| 摘要 |
PURPOSE:To prevent the flowing of inrush currents through a laser diode by providing a power-supply interrupting means interrupting power supply from a power circuit for a fixed time when a power supply is turned ON. CONSTITUTION:Voltage on a 24V supply line is divided by resistors 71, 72 in a laser-diode control circuit 42 on the rise of a power supply, and divided voltage and the reference voltage of a battery 74 are compared by a comparator 73. Since divided voltage is made smaller than reference voltage at first, a transistor 75 is turned ON, and transistors 78, 81 are turned OFF, thus preventing the supply of voltage to a power circuit 82. When divided voltage is made higher than reference voltage, the transistor 75 is turned OFF, and constant currents are made to flow through a capacitor 79 from a constant current circuit 76 and the capacitor is charged. When the time of the time constant of the capacitor 79 passes and a driver 77 is turned ON, the resistors 78, 81 are turned ON, thus supplying the power circuit 82 with the voltage of the 24V supply line. Accordingly, inrush currents to a laser diode at the time of the rise of the power supply can be prevented positively. |
