JPS61133902A - Reflection mirror for automobile - Google Patents

Abstract

PURPOSE:To form a metal film having 65-85% a reflection factor with a cheap and an ease by applying an alloy of Al contg. a metal having a less reflection factor than that of Al to the metal film on the reflection mirror. CONSTITUTION:The titled mirror is prepared by forming a film 2 of a transpar ent conductive body composed of TiO2 on a surface of a glass substance 1 by means of a vacuum evaporation method, and then by forming a metal film 3 on the prescribed film 2. The metal 3 is the alloy of Al cong. Ti or Cr. By mixing Ti to Al, the obtd. alloy increases a durability. In order to obtain 65-85% reflection factor, metal film 3 is prepared from an Al alloy contg. 6-32wt% Ti or an Al alloy contg. 6-24wt% Cr, thereby obtaining the metal film having 65-85% reflection factor with the cheap and the ease, and satisfying an automobile standard of >=38% a luminous reflectance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reflector for automobiles, and is effective when used, for example, as a fender mirror mounted outside the cabin of an automobile.

[Conventional technology]

Conventionally, a method has been known in which an ailiil is formed on a glass substrate, a metal film is further formed on the glass substrate, light is interfered with between the thin film and the metal film, and the mirror surface is colored by the interference effect of this light. For example, JP-A-54-8986
The one described in Publication No. 6 is publicly known.

By the way, the luminous reflectance of an automobile reflector must be 38% or more according to automobile standards.

Therefore, when a titanium oxide (T i 02 ) N@ film is used as a transparent dielectric film for the vr# film formed on a glass substrate, it is possible to obtain a specular coloring effect while ensuring a luminous reflectance of 38% or more. As a result of experiments and studies by the present inventors, it was found that the reflectance of the metal film should be as follows. That is, it is 65-85% for blue, 60-90% for green, 55-90% for yellow-green, 60-90% for yellow, and 60-85% for red.

Therefore, it can be seen that the reflectance of the metal film suitable for all these hues is 65 to 85%.

The metal film used here can be used for spectroscopy in the visible range.

It is desirable that the reflection characteristics be flat, and the reflectance of the main metal film (by vacuum evaporation method) with relatively flat spectral characteristics (
The value at a wavelength of 550 fi) is as follows.

That is, 6M (Ag) is 98% aluminum (, l
) is 92%, nickel (Ni) is 55%, titanium (T
t) is 40%, chromium (Cr) is 35%, 2.7 Kel.
Chromium (Ni-Cr, 80-20wt%) is 65%, rhodium (Rh) is 78%, --Fucel cobalt (N
1-Co, 80-20wt%) is 59%, nickel.
Chromium (Nt-Cr.

60-40wt%) is 49%. Among the metal films mentioned above, Rh with a reflectance of 78% and pJi-Cr (80-20w
t%).

[Problem that the invention seeks to solve]

However, since Rh is a noble metal, it is expensive, and in order to always maintain a reflectance of 65% with Ni-Cr films, the composition of the vapor deposition material, vapor deposition conditions, etc. must be strictly controlled, and mass production is not possible. The problem is that it's not suitable.

[Means for solving problems]

In view of the above-mentioned problems, the present invention aims to inexpensively and easily form a metal film having a reflectance of 65 to 85%, and employs the following means. In other words, it includes a glass substrate, a transparent dielectric film made of titanium oxide formed on one surface of this glass substrate, and a metal film formed on the top surface of this transparent dielectric film, and this metal film is more reflective than aluminum. The reflector for an automobile is made of an alloy in which aluminum contains an element with a low index, and has a reflectance of 65 to 85%.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a sectional view of this embodiment. A transparent dielectric film 2 made of titanium oxide (TiO2) is formed on one surface of the glass substrate 1.
is formed by vacuum evaporation, and a metal film 3 is further formed on the upper surface of this transparent dielectric film 2. This metal film 3 is made by mixing aluminum (/l) with titanium (Ti). Titanium has a lower reflectance than aluminum, and when mixed with aluminum to form an alloy, the durability of the alloy improves. It is. FIG. 3 is a diagram showing the relationship between the titanium content and the reflectance and resistivity of the alloy. As can be seen from this figure, the reflectance is 65 to 85% when the titanium content is 6 to 32 wt%, and in this example, the titanium content is 6 to 32 wt%.

This alloy film 3 of titanium and aluminum is made of the conventionally known 2
It may be formed by an original sputtering method or a two-point vapor deposition method, or by preparing an alloy material having an appropriate composition in advance and attaching it to the surface of the glass substrate 1 by a conventionally well-known sputtering method or vacuum vapor deposition method. In this example, the metal film 3 was used only as a light reflecting film, but this gold W
The film 3 can also be used as a defrost heater film by energizing the film 3 and utilizing its heat generation effect.

