Makoto Mizukami

Characteristics of heat transfer in small disk enclosures at high rotation speeds

Experimental results are reported on heat transfer in small disk enclosures (DEs) containing several 5.25-inch-diameter disks and two symmetrical brushless DC motors mounted on a spindle. Windage loss decreases with disk diameter, and the ratio of windage loss in the 5.25-inch-diameter disk to that in 10.5-inch-diameter disks is 1/16. Air flow over the disk surface is probably turbulent at rotation speeds of more than 5400 RPM. The windage loss dominates the total at rotation loss speeds of more than 5400 RPM. An effective forced convection suppresses the temperature increase of the DE to less than 5 degrees C, due to the higher thermal conductivity of the DE surface. High track densities of more than 100 tracks/mm are feasible as a result of the low thermal off-tracking, less than 0.3 mu m, and the small deviation in head positioning, less than 0.5 mu m. These low values arise from the thermally and mechanically symmetrical DE structure and a ceramic positioner with high stiffness. >

Real-time staging in optical disk library

A new real-time staging technique in which disks are rated according to the likelihood of use, even with respect to storage location, is explained. In this technique, the exchange algorithm for the disks in a storehouse is simplified by disk management in groups; i.e., disks are exchanged between groups according to likelihood of use. Here, if a storehouse in an optical disk library is divided into N groups, real-time staging can reduce the total travel length of a robotic hand to as little as 1/N of the conventional method. Moreover, if the prefetch and postrestore processes are also used to speed up the disk exchange operation at the disk drive, the total travel length is similarly shortened to 2/3N of the conventional method, and the total travel time to 1/3.

High-Precision Head Positioning Using Multiple Offset Beams

This paper describes a new tracking technique with a multiple beam mechanism that will lead to low profile optical disk storage units with faster access speeds. In this technique, data tracking involves selection among multiple beams with minute offsets. It can accommodate four-beam laser diodes while assuring twice the tracking accuracy and ten times the tracking bandwidth of conventional approaches. Its servo performance depends on the total distance between the two outermost beams in the beam series on the medium.

High-speed image file server for super high-resolution display system

We have developed a high-speed image file server for a super-high-resolution (SHR) image display system. The SHR system displays images with a resolution of 2000 TV lines, and the data of one still image is about 24 MB in size. Therefore we need an image file server that has a 24 MB/s data-transfer rate and that enables random access to any of the stored data. We applied this high-speed image file server to the SHR system that requires 24 MB of image data per frame (equivalent in quantity to the UDTV1 standards) and is capable of continuously displaying one frame per second.

Optical disk array system

An optical disk array using four magneto-optical disk drives has been developed. This system uses ISO standard format 130 mm disks and has a standard SCSI-2 interface to the host computer. The system functions as a fast, large-capacity single-disk subsystem for host computers.