Control mechanism of an optical head for 130-mm read/write disk drives

To cope with the trend of high-speed access, a high-performance optical head with a sliding and rotary-type of lens actuator has been developed. An advantage of this type of lens actuator is that the moving part of the actuator is dynamically well balanced so that the objective lens is not shaken by acceleration or deceleration during seeking. As a result, the stability of the velocity control during seeking has been improved and the waiting time when the operation mode changes from the seek mode to the tracking mode has been reduced. To cope with the trend of high-speed transfer, we have increased driving efficiency and set the frequency of the parasitic resonance sufficiently high. Also, the rotational latency, which is an important factor of the access time, has been shortened. As a result, a data transfer rate of 7.4 Mbits/s and average access time of 48 ms have been attained in a 130-mm rewritable optical disk drive.