# US 4,383,311 A · Optical recording medium and information record with indented overcoat > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,383,311 A - Document ID: US4383311A - Status: Granted - Kind: A - Application number: 06/199,314 - Filed: 1980-10-21 - Granted: 1983-05-10 - Earliest claimed: 1980-10-21 - Assignees: RCA Corporation - Inventors: Michael Ettenberg - Web page: https://patentgrep.com/patent/US4383311A ## CPC - G11B 7/24053: Protective topcoat layers lying opposite to the light entrance side, e.g. layers for preventing electrostatic charging - G11B 7/24085: Pits - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract An improved overcoated optical recording medium comprises a light absorptive layer and an overcoat overlying the absorptive layer wherein the overcoat has a plurality of indentations in the surface which contacts the absorptive layer thereby forming a first region of the recording medium wherein the overcoat layer does not contact the absorptive layer and a second region wherein the overcoat layer does contact the absorptive layer. The recording sensitivity in the first region is greater since the heat loss to the overcoat layer in these regions is reduced and the mechanical constraints on the formation of deformations in the absorptive layer are relaxed. The invention also includes an improved information record having information recorded in a portion of the first region as a change in the local optical properties. ## Claims ### Claim 1 In an optical recording medium which comprises a substrate; an absorptive layer which overlies the substrate and which is composed of a material which is absorptive of light at the wavelength of a recording light beam; and an overcoat layer, contacting the absorptive layer, which is transmissive of light at the wavelength of the recording light beam; the improvement which comprises: the overcoat layer having one or more indentations in the surface which contacts the absorptive layer thereby forming first regions of the recording medium wherein the overcoat layer does not contact the absorptive layer and second regions wherein the overcoat layer does contact the absorptive layer and wherein the first regions are arranged as circular or spiral grooves spaced apart from one another by the second regions. ### Claim 2 (depends on 1) An optical recording medium according to claim 1 further comprising a reflective layer underlying the absorptive layer which reflects a substantial portion of the light incident thereon at the wavelength of the recording and a readout light beam. ### Claim 3 (depends on 2) An optical recording medium according to claim 2 wherein the thickness of the absorptive layer in the first regions is so chosen that the reflectivity of the recording medium is reduced. ### Claim 4 (depends on 2) An optical recording medium according to claim 2 further comprising a spacer layer interposed between the reflective and absorptive layers. ### Claim 5 (depends on 4) An optical recording medium according to claim 4 wherein the thicknesses of the spacer and absorptive layers are so chosen that the reflectivity of the recording medium in the first regions is reduced. ### Claim 6 (depends on 2, 4) An optical recording medium according to claim 2 or 4 wherein the reflectivity of the recording medium is minimized. ### Claim 7 (depends on 2) An optical recording medium according to claim 2 wherein the absorptive layer is an organic material. ### Claim 8 (depends on 4) An optical recording medium according to claim 4 wherein the spacer layer is composed of a material selected from the group consisting of silicon dioxide, silicon monoxide, aluminum oxide and titanium dioxide. ### Claim 9 (depends on 4) An optical recording medium according to claim 4 wherein the spacer layer is an organic material. ### Claim 10 (depends on 1, 4) An optical recording medium according to claim 1 or claim 4 wherein the absorptive layer is composed of a material selected from the group consisting of titanium, rhodium, tellurium, selenium, tellurium-based alloys, selenium-based alloys, arsenic trisulfide and arsenic triselenide. ### Claim 11 (depends on 1) An optical recording medium according to claim 1 wherein the indentations extend a distance into the thick overcoat layer greater than about 100 nanometers. ### Claim 12 (depends on 1) An optical recording medium according to claim 1 wherein a subbing layer is interposed between the substrate and the absorptive layer. ### Claim 13 In an information record having an information track therein which comprises: a substrate; an absorptive layer which overlies the substrate and which is composed of a material which is absorptive of light at the wavelength of a recording light beam; and an overcoat layer, overlying the absorptive layer, which is transmissive of light at the wavelength of the recording light beam and a readout light beam; the improvement which comprises: the overcoat layer having one or more indentations in the surface which contacts the absorptive layer thereby forming first regions of the information recording medium wherein the overcoat layer does not contact the absorptive layer and wherein the first regions are arranged as circular or spiral grooves spaced apart from one another by the second regions; wherein the information track comprises areas of the first region having different optical properties from the unperturbed portions of the first region and which are spaced apart from one another along the groove only by unperturbed portions of the first region. ### Claim 14 (depends on 13) An information record according to claim 13 wherein a subbing layer is interposed between the substrate and the absorptive layer. ### Claim 15 (depends on 13) An information record according to claim 13 comprising a reflective layer, underlying the absorptive layer, which reflects a substantial portion of the light incident thereon at the wavelength of the recording and the readout light beam; ### Claim 16 (depends on 15) An information record according to claim 15 wherein the thickness of the absorptive layer is so chosen that the reflectivity of the record is reduced. ### Claim 17 (depends on 15) An information record according to claim 15 wherein a spacer layer is interposed between the reflective layer and the absorptive layer. ### Claim 18 (depends on 17) An information record according to claim 17 wherein the thicknesses of the spacer and absorptive layers are so chosen that the reflectivity of the record is reduced. ### Claim 19 (depends on 17) An information record according to claim 17 wherein the spacer layer is composed of a material selected from the group consisting of silicon monoxide, silicon dioxide, aluminum oxide, and titanium dioxide. ### Claim 20 (depends on 17) An information record according to claim 17 wherein the spacer layer is an organic material. ### Claim 21 (depends on 15) An information record according to claim 15 wherein the absorptive layer is an organic material. ### Claim 22 (depends on 13, 17) An information record according to claim 13 or 17 wherein the absorptive layer is composed of a material selected from the group consisting of titanium, rhodium, tellurium, selenium, tellurium-based alloys, selenium based alloys, arsenic trisulfide and arsenic triselenide. ### Claim 23 (depends on 13) An information record according to claim 13 wherein the indentations extend a distance into the overcoat greater than about 100 nanometers. ### Claim 24 In an optical recording medium which comprises: a substrate; an absorptive layer which overlies the substrate and which is composed of a material which is absorptive of light at the wavelength of a recording light beam; and an overcoat layer, contacting the absorptive layer, which is transmissive of light at the wavelength of the recording light beam; the improvement which comprises: the overcoat layer having one or more indentations in the surface which contacts the absorptive layer thereby forming first regions of the recording medium wherein the overcoat layer does not contact the absorptive layer and second regions wherein the overcoat layer contacts the absorptive layer and wherein the surface of the absorptive layer which contacts the indented surface of the overcoat layer is smooth. ### Claim 25 (depends on 24) The article of claim 24 having an information track recorded therein wherein the information track comprises areas of the first regions having different optical properties from the remainder of the first regions. ### Claim 26 (depends on 24, 25) The article of claim 24 or 25 further comprising a reflective layer interposed between the substrate and the absorptive layer. ### Claim 27 (depends on 26) The article of claim 26 wherein the thickness of absorptive layer is such that the reflectivity of the optical recording medium is minimized. ### Claim 28 (depends on 26) The article of claim 26 further comprising a spacer layer interposed between the reflective and absorptive layers. ### Claim 29 (depends on 28) The article of claim 28 wherein the thickneses of the spacer and absorptive layers so adjusted that the reflectivity of the optical recording medium is minimized.