JPH0389201A - Multilayered light interference film - Google Patents

Abstract

PURPOSE:To greatly improve the heat resistance and weatherability of the multilayerd light interference films by specifying the respective compsn. rations of the zinc sulfide forming high-refractive index layers and the magnesium fluoride forming low-refractive index layers. CONSTITUTION:The multilayerd light interference films (visible light reflecting IR transmission films) formed by alternately laminating the high-refractive index layers 2H consisting of the zinc sulfide and the low-refractive index layers 21 consisting of the magnesium fluoride on the surface of a base body (reflecting mirror 1) are constituted by specifying the compsn. ratio of the zinc element and sulfur element constituting the zinc sulfide to >=0.60 and <=0.90. The heat resistance and weatherability are improved in such constitution and the compsn. ratio of the magnesium element and fluorine element constituting the magnesium fluoride from >=0.60 to <=0.90, the film hardly peel even after long-term use. These films withstand severe conditions.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a multilayer optical interference film with improved heat resistance and weather resistance.

(Prior art) Conventionally, a halogen light bulb with a reflector has a visible light reflecting and infrared transmitting film formed on the inner surface of a glass reflector, and a halogen bulb is placed inside the reflector. Of the light, visible light is reflected by a visible light reflective infrared transmitting film and projected forward, and infrared light is transmitted through the visible light reflective infrared transmitting film and directed backward. As a result,
This halogen light bulb with a reflector emits visible light, so-called cold light, with little infrared rays, and is often used in floodlights, store lighting, medical lighting, etc.

Therefore, the above-mentioned visible light reflective infrared transmitting film has a high refractive index layer made of zinc sulfide (ZnS) or the like and a low refractive index layer made of magnesium fluoride (MgFz) silica (SiOz) or the like on the reflective mirror surface. It is made up of 25 layers laminated alternately and reflects visible light and transmits infrared rays through optical interference.

In addition, halogen light bulbs are used as light sources for exposure in electronic copiers, facsimile machines, etc., with a filament arranged along the center line of a quartz tube-shaped bulb and a visible light-transmissive infrared reflective film formed on the outer surface of the bulb. ing. Of the light emitted from the filament, visible light passes through a visible light transmitting infrared reflective film and is radiated to the outside world, and infrared light is reflected by the visible light transmitting infrared reflective film and returns to the filament, where it is heated. By improving efficiency, it emits visible light with less infrared rays, so-called cold light, and has the advantage of high luminous efficiency.

The above-mentioned visible light-transmitting infrared-reflecting film has a high refractive index layer made of zinc sulfide or the like and a low-refractive index layer made of magnesium fluoride, silica, etc. on the outer surface of the bulb, similar to the visible light-reflecting infrared-transmitting film described above. It is made up of 21 alternately laminated layers, and by changing the thickness of the layers, it transmits visible light and reflects infrared rays.

In this way, the visible light-reflecting, infrared-transmitting film and the visible-light-transmitting, infrared-reflecting film have the same structure, and by simply changing the layer thickness, light in the desired wavelength range can be transmitted using light interference. , which reflects light in a desired wavelength range. Therefore, such a visible light-reflecting, infrared-transmitting film and a visible-light-transmitting, infrared-reflecting film are collectively referred to as a multilayer optical interference film.

(Problem to be solved by the invention) The above-mentioned ZnS/MgFi alternating layer optical interference film and ZnS/Si
n. A halogen lamp with a reflector on which an alternating layer optical interference film is formed has the disadvantage that it is easily peeled off due to the heat load caused by lighting the lamp or a high temperature and humid atmosphere. Therefore, the heat resistance and weather resistance under such conditions were evaluated by the time taken until the optical interference film peeled off under the conditions shown in Table 1.
Shown in the table.

Table 1 As is clear from this table, ZnS/MgF-based optical interference films have good weather resistance but poor heat resistance, so they are suitable for long-life halogen light bulbs with relatively low heat load. Also, Zns/
Sin-based interference films have good heat resistance but poor weather resistance.
Suitable for light sources with high heat load and short life, such as high output and short life halogen bulbs. For this reason, there has been a demand for a multilayer optical interference film that simultaneously satisfies high levels of heat resistance and weather resistance.

Therefore, an object of the present invention is to simultaneously improve the heat resistance and weather resistance of a multilayer optical interference film.

