JPH04240803A - Reflection mirror made of multilayered films - Google Patents

Abstract

PURPOSE:To obtain the reflection mirror made of multilayered films having excellent heat resistance and moisture resistance and to allow the application of this mirror to a light source, such as high-output long-life halogen lamp, by lowering a sulfur dissociation rate and fluorine dissociation rate. CONSTITUTION:The multilayered films 6 which are visible light reflective and IR transmittable films are deposited on the surface of a reflection substrate 1. The multilayered films 6 are alternate layers consisting of 25 layers of ZnS/ MgF2 constitution alternately laminated with high-refractive index layers 6H consisting of thin films of zinc sulfide (ZnS) and low-refractive index layers 61 consisting of thin films of magnesium fluoride (MgF2) and the optical film thicknesses of the respective layers are 1/4lambda. The thin films of the zinc sulfide and the thin films of the magnesium fluoride have respective film characteristics of <=1% sulfur dissociation rate and fluorine dissociation rate.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

[Industrial Application Field] The present invention relates to a multilayer film reflector used for floodlights, exposure light sources, etc., and in particular, a multilayer film reflector that uses a cold light mirror as a base and has excellent heat resistance and moisture resistance. Regarding.

0002

[Prior Art] Conventionally, multilayer reflective mirrors based on cold light mirrors have been widely used as light sources for floodlights, store lighting, or medical lighting. A visible light reflecting infrared transmitting film is formed, and the visible light emitted from the halogen bulb installed in the multilayer reflector is reflected by the visible light reflecting infrared transmitting film and projected forward. In addition, the infrared rays pass through the visible light-reflecting infrared-transmissive film and head backwards, thereby reducing the possibility that the illuminated object will be heated by the heat rays, and the substrate will not be heated when the heat rays pass through the multilayer film. It has special features.

[0003] However, the above visible light reflective infrared transmitting film is
It is formed as a multilayer film in which thin films of high refractive index materials and thin films of low refractive index materials are alternately laminated on the surface of a reflective substrate made of hard glass by vacuum evaporation, and the higher the ratio of the refractive indexes of the laminated materials, the more It has high reflectance and a wide reflection band. Generally, a thin film made of zinc sulfide (ZnS) is used as a high refractive index layer, and a thin film made of magnesium fluoride (MgF2) is used as a low refractive index layer.
), or ZnS/MgF2, in which a thin film of zinc sulfide (ZnS) as a high refractive index layer and a thin film of silicon oxide (SiO2) as a low refractive index layer are alternately laminated. Alternating layers of SiO2 are employed as the multilayer of the reflector.

[0004] The above ZnS/MgF2 alternating layers or Zn
Table 1 shows the times at which film peeling occurred when the lamp was turned on and when the mirror was left in a high temperature and humid atmosphere for a multilayer film reflector coated with alternating S/SiO2 layers. In Table 1, the heat load due to lamp lighting is 300° C. and 350° C., and the high temperature and humidity atmosphere is when the reflecting mirror is left in an atmosphere with a temperature of 50° C. and a humidity of 90%.

[0005]

[0006] As is clear from Table 1, ZnS/MgF
Since the 2-based multilayer film has good moisture resistance but poor heat resistance, it is applied to light sources with relatively low heat load and long life, such as low-output, long-life halogen lamps. Also, ZnS/Si
O2-based multilayer films have good heat resistance but poor moisture resistance, so they are applied to light sources with a high heat load and short life, such as high-output, short-life halogen lamps.

[0007]

[Problems to be Solved by the Invention] However, when forming the above multilayer film, a thin film of zinc sulfide and magnesium fluoride is formed by vacuum evaporation or ion plating in an atmosphere of an inert gas, such as argon gas. However, in zinc sulfide (ZnS) and magnesium fluoride (MgF2), sulfur and fluorine dissociate at high temperatures, resulting in ZnS1-α+αS and MgF2(1-α).
+2αF, and the formed film loses sulfur and fluorine by the dissociation rate α. This dissociation of sulfur and fluorine contributes to the reduction in heat resistance and moisture resistance of the multilayer film.

Zinc sulfide (ZnS) and magnesium fluoride (ZnS) were formed by vacuum evaporation in an argon gas atmosphere.
Table 2 shows the values of the dissociation rate α of MgF2).

[0009]

[0010] As mentioned above, the conventional multilayer film reflector is
Because they have shortcomings in either heat resistance or moisture resistance, a suitable light source was selected depending on the performance of the light source, but in recent years light sources have become higher in output and have a longer lifespan. With the progress of the development, there was a problem that the dissociation rate of sulfur and fluorine was high in strengthening the heat resistance and moisture resistance of multilayer film reflecting mirrors.

The present invention has been made in view of the above-mentioned circumstances, and provides a multilayer film reflecting mirror with excellent heat resistance and moisture resistance by reducing the sulfur dissociation rate and fluorine dissociation rate in a ZnS/MgF2 multilayer film. The purpose is to

[Configuration of the invention]

[0013]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a multilayer reflector in which a thin film of zinc sulfide and a thin film of magnesium fluoride are alternately laminated on the surface of a reflective substrate. The zinc sulfide thin film and the above-mentioned magnesium fluoride thin film are characterized in that they have film properties of a sulfur dissociation rate and a fluorine dissociation rate of 1% or less, respectively.

