ADAPTIVE-SPEED CAV ALGORITHM IN A CD-ROM DRIVE TO ACCOMPLISH HIGH DATA TRANSFER RATE AND LOW-POWER CONSUMPTION/

This paper presents an adaptive-speed/CAV algorithm which regulates th e disc velocity in a CD-ROM system to accomplish high data throughput (bit rate) during continuous playback and low power consumption during continuous data access. The adaptive-speed profile is based upon quas i-CLV control [1] which allows drive optimization towards both data th roughput and access time. The presented algorithm can automatically di stinguish between two operating modes - continuous access and continuo us playback. By detecting the state of continuous access, the CD-ROM d rive switches its spindle-motor loop into a constant angular velocity (CAV) mode, avoiding therefore the acceleration/braking of the motor, and thus reducing the power consumption. By detecting the state of con tinuous playback, the spindle motor will be set to follow an adaptive- speed profile which is highly optimized for data transfer rate. The so ftware and hardware implementation of the CAV/quasi-CLV switching tech nique in a CD-ROM system is also described.