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Optical Disk Family

IP.com Disclosure Number: IPCOM000039639D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Arter, NK: AUTHOR [+6]

Abstract

A family of optical disks are constructed and arranged such that each disk has its data surface located at about the same plane relative the optical head. In this way, focusing excursions of the head are of about the same magnitude for all types of disks. The types of disks contemplated are read-only, write-once, and combination read-only and write-once. With this arrangement, the optical head's lens is servo- centered for all members of the disk family. The combination of read- only and write-once allows the system to have on line large amounts of read-only data (permanent data) as well as a large amount of rewritable data at the same time without changing disks. Fig. 1 shows a portion of a side view of an air-incident disk which includes preformed read-only data 10 and a write-once surface 11.

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Optical Disk Family

A family of optical disks are constructed and arranged such that each disk has its data surface located at about the same plane relative the optical head. In this way, focusing excursions of the head are of about the same magnitude for all types of disks. The types of disks contemplated are read-only, write-once, and combination read-only and write-once. With this arrangement, the optical head's lens is servo- centered for all members of the disk family. The combination of read- only and write-once allows the system to have on line large amounts of read-only data (permanent data) as well as a large amount of rewritable data at the same time without changing disks. Fig. 1 shows a portion of a side view of an air-incident disk which includes preformed read-only data 10 and a write-once surface 11. The disk is mounted to the spindle of a disk drive (not shown) by way of opening 14 which is formed in the center of the disk. Data 10 may

(Image Omitted)

be, for example, a system program of the computer with which the disk is intended to be used. Write-once surface 11 is carried by substrate 15, and is written by the user, to contain the user's data base, etc. The optical disk drive's head (not shown) includes a laser beam which must focus on the different- spaced planes of data 11 and surface 11 as these two surfaces are read. In both cases, the beam must penetrate transparent cover 12. Since the thickness of air space 13 is very small, the lens can...