| 摘要 |
PURPOSE:To obtain a cheap device able to control a semiconductor laser very accurately and safely in an emitting light volume with a small number of bits by a method wherein a bias current of the semiconductor laser is digitally controlled by a potential supplied from a power source different in polarity through a transistor grounded to a base. CONSTITUTION:A CPU 1 is equipped with a built-in A/D converter, and a light emitting current ID and a bias current IB of a semiconductor laser LD are controlled by regulating the drive of a driving and constant current circuit 3 of a constant current circuit 15 through the control ot an input BX of a specified number of bits to the A/D converter 2 and an input DX of a specified number of bits to a D/A converter 17. The constant current circuit 15 drives a light volume signal detected by a light volume detecting section 11 through an output potential from the D/A converter 17 to control the light emitting current ID so as to make an emitting light volume of the semiconductor laser LD reach a target value previously preset. By these processes, an emitting light volume of the semiconductor laser LD can be controlled to be a target value through only the input DX of a specified number of bits from the CPU 1 to the D/A converter 17. |
