JPH02120802A - Surface reflecting mirror made of multilayered film - Google Patents

Abstract

PURPOSE:To obtain the surface reflecting mirror which is not only excellent in an antidazzle property and visibility but excellent in productivity and cost as well by providing a metal or semiconductor film onto one surface of a base material and further providing multilayered dielectric films as well on this film. CONSTITUTION:For example, this reflecting mirror has the glass substrate 1, a Cr film 2, a low-refractive index film layer (2L layer) 3 consisting of MgF2 of 1.38 refractive index and having lambda0/2 optical film thickness (lambda0 is the wavelength of light which is the center of design). Further, the reflecting mirror consists of a high-refractive index film layer (H layer) 4 consisting of Al2O3 of 1.63 refractive index and having lambda0/4 optical film thickness. Namely, the multilayered films are formed on one surface of the glass substrate 1 in order of the Cr film 2, the 2L layer 3 and the H layer 4, from the substrate 1 side. The surface reflecting mirror made of the multilayered films having the advantages in the antidazzle property, visibility, ornamentality, property to cut harmful light, etc., in spite of the smaller layer number of the multilayered dielectric films is obtd. with the high productivity and the low cost in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reflecting mirror, and particularly to a multilayer surface reflecting mirror that is excellent in anti-glare properties, high visibility, decorative properties, productivity, cost efficiency, etc. The multilayer film surface reflecting mirror of the present invention is mainly used for automobile rearview mirrors, convex mirrors (curved mirrors) for road hazard prevention, decorative mirrors, etc., but is also widely used for other purposes.

[Prior art 1 As an example of a multilayer film surface reflecting mirror, Japanese Patent Laid-Open No. 1658-1983
No. 05 discloses that a dielectric multilayer film is provided on one side of a glass substrate, and a light absorption film is further provided on the back side of the same substrate, and the dielectric multilayer film has three dielectric films having different refractive indices alternately. It is constructed by sequentially laminating ~6 layers, and at least one layer of the 3 to 6 dielectric films constituting the dielectric multilayer film has λ
A multilayer surface reflector having an optical thickness of /2 is disclosed.

The scotopic ratio V′(λ)(
(see curve (1) in the figure), spectral energy characteristics P (λ) of automobile headlights (halogen lamps) (see line (2) in the figure), and their product P (λ) x V' (λ)
(See curve (3) in the same figure) As is clear from the figure, the wavelengths of light perceived by the headlights of vehicles following at night are mainly 4.
80 nm to 550 nm, and a low reflectance in this wavelength range is an important factor for obtaining an anti-glare effect. As shown in FIG. 9, its spectral reflectance characteristics are low in the wavelength range of 480 nm to 550 nm, and the anti-glare effect is excellent. Further, this reflecting mirror has a low reflectance in the wavelength range necessary for anti-glare, and a high reflectance in other wavelength ranges, so it has excellent visibility.

[Problems with the Prior Art] However, the multilayer film surface reflecting mirror described in JP-A No. 63-165805 has many dielectric multilayer films, 3 to 6 layers, provided on one side of the glass substrate. Not only is the vacuum deposition process for forming multilayer films complicated;
Painting on the back side of the same substrate in a separate process from the vacuum deposition process,
Since it is necessary to form a light absorber film by firing, there are disadvantages in that productivity is poor and costs increase.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems of conventional surface reflecting mirrors, and to achieve not only excellent anti-glare properties and visibility, but also productivity and cost efficiency. It is an object of the present invention to provide an excellent surface reflecting mirror for various purposes such as the above.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and the multilayer film surface reflecting mirror of the present invention includes a metal or semiconductor film provided on one side of a base material, Further, a dielectric multilayer film is provided thereon, and the dielectric multilayer film includes a single layer of a low refractive index material film with an optical thickness of λ0/2 (λO is the wavelength that is the center of the design). , the optical thickness of one layer is 0.0·5λO (λ
o/20> ~ 0.4λO (215λ0), the low refractive index material film is present on the metal or semiconductor film side in relation to the high refractive index material film, Meanwhile, the high refractive index material film is located on the air side in relation to the low refractive index material film.

