JP2687243B2 - Multilayer optical interference film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention is a multilayer optical interference film in which required characteristics can be obtained even with a small number of layers and durability is improved. .

(Prior Art) For example, in a halogen bulb with a reflector, a visible light-reflecting infrared ray transmissive film is formed on the reflecting surface of a glass reflector, and visible light is reflected as much as possible out of the light emitted from the halogen bulb. It is often used to project visible light with less infrared light, so-called cold light, by radiating the light to the rear and transmitting the infrared light.

In addition, the halogen bulb has a visible light-transmitting infrared reflective film formed on the outer surface of the cylindrical glass bulb, which radiates visible light out of the light emitted from the filament to the outside world and reflects as much infrared light as possible to return to the filament. A lamp is often used in which the lamp is heated to radiate visible light with little infrared rays, that is, cold light, and has high luminous efficiency.

Therefore, the visible light-reflecting infrared ray transmissive film and the visible light-transmitting infrared ray transmissive film are both made of a high refractive index layer made of zinc sulfide (ZnS) or the like and magnesium fluoride (MgF ₂ ) or the like on the surface of a substrate such as glass. It is formed by alternately laminating 11 to 19 layers of a low refractive index layer, which utilizes light interference by appropriately adjusting the thickness of each of the high refractive index layer and the low refractive index layer. It reflects light in a desired wavelength range and transmits light in a desired wavelength range, and has a higher reflectance and a wider reflection band as the refractive index ratio increases. Therefore, the visible light reflecting infrared ray transmitting film and the visible light transmitting infrared ray reflecting film described above are collectively referred to as a multilayer optical interference film.

Table 1 shows combinations of substances used to form such a multilayer optical interference film and their refractive index ratios.

From Table 1, it is advantageous to employ alternating stacking of ZnS-MgF ₂ to obtain a wide reflection band.

(Problems to be solved by the invention) The above-mentioned ZnS-MgF ₂ alternating laminated layers have a high refractive index ratio but heat resistance,
There is a problem with weather resistance, and in comparison with this, the TiO ₂ —SiO ₂ alternate laminated layer is superior in heat resistance and weather resistance. This state is shown in Table 2 below.

That is, when the ZnS-MgF ₂ layer is applied to a halogen lamp bulb or a reflector close to the lamp, the ZnS-MgF ₂ layer peels off in a short period of time due to high temperature, and ZnS in the surface layer is oxidized and becomes cloudy. Normal,
When the halogen bulb is turned on, the heat load on the reflector is 350 ° C.
It becomes unusable after 30 hours at 100 ° C and 100 hours at 300 ° C.
Since ZnS has a hygroscopic property, if it is left in an atmosphere of a temperature of 50 ° C. and a humidity of 90% for 50 hours, the film peels off and there is a problem in weather resistance.

On the other hand, the TiO ₂ -SiO ₂ alternate lamination has excellent heat resistance and weather resistance, but if it is attempted to obtain the same optical characteristics as the ZnS-MgF ₂ alternate lamination with this configuration, the number of layers It is necessary to increase the value by 50%, and it becomes expensive, so there is a problem in practicality from the economical aspect.

Therefore, an object of the present invention is to provide a multilayer optical interference film that can obtain the required optical characteristics even with a small number of layers, and that has excellent heat resistance and weather resistance.

[Effects of the Invention] (Means for Solving the Problems) The multilayer optical interference film of the present invention is formed by alternately laminating a high refractive index layer made of titanium oxide and a low refractive index layer made of barium fluoride on the surface of a substrate. By doing so, the required optical characteristics can be obtained with a small number of layers, and the heat resistance and weather resistance are improved.

(Function) Barium fluoride (BaF ₂ ) is chemically stable, has excellent heat resistance and weather resistance, and has a small refractive index. Since the titanium oxide layer and the barium fluoride layer have a large refractive index ratio, the required optical properties can be obtained with a small number of layers, and because the compatibility of the lamination of both is good, it is difficult to peel off, and it has excellent heat resistance and weather resistance. A film is obtained.

