Protective layer for optical information recording medium

• US 4,847,132 A
• Filed: 10/15/1987
• Issued: 07/11/1989
• Est. Priority Date: 10/20/1986
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited 1006 OAZA Kadoma-Shi Osaka Japan
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kurumizawa, Toshimitsu, Takao, Masatoshi, Kimura, Kunio, Nagata, Kenichi
• Primary Examiner(s): Robinson, Ellis P.
• Assistant Examiner(s): RYAN, PATRICK J
• Application Number:
  US07/108,649
• Time in Patent Office: 635 Days
• Field of Search: 369/283, 430/495, 428/64, 428/65, 428/137, 428/688, 428/913, 428/215, 428/216, 428/323, 428/331, 428/698, 428/704, 346/76 L, 346/135.1
• US Class Current: 428/64.6
• CPC Class Codes: G11B 2007/24312 group 14 elements (e.g. Si, Ge, Sn)
• CPC Class Codes: G11B 2007/24316 group 16 elements (i.e. chalcogenides, Se, Te)
• CPC Class Codes: G11B 2007/2432 Oxygen
• CPC Class Codes: G11B 2007/25706 containing transition metal elements (Zn, Fe, Co, Ni, Pt)
• CPC Class Codes: G11B 2007/25708 containing group 13 elements (B, Al, Ga)
• CPC Class Codes: G11B 2007/2571 containing group 14 elements except carbon (Si, Ge, Sn, Pb)
• CPC Class Codes: G11B 2007/25713 containing nitrogen
• CPC Class Codes: G11B 2007/25715 containing oxygen
• CPC Class Codes: G11B 2007/25716 containing sulfur
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/2533 comprising resins
• CPC Class Codes: G11B 7/2534 polycarbonates [PC]
• CPC Class Codes: G11B 7/254 of protective topcoat layers
• CPC Class Codes: G11B 7/256 of layers improving adhesion between layers
• CPC Class Codes: G11B 7/2578 consisting essentially of inorganic materials
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/24322 Composite web or sheet
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/259 : Silicic material

Abstract

A protective layer which is applied to rewritable optical information recording medium comprising a substrate and a photosensitive thin film. When exposed to optical energy, the thin layer is capable of undergoing a reversible phase change by which an optical reflectivity is changed between two states. The protective layer is inhibiting the thermal damages of the substrate during light irradiation and also controlling thermal and optical boundary conditions. The protective layer is made of the mixture of mutually solid insoluble materials. The typical choice of the mixture of small crystalline grains of ZnS and noncrystalline SiO₂.

Claims

1. An optical information recording medium comprising heat resistant protective layers, which are interfaced with a single side or both sides of an active recording layer, all of said layers being formed on a substrate successively layer by layer, and said protective layers consisting of a homogeneously mixed substance consisting of several constituent compounds, wherein at least two of said constituent compounds do not form a solid solution with each other.

2. The optical information recording medium according to claim 1, wherein at least one of said constituent compounds is a non-crystalline glass forming material, and at least one of said constituent compounds is a crystalline material.

3. The optical information recording medium according to claim 1, wherein at least one of said constituent compounds is a metallic crystalline chalcogenide and at least one of said constituent compounds is a glass forming oxide.

4. The optical information recording medium according to claim 3, wherein said metallic crystalline chalcogenide is a zinc chalcogenide and said oxide is a glassy oxide.

5. The optical information recording medium according to claim 4, wherein said zinc chalcogenide is at least one selected from ZnS, ZSe and ZnTe, and said glossy oxide is at least one selected from SiO₂, GeO₂, SnO₂, In₂ O₃ and TeO₂.

6. The optical information recording medium according to claim 3, wherein said metal chalcogenide is a lead chalcogenide and said oxide is glassy.

7. The optical information recording medium according to claim 6, wherein said lead chalcogenide is at least one selected from PbS, PbSe and PbTe, and said glassy oxide is at least one selected from SiO₂, GeO₂, SnO₂, In₂ O₃ and TeO₂.

8. The optical information recording medium according to claim 1, wherein at least one of said compounds is a metal chalcogenide and at least one of said compounds is a nitride.

9. The optical information recording medium according to claim 8, wherein said metal chalcogenide is a zinc chalcogenide and said nitrides is a glassy nitride.

10. The optical information recording medium according to claim 9, wherein said zinc chalcogenide is at least one selected from ZnS, ZnSe and ZnTe, and said nitride is Si₃ N₄.

11. The optical information recording medium according to claim 1, wherein at least one of said compounds is a metal chalcogenide and at least one of said compounds is a carbide.

12. The optical information recording medium according to claim 11, wherein said metal chalcogenide is a zinc chalcogenide and said carbide is glassy.

13. The optical information recording medium according to claim 12, wherein said zinc chalcogenide is selected from ZnS, ZnSe and ZnTe and said glassy carbide is SiC.

14. The optical information recording medium according to claim 1, wherein at least one of said compounds is a metal chalcogenide, and at least one of said compounds is an oxynitride.

15. The optical information recording medium according to claim 1, wherein a size of the microstructural unit of said protective layer is smaller than a size of the microstructural unit of each of the constituent compounds of said protective layers when said layers are made of said constituent compounds only.

16. The optical information recording medium according to claim 15, wherein at least one of said constituent compounds is a metal chalcogenide, and at least one of said constituent compounds is an oxide.

17. The optical information recording medium according to claim 16, wherein said metal chalcogenide is a zinc chalcogenide and said oxide is glassy.

18. The optical information recording medium according to claim 17, wherein said zinc chalcogenide is at least one selected from ZnS, ZnSe and ZnTe and said glassy oxide is at least one selected from SiO₂, GeO₂, SnO₂, In₂ O₃ and TeO₂.

19. The optical information recording medium according to claim 15, wherein said microstructural unit (grain) has an average grain size of 10 nm or less.

20. The optical information recording medium according to claim 19, wherein said microstructural unit is constituted by at least one selected from ZnS, ZnSe and ZnTe.