Optical disc and optical disc device

Details Optical disc and optical disc device Optical disc and optical disc device

1998-05-29

2001-06-05

Edun, Muhammad (Department: 2651)

Dynamic information storage or retrieval

Storage medium structure

Optical track structure

C369S047100

Reexamination Certificate

active

06243352

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the invention
This invention relates to a novel optical disc of a small diameter and a large capacity. More particularly, it relates to an optical disc device employing the optical disc.
2. Related Art
Large-capacity data, such as that for a still picture or a moving picture, is stored on a recording medium, such as an optical disc, and is random-accessed and reproduced whenever so required.
The optical disc can be random-accessed, and is higher in recording density than the magnetic recording medium, such as a so-called floppy disc, while data can be rewritten if the disc is a magneto-optical disc. Therefore, the optical disc is suited for storage of the large-capacity data.
Recently, a demand is raised for increasing the capacity of the optical disc further, such that, in view of ease in handling, development of a small-sized optical disc of a large capacity is incumbent.
As the small-sized optical disc, there is known a magneto-optical disc 64 mm in diameter, that is a so-called mini-disc (MD), while there has also been proposed so-called MD data for recording digital information signals. However, the recording capacity cannot be raised beyond 140 MB.
This recording capacity of 140 Mb cannot be said to be sufficient.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel optical disc which is interchangeable with the conventional MD or MD data and which nevertheless has a capacity significantly larger than these optical discs. It is another object of the present invention to provide an optical disc device employing this optical disc.
The optical disc according to the present invention achieves the user recording capacity exceeding 650 MB for the diameter of the recordable area thereof not larger than 65 mm. With the optical disc of the present invention, the jitter produced when random pattern signals are recorded on one track only is not more than 8.4% and jitter increase on recording signals also on both side neighboring tracks is not more than 4.9%.
An optical disc according to the present invention includes an optical disc and an optical system for illuminating a recording light beam and/or a reproducing light beam on the optical disc, wherein the optical system has a wavelength of 635 to 680 nm and a numerical aperture NA of 0.52±0.02, and wherein recording and/or reproduction is carried out in a range of the track pitch not less than 0.90 &mgr;m and not more than 1.00 &mgr;m, a bit length not less than 0.326 &mgr;m and not more than 0.362 &mgr;m and a product of the track pitch and the bit length not more than 0.326 &mgr;m
2
.
An optical disc according to the present invention similarly includes an optical disc and an optical system for illuminating a recording light beam and/or a reproducing light beam on said optical disc, wherein the jitter produced when recording random-pattern signals on only one track of the optical disc is not more than 8.4% and wherein jitter increase on recording signal also on both side neighboring tracks is not more than 4.9%.
The present invention realizes an optical disc system which, while having interchangeability with the MD and MD data, has a user recording capacity not less than 650 MB which far exceeds the current recording capacity of 140 MB.
The capacity of 650 MB is selected in consideration that
(a) universal application can be instigated with the same capacity as the CD-ROM; and
(b) moving pictures continuing for not less than 20 minutes can be recorded at a transfer rate of 4 Mb/s required for actual MPEG2 pictures to make possible application to, for example, a digital video camera.
The optical disc and the optical disc device according to the present invention take into account the constraints of the skew accompanying the increased recording density. By setting the jitter produced when recording random pattern signals on one track only to not more than 8.4% and by setting jitter increase on recording signals also on both side neighboring tracks to not more than 4.9%, the skew margin in the radial direction of not less than ±0.7° and that in the running direction (circumferential direction) of not less than ±0.6° are assured. According to the present invention, there are provided an optical disc and an optical disc device having a hitherto unprecedented large capacity.


REFERENCES:
patent: 5430706 (1995-07-01), Utsunomiya et al.
patent: 0 595 349 A1 (1994-04-01), None
patent: 0 662 685 A1 (1995-12-01), None
Patent Abstracts of Japan, vol. 097, No. 009, Sep. 30,1997 & JP 09 115176 A (Seiko Epson Corp.) May 2, 1997.

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