The present invention will be explained in detail below.

The base material used in the multilayer film surface reflecting mirror of the present invention is preferably a transparent base material, but the base material does not have to be transparent. ...This base material may be a substrate with flat surfaces on both sides, or a substrate with at least one convex or concave surface (for example, a plano-concave plate,
A plano-convex plate, a concave-convex plate, a biconcave plate, a biconvex plate, etc.) are preferable. Preferred materials for the base material 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 side of the base material, and a dielectric multilayer film is further provided on the metal or semiconductor film.

First, a description will be given of the metal or semiconductor film provided on one side of the base material in the multilayer film surface and reflective mirror of the present invention.

This metal or semiconductor film functions as a reflective film, and it is preferable to use one having a reflectance of 30% or more, particularly 50 to 80%. Such metal or semiconductor films include Cr, Ni, AI, Ag, Co, Fe,
Used are simple metals or semiconductors such as Si or Ge, or alloys containing at least one of these metals or semiconductors.

Examples of alloys include Inconel (Ni 80% by weight, Cr
Mainly composed of 14% by weight, 6% by weight of Fe, and contains trace amounts of other impurities), chromel (80% by weight of Ni,
(mainly composed of Cr2O (wt%) and contains trace amounts of other impurities).

As a method for forming this metal or semiconductor film, the same coating method (vapor deposition method, sputtering method, ion blasting method, CVD method, etc.) as in the case of the dielectric multilayer film described later is adopted.

Next, the dielectric multilayer film provided on the metal or semiconductor film will be explained. This dielectric multilayer film has one layer of a low refractive index material film and one layer of a 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, and examples of such low refractive index materials include fluorides such as MgF2, etc. A mixture containing the above may be used as appropriate. Further, the high refractive index material film is preferably formed of a high refractive index material having a refractive index of 1.4 to 2.4, and such high refractive index materials include Sin, Ti. Ta205. ZrO2, HfO2, Al2O3,
Oxides such as 5i02, fluorides such as CeF3, and ZnS
Sulfides such as and mixtures thereof are used as appropriate. However, the refractive index of the high refractive index material film and the low refractive index material film is not limited to the above-mentioned range. It can also be used as a low refractive index material film. That is,
Whether it is used as a high refractive index material film or a low refractive index material film is determined by the relative height of the refractive index between the film materials constituting the dielectric multilayer film.

The optical thickness of the above low refractive index material film is limited to λo/2 (λO is the central wavelength of the design), while the optical thickness of the above high refractive index material film is limited to 0.05~ limited to 0°4λO. The reason why the film thicknesses of these films are limited to the above range is that only by these limitations can reflective properties with excellent anti-glare properties and visibility be obtained. It is particularly preferable that the optical thickness of the high refractive index material film is λo/8 or ^0/4.

In addition, the optical film thickness can be reduced to λ0/2 by one type of low refractive index material film with an optical film thickness of λO/4 and another type of low refractive index material adjacent to this with an optical film thickness of λO/4. A refractive index material film may also 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 surface reflecting mirror of the present invention, the relative positions of the low refractive index material film and the high refractive index material film are also determined, and the former low refractive index material film is made of metal or metal. It is provided on the semiconductor M side, and the latter high refractive index material film is provided on the air side. The reason why the relative positions of both films are limited in this way is that only by limiting the relative positions of both films in this way can reflection characteristics with excellent anti-glare properties and visibility be obtained.

Examples of methods for forming this dielectric multilayer film include physical coating methods such as vapor deposition, sputtering, and ion-blating, and coating methods such as CVD and thin film formation from an organic solution.

