JPH04275503A - Rear surface reflection mirror of two-layered film - Google Patents

Abstract

PURPOSE:To prevent the dazzler by providing a reflection film in common use as a light absorptive film further on a specific thin film. CONSTITUTION:The thin film 2 consisting of dielectrics having 1.7 to 3.0 refractive index is formed at an optical film thickness of 1/4 to 2 times the central wavelength on one surface of a transparent substrate 1 and the reflection film 3 in common use as the light absorptive film is further provided on the thin film 2. Any of Cr, Ni, 'Inconel(R)', and 'Chromel(R)' is used as the material of the reflection film 3. Any of TiO2, CeO2, ZrO2, ZnS, Ta2O2 is used as the dielectrics of the thin-film material. An adhering means is provided directly or via a protective layer on the reflection film in such a case. Consequently, the rear surface reflection of the two-layered films which has excellent antidazzle and ornamental properties, has good productivity and can be produced at a low cost is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a two-layer film back reflecting mirror. This invention can be particularly suitably applied to mirrors for automobiles and the like.

0002

[Prior Art] Conventionally, a single-layer metal film such as Al or Cr is formed as a reflective film on one side of a transparent substrate made of glass or plastic, etc., which has been commonly used as rearview mirrors and side mirrors for automobiles. '' has almost no ``anti-glare effect'' that reduces the ``dazzle'' of sunlight in the morning and evening or the headlights of following cars at night.

As a mirror intended for the above-mentioned anti-glare effect, two low refractive index thin films and two high refractive index thin films are alternately formed on a transparent substrate.
It is known that the film is formed in ~8 layers, and a light absorption film and a reflection film are further formed thereon (for example, Japanese Patent Laid-Open No. 63-16
Publication No. 5805).

[0004] Mirrors intended for the above-mentioned anti-glare effect exhibit a unique color due to the spectral reflectance characteristics of their multilayer reflective film, and are widely popular because they have excellent decorative properties as well as anti-glare effects. Since the number of layers of the reflective film is as large as 2 to 8, it takes a long time to form the film, resulting in poor productivity and high cost.

[0005]

[Problems to be Solved by the Invention] This invention has been made in view of the above-mentioned circumstances, and provides a novel two-layer film back surface that has excellent anti-glare properties and decorative properties, and can be manufactured at low cost with good productivity. The purpose is to provide a reflective mirror.

[0006]

[Means for Solving the Problems] As shown in FIG. 1, the two-layer film back reflecting mirror of the present invention has a thin film 2 made of a dielectric material having a refractive index of 1.7 to 3.0 on one side of a transparent substrate 1. , the optical film thickness is 1/4 to 2 times the center wavelength λ0, and the thin film 2
A reflective film 3 which also serves as a light absorption film is further provided on top of the light absorbing film.

[0007] Light enters from the side of the transparent substrate 1 and passes through the reflective film 3.
The reflected light whose spectral reflectance is determined by the dielectric thin film 2 is emitted toward the transparent substrate 1 side.

[0008] As the transparent substrate 1, glass, plastic, etc. can be used.

[0009] Examples of the "dielectric material having a refractive index of 1.7 to 3.0" include TiO2, CeO2, ZrO2, ZnS, Ta
2O5 and the like are preferred (Claim 2).

"Optical film thickness" is, of course, the product of the physical thickness of the thin film and the refractive index of the thin film. The "reflection film 3" also serves as a light absorption film. Materials for this reflective film include Cr, Ni,
Inconel, chromel, etc. are preferred (Claim 3).

A "protective layer" may be formed on the reflective film 3 to facilitate handling (claim 4), or a "protective layer" may be formed on the reflective film 3 directly or through the protective layer. A means may be provided (claim 5), and the two-layer film back reflecting mirror may be adhesively fixed at a desired position by this adhesive means.

In this case, the shape of the reflecting mirror may be formed in advance into the shape of a rearview mirror or a side mirror of an automobile or motorcycle (claim 6).