[Structure of the invention]

(Means for Solving the Problems) The present invention relates to improvement of a ZnS/MgF-based multilayer optical interference film, and the first claim is that the composition ratio S/Zn of zinc element (Zn) and sulfur element (S) is 0.60 or more and 0.90 or less,
In addition, heat resistance and weather resistance are improved by setting the composition ratio F, /Mg of magnesium element (Ng) and fluorine element (F) to 0.60 or more and 0.90 or less. Moreover, the second aspect of the present invention is to improve heat resistance and weather resistance by setting the layer density of the high refractive index layer to 0.96 or more and the layer density of the low refractive index layer to 0.98 or more.

(Function) The zinc sulfide and magnesium fluoride that make up the multilayer optical interference film are usually represented by the chemical formulas ZnS and MgF, but the actual substances that make up each layer do not necessarily have the above-mentioned integer ratio; Expressing this in chemical formula, Zn5(1-X
) # MgFt (x-y>(0<z<l,Q<y
<l). Therefore, the ratio of the two elements that make up the actual layer, for example, the quotient obtained by dividing the number of atoms of sulfur divided by the number of atoms divided by the number of atoms divided by the valence of zinc, is called the composition ratio.

In addition, the layer density is the quotient obtained by dividing the density of the layer (the number of η per 1aJ) by the original density of the material that makes up the layer, or in other words, the density of the crystal of that material (the number of children per lcj). . Even in a multilayer optical interference film, as the layer density of the high refractive index layer and the low refractive layer approaches 1, the crystal structure becomes denser and becomes chemically and physically stable.

If the composition ratio of each layer is optimized and the layer density is improved at the same time, the heat resistance and weather resistance of the resulting multilayer optical interference film will be dramatically improved.

(Examples) Hereinafter, details of the present invention will be explained with reference to each illustrated example. FIG. 1 shows a halogen light bulb with a reflector to which the first embodiment is applied, where ω is a reflector and ■ is a type of multilayer optical interference film formed on the inner surface of this reflector (1). A light-reflecting, infrared-transmitting film, (3) a halogen bulb attached to the reflector, and (2) a heat-resistant adhesive that fixes the halogen bulb (2) to the reflector.

The reflecting mirror (1) is made of hard glass and has a cylindrical base part (12) behind a reflecting part (11) whose inner surface forms a paraboloid of revolution.
) are arranged in series.

As shown schematically and enlarged in Fig. 2, the visible light reflective infrared transmitting film (2) has a high refractive index layer (2H) made of zinc sulfide (ZnS) and a low refractive index layer made of magnesium fluoride (MgFi). (2L) are alternately laminated on the inner surface of the reflective part (11), with a total of 25 layers, and the optical thickness of each layer is 1/4
It is λ. Among these, the first to thirteenth layers are λ, ~i
It was controlled to a=600 nm. That is, λ=600n
A high refractive index layer (2H) of λ = 600 nm and a low refractive index layer (2L) of λ = 600 rv+ are alternately laminated in 6 layers each, and one high refractive index layer (2H) of λ = 600 nm is added thereon. It has 13 layers. Furthermore, layers from the 14th layer to the 25th layer are layered with λ1. ~ii=450 nm.

That is, a high refractive index layer (2H) with λ=450 nm and λ=
Six 450 nm low refractive index layers (2L) are alternately laminated. The first feature of the example is that the S/Zn composition ratio is 0.6 (1"0.90.Fz
/Mg composition ratio is 0.60 to 0.90. The second feature of this embodiment is that the layer density of the high refractive index layer (2H) is 0.96 or more and is 0.98 or more than the layer density of the low refractive index layer (2L).

The above halogen light bulb (■) is made by crushing the base of a cylindrical (T-shaped) bulb (31) made of heat-resistant glass such as quartz glass to form a sealing part (32) and enclosing a filament (33). Position the stop part (32) inside the cap part (12) and fix it with adhesive ■, and attach the filament (33) to the reflective part (1).
It is located at the focal point of 1).

Next, a method for forming the above-mentioned visible light reflective and infrared transmitting film (2) will be explained. Both the high refractive index layer (2H) and the low refractive index layer (2L) are obtained by a formation method that simultaneously performs the ion plating method and the ion assist method, and the layer density is improved by bombardment of ions and electrons by the ion assist method. do. In addition, the layer (
The composition ratio of 2H) and (2L) is determined. That is, the third
In the electron beam film device (■) shown in the figure, magnesium fragments are housed in a crucible (51) that can accommodate a plurality of evaporation base materials, and are heated and evaporated by an electron beam from an electron gun (52). . In this case, the acceleration voltage is 6KV
It is. Further, the emission current value is 42 μAm.

Zinc sulfide is heated and evaporated by resistance heating using a boat (53). Incidentally, this boat (53) is made of tungsten, and the current value when energized is, for example, 290A.

