Electric lamp and discharge devices: systems – Pulsating or a.c. supply
Reexamination Certificate
2000-06-14
2001-07-10
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Pulsating or a.c. supply
C313S607000
Reexamination Certificate
active
06259214
ABSTRACT:
The invention relates to a method for operating a discharge lamp in which a first dielectrically impeded discharge and a second dielectrically unimpeded discharge are generated in the discharge lamp.
I. PRIOR ART
Such a method is disclosed, for example, in laid-open patent application WO 96/36066. This publication describes an operating method for a discharge lamp in which a first, dielectrically impeded discharge and a second, dielectrically unimpeded discharge are generated in the discharge lamp. The dielectrically impeded discharge is superimposed on the dielectrically unimpeded discharge, or made to precede it temporally. The color locus of the light emitted by the discharge lamp is specifically set via the ratio of the electric powers of both discharges. Neon gas serves as discharge medium. The dielectrically impeded discharge generates neon excimers which emit as they decay UV radiation which is, in turn, converted into light by means of a fluorescent material, while the dielectrically unimpeded discharge emits predominantly red light. This method does not permit dimming of the discharge lamp, since changes in the electric power of the two discharges lead to a shift in the color locus of the emitted light.
II. SUMMARY OF THE INVENTION
It is the object of the invention to provide a method for operating a discharge lamp in which a dielectrically impeded and a dielectrically unimpeded discharge are generated in the discharge lamp, and which permits brightness control of the light emitted by the discharge lamp. Moreover, the aim is to dispense with the use of mercury in the discharge lamp.
This object is achieved according to the invention by means of the characterizing features of claim
1
. Particularly advantageous designs of the invention are described in the subclaims.
The operating method according to the invention generates in the discharge lamp two different gas discharges, specifically a dielectrically impeded discharge and a dielectrically unimpeded discharge, xenon being used as discharge medium in both cases. According to the invention, by forming xenon excimers, the dielectrically impeded discharge generates ultraviolet radiation which is converted into light by fluorescent materials, while the dielectrically unimpeded discharge is formed as a xenon low-pressure discharge emitting ultraviolet radiation, the UV radiation emitted by the xenon low-pressure discharge likewise being converted into light by fluorescent materials. In the brightness control of the light emitted by the discharge lamp, according to the invention the dielectrically impeded discharge is generated for the purpose of setting the undimmed operating state, and the xenon low-pressure discharge is generated for the purpose of setting a dimmed operating state.
This mode of operation of the discharge lamp according to the invention unites with one another the high light yield of a dielectrically impeded discharge and the good dimmability of a low-pressure discharge. Since xenon gas is used as a discharge medium, it is predominantly ultraviolet radiation which is produced in the case both of the dielectrically impeded and the low-pressure discharges, which radiation is converted into white light or monochromatic light by fluorescent materials, with the result that it is possible to dispense with the addition of mercury in the discharge space. The color of the light emitted by the discharge lamp is determined only by the fluorescent materials. Consequently, the mode of operation according to the invention produces no color locus shifts by changing the electric power of the two types of discharge. It is advantageously only the dielectrically impeded discharge which is generated for the purpose of setting the undimmed operating state in the discharge lamp, since said discharge ensures a higher light yield than the dielectrically unimpeded discharge. In order to reduce the brightness, the electric power of the dielectrically impeded discharge is firstly advantageously reduced, and for the purpose of further reducing the brightness, the dielectrically impeded discharge is switched off and only the xenon low-pressure discharge is generated, the electric power of the xenon low-pressure discharge being set as a function of the desired brightness or dimming stage. The xenon low-pressure discharge can be dimmed to a substantially greater extent than the dielectrically impeded discharge, without having to fear extinction of the discharge or without the occurrence of an inhomogeneous discharge.
The dielectrically impeded discharge is advantageously generated by means of two outer electrodes which are mounted on the outer surface of the discharge vessel in order to ensure a discharge which is as homogeneous as possible. The dielectrically unimpeded discharge is advantageously generated by means of two cold cathodes arranged inside the discharge vessel. In order to generate the dielectrically impeded discharge, the two outer electrodes are advantageously subjected to high-voltage pulses, while for the purpose of generating the xenon low-pressure discharge, the cold cathodes are advantageously subjected to a medium-frequency AC voltage or to high-voltage pulses.
REFERENCES:
patent: 5523655 (1996-06-01), Jennato et al.
patent: 5604410 (1997-02-01), Vollkommer et al.
patent: 5965988 (1999-10-01), Vollkommer et al.
patent: 6157145 (2000-12-01), Vollkommer et al.
patent: 197 18 395 (1998-10-01), None
patent: 96/36066 (1996-11-01), None
Doell Gerhard
Enders Martin
Riehl Hartwig
Bessone Carlo S.
Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen MBH
Philogene Haissa
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