JP2799286B2 - Vehicle lighting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular lamp such as a headlamp for a vehicle, and more particularly, to a multi-layer film for blocking heat rays formed on a glass substrate provided between a light source and a front lens. The present invention relates to a vehicular lamp that has been used.

[0002]

2. Description of the Related Art Conventionally, a headlamp used as a vehicular lamp includes an inner surface of a front lens, a light source and a front lens in order to block a heat ray emitted from the light source and prevent the front lens from being damaged by the heat ray. A heat ray blocking film is formed on the surface of a glass substrate disposed between the light source and the surface of a cap disposed near the light source and covering the light source.

[0003] A film having the following structure is employed as the heat ray blocking film. That is, for example, indium oxide (In ₂ O ₃ ) or tin oxide (S
As in the case of nO ₂ ), the film itself uses a single-layer film that absorbs heat rays, and absorbs and blocks heat rays. For example, titanium dioxide / silicon dioxide (TiO ₂ / Si
O ₂ ) A multilayer film having the property of reflecting heat rays, such as a multilayer film, is used to reflect and block heat rays. Such a single-layer film or a multi-layer film is employed.

[0004]

However, the single-layer film or the multilayer film has the following disadvantages.

[0005] That is, when a single-layer film is employed, since it is a single-layer film, it is excellent in cost and productivity, but the absorption region of heat rays is determined by the substance used as the single-layer film. For example, a single layer film made of indium oxide has a thickness of 2 μm (2000
nm), heat rays having a wavelength shorter than that are absorbed, but heat rays having a wavelength shorter than that are transmitted. Therefore, in the near infrared region (0.8
(1.5 μm), there is almost no absorption, and there is a problem that the absorption rate of heat rays is poor for tungsten lamps for head lamps having a heat ray peak near 1 μm.

When a multilayer film is employed, the reflection range of the heat rays can be freely set, but there is a problem that the cost increases as the number of film layers increases.

Further, a TiO ₂ / SiO ₂ based multilayer film (27 layers) usually used as an infrared reflective multilayer film is shown in FIG.
As shown in the curve (b), heat rays between 0.8 and 1.2 μm are reflected, but heat rays of a longer wavelength are transmitted, and heat rays of a wavelength of 1.2 μm or more are reflected. Is
This is possible by increasing the number of film layers of the multilayer film to, for example, forty or more layers, but there is a problem that the transmittance of visible light is reduced, and a large number of film layers reflects a wide range of heat rays. The configuration of the multilayer film was difficult.

The present invention has been made in view of the above circumstances, and provides a vehicle lamp including a glass substrate coated with a multilayer film that absorbs and reflects heat rays in a wide wavelength range with a small number of layers. The purpose is to:

[0009]

According to the present invention, in order to achieve the above object, a glass substrate having a multilayer film for blocking heat rays is provided between a light source and a front lens disposed in front of the light source. The provided vehicle lamp is characterized in that an indium oxide film or an indium oxide mixed film is laminated as a part of the high refractive index film forming the multilayer film.

[0010]

According to the present invention, a heat ray having a wavelength not shorter than the near-infrared region is absorbed and reflected by the multilayer film.
Heat radiation can be blocked over a wide area with a small number of film layers.

[0011]

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

FIG. 1 is a sectional view showing an embodiment of a vehicular lamp according to the present invention, for example, a cross section of a headlamp for use in a vehicle.

In FIG. 1, reference numeral 1 denotes an aluminum reflecting mirror. A front lens 2 is attached to the periphery of the front opening of the Al reflecting mirror 1 by an adhesive.
At the center of the concave portion, a tungsten bulb 3 is mounted as a light source. A glass substrate 4 is attached to the inner surface side of the front lens 2 in close contact therewith, and the glass substrate 4 is coated with a multilayer film 5 as a heat ray blocking film for blocking heat rays.
FIG. 2 is an enlarged view of a portion A of the glass substrate 4 coated with the multilayer film 5.

As shown in FIG. 2, a multilayer film 5 as a heat ray blocking film is formed on the inner surface of a glass substrate 4 by vacuum evaporation.
Films are formed in nine layers.

That is, first, 4 × 10
After evacuation to a vacuum degree of ^-3 Pa, oxygen gas is introduced to set a coat vacuum degree of 5 × 10 ^-2 Pa.

After setting the coating vacuum in the chamber,
Magnesium fluoride (MgF ₂ ) film 6 as a low refractive index film,
Indium oxide (In ₂ O ₃ ) mixed film as high refractive index film
7 are alternately formed into a total of 16 layers of 8 layers. Here, the indium oxide (In ₂ O ₃ ) mixed film 7 is at least one of indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), antimony oxide (SbO ₂ ), and tungsten oxide (WO ₃ ). 1 to 20% by weight, and magnesium fluoride (MgF ₂ ) to be formed into a film.
Film thickness n of film 6 and indium oxide (In ₂ O ₃ ) mixed film 7
_d is set to n _d = λ / 4 (λ = 850 nm).

