Illumination – Light source and modifier – Ionized gas or vapor light source
Patent
1997-09-09
1999-09-28
O'Shea, Sandra
Illumination
Light source and modifier
Ionized gas or vapor light source
362226, 362440, 362444, 362437, 362443, F21K 2700
Patent
active
059575697
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to electric lamps and particularly to vehicle lamps. More particularly the invention is concerned with a replaceable vehicle lamp.
BACKGROUND ART
The invention relates to an electric lamp based without cement. An electric lamp based without cement is disclosed in U.S. Pat. No. 4,412,273. The lamp described therein is a single base incandescent halogen lamp for use in a motor-vehicle headlight. The lamp in U.S. Pat. No. 4,412,273 consists of a lamp base made of metal and plastic parts. The lamp base has a cup-like metal fastening ring, a metal support sleeve and a plastic base which is provided with the electrical connections for the lamp. The support sleeve protrudes telescopically out of the base in which it is anchored, and is welded to the fastening ring using a plurality of integrally formed welding tabs. The fastening ring has a recess in which the end of the pinch of the lamp bulb is fixed. The plastic base has an annular flange and an alignment plate. Between the flange and the alignment plate, there is an annularly extending groove for receiving a gasket which seals off the reflector opening. The alignment plate ends approximately at the inner side of the reflector.
A disadvantage of the lamp in U.S. Pat. No. 4,412,273 is that the plastic alignment plate for the base is directly exposed to the infrared radiation emitted by the lamp. Because the plastic tends to give off vapors when heated, exposure of the plastic alignment plate to the infrared radiation results in fogging of the reflector. Furthermore, the plastic has a comparatively high coefficient of thermal expansion, so that heating the alignment plate by the infrared radiation generated by the lamp causes a misalignment of the light source. In addition, the telescopic design of the support sleeve has the disadvantage that the lamp has a comparatively large overall length and requires correspondingly deep reflectors.
DISCLOSURE OF THE INVENTION
The object of the invention is to provide an electric lamp, having an improved lamp base for installation in a reflector wherein the improved lamp base is based without cement.
The electric lamp, based without cement, is intended for installation in a reflector, for example the reflector of a motor-vehicle headlight. The lamp has a lamp base made of metal and plastic parts. The lamp base has a metal holder part in which the lamp bulb is fixed, a metal support sleeve supporting the holder part and a plastic base part which is provided with the electrical connections of the lamp and in which the support sleeve is anchored.
The plastic base part has a plurality of reference lugs, located in a common plane, which on the one hand are used for holding the lamp in the reflector, and on the other hand are used to determine the position of the light source in the reflector and define the reference plane for aligning the light source when the lamp base is being fitted in place. The plastic reference lugs engage the reflector opening, which is formed as a lamp socket, and according to the invention each lug is covered by a cover tab, integrally formed on the metal support sleeve, so that the reference lugs are screened against the electromagnetic radiation generated by the lamp, and in particular against infrared radiation. For this purpose the cover tabs preferably cover the upper sides of the reference lugs facing the lamp bulb. The cover tabs prevent, on the one hand, the plastic reference lugs from giving off vapors and fogging the reflector and, on the other hand, the light source from migrating from its originally exactly adjusted position as a result of the thermal expansion of the reference lugs. The metal cover tabs have a much lower thermal expansion as well as higher stiffness than the plastic reference lugs, and prevent thermally induced deformation of the reference lugs and the concomitant misalignment of the light source in the reflector. The reference lugs then give the lamp base greater mechanical stability, particular when heated.
In another embodiment
REFERENCES:
patent: 1139684 (1915-05-01), Humphrey
patent: 4412273 (1983-10-01), Helbig et al.
patent: 4473770 (1984-09-01), Baba et al.
patent: 4682274 (1987-07-01), Freudenreich et al.
patent: 4751421 (1988-06-01), Braun et al.
Helbig Peter
Steiner Hermann
DelGizzi Ronald E.
Meyer William E.
O'shea Sandra
Patent-Treuhand-Gesellschaft fuerelektrische Gluehlampen mbH
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