A plurality of reflective mirror ω glasses (13) are mounted on a dome (54), and this dome is connected to a rotating mechanism (54).
5), the reflecting mirror glass (13) is moved by rotating at a speed of 900 to 1500 revolutions per working hour.

At this time, the glass (13) is heated to 100 to 300°C by radiation from the heater (56). Ion gun (57
) is an end-hole type ion gun, and argon was commonly used as the gas introduced for ionization when forming the zinc sulfide layer and the magnesium sulfide layer. The total pressure of argon for this ionization and as background is 8X10-"1.0X
The pressure was set at 10-'Torr. 6 is a film thickness control device, and a light source (
61) is reflected by a monitor board (63) that can accommodate a plurality of rotating mechanisms (62), and this reflected light is passed through an interference filter (64) with a controlled wavelength of λn to a monitor board (63) that can accommodate several monitor boards (63). The optical film thickness is controlled layer by layer, thereby forming each layer (2H) and (2L) of the visible light reflecting and infrared transmitting film (2) on the reflecting mirror glass (13). In other words, in this embodiment, an optical film thickness control method is used. The above-mentioned conditions for the ion gun (57) include a cathode current of 2 OA to emit thermoelectrons to positively ionize the introduced gas.

Accelerating voltage for discharge is 100V, discharge current is 4.5A
shall be. Further, the atmosphere during the layering is a plasma atmosphere. This plasma is generated by applying a high frequency voltage of 50 V to 10 V from a high frequency power source (58) with a frequency of 13.56 MH2 to a coil (59) in the device (2) through a matching box (58a).
).

Next, the effect of the halogen bulb on the reflector of this embodiment will be explained. When you turn on a halogen bulb, the filament (
33), a large amount of infrared rays are emitted along with visible light.

When these lights enter the visible light reflecting infrared transmitting film ■, the visible light is reflected by the visible light reflecting infrared transmitting film ■ and projected forward, and the infrared light passes through the visible light reflecting infrared transmitting film ■, and then The reflector (11) is transmitted through the reflector (11) toward the rear, and thus this reflector axis).The rogen bulb emits visible light, so-called cold light, with little infrared radiation. At this time, due to the heat transfer and light absorption from the halogen bulb (2), the visible light reflective infrared transmitting film (2) and the reflective portion (11) are heated to a high temperature. Because it has excellent heat resistance, it will not peel off.Furthermore, the visible light reflective infrared transmitting film (■) of this example also has excellent weather resistance, so it will not peel off even if left in a humid atmosphere for a long time. .

Next, the reason why the composition ratio and layer density of both layers (2H) and (2L) of the visible light reflecting infrared transmitting film (2) of the reflecting mirror ω formed in this manner are limited as described above will be explained.

First, a high refractive index layer (2H) and a low refractive index layer (2L)
Heat resistance and weather resistance were investigated by varying the composition ratio of each layer (2H) and (2L) by applying high frequency while maintaining the layer density of each layer at 0.98. Heat resistance is 300℃, which is the temperature at which the reflector (11) is normally subjected to when the lamp is lit.
and 350℃, and the weather resistance is 50℃ and relative humidity (H)
90% was taken and expressed as the time until peeling occurred.

The results are shown in Table 2.

(Margins below) Table (Time) As is clear from Table 2, the S/Zn composition ratio is 0°6
0 or more and 0.90 or less, and the composition ratio of KaFa/Mg is 0.
When it is 60 or more and 0.90 or less, heat resistance and weather resistance are excellent.

Next, the high refractive index layer (2H
) S/Zn composition ratio and F2 of the low refractive index layer (2L)
/Mg composition ratio was set to 1.0 in each case, and the heat resistance and weather resistance were investigated with respect to films with varying film densities when high frequency was not applied. The investigation was conducted in the same manner as in Table 2. The results are shown in Table 3.

Table 3 (Time) As is clear from Table 3, the layer density of the high refractive index layer (2H) is 0.96 or more and the layer density of the low refractive index layer (2L) is 0.
．． When it is 98 or higher, heat resistance and weather resistance are excellent.

To summarize and restate the above, the high refractive index layer (2H) and the low refractive index layer (2L) have a composition with slightly reduced sulfur and fluorine, such as ion plating, compared to those deposited in vacuum. This has higher heat resistance and weather resistance, and by further increasing the layer density, excellent heat resistance and weather resistance can be obtained. And each layer (2H).

When the S/Zn and Fz/Mg composition ratios of (2L) are within the above-mentioned range and the layer density is above the above-mentioned values,
Heat resistance and weather resistance are significantly improved compared to the case where only one of the conditions of composition ratio and layer density is satisfied.

