JP2000206306A - Antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection film of low reflectance over a wide range of wavelengths. SOLUTION: This antireflection film formed on at least one side of a light transmissive backing is characterized by being laminated with a first, a second and a third layer in order. The first layer is of refractive index 1.60-1.80 from the light transmissive backing side to air layer side and of optical film thickness 0.20λ-0.30λ. The second layer is of refractive index 2.0-2.45 and of optical film thickness 0.45λ-0.55λ. The third layer is of refractive index 1.35-1.52 and of optical film thickness 0.20λ-0.30λ and made from a material whose refractive index becomes larger with increasing wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an antireflection film.

[0002]

2. Description of the Related Art Conventionally, many display devices such as a CRT (cathode ray tube), a liquid crystal display device, and a PDP (plasma display panel) have external light incident on the screen of the display device regardless of whether indoors or outdoors. Used in environments. There is a problem that the display becomes difficult to see due to the reflection of the incident light on the surface. As a measure against this problem, display quality has been improved by providing an antireflection film on the surface of a light-transmitting substrate.

[0003] However, an antireflection film having a sufficient antireflection effect over the entire wavelength region of visible light has not been known so far.

[0004]

The inventors of the present invention have made intensive studies to develop an antireflection film having a low reflectance over a wide wavelength range, and have found that the antireflection film has a three-layer structure, It has been found that by making a layer having a property such that the wavelength dispersion of the refractive index is such that the refractive index increases as the wavelength increases, an effective antireflection effect can be obtained in the entire visible light region. Reached.

[0005]

That is, the present invention relates to an antireflection film provided on at least one surface of a light-transmitting substrate, wherein the refractive index is 1.60 from the light-transmitting substrate side to the air layer side.
A first layer having an optical thickness of 0.20λ to 0.30λ and a first layer having a refractive index of 2.0 to 2.45 and an optical thickness of 0.45λ to 0.55λ. Two layers, the refractive index is 1.35 to 1.52, and the optical film thickness is 0.20λ to 0.2.
It is an object of the present invention to provide an antireflection film characterized in that a third layer having a wavelength of 30λ and having a refractive index increasing with increasing wavelength is sequentially stacked.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The translucent substrate used in the present invention may have a planar shape such as a plate, a film, a sheet, or the like, or may have a curved surface such as a lens. .

The light-transmitting substrate has a refractive index of, for example, 1.48 to 1.60, and is not particularly limited as long as it has a light-transmitting property. Polymer, polyarylate polymer, polyester polymer, acrylic polymer, functional norbornene polymer, polysulfone,
Substrates made of resin such as polyethersulfone, and substrates made of glass are exemplified. Further, optical components such as a polarizing plate, an optical filter for a display device such as a CRT, and a touch panel may be used.

[0008] The translucent substrate may have an intermediate layer on its surface for improving the adhesion to the first layer. Examples of the intermediate layer for improving adhesion include a polymer film made of a polymer such as an acrylic resin, a urethane resin, a silicon resin, a cardo resin, and polysilazane. Further, SiOx, Al having a thickness of about 30 to 200
A layer made of 2O3 or the like or a layer made of Cr or the like can also be used.

In addition, the surface is provided with irregularities,
Anti-glare properties may be provided. In order to impart antiglare properties, for example, a layer in which silica gel, resin beads, glass beads, or the like are dispersed in a resin may be provided, or the surface of the base material may be subjected to an etching treatment, a mat treatment, or the like.

[0010] The surface of the translucent substrate may be subjected to a surface treatment. Examples of the surface treatment include a heat treatment in a vacuum, a corona treatment, an ion bombardment treatment, a plasma treatment, an ultraviolet irradiation treatment, and an electron beam irradiation treatment.

The first layer needs to have a refractive index of 1.60 to 1.80, preferably 1.65 to 1.75.
It is about. Here, the refractive index is a value measured at a wavelength of 550 nm. Further, the transmittance in the visible light region is preferably 80% or more. As the first layer, for example, a layer made of an inorganic dielectric is mentioned, and specifically, a layer made of a mixture of a low refractive index material and a high refractive material is mentioned. As the low refraction material, for example, SiO2, Al2O3
And the like. Examples of the high refractive index material include TiO.
2, Nb2O5, Ta2O5, WO3 and the like. Among them, a mixture of SiO2 and Nb2O5, a mixture of Al2O3 and Nb2O5, a mixture of Al2O3 and TiO2, and the like are preferable from the viewpoints of productivity, cost, and the like.

The first layer has an optical thickness of 0.20λ to
0.30λ, preferably 0.20λ.
3λ to 0.27λ. Here, λ is a design wavelength, and when it is used for a display device such as a liquid crystal display device, it is usually set arbitrarily from the wavelength range of visible light, and is generally set to 550 nm.

The second layer has a refractive index of 2.0 to 2.45.
It is necessary to be. Here, the refractive index is 550 n
It is a value measured in m. Further, the visible light transmittance is preferably 80% or more. As the second layer, for example, a layer made of an inorganic dielectric is cited, and specific examples of such an inorganic dielectric include Nb 2 O 5, Tb
Those containing iO2 and Ta2O5 as main components are exemplified.

