| 摘要 |
<p>PURPOSE:To protect an inverter circuit in the last stage of lifetime of a discharge lamp using simple configuration and at a low cost by furnishing a heat emitting body in a location close to ferrite, and allowing it to make heat emission when a sensing means has sensed that the lamp is in its last stage of lifetime. CONSTITUTION:A switching element 7 of an inverter circuit 4 is put on to convert the DC power from a DC power supply 3 into high frequency output, while the output of the inverter circuit 4 is fed back to the switching element 7 by a current transformer 11 and then the switching element 7 is operated. If it is sensed that a discharge lamp concerned 12 has launched into its last stage of lifetime, a heat emitting body 16 is put in its work for heat emission to raise the ferrite temp. of the current transformer 11 to the Curie point, and thereby the magnetic permeability is lessened, and feed to the switching element 7 is stopped to stop the feed to the inverter circuit 4. Thereby the inverter circuit 4 can be protected simply and uncostly at the last stage of lifetime of the discharge lamp 12.</p> |
