid -(N, N-dibenzylamino) methyl, unsaturated substituted substituted alcoholic esters such as 2- (N, N-diethylamino) propyl acrylate, unsaturated carboxylic acid amides such as acrylamide and methacrylamide, ethylene Guri Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, triethylene glycol diacrylate, and other compounds, dipropylene glycol diacrylate, ethylene glycol diacrylate, propylene glycol dimethacrylate, diethylene glycol Polyfunctional compounds such as dimethacrylate and / or polythiol compounds having two or more thiol groups in the molecule, such as trimethylolpropane trithioglycolate, trimethylolpropane trithiopropylate, pentaerythritol tetrathioglycolate, etc. Is mentioned.

Usually, as the monomer in the ionizing radiation-curable resin composition, one or a mixture of two or more of the above compounds is used as necessary. In order to provide suitability, it is preferable that the content of the prepolymer or oligomer is 5% by weight or more and the content of the monomer and / or polythiol compound is 95% by weight or less.

When flexibility is required when the ionizing radiation-curable resin composition is cured, the amount of the monomer may be reduced or an acrylate monomer having one or two functional groups may be used. When abrasion resistance, heat resistance, and solvent resistance are required when the ionizing radiation-curable resin composition is cured, an ionizing radiation-curable resin such as an acrylate monomer having three or more functional groups is used. Composition design is possible. Here, assuming that the functional group is 1, 2-
Hydroxy acrylate, 2-hexyl acrylate,
Phenoxyethyl acrylate is exemplified. As those having two functional groups, ethylene glycol diacrylate;
1,6-hexanediol diacrylate is exemplified. As those having three or more functional groups, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate,
And dipentaerythritol hexaacrylate.

In order to adjust physical properties such as flexibility and surface hardness when the ionizing radiation-curable resin composition is cured, a resin which is not cured by ionizing radiation irradiation is added to the ionizing radiation-curable resin composition. Can also. Examples of specific resins include the following. Thermoplastic resins such as polyurethane resin, cellulose resin, polyvinyl butyral resin, polyester resin, acrylic resin, polyvinyl chloride resin, and polyvinyl acetate. Above all, addition of a polyurethane resin, a cellulose resin, a polyvinyl butyral resin or the like is preferable from the viewpoint of improving flexibility.

When the ionizing radiation-curable resin composition is cured by ultraviolet irradiation, a photopolymerization initiator or a photopolymerization accelerator is added. As the photopolymerization initiator, in the case of a resin system having a radically polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether or the like is used alone or as a mixture. In the case of a resin system having a cationically polymerizable functional group, an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic iodonium salt, a metaceron compound, a benzoin sulfonic acid ester, or the like is used alone or as a mixture as a photopolymerization initiator. . The addition amount of the photopolymerization initiator is 0.1 to 1 with respect to 100 parts by weight of the ionizing radiation-curable resin composition.
0 parts by weight.

The following organic reactive silicon compound may be used in combination with the ionizing radiation-curable resin composition.

One of the organosilicon compounds has the general formula R _m Si
(OR ') _n and R and R' have 1 carbon atom
Represents an alkyl group of 10 to 10, and the suffix m of R and the suffix n of R ′ are each an integer satisfying a relationship of m + n = 4.

Specifically, tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane , Tetrapentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-
Butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane,
Dimethyldiethoxysilane, dimethylethoxysilane,
Dimethylmethoxysilane, dimethylpropoxysilane,
Examples include dimethylbutoxysilane, methyldimethoxysilane, methyldiethoxysilane, hexyltrimethoxysilane, and the like.

The organosilicon compound 2 which can be used in combination with the ionizing radiation-curable resin composition is a silane coupling agent.

Specifically, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, β-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ
-Methacryloxypropylmethoxysilane, N-β-
(N-vinylbenzylaminoethyl) -γ-aminopropylmethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, aminosilane, methylmethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ- Chloropropyltrimethoxysilane, hexamethyldisilazane, vinyltris (β-methoxyethoxy) silane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, methyltrichlorosilane, dimethyldichlorosilane and the like can be mentioned.

The organosilicon compound 3 that can be used in combination with the ionizing radiation-curable resin composition is an ionizing radiation-curable silicon compound. Specific examples include a plurality of functional groups that react and crosslink by irradiation with ionizing radiation, for example, an organosilicon compound having a molecular weight of 5,000 or less and having a polymerizable double bond group, and more specifically, one end. Examples include vinyl-functional polysilanes, vinyl-functional polysilanes at both ends, vinyl-functional polysiloxane at one terminal, vinyl-functional polysiloxane at both terminals, and vinyl-functional polysilane or vinyl-functional polysiloxane obtained by reacting these compounds.

