Pulse width modulation optical disk drive with pulsed laser preheating between marks
Semiconductor laser driving apparatus utilizing three current sources to control read and write light power Patent #: 5568464
ApplicationNo. 626029 filed on 04/01/1996
US Classes:369/53.3, Of relative motion producing mechanism369/116Light intensity adjustment or maintenance
ExaminersPrimary: Nelms, David C.
Assistant: Chu, Kim-Kwok
Attorney, Agent or Firm
Foreign Patent References
International ClassesG11B 007/00
Foreign Application Priority Data1995-03-31 JP
AbstractAn optical recording process for recording data on a recording medium of phase-change type employs laser power modulation scheme for mark-length modulation recording. The process selects one of pulse division schemes for modulating the laser power in accordance with a linear velocity on the disc. The recording laser includes m pulses for nT mark having a power level Pw and a duration of i T, with m intervals ଲi T sandwiched therebetween, wherein on condition that m=n-k and Σi +Σଲi =n-j, i or bias power Pbi is changed in accordance with the linear velocity, Pbi being a bias power level for modulation, k and j being an integer and a real number, respectively, both selected between 0 and 2. A large range of the linear velocity margin can be obtained for the disc without changing either the composition of the phase-change material or multi layer structure on the disc.