[Examples] Preferred specific examples of the present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Embodiment 1 FIG. 1(A) is an enlarged cross-sectional view of the main parts of a preferred embodiment of the multilayer film surface reflecting mirror of the present invention, in which 1 is a glass substrate;
2 is a Cr film, 3 is an MgF2 film with a refractive index of 1638, and has an optical film thickness of λO/2 (in this example, the wavelength λO of light, which is the center of the design, is 54 onm, so λO/2 is 2
70 layers m) low refractive index film layer (2L layer), 4 is an optical film thickness λo/4 (1
It is a high refractive index film layer (H layer) of 35 layers (m). That is,
In the multilayer film surface reflecting mirror of this embodiment, a multilayer film is formed on one side of a glass substrate in the order of Cr film→2L layer→H layer from the substrate side. The spectral reflection characteristics of this multilayer film surface reflecting mirror are shown in FIG. As is clear from FIG. 2, the multilayer film surface reflector of this example has a region of 4sonm to 550nm where the product of the scotopic specific luminous efficiency and the spectral energy of the headlight is higher than that of the conventional multilayer film surface reflector. 400 layer m to 480 nm, which is the blue and red wavelength that has low brightness sensitivity to the human eye.
(blue) and 580 nm to 700 nm (red), the visibility is excellent.

Embodiment 2 FIG. 1(B) is an enlarged sectional view of main parts of another embodiment of the multilayer film surface reflecting mirror of the present invention, in which 11 is a glass substrate;
2 is a Cr film, 13 is an M g F 2 film with a refractive index of 1.38, and has an optical film thickness of λO/2 (in this example, the wavelength λO of light, which is the center of the design, is 6oonm, so λO
14 is a high refractive index film layer (872 layers) with an optical thickness of λo/8 (75 nm) made of A1203 with a refractive index of 1.63. . That is, in the multilayer film surface reflecting mirror of this embodiment, multilayer films are 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. 3, this multilayer surface reflector exhibits the same spectral reflection characteristics as the multilayer surface reflector of Example 1, and has excellent anti-glare properties and visibility.

Embodiment 3 FIG. 1(C) is an enlarged sectional view of main parts of another embodiment of the multilayer film surface reflecting mirror of the present invention, in which 21 is a glass substrate;
2 is a Cr film, 23 is an MgF2 film with a refractive index of 1.38, and has an optical film thickness of λO/2 (in this example, the wavelength λO of light, which is the center of the design, is 54Q nm, so λO/2 is 270 layers m). ) low refractive index film! (2L layer), 24 is an optical film thickness λO/4 (
It is a high refractive index film layer (H layer) of 135 layers (m). That is, in the multilayer film surface reflecting mirror of this embodiment, a multilayer film is formed on one side 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 is
It exhibits the same spectral reflection characteristics as the multilayer film surface reflector of Example 1, and has excellent anti-glare properties and visibility.

Embodiment 4 FIG. 1(D) is an enlarged sectional view of main parts of another embodiment of the multilayer film surface reflecting mirror of the present invention, in which 31 is a glass substrate;
2 is a Ge film, and 33 is an optical film thickness made of M g F 2 with a refractive index of 1.38, λO/2 (In this example, the wavelength λO of light, which is the center of the design, is 540 layers m, so λ
0/2 is 270 layers m) low refractive index film layer (2L layer)
, 34 is an optical film thickness λ made of 5iOz with a refractive index of 1.46.
It is a high refractive index film layer (H layer) of O/4 (135 layer m).

That is, in the multilayer film surface reflecting mirror of this embodiment, a multilayer film is formed on one side of a 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
It exhibits the same spectral reflection characteristics as the multilayer film surface reflector of Example 1, and has excellent anti-glare properties and visibility.

