JP2874069B2 - Halogen bulb - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halogen bulb used in an automobile headlight or the like having an improved color temperature of emitted light.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a high color temperature headlight for an automobile using a discharge lamp instead of a halogen bulb. However, this is more expensive than conventional halogen bulbs. Therefore, in a halogen lamp, it is expected to increase the color temperature by forming a multilayer interference film on the outer surface of the bulb. FIG. 4 shows a conventional halogen lamp with a multilayer interference film having a high color temperature. In this halogen bulb, the wavelength 6 is applied to the outer surface of the bulb 9 made of glass.
Multilayer interference film 10 having improved reflectance of 40 nm to 800 nm
Is formed.

In FIG. 4, reference numeral 11 denotes a lead wire, and reference numeral 12 denotes a filament. In such a conventional high color temperature halogen lamp with a multilayer interference film, the color temperature of light emitted by reflecting red light (wavelength: 640 to 800 nm) by the multilayer interference film 10 is increased.

[0004]

However, in the multilayer interference film, the wavelength region to be reflected changes depending on the difference in the incident angle.
Therefore, the angle of the light emitted from the filament entering the multilayer interference film decreases toward the two ends of the bulb, and light other than the light having the desired high color temperature is emitted, resulting in color unevenness.

The present invention has been made to solve such a problem, and it is an object of the present invention to provide a halogen bulb having a high emission color temperature with reduced color unevenness.

[0006]

According to the present invention, there is provided a halogen bulb in which a multi-layered interference film is formed by alternately laminating a high refractive index layer and a low refractive index layer on the outer surface of a one-side sealed type bulb. In a halogen bulb in which a filament is arranged along the central axis of the bulb, the multilayer interference film is perpendicular to the central axis of the bulb and passes through one end of the filament and perpendicular to the central axis of the bulb. A first interference film formed on the outer surface of the valve separated by a plane passing through the other end of the filament; and a first interference film formed on the outer surface of the valve from one end of the first interference film toward the top of the valve. and 2 interference film, Ri Do and a third interference film formed on the valve exterior surface toward the other end of said first interference film in the direction of the sealing portion of the valve, the first interference film, the second Dried
The optical thicknesses of the thin film and the third interference film are different from each other.
Have a thickness .

[0007]

The wavelength region to be reflected by the multilayer interference film changes depending on the angle of the incident light. In the case of the present invention, the angle of light incident on the first interference film is vertical, and the angle of light incident on the second and third interference films is smaller than the vertical. The color temperature of light emitted from the first to third interference films is changed by changing the optical film thickness of the second and third interference films based on the first interference film based on the difference in the reflection wavelength region due to the difference in the incident angle. Can be the same. In addition, since the multilayer interference film including the first to third interference films reflects red light (wavelength: 640 to 800 nm), long wavelength light decreases and the color temperature increases.

[0008]

FIG. 1 is a front view of a halogen bulb for an automobile headlight according to an embodiment of the present invention. In FIG. 1, a filament 2 is provided in a bulb 1 made of quartz glass so as to coincide with a central axis thereof. Both ends of the filament 2 are connected to lead wires 3 and 4. The outer surface of the bulb 1 is formed on the outer surface of the bulb 1 divided by a plane perpendicular to the central axis of the bulb 1 and passing through one end of the filament 2 and a plane perpendicular to the central axis of the bulb 1 and passing through the other end of the filament 2. A first interference film 5, a second interference film 6 formed on the outer surface of the valve 1 from one end of the first interference film 5 toward the neck of the valve 1, A multilayer interference film 8 composed of a third interference film 7 formed on the outer surface of the bulb 1 toward the sealing portion is formed.

Next, a method of forming a multilayer interference film on a valve will be described.
explain about. Tetrabutyl titanate in ethanol
The valve 1 is immersed in a solution dissolved in a system solvent. next,
First interference film portion, second interference film portion, and third interference film portion
The pulling speed is set to 3 so that each has a predetermined optical film thickness.
Pull up valve 1 while changing in steps
A film is attached to the outer surface. After that, fire this valve.
Then, on the bulb 1, titanium oxide as a material for the high refractive index layer
(TiO_Two) A film is formed. After cooling, as above
Dissolved ethyl silicate in ethanol-based solvent
Immerse valve 1 in the solution. Next, the first interference film portion,
The second interference film portion and the third interference film portion each have a predetermined optical film
While changing the lifting speed to 3 levels so that it becomes thicker,
Then, the valve 1 is pulled up and a film is attached. After a while
When the valve 1 is fired, a low refractive index layer is formed on the titanium oxide film.
Oxide (SiO 2) _Two) Film is formed
You. By repeating the above process twice alternately, from four layers
A multilayer interference film 8 is formed on the bulb 1. However,
To make the optical thickness of the fourth layer half the optical thickness of the second layer
Use a solution with half the concentration of ethyl silicate
A film is formed in the same manner as the above layer.

