JP2719368B2 - Multi-layer surface reflector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector, and more particularly to a multilayer surface reflector excellent in anti-glare properties, high visibility, decorativeness, productivity, and cost. The multilayer film surface reflecting mirror of the present invention is mainly used for a rearview mirror for automobiles, a convex mirror for preventing danger on a road (curve mirror), a decorative mirror, and the like, but is also widely used for other purposes.

[Prior Art] As an example of a multilayer film surface reflecting mirror, JP-A-63-165805 discloses that a dielectric multilayer film is provided on one side of a glass substrate and a light absorbing film is further provided on the back surface of the same substrate. The dielectric multilayer film is formed by alternately forming dielectric films having different refractive indices from three to three.
There is disclosed a multilayer film surface reflecting mirror which is formed by sequentially laminating six layers and at least one of three to six dielectric films constituting a dielectric multilayer film has an optical film thickness of λ / 2. ing.

The dark adaptation ratio luminous efficiency V '(λ) of the human eye shown in FIG.
(See FIG. 1, curve (1)) and spectral energy characteristics P (λ) of an automobile headlight (halogen lamp) (see FIG.
Line (2)) and their product P (λ) × V ′
(Λ) (see the same figure, curve (3)).
The wavelength of light that the headlights of a night-following vehicle perceive to the eyes is mainly 480 nm to 550 nm, and a low reflectance in this wavelength region is an important factor for obtaining an antiglare effect. The multilayer film surface reflecting mirror described in JP-A-63-165805,
As shown in FIG. 9, the spectral reflectance characteristics are 480 nm to 580 nm.
In the wavelength region of nm, the reflectance is low and the anti-glare effect is excellent. Further, this reflector has a low reflectance in a wavelength region necessary for anti-glare, and has a high reflectance in other wavelength regions, so that it is excellent in visibility.

[Problems of the Prior Art] However, the multilayer film surface reflecting mirror described in Japanese Patent Application Laid-Open No. 63-165805 has a large number of dielectric multilayer films provided on one side of a glass substrate of 3 to 6 layers. Not only is the vacuum deposition process for forming the body multilayer film complicated, but also on the back surface of the same substrate, it is necessary to apply a different process from the vacuum deposition process and bake to form a light absorber film. There was a disadvantage that productivity was poor, leading to an increase in cost.

[Problems to be Solved by the Invention] The object of the present invention is to solve the above-mentioned problems of the conventional surface reflector, and to not only have excellent anti-glare properties and excellent visibility, but also
An object of the present invention is to provide a surface reflector excellent in productivity, cost, and the like.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and the multilayer film surface reflector of the present invention has a metal or semiconductor film provided on one surface of a base material, Furthermore it is provided a dielectric multilayer film thereon, the dielectric multilayer film, the optical film thickness of lambda _0/2
(Λ ₀ is the wavelength at the center of the design, and is set so that the spectral reflectance characteristic of the multilayer film surface reflecting mirror has a low reflectance valley in the wavelength range of 480 nm to 580 nm) and a low refractive index material layer, 1 an optical film thickness of 0.05～0.4Ramuda ₀
A high-refractive-index material film, wherein the low-refractive-index material film is present on the metal or semiconductor film side in relation to the high-refractive-index material film, while the high-refractive-index material film is
Exists on the air side in relation to the low refractive index material film,
The spectral reflectance characteristic of the multilayer film surface reflecting mirror having the above configuration has a valley having a low reflectance in a wavelength range of 480 nm to 580 nm.

 Hereinafter, the present invention will be described in detail.

The substrate used in the multilayer film surface reflecting mirror of the present invention is preferably a transparent substrate, but the substrate need not be transparent. The substrate is preferably a substrate having a flat surface on both sides, or a substrate having at least one surface having a convex or concave surface (for example, a plano-concave plate, a plano-convex plate, an uneven plate, a biconcave plate, a biconvex plate, etc.). Preferred materials for the substrate include glass and plastic, but other materials can also be used.

In the multilayer film surface reflecting mirror of the present invention, a metal or semiconductor film is provided on one surface of the base material, and a dielectric multilayer film is further provided thereon.

Therefore, first, a metal or semiconductor film provided on one surface of a substrate in the multilayer film surface reflecting mirror of the present invention will be described.