Light enters from the direction indicated by the arrow in Figure 1, passes through the substrate glass 1 and the transparent dielectric Al film 2, is reflected on the surface of the metal film 3, passes through the transparent dielectric thin film 2 and the substrate glass 1 again, and enters. Return to direction. At this time, the surface of the transparent dielectric film 2 also reflects an amount of light determined by its refractive index. When the light reflected on the surface of the metal FJ 3 and the light reflected on the surface of the transparent dielectric thin film 2 interfere with each other, the spectral characteristics of the reflected light are no longer flat, giving a coloring and anti-glare effect. The color tone and reflectance at this time are transparent dielectric thin 111
1! 2, the optical film thickness (the product of the film thickness and the refractive index, which is the film thickness when the refractive index is fixed), and the shade of color is determined by the refractive index. This will be explained below.

FIG. 3 shows the relationship between the thickness of the transparent dielectric thin film 2 and the hue.
The hue of the reflected light when the standard light C defined by C is perpendicularly incident is expressed in chromaticity coordinates. Usually, the refractive index of a vacuum-deposited thin film is smaller than that of the bulk.For example, the refractive index of titanium oxide is 2.4 when the wavelength of light is 4500 nm.
6. When the previous wavelength is 6,500, it is 2.30, which is slightly smaller than the bulk refractive index. In Figure 3, the chromaticity coordinates are: (is the red component, 1 is the green component, 1, -
(X+'l) represents the blue component. Roughly speaking, the area G surrounded by the dotted line in Figure 3 is green, the area Y is yellow, the area R is red, the area V is purple, and the area B is blue. The hue of the area is taken, and the intermediate color is used between each area. The relationship between film thickness and hue is as follows: chromaticity for every 400 people is 0, and chromaticity for every 40 people is represented by . As is clear from FIG. 2, any hue is possible by selecting an appropriate film thickness.

Next, other embodiments of the present invention will be described. In the above embodiment, aluminum containing titanium was used as the metal IPJ3, but in this embodiment, aluminum containing chromium (Cr) was used. Figure 4 shows the relationship between the chromium content and the reflectance and resistivity of the metal film 3, and as can be seen from this figure, the reflectance is 65 to 85%.
In order to achieve this, the chromium content must be 6 to 24 wt%, and in this example, the chromium content is also 6 to 24 wt%.
It was set at 24 wt%. Incidentally, in this embodiment as well, it is also possible to use the metal film 3 as a defrosting heater film, as in the above-mentioned embodiments.

5 to 8 show the hue of reflected light when standard light C defined by JIS Z87.01 is incident perpendicularly, using chromaticity coordinates. In Figure 5, the reflectance of the metal film 3 is 65.
%, and the solid line in the figure is the area where a luminous reflectance of 38% or more can be ensured. This figure shows that if the reflectance of the metal film 3 is 65%, all hues can be set. In addition, the area indicated by G in the figure is green, and the area indicated by Y
indicates yellow, R indicates red, and B indicates blue. FIG. 6 shows a case where the reflectance of the metal film 3 is 85%, and in this case as well, all hues can be exhibited.

FIG. 7 shows the case where the reflectance of gold 11[113 is 60%, and it can be seen that in this case, a blue color cannot be expressed. Figure 8 is Metal III! 3 shows when the reflectance is 90%, and the spread of the locus of chromaticity coordinates is the same as the above-mentioned 5th to 7th.
It is smaller than the one in the picture, and has almost no color. In FIGS. 5 to 8, the farther the trajectory is from the zero point, the darker the color becomes, and the closer the trajectory is, the lighter the color becomes.

〔Effect of the invention〕

As explained above, by using the automotive reflector of the present invention, a metal film with a reflectance of 65 to 85% can be obtained easily and inexpensively, and the luminous reflectance is 38%, which is the automotive standard.
It has the excellent effect of satisfying the above regulations and being able to set any specular hue.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of an example of the present invention, Figure 2 is a diagram showing the relationship between the weight percent of titanium contained in the metal film, reflectance, and resistivity, and Figure 3 is a diagram showing the relationship between the thickness of the transparent dielectric film and the thickness of the transparent dielectric film. Figure 4 shows the relationship between the weight percent of chromium contained in the metal film and the reflectance and resistivity. Figures 5 to 8 are the chromaticity coordinates to show the effects. be. 1...Glass substrate, 2...Transparent dielectric film (Ti02
), 3...metal film.

Claims (3)

[Claims] (1) A glass substrate, a transparent dielectric film made of titanium oxide formed on one surface of this glass substrate, and a metal film formed on the top surface of this transparent dielectric film, and this metal film is made of aluminum. A reflector for an automobile, characterized in that it is made of an alloy in which aluminum contains an element with a low reflectance, and has a reflectance of 65 to 85%. (2) The automobile reflector according to claim 1, wherein the metal film is formed by containing 6 to 32% by weight of titanium in aluminum. (3) The automobile reflector according to claim 1, wherein the metal film is formed by incorporating 6 to 24% by weight of chromium in aluminum.