| 摘要 |
PURPOSE:To prevent inrush current when a power source is turned ON by a constitution wherein a current limiting FET is added to a power source line between a power source circuit and an LD cooling circuit. CONSTITUTION:An LD cooling Peltier element 2 and a temperature sensing thermister 3 are externally connected to an LD(laser diode) cooling circuit 4. The cooling circuit is operated by receiving power from a power source circuit 5. A current limiting FET 6 is inserted between the power source circuit 5 and the LD cooling circuit 4. A drain of the FET is connected to the power source circuit. A source which is short-circuited to a gate is connected to the LD cooling circuit. Thus an inrush-current preventing function is formed. When the power source is turned ON and the ambient temperature around the LD is in a very high or low state, excessive current tends to flow through the FET 6. However, the instantaneous inrush current when the power source is turned ON is prevented by the inrush current preventing function of the FET 6. |
