Method for making a reflective laser recording and data storage medium with a dark underlayer

• US 4,363,870 A
• Filed: 09/11/1981
• Issued: 12/14/1982
• Est. Priority Date: 09/11/1981
• Status: Expired due to Fees

• Current Assignee: LaserCard Corp. (Assa Abloy AB)
• Original Assignee: Drexler Technology Corporation (Assa Abloy AB)
• Inventors: Bouldin, Eric W.
• Primary Examiner(s): Schilling, Richard L.
• Application Number:
  US06/301,203
• Time in Patent Office: 459 Days
• Field of Search: 430/246, 430/414, 430/415, 430/416, 430/616, 430/346, 430/964, 430/510, 346/135.1
• US Class Current: 430/510
• CPC Class Codes: G03C 5/30 Developers
• CPC Class Codes: G03C 5/58 Processes for obtaining metallic images by vapour deposition or physical development images obtained by photomechanical means, e.g. by etching G03F
• CPC Class Codes: G03C 8/06 Silver salt diffusion transfer
• CPC Class Codes: Y10S 430/165 Thermal imaging composition

Abstract

A method for making a laser recording and data storage medium by first exposing a Lippman emulsion to light in order to form a depthwise nuclei gradient, then physically developing the emulsion until a reflective surface layer of spheroid silver particles, having the desired degree of reflectivity, is attained and then chemically developing the remaining nuclei to form a dark underlayer of filamentary silver particles.

Claims

1. A method of making a reflective laser recording and optical data storage medium comprising,

forming a layer of silver precipitating nuclei from a portion of the silver halide within a fine-grained, photosensitive silver-halide emulsion layer of uniform thickness, disposed on a substrate, the nuclei layer having a major surface distal to the substrate with a depthwise nuclei gradient with greatest nuclei density distal to the substrate,

contacting said nucleated emulsion layer with a monobath solution comprising a silver-halide solvent and a low-activity silver-reducing agent of sufficient concentration to cause another portion of silver halide to form soluble silver ion complexes and be transported by diffusion transfer to said precipitating nuclei, where said silver ion complexes are reduced to non-filamentary silver particles to form a reflective surface layer in said emulsion layer without causing reduction of silver ions in the solution,

contacting said nucleated and monobath-treated emulsion layer with a strong chemical developer whereby remaining silver halide is converted into black filamentary silver particles to form a light absorptive underlayer in said emulsion layer.

2. The method of claim 1 wherein said nuclei layer is formed by exposure to light.

3. A method of making a reflective optical data storage medium comprising,

forming a layer of silver precipitating nuclei from a portion of the silver halide within a fine-grained photosensitive silver-halide emulsion layer of uniform thickness disposed on a substrate, the nuclei layer having a major surface distal to the substrate with a depthwise nuclei gradient with greatest nuclei density distal to the substrate,

contacting said nucleated emulsion layer with a monobath comprising concentrations of an active silver-halide solvent and a photographic developer of low reducing activity such that reflective spheroid particles and agglomerates are formed on the nuclei in said nuclei layer without causing reduction of particles and agglomerates in the solution, and

contacting said nucleated and monobath-treated emulsion layer with a strong chemical developer until the remaining silver halide is converted into black filamentary silver particles to form a light absorptive underlayer in said emulsion layer.

4. The method of claim 3 wherein said nuclei layer is formed by exposure to light.