Electric lamp and discharge devices: systems – Special application – Vehicle
Reexamination Certificate
1999-01-08
2001-02-27
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Special application
Vehicle
C315S060000, C313S318090, C362S265000
Reexamination Certificate
active
06194834
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a gaseous-discharge lamp, in particular for motor-vehicle headlamps.
BACKGROUND INFORMATION
German Patent Application No. 35 19 611 describes gaseous-discharge lamps or high-pressure discharge lamps. The ballast unit required to supply the lamps with the necessary ignition voltage and maintaining voltage is arranged in a shaped housing, which is configured on the rear part of the reflector of the motor vehicle's headlamp unit. This housing increases the overall depth of the motor vehicle's headlamp unit, it being necessary for the high-voltage conducting lines to be run from the shaped housing to the lamp's burner vessel. This entails insulation problems and line losses.
European Patent No. 150 799 describes a low-pressure gaseous-discharge lamp, in which the ballast unit is arranged at the lamp base. However, such a low-pressure gaseous-discharge lamp is not suited for motor-vehicle headlamps, and the problems associated with electrode bushings arranged at opposite end regions, in conjunction with a ballast unit configured in the lamp base, are neither addressed nor solved by this publication.
SUMMARY OF THE INVENTION
By electrically feeding back the electrode bushing arranged in the end region of the burner vessel that is distant from the lamp base via an external line to the lamp base or to the ballast unit configured therein, an altogether simple, cost-effective, and compact means is achieved for fulfilling the objective, which is suited, above all, for applications in motor-vehicle headlamps.
By integrating the ballast unit in the lamp base (i.e., cap), a very small overall volume can be achieved with virturally no increase in the size of the motor-vehicle headlamp unit as such. When the means for generating ignition voltage are accommodated in the lamp base, they are arranged virtually directly next to the an electrode of burner vessel and form a permanent unit, the result being minimal line length for the high-voltage conducting lines, in particular of the external line at the burner vessel. As a result, less line capacitance and, thus, less energy is required to arrive at the ignition voltage, and the size of the firing-pulse transformer is reduced, facilitating in turn direct installation on the burner vessel. The short (i.e., minimal length of the high-voltage carrying lines results in diminished insulation problems, and less ignition voltage is needed in the ballast unit. Should malfunctions or defects arise, merely replacing the gaseous-discharge lamp replaces the ballast unit and the high-voltage lines at the same time, making it possible to eliminate most sources of error quickly and simply.
According to one advantageous exemplary embodiment of the present invention, an inductive ignition component, is particular a firing-pulse transformer, contained in the ballast unit, has an encapsulated (i.e., toroidal) core, preferably an annular core, which makes it possible to achieve a high inductance using a small number of turns. This leads to a slow ignition pulse, and the ignition voltage can be maintained at a low level. Furthermore, the small number of turns renders possible a compact and small-volume type of construction.
The encapsulated core preferably wraps around one of the end regions of the burner vessel provided with an electrode bushing, which likewise plays a role in size reduction.
By at least partially extrusion-coating or sealing in the components required for the ballast unit, together with an end region of the burner vessel, using plastic (i.e., molding) material, a lamp base can be produced simply and cost-effectively, which besides fulfilling its task as a lamp base, will also hold the components together and bond them to the burner vessel. At the same time, this lamp base fulfills the function of an insulator, it being beneficial for the electrical connnecting terminals of the lamp base to be extrusion-coated or sealed in along with the components, so that virtually the entire lamp base is produced in one sequence of operation.
A simpler and cost-effective means for achieving the objective makes it possible for the region of this external line running in the lamp base to be advantageously extrusion-coated or sealed in at the same time.
Besides reducing ignition energy losses by using short high-voltage lines, one can also advantageously reduce the ignition voltage by installing an auxiliary electrode. It is beneficial in this case for the external line to be connected to an auxiliary electrode or to form such an electrode, this auxiliary electrode being preferably arranged near the first main electrode next to the base.
One achieves ease of manufacturing and a cost-effective way to fulfill the objective by configuring the auxiliary electrode as a wire or conductive strip adjoining the burner vessel on the outside.
In another advantageous exemplary embodiment, the polarity of the first main electrode next to the base is negative in comparison to the polarity of the other, second main electrode linked to the auxiliary electrode. This ensures that, following the initial spark, which jumps from the first main electrode near the base to the auxiliary electrode and, in fact, through the glass wall of the burner vessel, the subsequent sparks can follow in the direction of the second main electrode, without any polarity reversal of the first main electrode.
REFERENCES:
patent: 4097777 (1978-06-01), Bacharowshi
patent: 4447759 (1984-05-01), Moerkens et al.
patent: 4714986 (1987-12-01), Wurster
patent: 4769578 (1988-09-01), Jacobs et al.
patent: 5059865 (1991-10-01), Bergman et al.
patent: 5436533 (1995-07-01), Fromm et al.
patent: 5489825 (1996-02-01), Rimmer
patent: 35 19 611 (1986-12-01), None
patent: 150 799 (1985-08-01), None
patent: 203 545 (1986-12-01), None
patent: 6-314555 (1994-11-01), None
“Lamps and Lighting,” A manual lamps and lights prepared by members of staff of Thorn Lighting Ltd., Henderson et al., Crane, Russak & Company, Inc., New York, 1972, pp. 327-33.
Kern Robert
Seiler Hartmut
Kenyon & Kenyon
Lee Wilson
Robert & Bosch GmbH
Vu David
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