Embodiment 5 FIG. 1(E) is an enlarged sectional view of main parts of another embodiment of the multilayer film surface reflecting mirror of the present invention, in which 41 is a glass substrate;
2 is a Cr film, 43 is an optical film made of MgF2 with a refractive index of 1.38, and has an optical thickness of λo/4 (in this example, the wavelength λO of the light that is central to the design is 540 nm, so λo/4 is 135 nm). ), 44 is a low refractive index film layer (1 layer) made of SiC2 with a refractive index of 1.46, and has an optical film thickness λo/4 (
135 nm) low refractive index film layer (L2 layer), 45 is an optical film layer λO/4 (135 nm) made of Al2O3 with a refractive index of 1°63.
5r1m) high refractive index film layer (H layer). That is,
In the multilayer film surface reflecting mirror of this example, a multilayer film is formed on one side of a glass substrate in the order of Cr film - L layer → L2 layer - H layer (the optical film thickness is A low refractive index film layer (two layers) of λo/2 is formed)
.

As is clear from FIG. 6, this multilayer film surface reflection mirror exhibits the same spectral reflection characteristics as the multilayer film surface reflection mirror of Example 1, and has excellent anti-glare properties and visibility.

Embodiment 6 FIG. 1(F) is an enlarged sectional view of main parts of another embodiment of the multilayer film surface reflecting mirror of the present invention, in which 51 is a glass substrate;
2 is a Cr film, and 53 is an optical film made of MgF2 with a refractive index of 1.38, which has an optical thickness ^O/4 (in this example, the wavelength λO of light, which is the center of the design, is 600 nm, so λo/4 is 150 nm. The low refractive index film layer (L1 layer) 54 has an optical film thickness λo/
4 (150 nm) is a low refractive index film layer (2 layers), 55 is an optical film layer made of Al2O3 with a refractive index of 163, and has an optical thickness λ0/8 (7
It is a high refractive index film layer (H3P layer) of 5 layers (m). That is, in the multilayer surface reflecting mirror of this embodiment, a multilayer film is formed on one side of a glass substrate in the order of Cr film → L layer → L2 layer → H72 layer (note that the L1 layer is the second layer and the optical film is formed by the second layer). A low refractive index film layer (two layers) with a thickness of λo/2 is formed.

As is clear from FIG. 7, this multilayer film surface reflection mirror exhibits the same spectral reflection characteristics as the multilayer film surface reflection mirror of Example 1, and has excellent anti-glare properties and visibility.

The multilayer film surface reflecting mirror of the present invention has been explained above using Examples 1 to 6. In the dielectric multilayer films of Examples 1 to 4, the two layers are changed from L layer to L2 layer or L2 layer to L1 layer. Similar results can be obtained if Also, in Example 5 and Example 6, the first layer→L2
Similar results can be obtained even if the layers are changed from L2 layer to L1 layer.

Even if each layer of the dielectric multilayer film in Examples 1 to 6 is replaced with an isolateral antrum, similar reflection characteristics can be obtained.

Furthermore, equivalent reflection characteristics can be obtained by using plastic instead of glass as the substrate.

Comparative Example Figure 1.0 is an enlarged cross-section of a main part of a multilayer surface reflector for comparison in which the high refractive index film layer (H layer) is removed from the multilayer surface reflector of Example 1 of the present invention. In the figure, 6
1 is a glass substrate, 62 is a Cr film, and 63 is a refractive index of 1.38.
A low refractive index film layer (two-layer layer) consisting of MgF2 with an optical thickness of λO/2 (in this comparative example, the wavelength λO of light that is the center of the design is 540 nm, so λ0/2 is 270 nm). That is, in the multilayer film surface reflecting mirror of this comparative example, a multilayer film is formed on one side of a glass substrate in the order of Cr film→2L layer from the substrate side.

The spectral characteristics of this multilayer film surface reflecting mirror are shown in FIG. As is clear from FIG. 11, unlike the surface reflectors of Examples 1 to 6, the surface reflector of this comparative example has a high product of scotopic specific luminous efficiency and headlight spectral energy in the region 480 nm-
Since the reflectance at 550 nm is high, the anti-glare property is poor, and the reflectance at 430 layer m to 480 layer m (blue) is low among the blue and red wavelengths to which the human eye has low brightness sensitivity. Because of this, visibility is also poor.

