Rapid Access Method For OpticaI Disk Drive Using Feedforward Brake Pulse

A rapid-access control method for optical disk drives has been developed. A brake pulse is fed forward to the objective lens actuator to rapidly reduce track crossing velocity of the light spot when in the close vicinity of the destination track during macro seeking. At the instant the light spot reaches the destination track, the track-following operation is performed by only the objective lens actuator until the linear motor stops. This rapid-access system was applied to a 3.5" optical disk drive, and it was found to provide a seek time for 256 tracks, excluding rotational latency, 30% shorter than a conventional direct access system.