JPH04128803A - Reflection mirror made of multilayered film - Google Patents

Abstract

PURPOSE:To obtain good productivity and an excellent antidazzle property and visibility by crimping a high-refractive index layer of 0.25lambda0 optical film thickness with two layers of low-refractive index layers having 0.25lambda0 optical film thickness with respect to a central wavelength lambda0, thereby forming dielectric layers having a 3-layered structure. CONSTITUTION:This reflection mirror has a substrate 1 consisting of transparent glass, the dielectric layers 2 of the 3-layered structure provided thereon and a reflection film 3 provided thereon. The transparent glass to be used as the substrate 1 has 1.52 refractive index. The dielectric layers 2 are formed by crimping the high-refractive index layer 22 of 0.25lambda0 optical film thickness with two layers of the low-refractive index layers 21, 23 having 0.25lambda0 optical film thickness with respect to the central wavelength lambda0. The central wavelength lambda0 is 600+ or -10nm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multilayer film reflecting mirror. The multilayer film reflecting mirror of the present invention can be suitably used for automobile mirrors, curved mirrors, and the like.

[Prior Art] Automotive mirrors and curved mirrors are required to have anti-glare properties and good visibility. Anti-glare property refers to the effective reduction of glare from reflected light from a mirror, and visibility refers to the ability to effectively recognize what is reflected in the mirror. If a car mirror or a curved mirror is configured with these mirrors with insufficient anti-glare properties and visibility, the glare and poor visibility could lead to a major accident.

A multilayer reflector has been proposed that has good anti-glare properties and visibility considering the visibility characteristics of the human eye (Japanese Patent Laid-Open No. 63
-74005, 63-165805, JP-A-2-64601, JP-A-2-64602)
.

[Problems to be Solved by the Invention] These conventional multilayer film reflecting mirrors have a 1/1/2 center wavelength in the multilayer film.
Since the multilayer film includes a thick dielectric layer with an optical thickness of 2 mm, it takes time to prepare a multilayer film, which poses a problem in terms of productivity.

The present invention was made in view of the above-mentioned circumstances, and
An object of the present invention is to provide a novel multilayer film reflecting mirror with good productivity and excellent anti-glare properties and visibility.

[Means for solving the problem] As shown in FIG. 1(a), the multilayer film reflecting mirror according to claim 1 has
It has a substrate 1 made of transparent glass, a dielectric layer 2 with a three-layer structure provided thereon, and a reflective film 3 provided thereon. Light enters from the substrate 1 side, is reflected by the reflective film 3 via the dielectric layer 2, has its spectral intensity distribution changed by the dielectric layer 2, and exits from the substrate 1 side. That is, the multilayer film reflecting mirror according to claim 1 is a so-called back mirror. The transparent glass plate used as the substrate 1 has a refractive index of 1.52.

As shown in FIG. 1(b), the multilayer film reflecting mirror of claim 2 includes a substrate IA, a reflective film 3 provided thereon, and a dielectric layer 2A having a three-layer structure provided thereon. have Light enters from the side of the dielectric layer 2A, is reflected by the reflective film 3, and has its spectral intensity distribution changed by the dielectric layer 2A.
eject from the side. That is, the multilayer film reflecting mirror according to claim 2 is a so-called surface mirror. Therefore, in the multilayer film reflecting mirror of the second aspect, the substrate IA does not need to be transparent. But on the other hand,
Since the dielectric layer 2A is directly exposed on the surface side, depending on the purpose of use, it is preferable to provide a transparent protective film on the dielectric layer to protect the dielectric layer (Claim 3). As the substrate IA, a metal plate, a glass plate, a plastic plate, etc. can be used as appropriate.

The dielectric layer 2 of the multilayer reflective mirror according to the first aspect of the invention satisfies the following conditions.

That is, the dielectric layer 2 having the three-layer structure is composed of two low refractive index layers 2 having an optical thickness of 0.25λ0 with respect to the center wavelength λ.
1.23, optical film thickness 0.25λ. with a high refractive index layer 22 sandwiched between them, and the center wavelength λ. is 600±10 nm.

The dielectric layer 2A of the multilayer reflective mirror according to the second aspect of the invention satisfies the following conditions.

That is, the dielectric layer 2A having a three-layer structure has a center wavelength λ.

In contrast, the low refractive index layer 21 has an optical thickness of 0.25λ0 and the optical thickness is 0.125λ. With the low refractive index layer 24, the optical film thickness is 0.25λ. with a high refractive index layer 22 sandwiched between them, and the center wavelength λ. is 650±10 nm.

