Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Discharge device load
Reexamination Certificate
2001-03-21
2002-06-25
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Discharge device load
C313S491000
Reexamination Certificate
active
06411039
ABSTRACT:
TECHNICAL FIELD
This invention relates to a discharge lamp designed for dielectrically impeded discharges. Such a discharge lamp has at least one cathode and at least one anode in a discharge vessel filled with a discharge medium, at least the anode being separated from the discharge medium by a dielectric layer. The mode of operation of dielectrically impeded discharges in such discharge lamps is not of individual interest here. Consequently, reference is made here to the prior art, in particular to the documents still to be cited below.
In particular, this invention relates to the electrode configuration in a discharge lamp for dielectrically impeded discharges.
PRIOR ART
The invention proceeds from strip-shaped electrodes known per se. Strip-shaped electrodes are provided, in particular, for discharge lamps in the form of flat radiators which essentially comprise two plane-parallel plates which are, if appropriate, connected by a frame. In this case, the strip-shaped electrodes are generally formed on one or more of the walls of these plates, it being possible for dielectrically impeded discharges to be produced in a correspondingly flat discharge volume between the plates. Generally, the strip-shaped cathodes and anodes run essentially parallel to one another in this case.
Strip-shaped electrodes are also, of course, possible on other discharge lamps, particularly in conjunction with differing discharge vessel geometries. They can also be deposited in the case of non-flat discharge vessels on inner or outer surfaces of boundary walls forming the discharge vessel, or also independently of a discharge vessel wall, for example on a plate, carrying the electrode strips, inside the discharge vessel. In particular, the invention is therefore directed towards strip-shaped electrodes which are applied to a wall of the discharge vessel or to a wall in the discharge vessel.
However, in principle this invention requires no carrier for the electrode strips.
The invention therefore proceeds from a discharge lamp having a discharge vessel filled with a discharge medium, a strip-shaped cathode and a strip-shaped anode as well as a dielectric layer between the anode and the discharge medium.
Essential criteria in the development and assessment of electrode configurations in the discharge lamps considered here, which have dielectrically impeded discharges are, in addition to an advantageous electrical performance of the electrode configuration as electrical component, the geometrical properties of the electrode configuration and/or the discharge structures to be produced using it. Importance can attach here, on the one hand, to the uniformity of the production of light both in time and in space, that is to say to the temporal freedom from fluctuation and to as homogeneous a surface distribution as possible. Of course, it is also possible for specific inhomogeneous surface distributions to be intended. Furthermore, interest also attaches, moreover, to the surface luminance to be achieved with the discharge lamp for specific applications, for example in the field of flat screen backlighting, or in signal lamps.
SUMMARY OF THE INVENTION
Overall, the present invention is based on the technical problem of specifying a discharge lamp for dielectrically impeded discharges having an improved electrode configuration, and a lighting system containing such a discharge lamp and also a suitable ballast.
According to the invention, this problem is solved by means of a discharge lamp of the type denoted above, which is characterized in that the anode runs in a meandering shape such that the spacing between the cathode and the anode is modulated by the meandering shape, or is characterized in that the cathode and the anode run in a meandering shape, the meandering shapes running in phase opposition locally relative to one another such that the spacing between the cathode and the anode is modulated by both meandering shapes.
Furthermore, the invention relates to a lighting system having one of these two discharge lamps and a ballast which is designed for pulsed coupling of active power into the discharge lamp.
Numerous preferred refinements of the discharge lamp and the ballast, and thus of the lighting system, are specified in the dependent claims and described in more detail below.
In its most general form, the invention is to be considered in two variants as regards the discharge lamp. The first variant presupposes the inventive meandering course of the electrodes only for the anode. The precise course of the strip-shaped cathode is basically open in this case, although the meandering shape of the anode is intended to modulate the spacing, decisive for the discharge, between the cathode and the anode. For this purpose, the cathode can have a straight form of strip, or else any other desired form of strip, as long as the modulation of the discharge spacing by the meandering shape is not nullified thereby or overlaid by a form which influences the discharge spacing in another way so strongly that the effect intended by the invention is lacking. In particular, however, it is also possible in this case for the cathode to have a meandering shape, this corresponding to a special case of the second variant of the invention.
In this case, it is a precondition for this first variant, discussed here, of the invention that the anode of the discharge lamp is distinguished from the cathode in some form, that is to say can be distinguished from the cathode in principle. This can be the case, in principle, in many different forms, in the simplest case by virtue of the fact that there is no dielectric layer between the cathode and the discharge medium.
However, use is also made occasionally of a dielectric layer on the cathode or cathodes, in order to protect them against sputtering damage by the ion bombardment from the discharge medium. In this case, the dielectric layer on the cathode or cathodes is frequently thinner than the dielectric layer as regards the anode. The anode is distinguished from the cathode in this case too.
This even includes the case in which the anode is distinguished only by an appropriate designation on the discharge lamp, for example by a polarity symbol on its electric connection. Basically, it may be stated in this context that both a bipolar and a unipolar power supply are possible in the case of discharge lamps for dielectrically impeded discharges. In the bipolar case, the cathodes and anodes naturally alternately exchange their electrical roles, and therefore cannot be distinguished from one another in operation. The statements made in this description for one of the two types of electrode then hold for both types of electrode. Conversely, this means for the first variant, just discussed, of the invention that such a discharge lamp is designed for a unipolar operation.
The second variant of the discharge lamp according to the invention will firstly be represented before then discussing in detail the effects and advantages of the meandering shape according to the invention. In this case, the meandering shape relates to both types of electrode, that is to say at least one cathode and at least one anode run in a meandering shape. It is provided in this case that the meandering shapes reinforce one another with regard to the modulation of the discharge spacing between the cathode and the anode. They run in phase opposition relative to one another for this purpose.
However, the invention is to be understood in this case to be generalized to the extent that the meandering shapes of the electrodes need not be periodic. Consequently, the term phase opposition possibly relates only to a periodicity which is local and altered at a different point, and possibly to nonperiodic cases as well in which, however, in essence “peak strikes trough” and “trough strikes peak” locally, the electrodes thus being guided towards or away from one another essentially at the same points.
It is also to be clarified that the described reinforcement of the meandering shapes in phase opposition need not necessarily m
Hitzschke Lothar
Jerebic Simon
Vollkommer Frank
Clark Robert F.
Patent-Treuhand-Gesellschaft fuer elektrische Gluehlampen mbH
Vu David
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