Method of and device for operating a gas discharge lamp
AssigneeKoninklijke Philips Electronics N.V.
InventorsGünther Hans Derra, Hanns Ernst Fischer, Thomas Krücken, Holger Moench, Xaver Riederer
Life of this patent
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Abstract
A method of and a device for operating a gas discharge lamp which is fed with an alternating voltage or an alternating current and wherein the instantaneous power of the lamp is increased at given time intervals are used to form the electrodes. The value of an operational datum of the lamp which varies in time is continuously or discontinuously measured and the frequency of the alternating voltage or the alternating current (operating frequency) is selected in dependence on the measured values.
Claims19
A method of operating a gas discharge lamp which is fed with an alternating electric power source, wherein the lamp has electrodes having respective electrode front faces, and the lamp has operational characteristics after lamp starting which vary in time over periods which are a multiplicity of cycles of said electric power source, comprising:
- providing lamp starting power at start-up frequencies, and after lamp start-up providing operating power at operating frequencies, and
- after start-up, increasing the instantaneous power of the lamp to a value greater than the mean lamp power during each of a succession of given time intervals shorter than said periods,
- characterized in that the method further comprises:
- measuring the values of at least one operational datum representative of at least one of said operational characteristics, and
- responsive to the measured values, causing growth of structures on said electrodes having respective cross sections less than the respective electrode front faces, and respectively forming projecting electrode tips, by selecting the operating frequency of the alternating electric power source.
A method of treating the electrodes of a gas discharge lamp which is fed with an alternating electric power source, wherein the lamp has electrodes having respective electrode front faces, and the lamp has operational characteristics after lamp starting which vary in time over periods which are a multiplicity of cycles of said electric power source, comprising:
- providing lamp starting power at start-up frequencies, and after lamp start-up providing operating power at operating frequencies, and
- after start-up, increasing the instantaneous power of the lamp to a value greater than the mean lamp power during each of a succession of given time intervals shorter than said periods,
- characterized in that the method further comprises changing the frequency of the alternating electric power for deliberate use of the transport of electrode material occurring during operation of the lamp to cause growth of structures on said electrodes, said structures having respective cross sections less than the respective electrode front faces, and respectively forming projecting electrode tips.
A device for operating a gas discharge lamp which is fed with an alternating electric power source, the lamp having electrodes having respective electrode front faces, the lamp having operational characteristics which vary in time over periods which are a multiplicity of cycles of said electric power source, and the device comprising means for providing starting power at start-up frequencies and providing operating power after start-up at operating frequencies,
- wherein after start-up and while the lamp is receiving operating power at operating frequencies the instantaneous power of the lamp is increased at given time intervals,
- characterized in that the device further comprises:
- means for measuring the values of at least one operational datum representative of at least one of said operational characteristics, and
- means, responsive to the measured values, for causing growth of structures on said electrodes having respective cross sections less than the respective electrode front faces, and respectively forming projecting electrode tips, by selecting the operating frequency of the alternating electric power source.
Dependencies are inferred from the claim text.