Subsequently, the film thickness n _d to be formed is represented by n _d = λ / 4.
(Λ = 1050 nm), a magnesium fluoride (MgF ₂ ) film 6 as a low-refractive-index film and a titanium dioxide (TiO ₂ ) film 8 as a high-refractive-index film are alternately formed into six layers,
Further, a magnesium fluoride (MgF ₂ ) film 6 is formed as an outermost layer, and a total of 13 layers are formed.

As described above, the multilayer film 5 of 29 layers in which the indium oxide (In ₂ O ₃ ) mixed film 7 is laminated on a part of the high refractive index film is formed on the glass substrate 4.

The multilayer film 5 thus formed has the spectral transmittance characteristics shown in FIG. 3 and is in the near infrared region or higher (0.8 μm
It was found that almost all the heat rays having the above wavelengths were blocked.

That is, indium oxide (In ₂ O ₃ )
To tin oxide (SnO ₂ ), antimony oxide (SbO ₂ ),
Alternatively, at least one of tungsten oxide (WO ₃ ) is mixed to form indium oxide (In ₂
The heat ray absorption region of the O ₃ ) mixed film 7 is indium oxide (In).
₂ O ₃ ) From the heat ray absorption region of a single film of 2 μm or more to 1.5
Since the indium oxide (In ₂ O ₃ ) mixed film 7 is laminated on a part of the high-refractive-index film, the heat ray reflection region of the multilayer film 5 is reduced to 27 μm as shown in FIG.
The heat ray reflection area of the multi-layer film is enlarged from 0.8 to 1.2 μm to 0.8 to 1.5 μm, and most of the heat rays are cut off.

Therefore, the multilayer film 5 of the present invention has a structure in which the indium oxide (In ₂ O ₃ ) mixed film 7 is laminated as a part of the high refractive index film, thereby providing a film of the conventional multilayer film. Heat rays can be cut off with the same number of film layers as the number of layers and without increasing the number of film layers.

Next, the operation of the vehicular lamp of the present invention having the above configuration will be described.

Since the heat rays are cut off by the multilayer film 5 formed on the glass substrate 4, the irradiation light transmitted through the glass substrate 4 and irradiated on the front lens 2 does not include the heat rays. The temperature rise does not occur in the lens 2 due to the heat rays, and the damage of the front lens 2 due to the heat rays is prevented.

In the above embodiment, the indium oxide mixed film 7 is used as a part of the high refractive index film forming the multilayer film 5.
However, instead of the indium oxide mixed film 7, an indium oxide film may be stacked, and the same operational effects as those of the multilayer film 5 having the indium oxide mixed film 7 stacked can be obtained.

In the above embodiment, the glass substrate 4 is brought into close contact with the front lens 2. However, the present invention is not limited to this, and the glass substrate 4 is placed at an appropriate position between the front lens 2 and the tongue bulb 3. It may be arranged, and the same operation and effect can be obtained.

Further, the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0027]

As described above in detail, according to the vehicular lamp of the present invention, an indium oxide film or an indium oxide mixed film is laminated as a part of the high refractive index film forming the multilayer film. In addition, heat rays having a wavelength equal to or greater than the near infrared region are absorbed and reflected by the multilayer film, and the heat rays can be blocked with a small number of film layers and over a wide range.

Further, since the irradiation light irradiated to the front lens does not include a heat ray, the temperature of the front lens does not rise due to the heat ray, so that the front lens can be prevented from being damaged by the heat ray.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a vehicular lamp of the present invention.

FIG. 2 is a cross-sectional view showing a main part of a multilayer film coated on a glass substrate.

FIG. 3 is a curve diagram showing a spectral transmittance characteristic of the multilayer film of the present invention.

FIG. 4 is a curve diagram showing spectral reflectance characteristics of a conventional multilayer film.

[Explanation of symbols]

 2… Front lens 3… Tungsten bulb (light source) 4… Glass substrate 5… Multilayer film 7… Indium oxide mixed film (high refractive index film)

Claims (1)

(57) [Claims] 1. A vehicular lamp in which a glass substrate on which a multilayer film for blocking heat rays is formed is disposed between a light source and a front lens disposed in front of the light source, wherein a high refractive index for forming the multilayer film is provided. A vehicle lamp characterized in that an indium oxide film or an indium oxide mixed film is laminated as a part of the film.