JPH0883506A - Multilayer film reflector - Google Patents

Abstract

PURPOSE: To provide a multilayer film reflecting mirror excellent in moisture resistance and heat resistance, and suitable for any kind of application of a light source. CONSTITUTION: After laminating titanium oxide and strontium fluoride alternately on a reflecting base 1 having a concave 2, a multilayer film 4 is formed by firing treatment at 300 deg.C or higher. Thereby, the multilayer film 4 excellent in moisture resistance and heat resistance is formed so as to suit a light source having higher output and longer life sufficiently, and to be applicable to the reflecting mirror of all kinds of light sources regardless of the applications of the light sources.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a multi-layer film reflecting mirror used for floodlighting and the like, and more particularly to a multi-layer film reflecting mirror having a cold-light mirror as a base.

[0002]

2. Description of the Related Art Conventionally, a so-called cold-light mirror is used as a substrate, which is provided with a multilayer film in which a thin film of a high refractive index material and a thin film of a low refractive index material are alternately laminated on a reflective substrate having a concave surface made of hard glass or the like. The multi-layered film reflecting mirror is often used as a light source for projectors, store lighting, medical lighting, and the like. This multilayer-film reflective mirror reflects visible light in a multilayer film and transmits long-wavelength infrared rays to reduce heating of illuminated objects by heat rays, and When heat rays pass through the multilayer film, the substrate is not heated due to absorption, and the larger the refractive index ratio of the laminated materials, the higher the reflectance and the wider the reflection area. ing.

Table 1 shows the relationship between the combination of substances generally used for a multilayer film and the refractive index.

[0004]

[Table 1] Since the multilayer films as shown in Table 1 are formed by laminating on a reflective substrate having a concave surface, so-called gas scattering vapor deposition method in which vapor deposition is performed in a gas atmosphere having a pressure of 10 ^-1 Pa (Pascal) grade. Thereby, the multilayer film is uniformly deposited on the reflective substrate.

In addition, the multilayer film in Table 1 is formed of zinc sulfide (Zn
S) and magnesium fluoride (MgF ₂ ) thin films alternately laminated ZnS / MgF ₂ alternating layers or zinc sulfide and silicon oxide (SiO ₂ ) thin films alternately laminated Z
A so-called soft coat film such as an nS / SiO ₂ alternating layer, and a TiO ₂ / SiO ₂ alternating layer in which thin films of titanium oxide (TiO ₂ ) and silicon oxide are alternately laminated, or of titanium oxide and magnesium fluoride. It is classified as a so-called hard coat film such as a TiO ₂ / MgF ₂ alternating layer in which thin films are alternately laminated. These multilayer films are selected depending on the intended use.

For example, among soft coat films, ZnS /
The MgF ₂ alternating layer is excellent in moisture resistance, but inferior in heat resistance, so it is applied to halogen lamps with low output and long life, which have a low heat load and a long life. Moreover, the ZnS / SiO ₂ alternating layer is It is excellent in heat resistance but inferior in moisture resistance, so it is applied to halogen lamps with high output and short life, which have a high heat load and a short life.

On the other hand, of the hard coat film, TiO ₂ /
The SiO ₂ alternating layer has excellent moisture resistance and heat resistance, is applied to a light source with a high heat load and a long life, such as a metal halide lamp or a high output / long life halogen lamp, and is also used as TiO ₂ / MgF ₂ The alternating layer is slightly inferior in heat resistance to the TiO ₂ / SiO ₂ alternating layer, but is superior in moisture resistance and heat resistance to the soft coat film, has a high heat load, and has a long life, high output and long life type halogen. Applied to the lamp.

Table 2 shows the evaluation results of the moisture resistance and heat resistance of each of the above multilayer films. Moisture resistance in Table 2 shows the peeling occurrence time of the multilayer film when the multilayer film coated on the reflective substrate is left in an atmosphere of a temperature of 50 ° C. and a humidity of 90%. It shows the peeling occurrence time of the multilayer film at a heat load of 300 ° C. and 350 ° C. due to the lighting of the mirror lamp.

[0009]

[Table 2] However, in recent years, along with the increase in the output power and the long life of the light source, the TiO ₂ / SiO ₂ alternating layer or the TiO ₂ / Mg alternating layer is used as a reflecting mirror for all light sources without selecting the application to be used.
Hard coat films of alternating layers of F ₂ have come to be used.

[0010]

However, TiO 2
_As shown in Table 2, the ₂ / SiO ₂ alternating layer is formed of TiO ₂ /
As compared with the MgF ₂ alternating layer, it has the drawback of being inferior in humidity resistance, and as shown in Table 1, since the ratio of the refractive indexes is small, it maintains the same optical characteristics as the TiO ₂ / MgF ₂ alternating layer. In order to do so, it is necessary to increase the number of laminated layers of the multilayer film by 50%, which has a drawback that the cost becomes high.

