Adaptive-Speed Quasi-CAV Algorithm in a CD-RW Drive

The performance of a CD-RW drive is evaluated mainly in terms of recording data rate, access time, and power consumption. Constant linear velocity CLV recording technology is broadly employed in almost all the commercially available CD-RW drives today. In the CLV mode, the spindle motor which is driven by the real-time linear velocity of the disc will always be braked while seeking outwards or accelerated for inward-oriented seeks. Since the motor driver is driven in saturation, additional power dissipation will occur. This is undesirable in a CD-RW drive especially during data recording and accessing and huge power consumption will thus take place. When a long sequence of recording and seek actions are taking place, the spindle motor keeps braking and accelerating to result in excessive heat generated. Further, with even higher than 1 6X CD-RW drives on the horizon, the CLV would not only cause over heating but also induce larger vibration to distort the system. A feasible approach to avoid the excessive heat and vibration is to employ constant angular velocity CAV to record the data in a CD-RW drive. Since CAV recording would require the on-the-fly optical power calibration OPC, this imposes a totally new generation of technology requirement on the chipset and system design which are not currently available yet to the mass market. A quasi-CAV recording technique is thus proposed in this paper. This quasi-CAV recording algorithm can not only effectively reduce the heat dissipation in a CD-RW drive during recording but also avoids the complicated interaction of on-the-fly write strategy adjustment.