The metal or semiconductor film functions as a reflection film, and it is preferable to use a film having a reflectance of 30% or more, particularly 50 to 80%. As such a metal or semiconductor film, a simple substance of a metal or semiconductor such as Cr, Ni, Al, Ag, Co, Fe, Si, Ge, or an alloy containing at least one of these metals or semiconductors is used. . Examples of alloys include Inconel (mainly composed of 80% by weight of Ni, 14% by weight of Cr and 6% by weight of Fe and containing a small amount of other impurities) and chromel (mainly composed of 80% by weight of Ni and 20% by weight of Cr, Trace amounts).

As a method of forming the metal or semiconductor film, the same coating method (evaporation method,
Sputtering, ion plating, CVD, etc.) are employed.

Next, the dielectric multilayer film provided on the metal or semiconductor film will be described. The dielectric multilayer film has one low-refractive-index material film and one high-refractive-index material film.
Here, the low-refractive-index material film is preferably formed of a low-refractive-index material having a refractive index of 1.3 to 1.4. As such a low-refractive-index material, a fluoride such as MgF ₂ or a mixture containing the same is used. Used as appropriate. Also the high refractive index material layer is preferably a refractive index is formed by a high refractive index material of 1.4 to 2.4, such as a high refractive index material SiO, TiO _2, Ta ₂ O
₅ , oxides such as ZrO ₂ , HfO ₂ , Al ₂ O ₃ , SiO ₂ , fluorides such as CeF ₃ , sulfides such as ZnS, and mixtures thereof are appropriately used. However, the refractive indices of the high-refractive-index material film and the low-refractive-index material film are not limited to the above ranges. For example, SiO ₂ (refractive index: 1.46), which has been mentioned as a high-refractive index material, has a low refractive index. It can also be used as a material film. That is, whether to use as the high-refractive-index material film or the low-refractive-index material film is determined by the relative height of the refractive index among the film materials constituting the dielectric multilayer film.

The optical thickness of λ _0/2 (λ ₀ of the low refractive index material layer is a wavelength that is central to the design, low reflectance spectral reflectance characteristic of the multilayer film surface reflection mirror in the wavelength range 480nm~580nm limitation is set to be have a valley), whereas, the optical thickness of the high refractive index material layer is limited to 0.05~0.4λ _0. The reason for limiting the thickness of these films to the above range is that
This is because, by these limitations, a reflection characteristic excellent in both antiglare property and visibility can be obtained. Note the optical thickness of the high refractive index material layer is particularly preferably from lambda _0/8 or λ _0/4.

One and a low refractive index material layer optical film thickness of lambda _0/4 Further, adjacent thereto, an optical film thickness by the other types of low refractive index material of the optical film thickness of lambda _0/4 is lambda ₀ / A low refractive index material film 2 may be formed. However, it is preferable that the difference in refractive index between these adjacent low refractive index material films be within 0.1.

In the dielectric multilayer film constituting the multilayer film surface reflection mirror of the present invention, the relative position between the low refractive index material film and the high refractive index material film is also determined, and the former low refractive index material film is made of metal or The latter is provided on the semiconductor film side, and the latter is provided on the air side. The reason why the relative positions of the two films are limited in this way is that only by limiting the relative positions of the two films in this way, a reflection characteristic excellent in both antiglare property and visibility can be obtained.

Examples of a method for forming the dielectric multilayer film include a physical coating method such as an evaporation method, a sputtering method, and an ion plating method, and a coating method such as a CVD method and a method for forming a thin film from an organic solution.

EXAMPLES Hereinafter, preferred specific examples of the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 FIG. 1 (A) is an enlarged sectional view of a main part of a preferred embodiment of a multilayer film surface reflecting mirror according to the present invention, wherein 1 is a glass substrate, 2 is a Cr film, and 3 is a refractive index of 1.38. optical film thickness lambda _0/2 consisting of MgF ₂ (in this embodiment, the wavelength lambda ₀ of the light that is central to the design is 540 nm, thus lambda _0/2 is 270 nm) of the low refractive index film layer (2L layer), 4 is the high refractive index film layer having an optical thickness of lambda _0/4 made of Al ₂ O ₃ having a refractive index of 1.63 (135 nm) (H layer).
That is, in the multilayer film surface reflecting mirror of this embodiment, a multilayer film is formed on one surface of a glass substrate in the order of Cr film → 2L layer → H layer from the substrate side. FIG. 2 shows the spectral reflection characteristics of this multilayer film surface reflecting mirror. As is apparent from FIG. 2, the multilayer surface reflector of this embodiment has a higher area of 480 nm to 550 nm where the product of the dark adaptation relative visibility and the spectral energy of the headlight is higher than the conventional multilayer surface reflector. 480 to 580 nm, which is almost responsive to light, is excellent in anti-glare properties because of its reduced reflectance, and is a blue and red wavelength with low brightness sensitivity for human eyes.
Since the reflectance at 0 nm to 480 nm (blue) and 580 nm to 700 nm (red) is increased, the visibility is excellent.