More specifically, the following compounds are used.

[0039]

Embedded image

Other organosilicon compounds that can be used in combination with the ionizing radiation-curable resin composition include (meth) acrylonitrile such as 3- (meth) acryloxypropyltrimethoxysilane and 3- (meth) acryloxypropylmethyldimethoxysilane. Acryloxysilane compounds and the like can be mentioned.

The shape of the fine irregularities 2 having a pitch equal to or less than the wavelength of light formed on the upper surface of the transparent layer 3 is shown in FIGS.
In addition to the shape of the fine unevenness 2 at the upper edge of the cross section as exemplified in FIG. 4A, the top 2a of the cross section as shown in FIG. FIG. 4 shows a straight-line shape, with the shape decreasing toward the top.
FIG. 4 shows a triangular wave shape with a sharp upper side as shown in FIG.
There can be various variations, such as a trapezoidal one whose cross section is as shown in FIG.

FIGS. 3 and 4 show the shapes of the fine irregularities.
4A, 4B, 4C, and 4D are preferable. When such a cross-sectional shape is used, the thickness direction of the transparent layer 3 is reduced. Depending on the position, the property that the refractive index of light changes continuously is imparted. In particular, when the shape shown in FIG. 3A, FIG. 4A, FIG. 4B, and FIG. 4C is present in the air, the transparent layer 3 Since the proportion of 3 present is infinitely close to 0%, the refractive index of the transparent layer is substantially lower than that of the surrounding substance (air in a normal living space, which is clearly lower than that of the transparent layer; .0), and at the lowermost part of the unevenness, the ratio of the transparent layer present is infinitely close to 100%. Therefore, it is equal to the refractive index of the material constituting the transparent layer 3, and in the middle part, The transparent layer 3 has a refractive index proportional to the area ratio of the transparent layer 3 at that height (that is, the ratio of the cross-sectional area of the transparent layer 3 at the slice level to the entire area). The property that the refractive index changes continuously between the refractive index of air and the refractive index of the transparent layer It has a function as an antireflection layer having a.

In the case of the fine irregularities having a sectional shape shown in FIG. 3B, the uppermost part of the transparent layer 3 is actually the transparent layer 4.
Is as close as possible to 100%, so that the top of the fine irregularities 2 has the refractive index of the transparent layer 4 and the lowest part of the irregularities is equal to the refractive index of the material forming the transparent layer 3 as in the previous example. The intermediate portion has a function as an antireflection layer having a property that the refractive index continuously changes depending on the area ratio of the transparent layer 3 and the area ratio of the transparent layer 4 at that height. Further, in the case of fine irregularities having a cross-sectional shape as shown in FIG. 4D, at the top of the transparent layer 3, the area ratio of the transparent layer 3 existing there and the refractive index determined by the refractive indexes of the transparent layer 3 and air. In the lowermost part of the unevenness, as in the previous example, the transparent layer 3
The intermediate portion has a function as an antireflection layer having a property that the refractive index continuously changes in proportion to the area ratio of the transparent layer 3 at that height. Although not shown, the unevenness having the shape shown in FIGS. 4 (b), 4 (c) and 4 (d) has different refractive indexes as described with reference to FIG. 3 (b). The transparent layer 4 may be stacked or the irregularities 2 may be filled.

As is clear from the above description, on the contrary,
Given the desired relationship between the position in the thickness direction and the refractive index, it is possible to design the cross-sectional shape of the fine irregularities 2. Depending on the cross-sectional shape, either a continuous or discontinuous change in the refractive index can be formed, but for a discontinuous refractive index, layers with different refractive indices should be stacked. Rather, it is preferable that the antireflection film of the present invention is manufactured so that the refractive index changes continuously, and the refractive index is changed from the refractive index of air to the refractive index of the transparent layer 3. More preferably, it changes continuously up to.