The refractive index of the low refractive index layer is 1.3 to 1.7, and its material is MgF2.5102. Al2O3, CeF
, + etc. are suitable. Further, the refractive index of the high refractive index layer is 1
．． 8 to 2.5, and the sonomaterials include TiO2, Zr0
z, CeO2, Ta205. YzO:+.

ZnS etc. are suitable.

The high and low refractive index layers are formed by vacuum evaporation, sputtering, and C.
This can be done with a VD, etc.

In the case of the back mirror of claim 1, [adhesion means can be provided directly on the reflective film or through a reflective film protective layer] (claim 4), and in the case of the front mirror of claim 2 or 3, the bonding means can be provided on the reflective film directly or via a reflective film protective layer. Adhesive means can be provided on the back surface (Claim 5).

Furthermore, when the adhesive means is provided, the shape of the reflecting mirror can be formed into "the shape of a rearview mirror or side mirror of an automobile" (claim 6).

Note that the reflective film 3 used has a flat spectral reflectance.

[Function] In both the multilayer film reflecting mirrors of claims 1 and 2, a film with a flat spectral reflectance is used for the reflecting film, so the spectral characteristics of the light reflected by the multilayer film reflecting mirror are determined by the dielectric layer 2.2A. Therefore, the typical spectral reflectance characteristic of the multilayer film reflector according to claim 1.2 is as shown by curve 2-1 in FIG.

That is, the multilayer film reflecting mirror of the present invention effectively reduces the reflection of light components with short wavelengths of 550 nm or less.

Due to such spectral reflectance characteristics, the multilayer film reflector of the present invention appears "golden yellow" to the eye. Generally speaking, golden color has an image of sparkling, and the reflected light seems to be dazzling, but this is not the case with the multilayer film reflector of the present invention.

Human eyes experience glare mainly at night. The spectral luminous efficiency of the human eye is the curve 2-2.2-3 shown in Figure 2.
This is a simple chevron characteristic.

Curve 2-2 is the photopic luminous sensitivity characteristic, and curve 2-3 is the scotopic luminous sensitivity characteristic. The phenomenon in which the visibility characteristic shifts from curve 2-2 to curve 2-3 toward shorter wavelengths as the environment changes from a bright state to a dark state is known as Purkinje shift.

At night when you feel dazzling, the visibility characteristic is curve 2- in Figure 2.
3, and since it reaches its maximum at a wavelength of about 500nr++, it is sensitive to light in the wavelength range near this wavelength. I feel dazzled by light that contains a strong amount of light with a wavelength of around 500 nm.

Since the multilayer film reflecting mirror of the present invention has a spectral reflectance as shown by curve 2-1 in FIG. 2, the "bluish light" that causes glare in reflected light is effectively removed, thereby preventing glare.

Further, the multilayer film reflecting mirror of the present invention has a substantially uniform and high reflectance for light having a wavelength larger than 550 nm, and therefore has a large amount of reflected light as a whole. Therefore, the mirror image reflected on the multilayer film reflecting mirror of the present invention is bright and therefore has good visibility.

Also, the color appearance in the mirror image is close to the natural state.

[Example] Specific examples will be described below.

Example 1 Transparent substrate Dielectric layer Reflective film material Glass MgF2 TlO2MgF2Cr film thickness
150nm 150nm 150nm 2
000 people Example 2 Transparent substrate Dielectric layer Reflective film material Glass SiO□TiO25i02 Cr film thickness
150nm 150nm 150nm 2
000 person Examples 1 and 2 are examples of the back mirror according to claim 1. The material of the low refractive index layer in the dielectric layer is MgF.
The material of the high refractive index layer is TlO2, and the optical thickness of each dielectric layer is 1 sonm (therefore, the center wavelength λ is 600 nm).

Example 3 Substrate Reflective film Dielectric layer material Glass CrMgF2 102MgF2 Film thickness
2000 people 162.5nm 162.5nm 81
．． 25nm Example 4 Substrate Reflective film Dielectric layer material Glass Cr 5102 TlO25102
This is an example. The material of the low refractive index layer in the dielectric layer is MgF.
2 or 5iO7, the material of the high refractive index layer is TiO□,
The optical thickness of each dielectric layer is 162.5 nm (1/4λ
o), 81.25 nm (1/8 λ.), and the center wavelength is 650 nm.

