Patent ID: 8362708

Claim:
A circuit arrangement for operating a discharge lamp, wherein the circuit arrangement comprises a commutating device, which is configured to exhibit an input which is coupled to a direct-current source and has an output for coupling to the discharge lamp; the commutating device being configured in such a manner that it couples the direct-current source to the output and a polarity with which the direct-current source is coupled to the output being commutated by a control device; the control device comprising a measurement input which is coupled to a measuring device which is configured to deliver a measurement value which is a measure of the magnitude of a lamp voltage; wherein the control device is configured to control the commutating device in such a manner that the polarity at which a higher lamp voltage prevails is coupled longer to the output, wherein the control device comprises a comparator which stores the measurement value in a first and in a second polarity, compares stored measurement values and delivers a marking signal which is used by the control device as information about the polarity at which the higher lamp voltage prevails.