When observing the transparent layer 3 having such a cross-sectional shape from the side having the concave-convex portions 2, the concave-convex portion 5 shown in FIG. As shown in FIG. 5 (b) or FIG. 5 (c) as viewed from above (concentric circles indicate contour lines), there may be ones arranged in a plane and arranged in parallel. . Both types have anti-reflective properties,
Since the groove type shown in FIG. 5A has directionality, the reflectance changes depending on the direction of incident light.
On the other hand, those having fine unevenness in a two-dimensional array in which the unevenness 2 is two-dimensionally arranged as shown in FIG. 5B or FIG. 5C are preferable because they have virtually no directionality. Of course, as shown in FIG. 5 (b) or FIG. 5 (c), the shape of the projections of the two-dimensionally arranged irregularities 2 is changed to an elliptical shape (in this figure, the projections are circular). Can be given a direction.

Although the shape of the uneven portion 2 itself can be various, the pitch (= period) of the wave of the unevenness appearing in the sectional shape
Must be finer than the wavelength of light, and the pitch is preferably 300 nm or less. The accuracy of the type,
In consideration of the reproducibility of the mold in the product, the pitch is preferably 100 nm or more, but there is no particular lower limit, and the pitch may be finer. It is preferable that the height difference is 100 nm or more, because the unevenness portion 2 has a larger difference in height and has a lower reflectance and an antireflection effect. There is no particular upper limit, but a normal pitch of 200 nm to 30
Assuming 0 nm, the pitch value is preferably about 50% to 200%, and more preferably about 100 nm to 600 nm. Of course, some may fall outside these ranges.

In order to form an uneven portion composed of fine unevenness on the upper surface of the transparent layer 3 using the ionizing radiation-curable resin composition, for example, when forming the transparent layer 3, a molding film having unevenness Cured while the coating film is coated with, or by applying a molding means such as a molding roll to the formed coating film while heating, if necessary, or a releasable substrate having irregularities on the release surface For example, a method of preparing a transfer film capable of transferring the transparent layer 3 by coating and forming the same thereon, and performing transfer using the transfer film may be employed.

A more preferable forming method is as follows.
First, a material obtained by laminating a photosensitive resin on an appropriate base material is prepared, and this is exposed by a laser light interference method. As the photosensitive resin, in addition to a general resin, a photosensitive material with a film which is commercially available for the production of a relief hologram can be used. It is an effective method. Exposure is performed by splitting the laser beam into two or more beams and causing interference, to obtain a cured portion and an uncured portion having a pitch equal to or less than the wavelength of the light. After exposure, a development method according to the type of the photosensitive resin, usually by removing uncured portions with a specific solvent, development is performed, and a pitch-shaped uneven surface with a myriad of fine irregularities whose pitch is equal to or less than the wavelength of light is formed. To obtain a prototype having
In addition, there is a sandblasting method for obtaining a prototype having an uneven surface with a myriad of fine irregularities having a pitch equal to or less than the wavelength of light by a method other than the laser light interference method. Also, by performing electron beam etching in photomask production on an appropriate substrate, for example, on a glass substrate or a metal layer on a glass substrate having a metal layer formed on the surface, the pitch can be adjusted to the wavelength of light. A prototype having an uneven mold surface on which the following innumerable fine irregularities are formed can be obtained.

The resulting prototype is made of a polymer having a relatively small molecular weight in order to facilitate the formation of irregularities, so that it has insufficient durability against solvents and is brittle. Doing duplication using
Not always preferred. Therefore, the first mold is plated with a metal such as nickel to form a first metal mold, and the first metal mold is used, or the first metal mold is plated. Then, it is preferable to form several second metal molds and use the obtained second metal mold to perform duplication. Note that these metal molds are often referred to as metal stampers.

More preferably, the shape of the mold surface obtained in this way is formed on a roll surface, and if necessary, a mold roll obtained by multiplying the plate (by applying multiple surfaces on the same plate surface), It is preferable to use a mold roll in which the shape of the mold surface is continuously formed in the surface length direction and the circumferential direction of the roll.

When duplicating the shape of the mold surface, the original mold and the second metal mold have the same shape, and the original mold and the first metal mold have an inverse relationship to each other. . Further, the shape of the fine irregularities of the antireflection film and the shape of the fine irregularities of the mold surface on the mold for manufacturing the antireflection film are reversed. Therefore, in order to obtain a desired shape as an anti-reflection film, it is preferable to further form a metal mold by plating to reverse the shape of the fine unevenness, if necessary. However, there are cases where there is no difference between the original mold shape and the inverse mold shape, such as a sinusoidal cross section of the fine unevenness. Except for the above exceptions, the anti-reflection film, as the fine irregularities on the mold surface of the mold used in the following description, is assumed to be formed in an inverted mold so that the desired fine irregularities can be obtained. .