FIG. 2 shows the spectral transmittance curves of the first interference film used for the halogen lamp of the present invention, curve A, second interference film B, and third interference film C.
As is clear from FIG. 2, the transmittance of the first to third interference films in the wavelength range of 640 to 800 nm is reduced. That is, it reflects red light. For this reason, the color temperature of the halogen lamp of the present invention increases.

In general, a multilayer interference film has such a characteristic that when the optical film thickness is reduced, the reflection wavelength region shifts to the shorter wavelength side. As can be seen from FIG. 2, the positions of the wavelengths at which the transmittance of the first interference film, the second interference film, and the third interference film are minimized are different. In the present invention, the angle at which light emitted from the filament enters the first to third interference films is perpendicular to the first interference film, and smaller than perpendicular to the second and third interference films. Considering the characteristics of the multilayer interference film and the incident angles of the first to third interference films, the optical thickness of the first to third interference films is adjusted so that the light transmitted through the first to third interference films becomes the same. Set. In the example of the present invention, the optical thickness of the first interference film was 160 nm, the second interference film was 180 nm, and the third interference film was 185 nm. When the multilayer interference film is formed under the above conditions, the wavelength regions reflected by the first to third interference films become the same. In other words, the color temperatures of the light transmitted through the multilayer interference film are the same. The spectral distribution curve of the halogen bulb obtained in this way is shown as curve D in FIG. In FIG.
Curve E shows a spectral distribution curve of a conventional halogen lamp without a multilayer interference film. The color temperature is 28 for conventional halogen bulbs.
In contrast to 50K, the halogen bulb of the present invention is 34K.
It was confirmed to rise to 20K. Further, in the conventional halogen lamp with a multilayer interference film, light having a different color temperature, that is, color unevenness was observed depending on the viewing angle, but it was confirmed that the halogen lamp of the present invention also reduced the color unevenness.

Although it is possible to further increase the color temperature by increasing the number of layers of the multilayer interference film, as the number of layers is increased, the range of the optical film thickness becomes narrower, so that manufacturing restrictions may be caused. In practice, the number of layers is preferably four or six.

In the above embodiment, an example was described in which titanium oxide was used as a film having a high refractive index and silicon oxide was used as a film having a low refractive index. However, tantalum oxide or titanium oxide was used as a film having a high refractive index. Similar effects can be obtained in the case of a combination using zircon oxide and silicon oxide as a film having a low refractive index.

[0014]

As described above, the present invention can provide a halogen bulb having a high color temperature with reduced color unevenness.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a halogen lamp according to an embodiment of the present invention.

FIG. 2 shows a first interference film used in the halogen lamp of the present invention;
Spectral transmittance curves of the second interference film and the third interference film

FIG. 3 is a spectral distribution curve diagram of the halogen lamp of the present invention.

FIG. 4 is a partially cutaway front view of a conventional halogen bulb with a multilayer interference film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bulb 2 Filament 3, 4 Lead wire 5 First interference film 6 Second interference film 7 Third interference film 8 Multilayer interference film

Claims (2)

(57) [Claims] (1) A halogen having a multilayer interference film formed by alternately laminating high-refractive-index layers and low-refractive-index layers on the outer surface of a one-side sealed bulb, and a filament disposed in the bulb along the central axis of the bulb. In the light bulb, the multilayer interference film is formed on the outer surface of the bulb divided by a plane perpendicular to the central axis of the bulb and passing through one end of the filament and a plane perpendicular to the central axis of the bulb and passing through the other end of the filament. A first interference film, a second interference film formed on the outer surface of the valve from one end of the first interference film toward the top of the valve, and a valve from the other end of the first interference film. Do and a third interference film formed on the valve exterior surface toward the direction of the sealing portions of Ri, the first interference
The optical thickness of the film, the second interference film and the third interference film is
Halogen bulbs characterized that you have have different thicknesses. 2. The multi-layer interference film, comprising: a first interference film;
The second interference film having an optical thickness larger than that of the first interference film;
2. A third interference film having an optical thickness larger than that of the interference film.
The halogen bulb according to claim 1, wherein