DRIVE CIRCUIT OF MULTIBEAM SEMICONDUCTOR LASER ARRAY

摘要

PROBLEM TO BE SOLVED: To eliminate the necessity for providing photodetectors of which the number corresponds to the number of beams to the outside of a multibeam semiconductor laser array and to control the quantity of a plurality of beams within an effective scanning period. SOLUTION: A monitor current corresponding to the quantity of the emitted beams of LDs 9-1-9-3 flows to a PD 10 to be converted to monitor voltage by a current/voltage converter circuit 2 and the monitor voltage is integrated by an integration circuit 3 to be converted to an integral value S2. Input image data D1-D4 corresponding to four lines are added by an adder circuit 4 and the obtained voltage is integrated by an integration circuit 5 to be converted to an integral value S1. An error detecting amplifier 6 sets the integral value S1 to reference voltage to compare the same with the integral value S2 and calculates the difference corresponding to the light output fluctuation quantity caused by the LDs 9-1-9-4 themselves to output the same to a bias current supply circuit 7 and the bias current supply circuit 7 forms bias currents B1-B4 making the quantity of the emitted beams of the LDs 9-1-9-4 constant on the basis of this difference. The bias currents B1-B4 are added to LD driving pulse currents I1-I4 to be applied to the LDs 9-1-9-4.