FIG. 6 shows a state in which the antireflection film 105 is manufactured by using the apparatus 10 for continuously manufacturing the antireflection film 105 by using a mold roller. In FIG. 6, the transparent substrate film 1 is unwound from the upper left side in the figure, and is guided between the nip roller 11a and the mold roller 12,
After making a half turn around the upper side of the mold roller 12, the nip roller 11b
And is discharged in the right direction. The mold roller 12 is driven so as to rotate in the clockwise direction indicated by an arrow in the mold roller 12, and the nip roller 11a,
And 11b are configured to rotate together with the rotation of the mold roller (the direction of rotation is indicated by an arrow in the roller). Further, a brake is installed on the unwinding side of the transparent base material film 1, and the tension during running can be adjusted by a winding motor installed on the discharge side. The tension between the nip rollers 11a and 11b is kept constant.

Immediately below the mold roller 12, a die head 13 is provided.
The die head 13 has a liquid reservoir 1 inside.
4. It has a slit 15 above and is configured to be supplied with an ionizing radiation-curable resin composition 17 from the outside via a pipe 16. A required amount of the ionizing radiation-curable resin composition 17 is extruded upward from the slit 15 in accordance with the travel of the transparent base film 1, applied to the surface of the mold roller, and ionized into the concave portion 12 a of the mold roller 12. When the radiation-curable resin composition 17 is filled and passes between the nip roller 11a and the mold roller, the amount of application is regulated.

Above the mold roller 12, an ionizing radiation irradiating device 18 is installed. When the ionizing radiation irradiates when passing under the irradiating device 18, the ionizing radiation curable resin composition on the transparent substrate film 1 is formed. The object is cross-linked and cured, and the transparent layer 3 and the transparent substrate film 1 adhere to each other. Thereafter, the antireflection film 105 having the transparent layer 3 which has been released from the mold roller and cured and is provided on the transparent base material film 1 is wound by the roller 11b.

When the transparent substrate film 1 is laminated, at least the concave portion 12a on the surface of the mold roller 12 is filled, and the transparent substrate film is in contact with the exposed surface of the filled ionizing radiation-curable resin composition. Sufficient, when not using a transparent substrate film, it is good to apply a sufficient amount of the ionizing radiation-curable resin composition so that the ionizing radiation-curable resin composition forms a continuous film on the mold surface. . In the example shown in the figure, the ionizing radiation-curable resin composition is applied to the mold roller 12, and this is more preferable. However, if it is possible to prevent air bubbles from being trapped during lamination, the ionizing radiation-curable resin composition may be used. May be applied to the transparent substrate film 1 side and then contact the mold roller 12.

After the ionizing radiation-curable resin composition is applied to the surface of the mold roller 12, doctoring may be performed if necessary. In the above, as the ionizing radiation, ultraviolet rays or electron beams are usually used, but other than these may be used. Further, the irradiation position is not limited to the upper one position, and irradiation may be performed by installing a desired number of ionizing radiation irradiation devices at an arbitrary position immediately after the application and before passing through the nip roller 11b. . Also, the mold roller 12
If a sufficient place cannot be secured around the nip roller 11b, irradiation may be performed by further installing an ionizing radiation irradiation device at a position after exiting the nip roller 11b.

The irradiation of ionizing radiation cures the ionizing radiation-curable resin composition 17 and produces an adhesive force between the resin composition 17 and the transparent substrate film 1. An antireflection film having a transparent layer 3 made of a cured ionizing radiation-curable resin composition laminated on a base film 1 and having fine irregularities on the surface of the transparent layer 3 reflecting the fine irregularities on the mold surface. Is obtained.

In order to obtain an antireflection film without a transparent substrate film, there is a method in which the lamination of the transparent substrate film is omitted, but the ionizing radiation-curable resin composition of the transparent substrate film 1 is used. The surface on the side to be applied is provided with releasability, and the transparent layer is separated from the mold surface and the transparent substrate film 1 is separated at the same time, or the transparent layer 3 is removed after only the transparent substrate film 1 is removed first. The antireflection film without the transparent substrate film 1 can also be obtained by peeling or by peeling the transparent substrate film 1 after peeling them together. It is preferable to use the transparent substrate film 1 during the process because the thickness of the transparent layer 3 can be easily regulated and the influence of dust in the air can be avoided.

