| 摘要 |
PURPOSE: To decrease the number of part items, construct in a small size, and suppress the costs. CONSTITUTION: A DC supply voltage is impressed on power input terminals 1, 2, and immediately after impression, a supply voltage is supplied to a control circuit 10 from the first power supply circuit 30, and the control circuit 10 starts the control of switching made by a semiconductor switch element 9. With this switching operation, the above-mentioned DC supply voltage is impressed intermittently on the primary winding 21 of a transformer 20. When the switch element 9 is off, a voltage is generated in the secondary winding 22, and with this voltage a power is supplied to a discharge lamp 5. When the element 9 is on, on the other hand, a voltage is generated in the tirtiary winding 23, and with this voltage, the second power supply circuit 40 is actuated so that voltage supply to the control circuit 10 is changed over automatically from the first power supply circuit 30 to the second power supply circuit 40. |