Further, while the TiO ₂ / MgF ₂ alternating layer is excellent in moisture resistance, it is TiO ₂ / SiO ₂ in heat resistance.
It has the disadvantage of being inferior to the alternating layers.

[0012] Therefore, with having a TiO ₂ / SiO ₂ alternate layers about the same heat resistance has a TiO ₂ / MgF ₂ alternating layer about the same moisture resistance, and the number of laminated multi-layer film of Ti
O ₂ / MgF ₂ alternating layer and the hard coat film is comparable is desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multilayer film reflecting mirror which is excellent in moisture resistance and heat resistance and which can be used in any light source.

[0014]

In order to achieve the above object, the present invention comprises alternately stacking titanium oxide and strontium fluoride on a reflective substrate having a concave surface, and then firing at a temperature of 300 ° C. or higher. It is characterized by being processed to form a multilayer film.

[0015]

Since the multi-layered film reflecting mirror of the present invention is constructed as described above, a multi-layered film having excellent moisture resistance and heat resistance, which is well suited for a light source with high output and long life, is formed. It can be used as a reflector for all light sources, regardless of the application.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a cross section of a multilayer film reflecting mirror according to an embodiment of the present invention. In FIG. 1, 1 is a reflecting substrate, for example, a reflecting substrate made of hard glass for a reflecting mirror for a halogen lamp. It is formed by a concave surface 2 of a paraboloid of revolution with one surface expanded. A halogen lamp 3 as a light source is mounted in the center of the concave surface 2, and a multilayer film 4 is deposited on the upper surface of the concave surface 2 by, for example, a gas scattering vapor deposition method to form a multilayer film reflecting mirror 5. The visible light emitted from the halogen lamp 3 is reflected by the multilayer film 4 attached to the multilayer film reflecting mirror 5 to illuminate the object to be illuminated, and the heat rays are reflected by the multilayer film reflecting mirror 5, that is, the multilayer film 4. And is transmitted to the rear of the reflective substrate 1 and radiated to the rear of the reflective substrate 1.

The multilayer film 4 employs titanium oxide (TiO ₂ : refractive index n = 2.3) as the high refractive index material H and magnesium fluoride (MgF ₂ : n = 1.3) as the low refractive index material L.
Various materials having a refractive index close to that of 8) were extracted, and strontium fluoride (SrF ₂ : n = 1.32) was selected and adopted from them.

That is, as a candidate for the low refractive index material L,
Lithium fluoride (LiF: n = 1.36), barium fluoride _{(BaF 2: n = 1.32)} , cryolite (Na ₃ Al
F ₆ : n = 1.36), SrF ₂ , sodium fluoride (N
aF: n = 1.30), and calcium fluoride (CaF
₂ : n = 1.40) and extract each material and TiO
A multilayer film 4 of ₂ and ₂ was deposited on the reflective substrate 1 under the following conditions.

The optical film thickness of the multilayer film 4 is designed to be 1 / 4λ, and the film structure is such that the reflective substrate 1 · (HL) ⁶ Hλ ₁ · (LH) 4
21 layers of λ ₂ and air were used. Where λ ₁ and λ ₂
Are design wavelengths, λ ₁ = 600 nm, λ ₂ = 45
0 nm, and the high-refractive index material H and the low-refractive index material L are alternately alternated 6 times at the design wavelength λ ₁ , and further one layer of the high-refractive index material H is added to form 13 layers, and then the design wavelength λ λ ₂ Then, the low-refractive index material L and the high-refractive index material H were alternately laminated four times, for a total of eight layers to form a total of 21 layers.

These multi-layered films 4 were formed by the gas-scattering vapor deposition method. (1) Vacuum degree 2.67 × 10 ^{-1 to} 1.07 × 10 ^-3 P
a (2) Scattering gas Argon (Ar) (3) Substrate temperature 250 to 300 ° C. (4) Evaporation source Film is formed under the electron beam (electron gun) vapor deposition conditions, and after the vapor deposition treatment, 30 in an electric furnace.
Heat treatment was performed at 0 ° C. or higher, for example, 400 ° C. for 1 hour.

Moisture resistance test, heat resistance test, and measurement of optical characteristics were carried out on the various multilayer films 4 thus formed, and the results are shown in Table 3. Humidity resistance test is temperature 50
The peeling time of the multilayer film 4 when left in an atmosphere of 90 ° C and a humidity of 90%, and the heat resistance test are the multilayer film at a heat load of 300 ° C and 350 ° C due to lighting of the halogen lamp 3.
4 shows the peeling occurrence time, and the optical characteristics show the width of the reflection region with a reflectance of 90% or more.

