| 摘要 |
PURPOSE:To make the output current of a constant-current circuit approximately constant and to make it possible to expose uniformly a film by a laser luminescence by a method wherein the potential at the grounding point of a switching means and the potential of the cathode of a laser diode are constituted of the same potential. CONSTITUTION:The anode of a laser diode 2 is provided with a switching means 42 and the amount of light of the laser diode 2 is substantially controlled by changing-over a current, which is fed to the laser diode 2 from the output of a constant voltage circuit 10 through a current setting resistor 4, according to the conduction/non-conduction of this switching means 2. Here, the grounding point of the switching means 42 and the cathode of the laser diode 2 are made so as to become the same potential point to make the output current of the circuit 10 approximately constant and the waveform distortion of the waveform of the current, which is fed to the diode 2, is decreased. Thereby, a film can be uniformly exposed by a laser light source and the quality of a regenerated image can be improved. |
