Optical recording medium

• US 5,238,722 A
• Filed: 11/26/1991
• Issued: 08/24/1993
• Est. Priority Date: 11/28/1990
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Ueda, Yutaka, Yashiro, Toru
• Primary Examiner(s): Ryan, Patrick J.
• Assistant Examiner(s): MULVANEY, ELIZABETH EVANS
• Application Number:
  US07/798,503
• Time in Patent Office: 637 Days
• Field of Search: 428/64, 428/65, 428/457, 428/913, 430/945, 346/76 L, 346/135.1
• US Class Current: 428/64.4
• CPC Class Codes: G11B 2007/2431 group 13 elements (B, Al, Ga, In)
• CPC Class Codes: G11B 2007/24312 group 14 elements (e.g. Si, Ge, Sn)
• CPC Class Codes: G11B 2007/24314 group 15 elements (e.g. Sb, Bi)
• CPC Class Codes: G11B 2007/2432 Oxygen
• CPC Class Codes: G11B 2007/24324 Sulfur
• CPC Class Codes: G11B 7/243 comprising inorganic materials only, e.g. ablative layers
• CPC Class Codes: G11B 7/2472 cyanine
• CPC Class Codes: G11B 7/2533 comprising resins
• CPC Class Codes: G11B 7/257 of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
• CPC Class Codes: G11B 7/258 of reflective layers
• CPC Class Codes: G11B 7/2585 based on aluminium
• CPC Class Codes: G11B 7/259 based on silver
• CPC Class Codes: G11B 7/2595 based on gold
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10S 430/146 Laser beam
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

An optical recording medium is composed of a substrate, a recording layer containing an inorganic material which includes as the main component a sulfide of at least one element selected from the group consisting of the elements of IIb, IIIb, IVb, Vb, and VIb groups, which is formed on the substrate, with a complex index of refraction of (n-ik), where n≧1.8, and k≦0.3, and a reflection layer formed on the recording layer. In this invention, an intermediate layer can be interposed either between the substrate and the recording layer, or between the recording layer and the reflection layer.

Claims

1. An optical recording medium comprising a substrate, a recording layer overlying said substrate, and a reflection layer overlying said recording layer, said recording layer having a complex index of refraction n-ik wherein n≧

1.8 and k≦

0.3 and consisting essentially of at least one sulfide of at least one element selected from the group consisting of the elements of IIb, IIIb, IVb, Vb and VIb groups.

2. The optical recording medium as claimed in claim 1, wherein said element is selected from the groups consisting of Sb, Sn, In, Ge, and O.

3. The optical recording medium as claimed in claim 1, wherein said sulfide is selected from the group consisting of Sb₂ S₃, SnS, (Sb₂ S₃)_x (In₂ S₃)_y, (Sb₂ S₃)_x (GeS)_y, (SnS)_x (In₂ S₃)_y, (SnS)_x (GeS)_y, (SnS)_x O_y, and (Sb₂ S₃)_x O_y, wherein 40≦

x<

100, 0<

y≦

60, and x+y=100.

4. The optical recording medium as claimed in claim 1, wherein said reflection layer is made of a metal selected from the group consisting of Au, Ag, Cu, Al, Cr, Ni and alloys of these metals.

5. The optical recording medium as claimed in claim 1, further comprising an undercoat layer which is interposed between said substrate and said recording layer.

6. The optical recording medium as claimed in claim 1, further comprising an intermediate layer which is interposed between said recording layer and said reflection layer.