Stock material or miscellaneous articles – Circular sheet or circular blank
Reexamination Certificate
1999-02-11
2001-04-10
Evans, Elizabeth (Department: 1774)
Stock material or miscellaneous articles
Circular sheet or circular blank
C428S064200, C428S064400, C428S913000, C430S270100, C430S495100, C430S945000, C369S288000, C156S282000
Reexamination Certificate
active
06214430
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a recording medium for recording an information, and more particularly to a disc recording medium that is capable of being rotated at a high speed.
2. Description of the Prior Art
Generally, a recording medium for recording an audio information, a video information and a binary information for a computer, etc. has been manufactured in a disc type or a tape cassette type. A disc type of recording medium, hereinafter referred to as “disc recording medium”, has been more spotlighted than a tape cassette type of recording medium in that an information is randomly accessed in the high speed. Nowadays, as such a disc recording medium has prevailed a hard disc, an optical disc, a magneto-optical disc and so on. These discs have a very large capacity and high density tracks to record a large amount of information. Also, the disc recording medium has been required to transfer a lot of information at a high speed, that is, to permit high-speed recording and reproduction of an information. The disc recording medium must be rotated at a high speed for a high-speed transfer of information.
A disc is influenced by an exterior interference such as air resistance due to a flow of air occurring upon its rotation. Accordingly, a vibration called a disk flutter is generated at the rotating disc depending on the driving condition of a driver and the state of the disc. In the disc driver, if the disc flutter is larger above the limit value, a head or a pick-up fails to trace signal tracks on the disc accurately to prevent an information from being recorded or reproduced. Because such a disc flutter becomes larger as a disc is rotated at a higher speed, the disc must be rotated below a speed of allowing an access of information. In other words, the disc must be rotated below the limit speed to disappear the disc flutter, the accurate information recording and reproducing can be secured. Accordingly, it is difficult to provide a recording and reproducing speed, that is, a transfer rate of information in the disc above a constant limit speed. Such a limit speed is called as a critical speed and the disc rotates unstably at the critical speed. Due to this, although the disc has a larger capacity and higher density tracks, the rotating speed of the disc is limited at the critical speed.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a disc recording medium that is capable of being rotated at a high speed, and a fabricating method thereof.
In order to achieve these and other objects of the invention, a disc recording medium according to one aspect of the present invention has a residual stress acting as a tensile force. The disc recording medium includes a disc, and a reinforcing member having a thermal expansive coefficient different from the disc and adapted to be bonded to the disc. The reinforcing member is bonded to the inner circumference or the outer circumference of the disc.
A disc recording medium according to another aspect of the present invention comprises having an outer circumference cooled in temperature lower than an inner circumference to obtain a residual stress acting as a tensile force.
A method of fabricating a disc recording medium according to another aspect of the present invention includes the steps providing a disc and a reinforcing member; and bonding the reinforcing member to the outer circumference of the disc to allow a radial tensile force to be applied to the disc.
A method of fabricating a disc recording medium according to another aspect of the present invention includes the steps of pressurizing a molten substrate material to mold a disc; and suddenly cooling a part of the disc and, at the same time, slowly cooling the remaining part of the disc. In the disc cooling step, the outer circumference of the disc is suddenly cooled.
An apparatus for fabricating a disc recording medium according to another aspect of the present invention includes: a stationary plate; a moving plate; cooling means installed at any one of the stationary and moving plates, the cooling means cooling a part of the disc different from the rest of the disc in the cooling speed, the cooling temperature and the cooling order.
A moving plate for pressurizing a molten substrate material onto the moving plate to mold a disc; and cooling means for suddenly cooling a part of the disc.
REFERENCES:
patent: 5538774 (1996-07-01), Landin
patent: 5681609 (1997-10-01), Kitayama
patent: 5725931 (1998-03-01), Landin
patent: 5733622 (1998-03-01), Starcke
patent: 5777832 (1998-07-01), Yi
patent: 5972461 (1999-10-01), Sandstrom
patent: 5987003 (1999-11-01), Yokota
patent: 0507515 (1992-03-01), None
Kim Soo Kyung
Park Seong Jin
Evans Elizabeth
LG Electronics Inc.
LandOfFree
Disc recording medium and method of fabricating the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Disc recording medium and method of fabricating the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disc recording medium and method of fabricating the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2448520