Takehito Yamada

A 16MB 3.5 inch Ba-Ferrite flexible disk drive with dual track following servo modes

A large capacity high-speed-access 3.5 inch flexible disk drive has been achieved, using a barium ferrite 3.5 inch flexible disk and newly developed sector servo technology. The flexible disk drive has a 16 megabyte unformatted capacity, a 50 millisecond average seek time and a 3 megabit/second data transfer rate. It can use both concentric track disks for conventional computer systems and spiral track disks for high speed data transfer systems, such as hard disk drive (HDD) back-up, image data storing, and so on.

A servo method for a large-capacity floppy disk drive with downward compatibility

A novel servo method, in which a linear voice coil motor (LVCM) with a simple optical scale is controlled by a mu CPU, has been developed. It has a downward read-compatible mode with 135 tracks/in (TPI) and a large-capacity 16-MByte mode with 542 TPI, and it achieves an average seeking time of 25 ms. The drive is expected to be used in such applications as peripheral memories and hard-disk-drive back-ups. >

Sector servo system for high speed seeking and high track density

A microprocessor-based sector servosystem, which uses servo information derived only from each data surface, has been developed. Applying this servosystem to a 5.25-in hard disk drive, a 12-ms average seek time (at 1500 TPI) and +or-0.5- mu m head-positioning accuracy were achieved. The system controls the read/write head position more swiftly and accurately then in conventional head-positioning systems with a dedicated servo surface. >