Patent ID: 7426226
Filing Date: 2008-09-16
Classification: H01S

Abstract:
1. A circuit for driving a semiconductor laser, comprising: an integrated semiconductor circuit to control the drive of the semiconductor laser, which is connected to one end of the semiconductor laser; a first power source for supplying a drive voltage to the one end of the semiconductor laser via the semiconductor integrated circuit; a second power source, connected to the other end of the semiconductor laser, supplying a drive voltage to the other end; and a voltage clamp circuit, connected to a connection terminal connecting the semiconductor laser and the semiconductor integrated circuit, for adjusting the electric potential of the connection terminal, wherein the first power source supplies a positive first drive voltage to the anode of the semiconductor laser, the second power source supplies a negative second drive voltage to the cathode of the semiconductor laser, the absolute value of the first drive voltage is smaller than a voltage that is required for the semiconductor laser to irradiate at a targeted light amount, the absolute value of the second drive voltage is equal or smaller than a voltage at which a forward current starts to flow in the semiconductor laser, and the sum of the absolute value of the first drive voltage and the absolute value of the second drive voltage is equal or larger than the voltage that is required for the semiconductor laser to irradiate at the targeted light amount.