High pressure lamp operating circuit with suppression of lamp flicker
AssigneeU.S. Philips Corporation
InventorsGunther H. Derra, Hanns E. Fischer, Hans G. Ganser, Holger Monch
Life of this patent
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Abstract
A circuit arrangement for operating a high pressure discharge lamp includes input terminals for connection to a supply voltage source and an apparatus coupled to the input terminals for supplying an alternating lamp current to the high pressure discharge lamp. A device (III) is provided for generating a current pulse in each half period of the lamp current. This current pulse has the same polarity as the lamp current and is superimposed on the lamp current in the latter part of a predetermined fraction of the half periods of the lamp current. The circuit substantially suppresses flickering of the discharge arc during lamp operation.
Claims23
Method for operating a high pressure discharge lamp comprising:
- supplying an alternating lamp current to the high pressure discharge lamp, generating a current pulse in a predetermined fraction of given half periods of the lamp current, said current pulse having the same polarity as the lamp current and being superimposed on the lamp current only in a latter part of the half period in which it is generated.
Circuit arrangement for operating a high pressure discharge lamp comprising:
- input terminals (K1, K2) for connection to a supply voltage source,
- means, coupled to the input terminals, for supplying an alternating lamp current
- to the high pressure discharge lamp, and
- means for generating a current pulse in a predetermined fraction of the half periods of the lamp current, said current pulse having the same polarity as the lamp current and being superimposed on the lamp current in a latter part of the half period in which it is generated.
A circuit for operating a high pressure discharge lamp comprising:
- input terminals for connection to a source of supply voltage,
- output terminals for connection to the high pressure discharge lamp,
- means including a switchable transistor coupled to said input terminals and to said output terminals for supplying an alternating lamp current to a high pressure discharge lamp when the lamp is connected to said output terminals, and
- means coupled to said lamp current supplying means for generating and supplying to the output terminals a current pulse in a given fraction of half periods of the lamp current, wherein said current pulse has the same polarity as the lamp current and is supplied to the output terminals only during a latter part of a half period of the lamp current.
Dependencies are inferred from the claim text.