Embodiment 2 FIG. 1 (B) is an enlarged sectional view of a main part of another embodiment of the multilayer film surface reflecting mirror of the present invention.
The Cr film 13 is an optical film thickness lambda _0/2 consisting of MgF ₂ having a refractive index of 1.38
(In this embodiment, the wavelength λ ₀ of light, which is the center of design, is 6
A nm, thus the low refractive index film layer of lambda _0/2 is 300 nm) (2L layer), 14 is a high refractive optical film thickness lambda _0/8 made of Al ₂ O ₃ having a refractive index of 1.63 (75 nm) It is a rate film layer (H / 2 layer). That is, the multilayer film surface reflecting mirror of this embodiment has a multilayer film formed on one side of a glass substrate in the order of Cr film → 2L layer → H / 2 layer from the substrate side.

As is clear from FIG.
It shows the same spectral reflection characteristics as the multilayer film surface reflecting mirror of Example 1, and has excellent antiglare properties and visibility.

Embodiment 3 FIG. 1 (C) is an enlarged sectional view of a main part of another embodiment of the multilayer film surface reflecting mirror of the present invention.
The Cr film 23 is an optical film thickness lambda _0/2 consisting of MgF ₂ having a refractive index of 1.38
(In this embodiment, the wavelength λ ₀ of light, which is the center of design, is 5
A 40 nm, thus lambda _0/2 is the low refractive index film layer (2L layer of a is) 270 nm), 24 is an optical film thickness lambda made of SiO ₂ having a refractive index of 1.46
_{It is} a high refractive index film layer (H layer) of 0/4 (135 nm). That is, in the multilayer film surface reflecting mirror of this embodiment, a multilayer film is formed on one surface of a glass substrate in the order of Cr film → 2L layer → H layer from the substrate side.

As is clear from FIG. 4, this multilayer film surface reflecting mirror exhibits the same spectral reflection characteristics as the multilayer film surface reflecting mirror of Example 1, and is excellent in antiglare property and visibility.

Embodiment 4 FIG. 1 (D) is an enlarged cross-sectional view of a main part of another embodiment of the multilayer film surface reflecting mirror of the present invention.
The Ge film, 33 is an optical film thickness lambda _0/2 consisting of MgF ₂ having a refractive index of 1.38
(In this embodiment, the wavelength λ ₀ of light, which is the center of design, is 5
A 40 nm, thus lambda _0/2 is the low refractive index film layer (2L layer of a is) 270 nm), 34 is an optical film thickness lambda made of SiO ₂ having a refractive index of 1.46
_{It is} a high refractive index film layer (H layer) of 0/4 (135 nm). That is, in the multilayer film surface reflecting mirror of this embodiment, a multilayer film is formed on one side of the glass substrate in the order of Ge film → 2L layer → H layer from the substrate side.

As is clear from FIG. 5, this multilayer film surface reflecting mirror exhibits the same spectral reflection characteristics as the multilayer film surface reflecting mirror of Example 1, and is excellent in antiglare property and visibility.

