JPH06215733A - Metal halide lamp for headlamp of automobile - Google Patents

Abstract

PURPOSE:To improve safety by restricting variation in the chromaticity point as well as the color rendering property at the time of starting of the light, and by contracting the time period from the starting of a lamp, at which the chromaticity point enters a white range defined by JIS. CONSTITUTION:A metal halide lamp is provided with a pair of electrodes 1a, 1b inside, and an arc tube 1 in which mercury, metal halide and rare gas are sealed. A fluorescent screen 4 consisting of tervalent europium activation yttrium vanadate phosphor and the like, is formed on the outer surface in the vicinity of the electrodes 1a, 1b of the arc tube 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp for a vehicle headlight.

[0002]

2. Description of the Related Art Recently, studies have been conducted on the use of metal halide lamps for automobile headlights.

Since a metal halide lamp requires a long time from startup to stabilization, when it is used as a vehicle headlight, an example is known in which a dedicated electronic ballast is used to instantly enable light rising. There is.

[0004]

However, in such a conventional method using an electronic ballast, the metal halide enclosed in the tube evaporates and emits light when the light rises, that is, at the time of startup, and stabilizes. For a few seconds until the stable time, the change in chromaticity point and color rendering is large because it is mainly due to the emission of mercury, and it takes a relatively long time until the chromaticity point falls within the white range of JIS. Therefore, there is a problem that it is not preferable for safety.

The present invention has been made in order to solve such a problem, and suppresses changes in the chromaticity point and the color rendering property at the time of rising of light, and the time until the chromaticity point falls within the white range of JIS. It is intended to provide a metal halide lamp for a vehicle headlight, which can shorten the life and enhance the safety.

[0006]

A metal halide lamp for an automobile headlamp according to the present invention has a pair of electrodes therein and has a pair of electrodes of an arc tube in which mercury, a metal halide and a rare gas are enclosed. A phosphor film is formed on the outer surface of at least one of them. Further, the talhalide lamp for an automobile headlight of the present invention has a pair of electrodes inside, and a phosphor film is formed on the outer surface in the longitudinal direction of the arc tube in which mercury, a metal halide and a rare gas are enclosed. is doing.

[0007]

With this configuration, in addition to the light emission of mercury in the visible region immediately after startup, it is possible to obtain the light emission in the visible region from the phosphor generated by receiving the light emission of mercury in the ultraviolet region. Further, when stable, the vapor pressure of the metal halide increases and the emission ratio of mercury decreases, so that the emission from the phosphor is suppressed. Further, in general, the phosphor has a lower emission intensity as the temperature rises. Therefore, when the fluorescent substance is stable, the temperature of the fluorescent substance becomes high, so that the fluorescent substance hardly emits light. From this, the light emission from the phosphor can supplement the light emission from mercury until the light emission from mercury is sufficiently obtained at the time of rising of the light, and the change in the chromaticity point and the color rendering can be reduced. . In addition, a stable light color can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a metal halide lamp for an automobile headlamp according to an embodiment of the present invention has a pair of electrodes 1a and 1b therein and is filled with mercury, a metal halide and a rare gas. This arc tube 1 is provided with
One end side of is supported by a base 2 made of a synthetic resin such as PPS (polyphenylene sulfide). An outer tube 3 containing an arc tube 1 is fixed to the base 2.
A phosphor film 4 made of a trivalent europium-activated yttrium vanadate phosphor is formed on the outer surface of the arc tube 1 in the vicinity of the electrodes 1a and 1b. This phosphor film 4 also has a heat retaining effect.

A metal halide lamp for an automobile headlamp (hereinafter referred to as "product of the present invention") of the above-described embodiment, and a conventional metal halide lamp (hereinafter referred to as "product of the present invention") which has the same structure as that of the present invention and whose arc tube is not treated FIG. 2 shows the change in chromaticity point at the time of rising of light, and FIG. 3 shows the change in color rendering property. In this figure, the curve A shows the product of the present invention, and the curve B shows the conventional product. In addition, for the product of the present invention and the conventional product, the chromaticity point is JIS D
Table 1 shows the time required to enter the white range of 5500.

[0010]

[Table 1]

As is apparent from FIGS. 2 and 3 and Table 1, the product of the present invention can suppress changes in the chromaticity point and the color rendering property at the time of rising of light as compared with the conventional product, and the chromaticity point is activated. It can be seen that the time from later to the time within the white range of JIS D 5500 can be shortened.

As described above, the metal halide lamp for an automobile headlamp according to the embodiment of the present invention is provided with the electrodes 1a, 1 of the arc tube 1.
By forming the phosphor film 4 on the outer surface in the vicinity of b, it is possible to receive the light emission in the ultraviolet region due to mercury at the time of rising of light and obtain the light emission in the visible region from the phosphor film 4, until the time of stabilization. Light emission from the metal halide can be supplemented. Therefore, it is possible to minimize changes in the chromaticity point and the color rendering property when the light rises, and the chromaticity point is J
Since the time required to enter the white range of IS D 5500 can be shortened, the safety can be improved as compared with the conventional product.

In the above embodiment, the phosphor film 4 is formed on the outer surface near the electrodes 1a and 1b, but it may be formed on the outer surface near one of the electrodes.

FIG. 4 shows a metal halide lamp for an automobile headlamp according to another embodiment of the present invention, which has a pair of electrodes 1a and 1b inside and emits light containing mercury, a metal halide and a rare gas. The tube 1 is provided, and the phosphor film 4 is formed on the outer surface of the arc tube 1 on the back side in the longitudinal direction. Also in this case, the same effect as that of the above-described embodiment can be obtained.

Although trivalent europium-activated yttrium vanadate phosphor was used for the phosphor film 4, other phosphors such as tin-activated magnesium orthophosphate, tin-activated strontium orthophosphate, and manganese-activated phosphor were used. Magnesium germanate, trivalent europium-activated yttrium oxide, trivalent europium-activated yttrium phosphovanadate, or the like may be used.

[0016]

As described above, the metal halide lamp for a vehicle headlight according to the present invention suppresses the change in chromaticity point and color rendering property at the time of light rising from the time when the lamp is started to the time when it is stable, and Since it is possible to shorten the time until the degree point falls within the white range of JIS D 5500,
The safety can be improved as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a metal halide lamp for an automobile headlamp according to an embodiment of the present invention.

FIG. 2 is a diagram showing a change in chromaticity point at the time of rising light.

FIG. 3 is a diagram showing a change in color rendering at the time of rising light.

FIG. 4 is a partially cutaway front view showing a metal halide lamp for a vehicle headlamp according to another embodiment of the present invention.

[Explanation of symbols]

 1 arc tube 1a, 1b electrode 2 base 3 outer tube 4 phosphor film

Claims (2)

[Claims] 1. A phosphor film is formed on an outer surface of the arc tube, which has a pair of electrodes inside and in which mercury, a metal halide and a rare gas are sealed, in the vicinity of at least one of the electrodes. A characteristic metal halide lamp for automobile headlights. 2. A vehicle headlight having a pair of electrodes inside, and a phosphor film formed on the outer surface of the rear side in the length direction of an arc tube in which mercury, a metal halide and a rare gas are enclosed. Metal halide lamp for light.