[0013]

[Operation] Among the light reflected from the rearview mirrors and side mirrors of cars and motorcycles, the first thing that drivers feel dazzled by is sunlight in the morning and evening, and the second is the headlights of cars following them at night. In the morning and evening, the sun is low and the angle of elevation relative to the sun is small, so direct reflections of sunlight from side mirrors and the like easily enter the driver's eyes. Furthermore, the light from the headlights of the following vehicle at night is almost at the same height as the driver's eyes, so it is easy to see the driver's eyes when reflected by the rearview mirror or side mirror.

In a bright place, the visibility of the human eye has a simple chevron-shaped spectral characteristic with a peak near a wavelength of 550 nm, as shown by the broken line in FIG. In this case, the sunlight in the morning and evening feels dazzling.

As the environmental condition becomes darker, the peak value of visibility shifts to around 500 nm due to the so-called Purkinje shift, as shown by the solid line in FIG. In this case, the headlights of a car behind you feel dazzling at night. Incidentally, the spectral energy of a halogen lamp used in automobile headlights is as shown by the chain line in FIG.

Therefore, in order to effectively prevent glare from rearview mirrors and side mirrors, it is preferable to effectively block light components in the wavelength range of about 500 to 550 nm.

Furthermore, by changing the optical thickness and center wavelength of the dielectric thin film, the color of the two-layer back reflecting mirror can be varied.

[0018]

[Example] Specific examples will be given below.

Example 1 A parallel flat glass plate with a thickness of 1.5 mm and a refractive index of 1.52 was used as a transparent substrate, and a thin TiO2 film with a refractive index of 2.35 was formed on one side of the glass by vacuum deposition as a dielectric thin film. .

[0020] The center wavelength λ0 is 550 nm, and the optical film thickness is 4
It is λ0/4 or 550 nm. Furthermore, a Cr thin film was deposited on this dielectric thin film as a reflective film that also served as a light absorption film.

FIG. 4 shows the spectral reflectance characteristics of the two-layer film back reflecting mirror thus obtained.

Example 2 As in Example 1, a thin film of TiO2 was formed on one side of the same transparent substrate as in Example 1 by vacuum evaporation. The center wavelength λ0 is 600 nm, and the optical film thickness is 2λ0/4 or 30
It is 0 nm.

[0023] On this dielectric thin film, C was applied in the same manner as in Example 1.
A thin film of r was formed by vapor deposition as a reflective film.

FIG. 5 shows the spectral reflectance characteristics of the two-layer film back reflecting mirror thus obtained.

Example 3 As in Example 1, a thin film of TiO2 was formed on one side of the same transparent substrate as in Example 1 by vacuum evaporation. The center wavelength λ0 is 600 nm, and the optical film thickness is 4λ0/4 or 60 nm.
It is 0 nm.

[0026] On this dielectric thin film, C was applied as in Example 1.
A thin film of r was formed by vapor deposition as a reflective film.

FIG. 6 shows the spectral reflectance characteristics of the two-layer film back reflecting mirror thus obtained.

Example 4 As in Example 1, a thin film of TiO2 was formed on one side of the same transparent substrate as in Example 1 by vacuum evaporation. The center wavelength λ0 is 450 nm, and the optical film thickness is 2λ0/4, or 22
It is 5 nm.

On this dielectric thin film, C was applied as in Example 1.
A thin film of r was formed by vapor deposition as a reflective film.

FIG. 7 shows the spectral reflectance characteristics of the two-layer film back reflecting mirror thus obtained.

Looking at the two-layer film back reflecting mirror of each of these examples from the aspect of its anti-glare effect, each example has a wavelength of 50 nm.
The reflectance for light in the vicinity of 0 to 550 nm is suppressed to about 50% or less. Therefore, the intensity of light in the wavelength range that is dazzling to the eyes is reduced regardless of whether it is a bright place or a dark place, and an effective anti-glare effect can be obtained. In particular, the wavelength of 500n, which makes the double-layer film back mirror of Example 3 feel dazzling to the eyes.
Since the light in the wavelength range before and after the light of m is extremely efficiently removed from the reflected light, it exhibits an outstanding anti-glare effect.