Embodiment 5 FIG. 1 (E) is an enlarged sectional view of a main part of another embodiment of the multilayer film surface reflecting mirror of the present invention.
Cr film, 43 is an optical film thickness lambda _0/4 composed of MgF ₂ having a refractive index of 1.38
(In this embodiment, the wavelength λ ₀ of light, which is the center of design, is 5
A 40 nm, thus the low refractive index film layer of lambda _0/4 is 135 nm) (L ₁ layer) 44 is an optical film thickness lambda made of SiO ₂ having a refractive index of 1.46
_0/4 (135 nm) of the low refractive index film layer (L ₂ layer) 45 refraction index 1.63
A high refractive index film layer of Al ₂ O ₃ having an optical thickness lambda _0/4 composed of a (134 nm) (H layer). That is, the multilayer film surface reflecting mirror of this embodiment has a Cr film → L ₁ layer →
A multilayer film is formed in the order of L ₂ layer → H layer (note that the L ₁ layer
Low refractive index film layer having an optical thickness of lambda _0/2 by the L ₂ layer (2L layer) are formed).

As is clear from FIG. 6, this multilayer film surface reflecting mirror has:
It shows the same spectral reflection characteristics as the multilayer film surface reflecting mirror of Example 1, and has excellent antiglare properties and visibility.

Embodiment 6 FIG. 1 (F) is an enlarged sectional view of a main part of another embodiment of the multilayer film surface reflecting mirror of the present invention. In FIG.
Cr film, 53 is an optical film thickness lambda _0/4 composed of MgF ₂ having a refractive index of 1.38
(In this embodiment, the wavelength λ ₀ of light, which is the center of design, is 6
A nm, thus lambda _0/4 low refractive index film layer is 150 nm) (L ₁ layer) 54 is an optical film thickness lambda made of SiO ₂ having a refractive index of 1.46
_0/4 (150 nm) of the low refractive index film layer (L ₂ layer) 55 refraction index 1.63
A high refractive index film layer having an optical thickness of lambda _0/8 made of Al ₂ O ₃ of (75nm) (H / 2 layer). That is, the multilayer film surface reflector of this embodiment has a multilayer film formed on one side of a glass substrate in the order of Cr film → L ₁ layer → L ₂ layer → H / 2 layer from the substrate (note that L ₁ layer and L ₂
Low refractive index film layer having an optical thickness of lambda _0/2 by a layer (2L layer) are formed).

As is clear from FIG.
It shows the same spectral reflection characteristics as the multilayer film surface reflecting mirror of Example 1, and has excellent antiglare properties and visibility.

Having thus described the surface of the multilayer film reflector of the present invention through examples 1 to 6, L ₁ layers of 2L layers in the dielectric multilayer films of Examples 1 to 4 → L ₂ layer or the L ₂ layer → L ₁ Similar results can be obtained when layers are formed. The Examples 5 and L ₁ layer in Example 6 → L ₂ layers of the L ₂ layer → L ₁ layer similar results to be obtained.

Similar reflection characteristics can be obtained by replacing each layer of the dielectric multilayer film in Examples 1 to 6 with an equivalent film.

Further, even if plastic is used as the substrate instead of glass, the same reflection characteristics can be obtained.

Comparative Example FIG. 10 is an enlarged sectional view of a main part of a multilayer film surface reflector for comparison, in which the high refractive index film layer (H layer) is eliminated in the multilayer film surface reflector of Example 1 of the present invention. There, reference numeral 61 denotes a glass substrate, 62 Cr film, 63 in optical thickness λ _0/2 (this comparative example consisting of MgF ₂ having a refractive index of 1.38, the wavelength lambda ₀ of the light that is central to the design in 540nm There is, therefore λ _0/2 is 270nm)
Is a low refractive index film layer (2L layer). That is, the multilayer film surface reflecting mirror of this comparative example has a Cr surface on one side of the glass substrate from the substrate side.
A multilayer film is formed in the order of film → 2L layer. FIG. 11 shows the spectral characteristics of this multilayer film surface reflecting mirror. As is clear from FIG. 11, the surface reflector of the present comparative example is different from the surface reflectors of Examples 1 to 6 in a region where the product of dark adaptation relative luminous efficiency and spectral energy of the headlight is high 480 nm-550 nm reflectance. 400nm-480nm out of blue and red wavelengths, which have poor anti-glare properties and low brightness sensitivity for human eyes
The visibility is poor because the reflectance in (blue) is low.

From the results of the above Examples and Comparative Examples, one layer of dielectric film is not enough to obtain a surface reflector having antiglare property and visibility, and one layer of low refractive index of the above-mentioned predetermined thickness. It has been found that a dielectric multilayer film composed of a high refractive index material film and one layer of the high refractive index material film having the predetermined thickness is required.

