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.

公开(公告)号：JPH04240787A

公开(公告)日：1992-08-28

申请号：JP4457491

申请日：1991-01-17

Applicant: IBM

Inventor： AMANO YOSHIRO ,  SOTOZONO KAZUO ,  SHIMOUSA TATSUO

IPC: G11B7/125 ,  G11B7/126 ,  H01S5/042

Abstract: PURPOSE: To obtain a laser drive device for increasing a switching speed easily, by providing both flow-out and flow-in constant current sources and a switching means for turning laser on or off. CONSTITUTION: A write data signal Sd and its inverted signal -Sd are inputted to the bases of transistors(Tr) 41A and 41B of a switch circuit 40. When the Tr41A is turned on and the Tr41B is turned off, a switch current Isa that flows through the Tr41A becomes equal to the flow-in current Ib of a flow-in constant current source 20, and a switch current Iab that flows through the Tr41B becomes zero. As a result, a laser current I1 becomes equal to an flow-out current Ia of a flow-out constant current source 30, thus turning on a laser 50. On the other hand, when the Tr41A is turned off and the Tr41B is turned on, the switch current Isa becomes zero and the switch current Isb becomes equal to the flow-in current Ib and the flow-out current Ia , thus setting the laser current I1 to zero and turning off the laser 50.