The anti-reflection film 105 exhibits a sufficient effect even when the fine irregularities 2 are exposed on the surface, but is more refracted than the transparent layer 3 in terms of preventing damage and contamination due to careless contact. It is preferable that a low refractive index layer 4 made of a resin composition having a low refractive index is laminated on the fine unevenness 2.

When the low refractive index layer 4 is formed of a fluorine resin or silicone resin material, the cured product of the ionizing radiation-curable resin composition has a refractive index of 1.3 to 1.4 in all cases. Is preferable since it is lower than the general refractive index of the transparent layer 3 (which is a cured product of an acrylate resin composition and the refractive index of light is 1.5 or more).
Since these materials have a contact angle with water of 100 degrees or more, they also have antifouling properties and are therefore preferable. When it is not necessary to provide the low refractive index layer 4 with a special function by using the above-mentioned fluororesin or silicone resin, the fluororesin selected in consideration of adhesion to the lower transparent layer 3 The low-refractive-index layer 4 may be made of a thermoplastic resin other than the silicone resin.

These materials may be formed by either a dry process such as vapor deposition or a wet process such as ordinary coating. Alternatively, a method in which the transparent layer 3 is preliminarily applied to a mold surface for providing fine irregularities, and an ionizing radiation-curable resin composition is applied thereon, and a method of laminating the transparent layer 3 may be employed. Alternatively, when the above-mentioned fluorine-based resin or silicone-based resin is mixed with an ionizing radiation-curable resin composition for forming the transparent layer 3 to form the transparent layer 3, Bleed out.

The anti-reflection film 105 has, in addition to the above-described structure, an antistatic treatment for preventing dust from adhering at the time of use, and fine irregularities 2 in consideration of convenience when applying the anti-reflection film. For example, an adhesive process may be performed on the side opposite to the side having the adhesive.

The antistatic treatment can be specifically performed by applying an antistatic agent or conductive fine particles. When the transparent layer 3 or the surface layer 4 is formed by coating, it is mixed with a coating composition to be used. It is good to apply. Alternatively, the antistatic treatment may be performed by applying an antistatic agent alone on the transparent layer 3. A conductive layer formed using a coating composition containing conductive fine particles between the base film 1 and the transparent layer 3 when the transparent layer 3 is provided below or with the transparent base film 1 Alternatively, an antistatic treatment may be performed by forming a metal oxide thin film.

The adhesive processing may be carried out by directly applying a polyacrylic acid ester or a rubber-based adhesive. However, it is usually applied by laminating a release paper coated with an adhesive and releasing the release paper. In order to prevent the adhesive from being exposed and inadvertently adhering or dust from adhering, it is preferable to keep the sticker until it is used. The thickness of the pressure-sensitive adhesive layer is preferably about 20 to 40 μm.

In the present invention, in order to apply the anti-reflection film 105 to the front light device, in any case, the transparent base film 1 side of the anti-reflection film and the back surface side of the light guide plate 102 are laminated via an adhesive layer. There is a so-called lamination method. The adhesive layer may be applied to one or both at the time of lamination, or may be applied in advance to the exposed surface side of the transparent base film 1 of the antireflection film 105.

The anti-reflection film 1 was added to the front light device.
To apply No. 05, in the process of manufacturing the light guide plate 102,
There is a method in which the antireflection film 105 is applied, or only the transparent layer 3 having the uneven portions 2 is applied.

When the light guide plate 102 is manufactured by casting polymerization of an acrylic resin or the like, a mold shape for obtaining the concavo-convex portion 2 is formed inside a mold for manufacturing the light guide plate 102. By performing casting polymerization using such a mold, the uneven portion 2 is formed. In this case, the uneven portion 2 and the light guide plate 105 are made of the same material, and the material is continuous. can get.

When the light guide plate 102 is manufactured by injection molding, an anti-reflection film is set in a mold,
Lamination can be performed using heat and pressure at the time of injection. When the light guide plate 102 is manufactured by hot pressing, an anti-reflection film can be set on any appropriate side of the material and can be laminated simultaneously with hot pressing. In the above description, the application of the antireflection layer or the antireflection film to the non-observation side of the light guide plate has been described. This is because when using a front light device, it is a point to improve the brightness of the image.However, the observation side of the light guide plate may also reflect external light such as indoor lighting or sunlight, and may impair the contrast of the image. Therefore, the anti-reflection layer or the anti-reflection film as described above can also be applied to the observation side of the light guide plate, applied to one of the observation side of the light guide plate, or the non-observation side, when applied to only one side On the other side, there may be a case where anti-reflection means is taken and a case where no anti-reflection means is taken.

