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Browse Prior Art Database

Optical Disk Drive with Fixed and Removable Media

IP.com Disclosure Number: IPCOM000106209D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 4 page(s) / 132K

Publishing Venue

IBM

Related People

Hearn, AR: AUTHOR [+2]

Abstract

Disclosed is an optical direct access storage device (DASD) with one non-removable annulus of fixed data and a removable disk both on a signal spindle, for replaceable data to be easily changed by non-skilled staff. By having fixed and removable data on one drive, time and difficulty is overcome of copying large files using a PC with a single optical disk drive as its sole DASD.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Optical Disk Drive with Fixed and Removable Media

      Disclosed is an optical direct access storage device (DASD)
with one non-removable annulus of fixed data and a removable disk
both on a signal spindle, for replaceable data to be easily changed
by non-skilled staff.  By having fixed and removable data on one
drive, time and difficulty is overcome of copying large files using a
PC with a single optical disk drive as its sole DASD.

      Use of optical disk drives for mass storage in laptop and
notebook PC's is attractive, because they provide low-cost
high-capacity storage combined with removability of the storage
medium.  There would be important savings in space and cost if the
functions currently performed by both the hard and floppy disks
commonly provided by PCs could be performed by a single optical
drive.  The difficulty is that if the disk is removable only in its
entirety, it becomes laborious to copy large files from one disk to
another.

      Disclosed is a scheme which makes it possible to design a
single optical disk drive, of which any desired fraction of the
storage capacity can remain fixed in the drive.  A single optical
drive can be used for working storage, data import and export, and
copying without the need for repeated disk swapping.  In magnetic
disk drives the problem has been tackled by provision of fixed and
removable disks on the same drive spindle:  the approach used in the
IBM 5444 is not useful in optical drives because the major cost and
space consumption is in the read/write head, which has to be
replicated to address multiple disks.

      The proposed design exploits a characteristic of the optical
recording method.  Because the optical read/write head is well
separated from the surface, the disk can be composed of several
annuli.  The inevitable small discontinuities in spacing at the
junctions can easily be accommodated by the focusing mechanism.  The
drive can be designed so that the annuli can be separated, and
independently removed from the drive.  Probably the most useful
implementation is the one described here, where part of the disk is
fixed in the drive, and part removable as a cartridge.

      Many possible variations on the mechanical implementation are
possible.  Either the inner or the outer annulus can be made
removable.  If the inner is removable, it constitutes a more compact
medium to store data on the shelf, and requires a smaller aperture in
the drive but it also requires the read/write head or "pen" to be on
the opposite side of the medium from the drive motor which may
complicate the mechanical package.  Two possible embodiments to
incorporate the annular disks are shown in Figs. 1 and 2.  Both
schemes use a magnet to hold the removable disk to the main spindle
thus the removable disk has a steel annular ring attached to it.  One
principle us...