Headlamp for motor vehicles

Details Headlamp for motor vehicles Headlamp for motor vehicles

1992-01-27

1993-11-09

Cole, Richard R.

Illumination

Vehicle steering mechanism or element moves pivoted lamp or...

Tie rod element controlled

362296, 362310, 362351, F21M 302, F21V 906

Patent

active

052608565

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates a headlamp for motor vehicles. More particularly, it relates to a headlamp for motor vehicles which has a discharge lamp inserted into a reflector and surrounded by a glass envelope which is transparent in certain sections to light of specific wavelengths.
Such a headlamp is disclosed in EP-A1-0 237 647. This headlamp has a discharge lamp whose discharge vessel is surrounded a glass envelope made of hard glass. The discharge vessel is melt-sealed into the glass envelope so that these parts are combined to form one unit. The space between glass envelope and discharge vessel is evacuated. The glass envelope is provided in certain sections with a coating which is non-transparent and by means of which an asymmetrical light distribution required in dipped headlamps is achieved. By means of the glass envelope, the UV-A light portion and UV-B light portion of the light transmitted by the discharge lamp is blocked to a specific degree since, due to its properties, glass generally inhibits the passage of these portions. However, the UV-C light portion which is injurious to health and also destroys plastics is not blocked by a glass envelope consisting merely of customary glass. In addition, if the glass envelope is touched when the headlamp is damaged, for example after an accident, there is a risk of combustion. The reason is that the high temperatures prevailing in the discharge vessel are transmitted to the glass envelope and if the electrical terminals of the discharge lamp are touched there is a risk of lethal injury since the lamp is operated at a high voltage.


SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a headlamp for motor vehicles, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a headlamp for motor vehicles, in which a discharge lamp is held in a lamp carrier and arranged in a space limited at least by the lamp carrier and the glass envelope, wherein the glass envelope blocking UV light in the UV-Am UV-B and UV-C wavelengths range.
When the headlamp for motor vehicle is designed in accordance with the present invention it has, in contrast with the above, the advantage that principally also the UV-C light portion is blocked by the glass envelope and thus there is no risk of injury to health and no risk of destruction of plastic parts. In addition, the risk of combustion is reduced by the glass envelope since the discharge lamp cannot be touched directly but rather only the glass envelope, which reaches a substantially lower temperature than the discharge lamp. The electrical terminals of the discharge lamp are also prevented by the glass envelope from being touched.
In accordance with a further feature of the present invention, electrical conductor tracks are arranged on the outer surface of the glass envelope and are part of an electrical line which is connected to a lamp ballast serving to supply the discharge lamp with high voltage, and the discharge lamp is prevented from operating when the line is interrupted. When the head-lamp is designed in accordance with these features, a further increase in safety is achieved since the discharge lamp cannot be operated with damaged conductor tracks and thus with a damaged glass envelope and also when the glass envelope is not mounted. In accordance with a further feature of the present invention, the headlamp has a shutter with an optically effective edge and a lens is arranged in the direction of the light reflected by the reflector, so that by means of the lens, an image of the edge of the shutter is formed as a light/dark border of the light distribution. The end of the glass envelope pointing in the direction of emergence of light receives the lens, and the lens, like the glass envelope, blocks light in the UV-A, UV-B and UV-C wavelengths range. When the headlamp is designed in accordance with these fea

REFERENCES:
patent: 4935660 (1990-06-01), Heider et al.
patent: 5107405 (1992-03-01), Makita
patent: 5113330 (1992-05-01), Makita
patent: 5130904 (1992-07-01), Ohshio et al.
patent: 5132881 (1992-07-01), Wakimizu et al.
patent: 5140504 (1992-08-01), Sato

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