Erasable optical data storage medium
AssigneeOptical Data, Inc.
InventorsClyde D. Feyrer, N. Ross Gordon, W. Eugene Skiens
Life of this patent
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Abstract
An erasable optical data storage medium including a substrate and a dual layer of a first material and a second material on the substrate. The dual layer is susceptible to expansion and contraction, to writing data thermally, to erasing data thermally and mechanically, and to reading data optically, the first material and the second material, respectively, being bonded together and remaining in the same physical state upon the expansion and relaxation of the dual layer. Methods and apparatus are also disclosed for recording data bits on the medium.
Claims21
An optical recording medium comprising:
- (a) a first layer of a first material;
- (b) a second layer of a second material adjacent to said first material;
- (c) said first and second layers cooperating as a medium for forming an optically detectable deformation therein by thermal expansion of said first material without liquefaction or gasification of said first or second materials when said first layer is locally heated with light radiation of a first preselected wavelength;
- (d) said first material and said second material being sufficiently bonded to each other to enable said second layer to hold said first material in stretched, expanded condition upon cessation of said light radiation and cooling of said first material, retaining said optically detectable deformation, said second layer being sufficiently strong and rigid to hold said first material in stretched, expanded condition.
An optical recording medium comprising:
- (a) a first layer of a first material having a glass transition temperature ("T.sub.g 1");
- (b) a second layer of a second material bonded to said first material, said second material having a glass transition temperature ("T.sub.g 2") above ambient temperature and also above T.sub.g 1;
- (c) said first and second layers comprising a dual layer recording medium;
- (d) said first material having a high coefficient of thermal expansion;
- (e) said second material being adapted to permit localized thermal expansion of said first material when said second material is above T.sub.g 2 and adapted to retain said first material bonded thereto in an expanded configuration when said second material is cooled below T.sub.g 2;
- and
- (f) said dual layer recording medium being adapted to form and retain an optically-detectable deformation therein by localized thermal expansion of said first material, without liquefaction or gasification of said first or second materials, when locally heated with light radiation of a first preselected wavelength.
An optical recording medium comprising:
- (a) a first polymer layer;
- (b) a second polymer layer bonded to said first layer;
- (c) said first layer having a high coefficient of thermal expansion and a first glass transition temperature ("Tg1"), said first layer adapted to produce a deformation due to localized thermal expansion upon heating;
- (d) said second layer having a glass transition temperature (Tg2) which is above ambient temperature and above Tg1, said second layer being adapted to permit localized thermal expansion of said first layer when said second layer is heated above Tg2 and adapted to retain said first layer in expanded configuration when said second layer is cooled below Tg2;
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- (e) said first and second layers cooperating as a medium for forming and retaining therein an optically-detectable deformation when locally heated with light radiation of a first preselected wavelength.
Dependencies are inferred from the claim text.