| 摘要 |
PURPOSE:To flexibly cope with the irregularity in semiconductor laser characteristics by a method wherein the luminous energy control timing by a counting means and the luminous energy control timing by an arithmetic unit are differentiated, and the driving current of the driving means is controlled using the calculated value of the prescribed luminous energy timing as the initial value in the luminous energy control by the arithmetic unit. CONSTITUTION:A counter control signal S11 is inputted to the counter 12 as the maintenance signal of a luminous energy control digital signal S12 in order to maintain the reset laser driving signal S14 on a control circuit 16. The luminous energy control analog signal S13 is maintained in that state. After the value of the counter output signal S12, in the prescribed luminous energy retained on a memory 17, has been set on the counter 12, the luminous energy control digital signal S12 is incremented by one and outputted to a D/A converter 13 by the control circuit 16. This control operation is repeated until a laser luminous energy signal S15 is converged in the vicinity of the voltage level of the laser luminous energy setting signal S2 which is set in advance in a signal comparator 10. |
