SEMICONDUCTOR LASER DRIVER

摘要

PURPOSE:To obtain a halftone image without contrast distortion by controlling a control circuit of a drive current provided separately with a resistance control circuit depending on the optical output of a semiconductor laser to stabilize the optical output when the characteristic of the laser is changed. CONSTITUTION:A prescribed optical output P1 is obtained by a few laser drive current IA at the low temperature of the semiconductor laser 1 and the output is reduced more than the output P1 at the current IA at high temperature. The reduction in the optical output is detected by a quantity-of-light monitor 13 and a quantity-of-light signal in reducing the internal impedance in supplied from a quantity-of-light detection circuit 14 to a voltage control element 12. The applied voltage to a series circuit comprising the laser 1 and a resistance control circuit 8 is increased by the decrease in the internal impedance of the element 12, the current of the laser 1 is increased creased and the same output P1 as that at low temperature is obtained. Thus, the stable optical output is obtained independently of temperature changes.