Patent ID: 6440248
Filing Date: 2002-08-27
Classification: G11B,Y10T

Abstract:
The method of making a recording medium comprising:forming a first substantially transparent plastic disc which has a first surface and a second surface opposite to said first surface on which first information is recorded by means of local changes in the distance of said second surface from said first surface; coating said second surface of said first disc with a semi-reflective coating which reflects a first portion of light passed through said first disc back through said first disc and which transmits a second portion of said light through said semi-reflective coating, said semi-reflective coating conforming to said local changes of said second surface so that said first portion of said light is reflected back through said first disc in accordance with the first information recorded by said local changes of said second surface; forming a second plastic disc which has a third surface and a fourth surface opposite to said third surface, a first portion of said fourth surface having second information recorded on it by means of local changes in the distance of said fourth surface from said third surface and a second portion of said fourth surface having graphical information formed thereon by surface modifications in said fourth surface which tends to scatter light directed to the fourth surface; coating said fourth surface of said second disc with a reflective coating which reflects said second portion of said light transmitted through said first disc back through said first disc, said reflective coating conforming to said local changes of said first portion of said fourth surface so that said second portion of said light is reflected back through said first disc in accordance with said second information recorded by said local changes of said fourth surface; and bonding said first disc to said second disc so that the bonded disc forms a permanent two-disc stack with said second surface of said first disc facing said fourth surface of said second disc such that said graphical information formed on said fourth surface is visible through said first disc having said first information and through said semi-reflective coating.