[0014]

[Function] Since the present invention is constructed as described above, a multilayer reflector having excellent heat resistance and weather resistance is obtained, and is applicable to light sources such as high-output, long-life halogen lamps.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a halogen lamp to which the multilayer reflector of the present invention is applied, and FIG. 2 is a schematic enlarged cross-sectional view of one embodiment of the multilayer reflector of the present invention.

As shown in the above figure, a reflective substrate 1 made of hard glass has a recess 2 in the shape of a paraboloid of revolution with one side expanded, and a cap 3 protruding behind the recess 2. It is formed by A halogen lamp 4 serving as a light source is installed in the center of the recess 2, and this halogen lamp 4
The cap part 3 of the reflective substrate 1 is attached with a heat-resistant adhesive 5.
Fixed.

A multilayer film 6, which is a visible light reflecting and infrared transmitting film, is deposited on the inner surface of the recess 2, thereby forming a multilayer film reflecting mirror 7. A front glass 8 is attached to the front of this multilayer film reflecting mirror 7 for safety.

As shown in FIG. 2, the multilayer film 6 has a high refractive index layer 6H made of a thin film of zinc sulfide (ZnS) and a low refractive index layer 6L made of a thin film of magnesium fluoride (MgF2) alternately. 25 of stacked ZnS/MgF2 composition
It is composed of alternating layers, and the optical thickness of each layer is 1/4λ. The 25 alternating layers are controlled so that the thickness of the first to thirteenth layers is λ1-13 = 600 nm, and the thickness of the fourteenth to 25th layers thereon is controlled to be λ14-25 = 450 nm. That is, the high refractive index layer 6H with λ=600 nm and λ
Six low refractive index layers 6L each having a thickness of 600 nm are laminated alternately, and a high refractive index layer 6H having a thickness λ=600 nm is laminated thereon.
One layer is added to make 13 layers. Furthermore, λ=450
nm low refractive index layer 6L and λ=450 nm high refractive index layer 6
Six layers of H and H are alternately laminated.

Vacuum deposition is generally used to form the multilayer film 6, and the film forming conditions are as follows.

[0021]

In the process of forming the multilayer film 6, when the temperature rises, the binding strength between Zn and S and between Mg and F becomes weaker, and the sulfur dissociation rate of ZnS and MgF2 become weaker.
The fluorine dissociation rate of gF2 increases. For this reason, when forming a ZnS film, CS2 gas containing sulfur and MgF2
By introducing CF4 gas containing fluorine as a scattering gas during film formation, the film has characteristics of having a low sulfur dissociation rate and a low fluorine dissociation rate. These low sulfur dissociation rates and fluorine dissociation rates are controlled to desired values by appropriately selecting the amounts of CS2 gas and CF4 gas introduced and the substrate temperature.

Multilayer film reflecting mirror 7 formed as described above
Regarding the sulfur dissociation rate of ZnS in multilayer film 6 and MgF2
Table 3 shows the peeling times of the multilayer film 6 when the lamp was turned on and when it was left in a high temperature and humid atmosphere when the fluorine dissociation rate was changed. In Table 3, the heat load due to lamp lighting is 300° C. and 350° C., and the high temperature and humidity atmosphere is when the reflecting mirror is left in an atmosphere with a temperature of 50° C. and a humidity of 90%.

[0024]

[Table 3] As is clear from Table 3, when the sulfur dissociation rate of ZnS and the fluorine dissociation rate of MgF2 are each 1% or less, the peeling time of the multilayer film 6 at high temperature and high temperature and humidity is significantly extended. I know that there is.

As described above, by reducing the sulfur dissociation rate and the fluorine dissociation rate, a multilayer reflector 7 with excellent heat resistance and moisture resistance can be obtained, which is sufficient for light sources such as high output and long life halogen lamps. may be applied.

In the above embodiments, the method for forming the multilayer film was vacuum evaporation, but the method is not limited to this, and may also be ion plating, ion assist, or CVD (chemical vapor deposition).
Other forming methods such as the Vapor Deposition method may also be used.

Further, in the above embodiment, an example was explained in which the multilayer film is applied to a visible light reflecting infrared transmitting film in a halogen lamp, but the invention is not limited to this, for example, it is applied to a film formed on the outer surface of a halogen light bulb to transmit visible light. It may be applied to a visible light transmitting infrared reflecting film that returns infrared rays to a filter, or an interference filter film that selectively transmits or reflects light in a specific wavelength range.

Furthermore, 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.

[0029]

Effects of the Invention As detailed above, the multilayer reflector of the present invention has a structure in which the sulfur dissociation rate of the zinc sulfide thin film and the fluorine dissociation rate of the magnesium fluoride film are each 1% or less. As a result, a multilayer reflector with excellent heat resistance and weather resistance can be obtained, and it is fully compatible with light sources such as high-output, long-life halogen lamps.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a halogen lamp to which a multilayer reflector of the present invention is applied.

FIG. 2 is a schematic enlarged sectional view of an embodiment of a multilayer reflective mirror according to an embodiment of the present invention.

[Explanation of symbols]

1...Reflection board 6...Multilayer film 6H…High refractive index layer 6L...Low refractive index layer 7...Multilayer reflective mirror

Claims (1)

[Claims] 1. A multilayer reflector comprising a thin film of zinc sulfide and a thin film of magnesium fluoride alternately laminated on a reflective substrate surface, wherein each of the thin film of zinc sulfide and the thin film of magnesium fluoride has a content of 1% or less. A multilayer film reflector characterized by having film characteristics of a sulfur dissociation rate and a fluorine dissociation rate.