The second layer has an optical thickness of 0.45λ to
0.55λ, preferably 0.45λ.
8λ to 0.52λ.

The third layer has a refractive index of 1.35 to 1.5.
It needs to be 2. Here, the refractive index is wavelength 550
It is a value measured in nm. Further, the transmittance in the visible light region is preferably 80% or more. Further, the third layer needs to be made of a substance having a property of increasing the refractive index as the wavelength increases. It is different from the material used for the barrier film. As the third layer, for example, a layer made of a mixture of SiO2 or MgF2 and a metal can be cited, and specifically, an inorganic dielectric obtained by doping SiO2 or MgF2 with a metal can be used. Examples of the metal include Cr, Ag, and Al. The doping amount of the metal is selected so that the refractive index increases as the wavelength increases, and is usually 5 mol or less per 100 mol of the total amount of SiO2 or MgF2 and the metal. If it is more than 5 moles, the transmittance will decrease due to the absorption of the metal.

The third layer has an optical thickness of from 0.20λ to 0.20λ.
0.30λ, preferably 0.20λ.
3λ to 0.27λ.

The first, second and third layers are formed by physical vapor deposition [PVD such as electron beam evaporation, induction heating evaporation, resistance heating evaporation, sputtering, etc.
(Physical Vapor Deposition method)], and can be provided on a light-transmitting substrate. In the case of a layer composed of a mixture, a binary evaporation method in which two kinds of evaporation materials are evaporated from separate evaporation sources to form a mixed film, a vacuum evaporation method using a mixture material of two kinds of inorganic dielectrics, It can be provided on the surface of the translucent substrate by a method such as a sputtering method.

The anti-reflection film may be provided on one side of the translucent substrate or on both sides.

The apparatus for producing the first layer, the second layer and the three layers may be a batch type, an in-line type, or the like when the light-transmitting substrate is a plate, a sheet, or a lens. Is used. When the light-transmitting substrate is in the form of a film, a roll-up type vacuum film forming apparatus can be used.

When the light-transmitting substrate is a polarizing plate, this antireflection body can be used in a liquid crystal display like a normal polarizing plate. When the light-transmitting substrate is an optical filter or a touch panel, it can be used by disposing it on the front of various display devices such as a CRT, a PDP, and a liquid crystal display. As a method of providing the antireflection film on a polarizing plate, an optical filter, a touch panel, or the like, a method of directly providing each layer on a polarizing plate, an optical filter, a touch panel, or the like, or a light-transmitting substrate provided with an antireflection film. There is also a method of laminating a material on a polarizing plate, an optical filter, a touch panel, or the like via an adhesive layer.

[0021]

According to the antireflection film of the present invention, as the third layer,
By forming a layer having a characteristic of increasing the refractive index as the wavelength increases, the layer has an excellent antireflection effect in the entire visible light wavelength region.

[0022]

EXAMPLES The present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 Triacetyl cellulose film (trade name: Fuji TAC)
A transparent polymer film formed by forming an acrylic resin film having a thickness of about 5 μm on a SH-80 (manufactured by Fuji Photo Film Co., Ltd.) was used as a light-transmitting base material, and the base material was made of Al2O3.
% And TiO2 of 8% (refractive index 1.68, thickness 810 °), Ta2O5 layer (refractive index 2.11, thickness 12)
80 °), a mixed layer of 98% MgF2 and 2% Cr (refractive index 1.40, thickness 970 °, refractive index at a wavelength of 400 nm is 1.386, refractive index at a wavelength of 800 nm is 1.404, wavelength FIG. 1 shows a reflection spectrum of an antireflection film capable of sequentially forming a refractive index.

[Brief description of the drawings]

FIG. 1 is a graph showing the spectral reflectance of an antireflection film obtained in Example 1.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Nobuyuki Kurata 2-10-1, Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Co., Ltd. F-term (reference) 2H091 FA08X FA08Z FA37X FA37Z FB02 FB06 FB08 FC21 FC23 FC25 FC26 FD06 KA01 2K009 AA06 AA10 CC03 CC06 CC14 FF02 5G435 AA01 BB12 DD12 FF05 GG11 HH02 HH03 KK07

Claims (5)

[Claims] An antireflection film provided on at least one surface of a light-transmitting substrate has a refractive index of 1.60 to 1.80 and an optical thickness of 0 from the light-transmitting substrate side to the air layer side. .20λ ~
A first layer of 0.30λ and a refractive index of 2.0 to 2.45
And a second layer having an optical film thickness of 0.45λ to 0.55λ and a refractive index of 1.35 to 1.52 and an optical film thickness of 0.45λ to 0.55λ.
An anti-reflection film, which has a thickness of 20λ to 0.30λ and a third layer made of a substance whose refractive index increases as the wavelength increases. 2. The antireflection film according to claim 1, wherein the third layer is a layer composed of SiO2 or MgF2 and a metal. 3. A polarizing plate provided with the antireflection film according to claim 1. 4. An optical filter for a display device, wherein the antireflection film according to claim 1 is provided on one surface or both surfaces. 5. A liquid crystal display device incorporating the anti-reflection film according to claim 1.