Next, a second embodiment is shown in FIG. 4. This is a halogen light bulb used for exposure in copying machines and facsimile machines, and a filament (2) is arranged along the center line of a tube-shaped bulb (0) made of quartz glass. A visible light transmitting infrared reflective film (2), which is another example of a multilayer light interference film, is formed on the outer surface of the bulb (0). The infrared rays are reflected by the visible light transmitting infrared reflective film 0 and returned to the filament (2) to heat it. Therefore, this halogen bulb emits cold light and is highly efficient.

The above-mentioned visible light-transmissive infrared-reflecting film (2) is made by alternately laminating a high refractive index layer made of zinc sulfide and a low-refractive index layer made of magnesium fluoride, similar to the above-mentioned visible light-transmitting infrared-transmissive film (2). By changing the brightness, it transmits visible light and reflects infrared rays.

Also, in this visible light-transmitting infrared-reflecting film (2), the S/Zn composition ratio is 0.6, similar to the visible light-reflecting infrared-transmitting film described above.
0 to 0.90, and F, /Ng is 0.60 to 0.9
When it is 0, the heat resistance and weather resistance are excellent, and the layer density of the high refractive index layer is 0.96 or more, and the layer density of the low refractive index layer is 0.
．． When it is 98 or more, heat resistance and weather resistance are excellent.

Furthermore, when the above-mentioned composition ratio conditions and layer density conditions are combined, the effects on heat resistance and weather resistance are much greater than when each condition is satisfied individually. .

In both of the above-mentioned embodiments, a visible light reflective infrared transmitting film and a visible light transmitting infrared reflective film are used as examples of the multilayer light interference film, but the present invention is not limited to this, and may reflect light in other wavelength ranges. It may be a material that transmits light in other wavelength ranges; in short, it may be a material that utilizes light interference to reflect light in a desired wavelength range and transmit light in a desired wavelength range. Furthermore, the multilayer optical interference film of the present invention can be applied not only to the above-mentioned examples but also to interference color filters, ultraviolet blocking filters, and the like. The base body may be made of ceramics or the like, and its shape is not limited.

〔Effect of the invention〕

As described above, the present invention relates to a ZnS/MgFx multi-calendar optical interference film, and the first claim is that the composition ratio S/Zn of zinc sulfide constituting the high refractive index layer is limited to 0.60 or more and 0.90 or less. In addition, the composition ratio F, /Mg of the magnesium carbide constituting the low refractive index layer is limited to 0.60 or more and 0.90 or less, improving heat resistance and weather resistance, and preventing peeling even after long-term use. It is difficult and can withstand harsh conditions. In addition, the second claim is that the layer density of the high refractive index layer is 0.96 or more, and the layer density of the low refractive index layer is limited to 0.98 or more, so that heat resistance and weather resistance are improved, and long-term use is achieved. It is difficult to peel off even when
Can withstand harsh conditions.

Furthermore, if the inventions of both claims are carried out simultaneously, there is an advantage that the heat resistance and weather resistance are further improved significantly.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a halogen light bulb with a reflector to which the first embodiment of the multilayer optical interference film of the present invention is applied, FIG. 2 is a schematic enlarged sectional view of the main parts, and FIG. FIG. 4, which is an explanatory diagram showing a method of forming an optical interference film, is a sectional view of a halogen light bulb to which the second embodiment is applied. (1)...Reflector (an example of a base) (11)...Reflector (13)...Glass for a reflector ■...Visible light reflective infrared transmitting film (an example of a multilayer optical interference film) ( 2L)...Low refractive index layer (31)...Bulb■...Adhesive (2H)...High refractive index layer■...Halogen bulb (33)...Filament■...Electronic Beam film forming device ■...Film thickness control device 0...Bulb (another example of substrate) ■...Filament■...Visible light transmitting infrared reflective film (another example of multilayer optical interference film)

Claims (2)

[Claims] (1) A high refractive index layer made of zinc sulfide and a low refractive index layer made of magnesium fluoride are alternately laminated on the substrate surface,
The composition ratio between the zinc element and the sulfur element constituting the zinc sulfide is 0.60 or more and 0.90 or less, and the composition ratio between the magnesium element and the fluorine element constituting the magnesium fluoride is 0.60 or more and 0. A multilayer optical interference film characterized in that the optical interference is .90 or less. (2) A high refractive index layer made of zinc sulfide and a low refractive index layer made of magnesium fluoride are alternately laminated on the substrate surface,
A multilayer optical interference film, wherein the high refractive index layer has a layer density of 0.96 or more, and the low refractive index layer has a layer density of 0.98 or more.