公开(公告)号：JPH04134737A

公开(公告)日：1992-05-08

申请号：JP25546890

申请日：1990-09-27

Applicant: IBM

Inventor： SOTOZONO KAZUO ,  SHINOHARA TATSUOKI ,  TOKIZONO AKIRA ,  UENO SHIGEO

IPC: G11B7/125 ,  G11B7/126

Abstract: PURPOSE: To enable a laser output to be set at the optimum value by determining such a digital value for setting an output as the laser output of a write mode is equal to that of a read mode and, on the basis of this value, deciding such a digital value for setting an output as a desired laser output is generated under the write mode. CONSTITUTION: A laser output from a laser diode 10 is detected by a light- quantity detector 16 and imparted in parallel to a voltage differential detector 18 and an analog-digital converter 20. The voltage differential detector 18, comparing this detected value with a reference voltage, imparting a voltage output in accordance with the comparison result to a driving circuit 26 through a switching circuit 24. In a read mode, the laser output is controlled so that the detection voltage of the light-quantity detector 16 is always equal to the reference voltage generated by a reference voltage generating circuit 22. Then, a digital value which generates a laser output equal to this reading power is detected and, on the basis of this value, a digital value which generates a desired laser output is determined. As a result, the laser output is set at the optimum value.