High-density optical disk and method of producing the same

Details High-density optical disk and method of producing the same High-density optical disk and method of producing the same

2001-01-09

2002-06-11

Evans, Elizabeth (Department: 1774)

Stock material or miscellaneous articles

Circular sheet or circular blank

C428S064400, C428S457000, C428S688000, C428S913000, C428S064200, C430S270110, C430S495100, C430S945000, C369S275100, C369S283000, C369S288000

Reissue Patent

active

RE037742

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical recording medium from which recorded information is reproduced by using a laser and method of producing the same and, more particularly, to a high-density recording medium which can densely record the information and from which the information is reproduced.
2. Description of the Related Art
Recently, a study of a high-density optical disk which is spotlighted as audio and video recording media has actively been made. A digital video disk (DVD) system which is a representative example of an information transmission medium of high picture quality and high sound quality has brought about the concept of a multimedia age combining digital video information with audio information. The birth of the DVD system includes prospects for a vast commercial market as a substitute demand for video cassette recorders and laser disks which are analog video systems, in addition to achieving technical innovation regarding the digitization of the video and audio information. Therefore, a fabrication method of a high-density substrate which can increase recording capacity has been demanded to provide for a next generation multimedia market.
A technique for fabricating the high-density substrate is disclosed in Korean Patent Application No. 95-1802, assigned to the same assignee as the present invention. In the above Korean Patent Application No. 95-1802, as shown in
FIG. 1
of the present application, a semitransparent layer
2
and a protective layer
4
B are sequentially formed at the lower portion of a substrate
1
having grooves and pits formed at both of its surfaces. At the upper portion of the substrate
1
, a reflective layer
3
and a protective layer
4
A are sequentially formed. However, if there is dust or a contaminant in the incident direction of a light beam, the above optical disk substrate may generate an error during reproduction since a spot of the light beam is scattered. The optical disk shown in
FIG. 1
has the protective layers
4
A and
4
B, each having a thickness of 30-40 &mgr;m. Thus, if there is dust having a thickness of 5 &mgr;m in the incident direction of a light beam, the spot of the laser beam can not be focused due to the dust. Moreover, since an information surface is exposed to the exterior, the information surface may be damaged when using the disk and it is necessary to supplement the durability of the optical disk.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a high-density optical disk which can increase recording capacity and ensure durability.
Another object of the present invention is to provide a high-density optical disk which can simplify work and raise yield.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing objects of the present invention are achieved by providing a high-density optical disk which includes reflective layers respectively formed at both information-recorded surfaces of a first substrate, and semitransparent layers respectively formed at one information-recorded surface of each of second and third substrates. The second and third substrates are respectively bonded at both sides of the first substrate.
The present invention will be more specifically described with reference to the attached drawings.


REFERENCES:
patent: 5805563 (1998-09-01), Nakano
patent: 5862121 (1999-01-01), Suzuki
patent: 5871881 (1999-02-01), Nishida

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