The spectral reflectance of the multilayer film reflecting mirrors of Examples 1 to 4 was as shown by curve 2-1 in FIG. 2.

In addition, in the back mirror of Example 1.2, the light enters through the glass substrate with a refractive index of 1.52, so the wavelength in the glass substrate is different from that in the air, so the spectral reflection as shown in 2-1 in Figure 2 occurs. In order to realize these characteristics, the center wavelength is set to 600'nm.

FIG. 3 diagrammatically shows one embodiment of the invention of claim 6. 1m thick with curvature according to car side mirrors
A glass plate (refractive index: 1.52) having a diameter of 1.5 mm was formed into the shape of a side mirror as shown in FIG. 3(a).

As shown in FIG. 3(b), a glass plate 30 was used as a transparent substrate, and a dielectric film 31 having a three-layer structure and a reflective film 32 made of Cr were formed on the back side thereof as shown in Example 1.2.

The spectral reflectance characteristics are as shown by curve 2-1 in FIG.

Furthermore, a double-sided adhesive 33 is placed on the reflective film 32 as an adhesive means.
has been established. Reference numeral 34 is the surface layer of the double-sided adhesive 33.

The surface layer 34 of this side mirror is peeled off to expose the adhesive surface, and the side mirror can be directly stuck and fixed onto the side mirror of an ordinary automobile.

When the anti-glare properties and visibility of the side mirror shown in Fig. 3 were examined, it was confirmed that both visibility and anti-glare properties were extremely good. That is, since the mirror surface is bright and golden, visibility is extremely high even in twilight or at night. In addition, even though automobile lights (halogen lamp bi-split energy is shown by curve 2-4 in Figure 2) are bright and easily visible because the long wavelength side is not cut off significantly, the reflection of the short wavelength side is effective. Indoor experiments have confirmed that the color is reddish and there is no glare at all.

[Effects of the Invention] As described above, according to the present invention, a novel multilayer film reflecting mirror can be provided. Since this reflecting mirror has the above-mentioned configuration, it has extremely excellent anti-glare properties and visibility, and the number of layers constituting the dielectric film is only 3, and the layer thickness is 1/4λ. ~1/8λ. Because it is thin, productivity is good. In particular, in the case of a back mirror, all three dielectric layers have the same optical film thickness, which facilitates film thickness control during production and improves productivity.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the structure of the multilayer film reflector of the present invention, Fig. 2 is a diagram for explaining the anti-glare property and visibility of the multilayer film reflector of the present invention, and Fig. 3 is a diagram for explaining the claim. FIG. 7 is a diagram for explaining an example in which the present invention is applied to a side mirror of an automobile in one embodiment of item 6; 199. Transparent substrate, LA, , substrate, 2.2A,
, , dielectric layer, 3106 reflective film
, 731, -1''') Agent Toru Kabayama,?Shi,P.

Claims (1)

[Claims] 1. It has a substrate made of transparent glass with a refractive index of 1.52, a dielectric layer with a three-layer structure provided on this substrate, and a reflective film provided on this dielectric layer. The dielectric layer with the three-layer structure is composed of two low refractive index layers having an optical thickness of 0.25λ_0 with respect to the center wavelength λ_0, sandwiching a high refractive index layer with an optical thickness of 0.25λ_0, A multilayer film reflecting mirror characterized in that the center wavelength λ_0 is 600±10 nm. 2. It has a substrate, a reflective film provided on the substrate, and a dielectric layer with a three-layer structure formed on the reflective film, and the dielectric layer with the three-layer structure has a wavelength with respect to the center wavelength λ_0. A low refractive index layer with an optical thickness of 0.25λ_0 and an optical thickness of 0.1
Optical film thickness 0.25 with low refractive index layer having 25λ_0
A multilayer film reflecting mirror comprising a high refractive index layer of λ_0 sandwiched therein, and characterized in that the center wavelength λ_0 is 650±10 nm. 3. The multilayer reflective mirror according to claim 2, further comprising a transparent protective film for protecting the dielectric layer provided on the dielectric layer. 4. The multilayer reflective mirror according to claim 1, further comprising an adhesive means provided directly on the reflective film or via a reflective film protective layer. 5. The multilayer film reflecting mirror according to claim 2 or 3, characterized in that adhesive means is provided on the back surface of the substrate. 6. The multilayer reflective mirror according to claim 4 or 5, wherein the shape of the reflective mirror is that of a rearview mirror or a side mirror of an automobile.