(Examples) Hereinafter, details of the present invention will be described with reference to the illustrated examples. FIG. 1 shows an example of a halogen bulb with a reflecting mirror to which the present invention is applied. In the figure, ( 1 ) is a glass reflecting mirror, and (2) is a multilayer optical interference film formed on the inner surface of this reflecting mirror ( 1 ). An example of a visible light-reflecting infrared ray transmitting film, (3) is a halogen light bulb mounted on the reflecting mirror ( 1 ), and (4) is a heat-resistant adhesive in which the halogen light bulb (3) is fixed to the reflecting mirror ( 1 ). It is an agent.

The reflector ( 1 ) has a reflecting portion (1) whose inner surface is a paraboloid of revolution.
A cylindrical base portion (12) is integrally connected behind 1), and a visible light reflecting / infrared transmitting film (2) is formed on the inner surface of the reflecting portion (11).

The visible light reflection / infrared transmission film (2) is a high refractive index layer made of titanium oxide (TiO ₂ ) from the glass side to the inner surface of the reflection part (11) forming the substrate, as shown in a model enlarged view in FIG. (2 _H ) (downward hatching) and barium fluoride (BaF ₂ ).
A low-refractive index layer (2 _L ) consisting of (upper right hatching) and a total of 17 layers are alternately laminated. The optical film thickness of these two layers (2 _H ) and (2 _L ) is 1 / 4λ, λ _1-9 = 600 nm for the first to 9th layers, and λ for the 10th to 17th layers.
_{10 to 17} = 450 nm. That is, a high-refractive index layer (2 _H ) with λ = 600 nm and a low-refractive index layer (2 _L ) with λ = 600 nm are alternately deposited four times in total for a total of eight layers, and the high-refractive index layer (2 _H ) 1
A total of 9 layers are laminated, and a low refractive index layer (2 _L ) and a high refractive index layer (2 _H ) having λ = 450 nm are alternately laminated 4 times for a total of 8 layers.

The halogen bulb (3) is formed by crushing the base portion of a tubular (T-shaped) glass bulb (31) to form a sealing portion (32) and sealing a filament (33). 32) is housed in the base (12) of the reflector ( 1 ) and the filament (3
3) is adjusted so as to be located at the focal point of the reflection part (11), and the base (12) is filled with the adhesive (4) to fix the sealing part (32) by adhesion.

To form the visible light reflection / infrared transmission film (2),
The titanium oxide layer is 8 × 10 ^-3 with oxygen and argon introduced.
Reflector temperature 100 to 300 in a low vacuum atmosphere of ~ 1 x 10 ^-4 Torr
The vapor-deposited base material is bombarded with an electron beam at ℃, and the barium fluoride layer is vapor-deposited by resistively heating the vapor-deposited base material at a reflector temperature of 100 to 300 ℃ in a low-vacuum atmosphere under the above-mentioned pressure in which argon is introduced.

When this halogen bulb with a reflector is turned on, visible light in the light emitted from the filament (33) is reflected by the visible light reflection infrared ray transmission film (2) and emitted forward, and infrared rays are transmitted through the visible light reflection infrared ray. The light is transmitted through the film (2) and further through the glass of the reflection part (11) to be emitted rearward. Therefore, this halogen bulb with a reflecting mirror can project visible light with little infrared light, so-called cold light.

Then, the optical characteristics of both substances forming the visible light reflecting / infrared transmitting film (2), that is, the multilayer optical interference film will be shown below.

Refractive index of titanium oxide (TiO ₂ ) layer N _H = 2.30 Refractive index of barium fluoride (BaF ₂ ) layer N _L = 1.30 Refractive index ratio of both layers N _H / N _L = 1.77 Therefore, conventional ZnS-MgF ₂ Even if the number of layers to be laminated is smaller than that of the alternate lamination, the same optical characteristics can be obtained and the reflection band can be widened. In addition, the compatibility of the lamination of titanium oxide and barium fluoride is extremely good as compared with the conventional lamination, and it is difficult to peel off against heat load,
Can withstand high temperature and high humidity environment. Therefore, this halogen bulb with a reflector has high output power, long life and good weather resistance.

