Illumination – Vehicle steering mechanism or element moves pivoted lamp or... – Tie rod element controlled
Patent
1992-02-12
1994-02-22
Cole, Richard R.
Illumination
Vehicle steering mechanism or element moves pivoted lamp or...
Tie rod element controlled
362 21, 362293, 362351, F21M 314
Patent
active
052893529
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a headlamp for motor vehicles.
More particularly, it relates to a headlamp which has a gas discharge lamp and a front plate which covers the light exit opening of the headlamp.
Such a headlamp is disclosed in the German Offenlegungsschrift 35 19 611. This headlamp has a reflector into which a gas discharge lamp is inserted as a light source. The light exit opening of the headlamp is covered with a front plate. Apart from visible light, the gas discharge lamp also transmits light in the UV wavelength region of high intensity. This UV light is, on the one hand, noxious and, on the other hand, can destroy plastics and glass. The heat radiation of the gas discharge lamp is substantially smaller in comparison with an incandescent lamp so that moisture which has penetrated the headlamp or has been precipitated on the front plate does not dry and moisture which has frozen onto the front plate does not thaw. In addition, under certain circumstances the light transmitted by the gas discharge lamp has an excessively high blue fraction.
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 in which the beam path of the light beams reflected by the reflector and the light beams transmitted directly to the front plate from the gas discharge lamp contains a disc-shaped filter which is arranged so as to at least partially absorb light in the UV region.
When the headlamp is designed in accordance with the present invention, it has, in contrast with the above, the advantage that the light transmitted by the gas discharge lamp in the UV wavelength region is absorbed by the filter and thus no UV radiation at a harmful intensity can emerge from the headlamp.
In accordance with another advantageous feature of the present invention, the front plate is provided with a coating which absorbs light in the UV wavelength region or consists of a UV light absorbing material and serves as the filter. With such a design of the front plate as a UV filter, a selective heating of the same is achieved so that during the operation of the gas discharge lamp moisture which has been precipitated on the front plate is dried and moisture which has frozen onto it thaws.
In accordance with another feature of the present invention, the lens is arranged in a holder, and the holder has a component with an electrical line, and the electrical line is interrupted when the lens impacts against the component with a specific force, and operation of the gas discharge lamp is prevented when the line is interrupted. When the headlamp is designed in accordance with these features it is ensured that even with a damaged UV filter no UV radiation emerges from the headlamp.
It is possible, in accordance with a further development, that the line is realized as a conductor track mounted on the component, and the component is broken in such a way by the lens when it impacts against the component that the conductor track is interrupted. In this construction the line is interrupted in the case of a lens which is moved out of the holder for example as a result of an impact and thus in a simple manner the failure of the lens is indicated.
Finally, a voltage divider circuit can be provided in the line, and the control device can have an evaluation circuit by means of which the operation of the gas discharge lamp is prevented in the event of a voltage drop in the line deviating from a voltage drop predetermined by the voltage divider circuit. In this case, it is ensured that the gas discharge lamp cannot be operated even with a damaged UV filter due to short circuiting of the signalling lines.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself
REFERENCES:
patent: 3767288 (1973-10-01), Gross
patent: 4862328 (1989-08-01), Nino
patent: 4868726 (1989-09-01), Segoshi
patent: 4951178 (1990-08-01), Shirai et al.
patent: 4985816 (1991-01-01), Seko
Delb Fred
Hege Gunter
Jager Christian
Kolberg Kay
Kusserow Peter
Cole Richard R.
Robert & Bosch GmbH
Striker Michael J.
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