Furthermore, since each of the examples has a relatively flat spectral reflectance characteristic as a whole, the amount of light of the entire reflected light, that is, the amount of light obtained by integrating the spectral reflectance characteristic curve of the reflected light, is quite large. has a size, so the mirror image is bright;
Good visibility.

When viewed from the decorative side, the two-layer film back reflector of Example 1 is green, and the two-layer film back reflectors of Examples 2, 3, and 4 are golden yellow, pink, and blue, respectively. The color is very aesthetically pleasing and decorative.

FIG. 3 schematically shows an embodiment of the invention according to claim 6. A glass plate having a thickness of 1 mm and a refractive index of 1.52 and having a curvature corresponding to the side mirrors of automobiles and motorcycles was formed into the shape of a side mirror as shown in FIG. 3(a).

FIG. 3(b) shows a sectional view taken along line bb in FIG. 3(a).
), a dielectric thin film 31 and a reflective film 32 as described in Example 3 were formed on the back surface of a glass plate as a transparent substrate 30.

Furthermore, a double-sided adhesive 33 was provided on the reflective film 32 as an adhesive means. Reference numeral 34 indicates the surface layer of the double-sided adhesive. By peeling off the surface layer 34 to expose the adhesive surface, this mirror can be directly stuck and fixed onto a side mirror of an automobile or the like.

[0037]

As described above, according to the present invention, a novel two-layer film back reflecting mirror can be provided. Since this reflecting mirror has the above-mentioned configuration, it has excellent anti-glare properties and decorative properties.

Further, since only one dielectric thin film is to be formed on the transparent substrate, it can be formed in a short time, and since the reflective film also serves as a light absorbing film, there is no need for painting and drying. Therefore, it has excellent productivity and can be realized at low cost.

In the above description, the application to mirrors of automobiles, etc. was mainly explained, but the double-layer film back reflecting mirror of the present invention is not limited to the above, but can also be applied to curved mirrors, for example. Due to its excellent decorative properties, it can also be used in makeup mirrors.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the structure of a two-layer film back reflecting mirror of the present invention.

FIG. 2 is a diagram for explaining the anti-glare effect of the two-layer film back reflecting mirror according to the present invention.

FIG. 3 is a diagram for explaining one embodiment of the invention of claim 6.

FIG. 4 is a diagram showing the spectral reflectance characteristics of the two-layer film back reflecting mirror of Example 1.

FIG. 5 is a diagram showing the spectral reflectance characteristics of the two-layer film back reflecting mirror of Example 2.

6 is a diagram showing spectral reflectance characteristics of the two-layer film back reflecting mirror of Example 3. FIG.

7 is a diagram showing spectral reflectance characteristics of the two-layer film back reflecting mirror of Example 4. FIG.

[Explanation of symbols]

1 Transparent substrate 2 Dielectric thin film

Claims (6)

[Claims] Claim 1: One side of a transparent substrate has a refractive index of 1.7 to 3.
．． A two-layer film back reflecting mirror formed by forming a thin film made of a dielectric material of 0 to an optical thickness of 1/4 to 2 times the center wavelength λ0, and further providing a reflective film that also serves as a light absorption film on the thin film. . 2. In claim 1, the dielectric of the thin film material is T.
A two-layer film back reflecting mirror characterized by being made of any one of iO2, CeO2, ZrO2, ZnS, and Ta2O5. 3. The two-layer film back reflecting mirror according to claim 1 or 2, wherein the material of the reflective film is Cr, Ni, Inconel, or chromel. 4. The two-layer film back reflecting mirror according to claim 1, wherein a protective layer is formed on the reflective film. 5. The two-layer film back reflecting mirror according to claim 1, wherein an adhesive means is provided on the reflective film either directly or via a protective layer. 6. The two-layer film back reflecting mirror according to claim 5, wherein the shape of the reflecting mirror is that of a rearview mirror or a side mirror of an automobile or motorcycle.