From the results of the above Examples and Comparative Examples, it is clear that one layer of dielectric film is insufficient to obtain a surface reflecting mirror with anti-glare properties and visibility; It has not been found that a dielectric multilayer film consisting of a material film and one layer of a high refractive index material film having the predetermined film thickness is required.

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

(i) Excellent anti-glare properties.

As is clear from FIGS. 2 to 7, the reflecting mirror of the present invention has an 8th
Figure, P, (λ) x V' as shown by curve (3)
Since the reflectance is low in the range from 480 nm to 550 layers m, where the value of (λ) is large, the anti-glare effect is excellent.

(ii) Excellent visibility.

As shown in Figures 2 to 7, the reflector of the present invention has low reflectance in the wavelength range necessary for anti-glare, and high reflectance in other wavelength ranges, ensuring excellent visibility. .

In addition, the reflector of the present invention has good brightness sensitivity in the green region (4
90nlT1~580nm) reflectance in the blue region (40nlT1~580nm)
0nm to 480nm) and red region (590n... to 75nm)
0 nm), and as a result, it sensitizes blue and red colors to which the eye has low sensitivity, which also has the advantage of improving color discrimination (contrast).

(iii) Excellent decorative and fashionable properties.

As a result of pursuing anti-glare properties and visibility, the reflecting mirror of the present invention has a magenta-tinged reflected color. This magenta color gives the mirror a sense of luxury and allows it to be differentiated from other reflective mirrors.

(IV) Excellent productivity and cost efficiency.

In manufacturing the reflecting mirror of the present invention, the advantages include that the number of layers of the dielectric multilayer film formed is small and that the metal or semiconductor film can be formed on the dielectric multilayer film by the same film forming method. Unlike the reflecting mirror disclosed in JP-A-63-165805, which has a large number of dielectric multilayer films and requires painting and baking a light absorber film, productivity and Excellent cost efficiency.

In summary, according to the present invention, a multilayer film surface reflecting mirror that has advantages such as anti-glare properties, visibility, decorative properties, and harmful light blocking properties can be produced even though the number of dielectric multilayer films is small. , can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the main parts of the multilayer film surface reflecting mirror of the present invention.
Figures 2, 3, 4, 5, 6 and 7 are spectral reflection characteristic diagrams of the reflector of the present invention, and Figure 8 is the scotopic specific luminous efficiency of the human eye and The spectral energy characteristics of automobile headlights and the spectral energy characteristics of automobile headlights as perceived by the human eye, which is the product of these characteristics. Figure 9 shows the spectral reflection of the multilayer film surface reflector described in JP-A-63-165805. FIG. 10 is an enlarged sectional view of a main part of a multilayer surface reflecting mirror of a comparative example, and FIG. 11 is a spectral reflection characteristic diagram of a multilayer surface reflecting mirror of a comparative example. 1, 11.21.31.41.51.61...Glass substrate, 2,12,22,32.42,52°62...
Metal or semiconductor film, 3.4, 13.14°23.24
．． 33, 34. 43. 44, 45. 53. 54, 55.
63...Dielectric film.

Claims (1)

[Claims] 1. A metal or semiconductor film is provided on one side of a base material, and a dielectric multilayer film is further provided thereon, and the dielectric multilayer film has an optical thickness of one layer of λ_0/ 2 (λ_0 is the central wavelength of the design) and one layer of a low refractive index material film with an optical thickness of 0.05 to 0.2 (λ_0 is the central wavelength of the design).
and a high refractive index material film of 4λ_0, 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 A multilayer film surface reflecting mirror, which is located on the air side in relation to the low refractive index material film. 2. The multilayer surface reflecting mirror according to claim 1, wherein the optical thickness of the high refractive index material film is λ_0/8 or λ_0/4. 3. The low refractive index material film with an optical thickness of λ_0/2 includes one type of low refractive index material film with an optical thickness of λ_0/4, and another adjacent low refractive index material film with an optical thickness of λ_0/4. 2. The multilayer surface reflecting mirror according to claim 1, wherein the multilayer film surface reflecting mirror is formed of a seed low refractive index material film.