[0023]

[Table 3] Results of tests and measurements shown in Table 3, by using the TiO ₂ / SrF ₂ alternating layer, the multilayer film 4 TiO ₂ / SiO ₂
It has the same degree of heat resistance as the alternating layers and the same degree of moisture resistance as the TiO ₂ / MgF ₂ alternating layers, and the number of laminated layers is TiO ₂ /
It has been found that a hard coat film is formed that is comparable to the MgF ₂ alternating layers. Further, the spectral transmittance characteristics of the TiO ₂ / MgF ₂ alternating layer are shown in FIG. 2, and as shown in FIG.
It was found that the width of the reflection region having a reflectance of 90% or more was about the same as that of the TiO ₂ / MgF ₂ alternating layer, and that it had the same optical characteristics.

Based on the results of the above test and measurement, M
SrF ₂ was selected from the various materials extracted as the low refractive index material L having a refractive index close to that of gF _{2, and} the TiO ₂ / SrF ₂ alternating layer was adopted as the multilayer film 4.

After the vapor deposition process, the multilayer film 4 was heat-treated at a temperature of 300 ° C. or higher in an electric furnace to be hardened. This is because the heat load when the halogen lamp 3 of the light source is turned on. This is because the multilayer film 4 that has a temperature of 300 ° C. or higher and is hardened at a temperature lower than 300 ° C. cannot withstand this heat load.

According to the above-mentioned embodiment, Ti is used as the multilayer film 4.
By adopting the O ₂ / SrF ₂ alternating layer, the multilayer film reflecting mirror 5 having excellent moisture resistance and heat resistance can be obtained, and can be sufficiently adapted to a light source with high output and long life.

Next, the multilayer film 4 employing the TiO ₂ / SrF ₂ alternating layer was applied to a metal halide lamp having a higher heat load than the halogen lamp 3, and the TiO ₂ / SiO ₂ alternating layer and the TiO ₂ / MgF ₂ alternating layer were formed. An example of comparison is shown.

The film structure is as follows: (1) TiO ₂ / SrF ₂ , TiO ₂ / SiO ₂ , TiO
₂ / MgF ₂ (2) Reflective substrate 1 ・ (HL) ⁶ Hλ ₁・ (LH) 4 λ ₂・
21-layered structure of air λ ₁ = 600 nm, λ ₂ = 450 nm, and vapor deposition conditions are as follows: (1) vacuum degree 2.67 × 10 ^{−1 to} 1.07 × 10 ⁻³ P
a (2) Scattering gas Argon (Ar) (3) Substrate temperature 250-300 ° C (4) Evaporation source Electron beam (electron gun), after vapor deposition, heat treatment at 400 ° C for 1 hour in an electric furnace gave.

A moisture resistance test, a heat resistance test, and measurement of optical characteristics were performed on the three types of multilayer films 4 formed under the above conditions, and the results are shown in Table 4. Moisture resistance test is a multilayer film when left in an atmosphere of temperature 50 ° C and humidity 90%
The peeling occurrence time of 4 and the heat resistance test show the peeling occurrence time of the multilayer film 4 at a heat load of 350 ° C. and 450 ° C. due to lighting of a metal halide lamp, respectively, and the optical characteristics show the width of the reflection region with a reflectance of 90% or more. Shows.

[0030]

[Table 4] Table 4 Results of tests and measurements shown in, the multilayer film 4 TiO ₂ / SiO ₂ alternate layers about the same heat resistance and TiO ₂ / MgF ₂ alternating layer about the same moisture with TiO ₂ / SrF ₂ alternating layer It has been found that the metal halide lamp has the same properties as the TiO ₂ / MgF ₂ alternating layer and has a high heat load compared with the halogen lamp 3 and has sufficient optical characteristics.

According to the other embodiment described above, by adopting the TiO ₂ / SrF ₂ alternating layer as the multilayer film 4, the multilayer film reflecting mirror 5 is excellent in moisture resistance and heat resistance and can be used for any light source. Can be obtained.

In the above embodiment, the method for forming the multilayer film 4 is the gas scattering vapor deposition method, but the method is not limited to this, and other forming methods such as an ion plating method and an ion assist method may be used.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0034]

As described above in detail, according to the multilayer mirror of the present invention, titanium oxide and strontium fluoride are alternately laminated on a reflecting substrate having a concave surface, and then the temperature is raised to 300 ° C. or more. By baking it to form a multilayer film, a multilayer film with excellent moisture resistance and heat resistance can be formed, and it can be sufficiently adapted to a light source with high output and long life, and the application of the light source can be selected. Instead, it can be applied as a reflecting mirror for all light sources.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of a multilayer-film reflective mirror according to an embodiment of the present invention.

FIG. 2 is a curve diagram showing a spectral transmittance characteristic of a TiO ₂ / SrF ₂ alternating layer.

[Explanation of symbols]

 1 ... Reflecting substrate 2 ... Concave surface 4 ... Multilayer film 5 ... Multilayer film mirror

Claims (1)

[Claims] 1. A multi-layered film reflective film, characterized in that titanium oxide and strontium fluoride are alternately laminated on a reflective substrate having a concave surface, and then a baking process is performed at a temperature of 300 ° C. or higher to form a multi-layered film. mirror.