| 摘要 |
A lighting device (101), comprising: an electrical connector (104) for fitting in a lamp socket; a fluorescent tube; an electrode (105) for ionising air, and a ballast circuit (301) configured to supply suitable electrical currents and voltages to the fluorescent tube (102) during starting and subsequent operation. The lighting device also has an ion generator circuit (302) configured to receive a relatively low ac voltage from the connector and supply a relatively high dc voltage to the electrode. The ion generator circuit itself comprises: a transformer (L41) having a primary winding and a secondary winding; and a semiconductor device (S41) connected in series with the primary winding. The semiconductor device is configured such that for voltages up to a threshold voltage the semiconductor device provides a very high resistance and for voltages above the threshold voltage the semiconductor device provides a low resistance. Consequently, in use, a current is generated in the primary winding when voltage across the semiconductor device rises to the threshold voltage.
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