| 摘要 |
PURPOSE:To protect a laser diode from an overcurrent of a control current, by returning an output voltage to a current control circuit and making the input to the current control circuit identified with a charging speed and a voltage of a resistor/capacitor. CONSTITUTION:When a power source switch 5 is turned ON to supply a dc power source 4, a reference voltage circuit 6 is connected to generate a reference voltage from a circuit 6. Charge of a capacitor 8 is started through a resistor 7 by this reference voltage. An output of an operational amplifier 10 in a buffer circuit 9 is connected with a base of a controlling transistor 11 and it is inputted to a current control circuit 3, with the emitter serving as its output. An output of the circuit 3 is returned to an inversion input of the amplifier 10. Then the input of the circuit 3 is raised to be identified with a charging speed and a voltage of the capacitor 8. Hence, a laser diode 1 is protected from an overcurrent of the control current 14. |
