Disc recording medium and method of fabricating the same

DETAILED DESCRIPTION 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