[Effect of the Invention] The multilayer film surface reflecting mirror of the present invention has the following technical effects.

(I) It has excellent anti-glare properties.

As is apparent from FIGS. 2 to 7, the reflecting mirror of the present invention has P (λ) × V ′ indicated by a curve (3) in FIG.
480n, which corresponds approximately from 480nm to 550nm with a large value of (λ)
It has an excellent anti-glare effect because it has a valley with low reflectance in the wavelength range from m to 580 nm.

(Ii) Excellent visibility.

As shown in FIGS. 2 to 7, the reflecting mirror of the present invention has a low reflectance in a wavelength region necessary for anti-glare and a high reflectance in other wavelength regions, so that excellent visibility is ensured. .

Further, the reflecting mirror of the present invention increases the reflectance in the green region (490 nm to 580 nm) with good brightness sensitivity to the blue region (400 nm to 480 nm).
And the red region (590 nm to 750 nm). As a result, there is also an advantage that the sensitivity of the blue and red eyes with low sensitivity is sensitized, so that the color discrimination (contrast) is improved.

(Iii) It has excellent decorativeness and fashionability.

As a result of pursuing the anti-glare property and visibility of the reflecting mirror of the present invention,
The reflection color has a magenta color. The magenta color gives a sense of quality, and can be differentiated from other reflecting mirrors.

(Iv) Excellent in productivity and cost.

In the manufacture of the reflecting mirror of the present invention, advantages such as a small number of dielectric multilayer films to be formed and the fact that the dielectric multilayer film and a metal or semiconductor film can be formed by the same film forming means. Therefore, the number of layers of the dielectric multilayer film formed is large, and the coating of the light absorber film, which requires firing, is different from the case of the reflector of JP-A-63-165805. Excellent cost performance.

As described above, according to the present invention, in spite of a small number of dielectric multilayer films, a multilayer film surface reflecting mirror having advantages such as anti-glare property, visibility, decorative property, and harmful light cutting property can be produced with high productivity. ,
It can be provided with good cost performance.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a multilayer film surface reflecting mirror of the present invention,
2, 3, 4, 5, 6 and 7 are spectral reflection characteristic diagrams of the reflecting mirror of the present invention, and FIG. FIG. 9 is a diagram showing the spectral energy characteristics of the vehicle headlight and the spectral energy characteristics of the vehicle headlight which are the product of the spectral energy characteristics of the vehicle headlight. FIG. 9 shows the spectral reflection of the multilayer film surface reflecting mirror described in JP-A-63-165805. FIG. 10 is an enlarged sectional view of a main part of the multilayer film surface reflecting mirror of the comparative example, and FIG. 11 is a spectral reflection characteristic diagram of the multilayer film surface reflecting mirror of the comparative example. 1,11,21,31,41,51,61 …… Glass substrate, 2,12,22,32,42,5
2,62 ... metal or semiconductor film, 3,4,13,14,23,24,33,34,
43,44,45,53,54,55,63 …… Dielectric film.

Claims (3)

(57) [Claims] A metal or semiconductor film is provided on one side of a substrate,
Thereon will be provided a dielectric multilayer film further the dielectric multilayer film, the optical film thickness of λ _0/2 (λ ₀ is the wavelength at the heart of the design, the spectral reflectance of the multilayer film surface reflection mirror first layer and a low refractive index material layer characteristics are is set to have a lower valley reflectance in the wavelength region 480nm~580nm), optical film thickness of one layer is 0.05～0.4Ramuda ₀ A high-refractive-index material film, wherein the low-refractive-index material film is present on the metal or semiconductor film side in relation to the high-refractive-index material film, while the high-refractive-index material film is Surface reflection mirror having a low reflectance in a wavelength range of 480 nm to 580 nm in a spectral reflectance characteristic of a multilayer surface reflector having the above structure, which is present on the air side in relation to the refractive index material film. mirror. Wherein the optical thickness of the high refractive index material film, λ _0/8
Or λ _0/4, the multilayer film surface reflector according to claim 1. Wherein the low refractive index material layer of the optical film thickness of lambda _0/2 is one of a low refractive index material layer of the optical film thickness of lambda _0/4, adjacent thereto, an optical film thickness lambda _0/4 of the other species is formed by the low refractive index material layer, the multilayer film surface reflector according to claim 1 or claim 2.