JP2640700B2 - Metal halide lamp light source for vehicle - 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 headlight, and more particularly to a vehicular lamp employing a metal halide lamp as a discharge lamp as a light source.

[0002]

2. Description of the Related Art As a conventional metal halide lamp employed as a light source in a vehicle lamp of this type, there is, for example, a metal halide lamp disclosed in Japanese Patent Application Laid-Open No. Hei 2-301953. A starting gas containing mercury, a metal halide, and xenon gas is sealed in the container.At the time of starting, a current several times higher than that at the time of stable operation is passed to shorten the starting time, and the xenon gas at this time is reduced. The aim is to improve the color rendering at the time of starting by using the light emission caused by the light.

[0003]

However, in the conventional metal halide lamp in which a starting gas containing xenon gas is filled, a curve K in FIG. Although high color rendering properties can be obtained as described above, immediately after startup, discharge by mercury with a lower discharge voltage becomes mainstream, whereby the emission spectrum by mercury becomes dominant and the color rendering properties become extremely high. The period until the light emission by the metal halide is started is continued, and there is a problem that a traffic sign or the like may be erroneously recognized during the period described above. It was supposed to be.

[0004]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, in a vehicle lamp using a metal halide lamp as a light source, the light emitted from the metal halide lamp of the vehicle lamp is used. A metal halide, characterized in that a filter for selectively attenuating a wavelength near 547 nm, which is one of the peak wavelengths of mercury emission, is inserted in the optical path from the front lens to the outside of the lamp. An object of the present invention is to solve the above-described conventional problem by providing a vehicular lamp having a lamp light source.

[0005]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 shows a first embodiment of the present invention as a main part. A metal halide lamp 2 as a light source of the vehicular lamp 1 is covered with a cap 3 formed of a transparent member such as glass. A multilayer interference filter 4 is formed on any of the inner and outer surfaces of the cap 3 so as to selectively attenuate a wavelength near 547 nm, which is one of the peak wavelengths of mercury emission.

[0006] By doing so, the vehicular lighting 1
As shown by the curve F in FIG. 3, the light emitted from the light source has a color rendering property in a period from immediately after the start of lighting to the start of light emission by the metal halide at one of the peak wavelengths of mercury emission by the multilayer interference filter 4. This is improved by focusing on a certain wavelength near 547 nm.

As is apparent from the curve K in FIG. 3, the metal halide lamp 2 emits light having no problem in color rendering due to light emission of the metal halide after a lapse of a predetermined time after lighting. The cap 3 may cover the metal halide lamp 2 for a predetermined time after activation, for example, for one minute, and after that time, may move forward, for example, to stop its operation. The loss of light quantity due to the insertion of the membrane interference filter 4 can be avoided during most of the use time of the vehicle lamp 1.

FIG. 2 shows a second embodiment of the present invention. In the previous embodiment, a cap 3 for covering a metal halide lamp 2 was provided, and a multilayer interference filter 4 was formed on the cap 3. On the other hand, in this embodiment, the multilayer interference filter 4 is formed on one of the front and back surfaces of the front lens 5 by utilizing the front lens 5 originally used as a component of the vehicle lamp 1. Therefore, the present invention can be implemented without providing new additional parts and the like, and the same operation and effect as those of the previous embodiment can be obtained.

That is, in the present invention, if the light is radiated from the metal halide lamp 2 and passes through the front lens 5 and is radiated to the outside of the vehicle lamp 1,
The multilayer interference filter 4 may be provided at any position. For example, an optimum position can be selected depending on conditions such as heat resistance of the multilayer interference filter 4.

[0010]

As described above, according to the present invention, in the optical path from the metal halide lamp to the outside of the lamp through the front lens and to the outside of the lamp, there is a peak wavelength of 547 nm which is one of the peak wavelengths of mercury emission. In the vehicle lamp of the metal halide lamp light source in which a filter for selectively attenuating the wavelength of light is inserted, the mercury emission becomes dominant in the interim period immediately after the start of the metal halide lamp, so that the color rendering properties are reduced and the JIS white light is reduced. Out of light is improved by selectively attenuating the emission spectrum of mercury with the filter, thereby preventing false recognition of traffic signs and the like, and improving the performance of this type of vehicle lamp. It has excellent effects.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a first embodiment of a vehicle lamp of a metal halide lamp light source according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the vehicle lamp of the metal halide lamp light source according to the present invention.

FIG. 3 is a graph showing the color rendering properties of a metal halide lamp light source for a vehicle immediately after startup.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vehicle lamp 2 ... Metal halide lamp 3 ... Cap 4 ... Multilayer interference filter 5 ... Front lens

Claims (1)

(57) [Claims] 1. A vehicular lamp using a metal halide lamp as a light source, wherein the metal halide lamp contains xenon in a filling gas, and is emitted from the metal halide lamp through a front glass and illuminated outside the lamp. Has 547n which is one of the peak wavelengths of mercury emission.
A metal halide lamp light source for a vehicle, wherein a filter for selectively attenuating a wavelength near m is inserted.