Next, the visible light reflecting infrared ray transmitting film (2) of the above-mentioned reflecting mirror ( 1 ) was tested for heat resistance and weather resistance. Table 3 shows the results. Here, the heat resistance is shown as the time until the start of peeling at 300 ° C and 350 ° C, which are the temperatures of the reflection part (11) when the lamp is turned on, and the weather resistance is peeled in an atmosphere at a temperature of 50 ° C and a humidity of 90%. The time to start is shown.

Comparing Table 3 with Table 2, it is clear that the examples are excellent in heat resistance and weather resistance, have a long life, and can withstand severe operating conditions.

Next, another embodiment is shown in FIG. This is a filament (6) along the centerline of a tubular quartz bulb (5).
Is a halogen bulb in which the visible light transmitting infrared reflecting film (7) is formed on the outer surface of the bulb (5), and a required halogen is enclosed together with argon in the bulb (5).

The visible light transmitting infrared reflecting film (7) is the same as the visible light reflecting infrared transmitting film (2) shown in FIG.
O ₂ high refractive index layer made) (2 _H) (was alternately downhill hatched) and the low refractive index layer made of barium fluoride _{(BaF 2) (2 L)} ( right up hatching) and an example total 15 layers laminated By changing the thickness of each layer ( _2H ) and ( _2L ),
It has a property of transmitting visible light and reflecting infrared rays.

When this halogen bulb is lit, visible light of the light emitted from the filament (6) passes through the visible light transmitting infrared reflecting film (7) and is emitted to the outside, and infrared rays are transmitted through the visible light transmitting infrared reflecting film (7). It is reflected and returned to the filament (6), which is heated to improve the luminous efficiency. Therefore, this halogen bulb emits cold light and is highly efficient.
Moreover, the visible light transmitting / infrared reflecting film (7) can obtain required optical characteristics with a relatively small number of layers as described above, has excellent heat resistance and weather resistance, and has a long life and withstands harsh usage conditions. .

The multilayer optical interference film of the present invention is not limited to the above-mentioned application examples, but has various uses such as a color filter film and an ultraviolet blocking film. In addition to the above-mentioned examples, the method of forming the multilayer optical interference film includes the ion plating method, the ion assist method, and the CVD method.
Other forming methods such as a method may be used. At least one of the titanium oxide layer and the barium fluoride layer may freely contain a glassy reinforcing agent, light diffusing fine particles and the like.
Furthermore, the substrate is not limited to the above-mentioned glass reflector and bulb,
For example, if it is suitable for the application such as a filter substrate,
Further, its shape and material are not critical, as long as a multilayer optical interference film can be formed.

EFFECTS OF THE INVENTION As described above, since the multilayer optical interference film of the present invention is constituted by alternately laminating the high refractive index layer made of titanium oxide and the low refractive index layer made of barium fluoride on the surface of the substrate, each component is It is chemically stable, has good compatibility in combination, and has a large refractive index ratio, so the required optical properties can be obtained even with a small number of layers, it has excellent heat resistance and weather resistance, and it has a long life and is suitable for severe operating conditions. Can bear.

[Brief description of the drawings]

FIG. 1 is a sectional view of a halogen light bulb with a reflecting mirror showing one embodiment of the multilayer optical interference film of the present invention, FIG. 2 is a model enlarged sectional view of the same main portion, and FIG. 3 is another embodiment. It is sectional drawing of a halogen bulb. ( 1 ) …… Reflecting mirror (example of base) (2) …… Visible light reflecting infrared ray transmissive film (example of optical interference film) (3) …… Halogen bulb, (33) …… Filament (5) …… Valve (Other example of substrate) (6) ...... Filament (7) ...... Visible light transmitting infrared reflecting film (other example of light interference film)

Claims (1)

(57) [Claims] 1. A multilayer optical interference film comprising a high refractive index layer made of titanium oxide and a low refractive index layer made of barium fluoride, which are alternately laminated on a substrate surface.