[0069]

According to the first aspect of the present invention, the anti-reflection layer whose refractive index changes in the thickness direction is laminated on the non-observation side of the front light device. Reflection can be effectively suppressed, the brightness of the image when viewed from the observation side is improved, and the anti-reflection layer is made up of fine irregularities, so the increase in thickness due to the improved anti-reflection function is suppressed. It is possible to provide a front light device having anti-reflection performance, which is capable of performing the above. According to the invention of claim 2, in addition to the effect of the invention of claim 1, since the anti-reflection layer has the form of an anti-reflection film laminated on a transparent substrate film, the production and the apparatus of the anti-reflection layer It is possible to provide a front light device having an anti-reflection performance, which can be easily applied to a front light device. According to the invention of claim 3, in addition to the effect of the invention of claim 1 or claim 2,
Since the anti-reflection layer is laminated via the adhesive layer, it is possible to provide a front light device having anti-reflection performance in which the lamination of the anti-reflection layer on the light guide plate is stable over the entire surface. According to the fourth aspect of the present invention, it is possible to provide a front light device having antireflection performance, which can utilize a method which is stably used at the time of manufacturing a hologram and can easily mass-produce fine irregularities. According to the invention of claim 5,
It is possible to provide a front light device having antireflection performance, which can utilize a method which is stably used for forming a photomask or the like and which can easily mass-produce fine irregularities. According to the invention of claim 6, it is possible to provide a display device having a front light device having the effect of any one of claims 1 to 5. According to the invention of claim 7,
A liquid crystal display device having the effects of the invention of claim 6 can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional example of a front light type liquid crystal display.

FIG. 2 is a diagram showing a front light type liquid crystal display of the present invention.

FIG. 3 is a view showing the shape of unevenness of an antireflection film.

FIG. 4 is a view showing the shape of unevenness of another antireflection film.

FIG. 5 is a diagram showing an arrangement of irregularities.

FIG. 6 is a diagram showing a method for producing fine irregularities.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 100 Liquid crystal display 101 Light source part (101a; light source, 101b; reflector) 102 Light guide plate 103 Liquid crystal display part 104 Reflector 105 Antireflection film 1 Transparent base film 2 Uneven part 3 Transparent layer 4 Surface layer 11 Nip roll 12 Type roll 13 Die head 14 Reservoir 15 Slit 16 Pipe 17 Ionizing radiation curable resin composition 18 Ionizing radiation irradiation device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G09F 9/00 336 G09F 9/00 336B F term (Reference) 2H042 BA03 BA12 BA20 CA12 2H091 FA14X FA23X FA31X FA37X FA41X FB02 FC19 FC25 FD06 LA30 5G435 AA03 AA18 BB12 BB16 EE22 FF08 GG24 HH02

Claims (7)

[Claims] 1. A light guide plate, comprising: a transparent light guide plate; and a light source unit disposed on an end face of the light guide plate and configured to allow light to enter the light guide plate, wherein the light guide plate has a uniform inclination on the observation side. ,
Alternatively, by forming a prism array in which each ridge line is parallel, the light incident on the light guide plate is configured to be reflected and emitted to the non-observation side, and the non-observation side of the light guide plate is configured. The anti-reflection performance is characterized by being laminated with an anti-reflection layer formed of a transparent material, consisting of countless fine irregularities with a pitch equal to or less than the wavelength of light, and changing the refractive index of light in the thickness direction. Having a front light device. 2. An antireflection film in which an antireflection layer comprising the fine irregularities is laminated on one side of a transparent film,
The front light device having antireflection performance according to claim 1, wherein the transparent film side faces the light guide plate side, and fine irregularities are formed by being laminated on the light guide plate. 3. The front light device having antireflection performance according to claim 1, wherein the antireflection layer is laminated on the light guide plate via an adhesive layer. 4. The method according to claim 1, wherein the fine irregularities are formed using a mold in which fine irregularities are formed on a photosensitive resin by a laser light interference method. Front light device with anti-reflection performance. 5. The fine irregularities are formed by using a mold in which fine irregularities are formed on a glass substrate or a metal layer on a glass substrate having a metal layer formed on the surface by an electron beam etching method. The front light device having anti-reflection performance according to any one of claims 1 to 3. 6. A display device, wherein the front light device according to any one of claims 1 to 5 is arranged on a front surface of a display unit. 7. The display device according to claim 6, wherein the display unit is a liquid crystal display unit.