Browse Prior Art Database

Multifunction Optical Storage Device

IP.com Disclosure Number: IPCOM000102372D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 4 page(s) / 152K

Publishing Venue

IBM

Related People

Belyeu, SM: AUTHOR [+4]

Abstract

This article describes an optical storage device that can read an industry standard compact disc read-only memory (CD-ROM), read a write once read many (WORM) device or perform read and write operations on an erasable media based on Magneto-Optic (MO) technology.

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

Multifunction Optical Storage Device

       This article describes an optical storage device that can
read an industry standard compact disc read-only memory (CD-ROM),
read a write once read many (WORM) device or perform read and write
operations on an erasable media based on Magneto-Optic (MO)
technology.

      The multifunction optical storage device of this disclosure is
shown in block diagram in Fig. 1.  The load mechanism will accept a
single, removable disc by using a disc caddy.  The caddy can be
loaded from the front of the drive, and it will accept a 120 mm
(4.72") CD-ROM disc, a 5.25" WORM disc, or a 5.25" M-O disc.  The
host computer interface provides a means to transfer data between the
drive and a small computer.  The drive is configured as a 5.25"
half-high form factor that can either be mounted inside a small
computer or inside an external enclosure with a power supply.  The
use of common features and the partitioning of unique features in the
drive control and error correction code (ECC)/decode electronics
enable use of very large-scale integration (VLSI).

      The optics section includes elements unique to the CD-ROM read
operation, elements unique to the M-O read/write operation, and
components that are common to both operations.  The WORM read
requirements can be met by the same configuration as is shown for the
CD-ROM.  The key to the operation of this section is that the
polarization of the light reflected from the surface of the disc is a
function of the direction of the magnetic field at a specific
location on the media.  The method used in the optics section to read
M-O media is based on an analysis of the light reflected from the
disc.  Since the CD-ROM and WORM read process also uses reflected
light, there are several common features of the optics section that
can be used to read both media.  Fig. 2 shows a block diagram of the
configuration of the optics section when a CD-ROM or WORM disc is
inserted in the drive.  The M-O disc read/write configuration is
shown in Fig. 3.  The common features are identified in each drawing.
These are mounted on a stationary portion of the head assembly.  The
unique elements are attached to a transfer device that is controlled
by the drive microcomputer.  When a CD-ROM or WORM disc is inserted
into the drive, the transfer mechanism selects the elements shown in
Fig. 2.  When a M-O disc is present, the elements in Fig. 3 are
selected.  The bias coil remains stationary.  It is not activated
when a CD-ROM or WORM media is installed.  The same laser is used for
all three media.  The read operation requires approximately 3 to 6 mW
for each type of disc, and the M-O write operation requires 10 to 30
mW.

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