Masahiro Takasago

Advanced Direct Seeking System For 5.25" Magneto-optical Disk Drive

1. lntroduct ion High speed accessing is very important feature of optical disk drive which could be used as the computer peripheral devices. In order to realize high speed accessing, various direct seeking system that a laser spot could get a target track directly without track jumping has been developed. In this paper, we described the newly developed direct seeking system which includes linearization method of tracking error signal for wider pull-in-range tracking servo system and two advanced detection methods, relative velocity detection method between a track and laser spot and distance detection method between present and target track. 2. Linearization of tracking error slanal Fig.1 shows the relation between the conventional tracking error signal and newly developed linear tracking error signal. Conventional sine wave shape tracking error signal make tracking servo gain variant and limit pull-in range. In order to expand this capability, triangle shape linear tracking error signal is made with conventional error signal and on-track signal. This tracking error signal is obtained by the following formula.