| 摘要 |
PURPOSE:To restrain the power loss of a current controlling part to a minimum, by keeping the voltage applied to a current controlling part in a necessary high voltage range at the time when discharge starts, decreasing the voltage to a necessary lowest value after discharge, and controlling the current of a high voltage power source applying the necessary lowest voltage to a controlling voltage. CONSTITUTION:When the output voltage of a high voltage power source 12 is applied to a laser tube 10, discharge starts and a discharge current flows into a current controlling part 18. Then voltages determined by voltage dividing resistors R1-Rn are applied between respective drains and sources of a current controlling element TR1 and transient current controlling elements TR2-TRn. In this case, a condenser C is charged by a current flowing through resistors R1-Rn. As the result of this, gate voltages of elements TR2-TRn rise, and the voltage (nE-E) shared by each element (FET) is decreased, whose amount of decrease is burdened by the element TR1. The drain voltage E of the element TR1 is fed back to the high voltage power source 12, and compared with a reference voltage. Then a specified high voltage is output from the high voltage power source 12. Accordingly, the controlling voltage applied to the element TR1 is always kept constant. |
