Reflective data storage medium made by silver diffusion transfer in silver-halide emulsion incorporating nuclei

• US 4,298,684 A
• Filed: 06/20/1980
• Issued: 11/03/1981
• Est. Priority Date: 07/06/1979
• Status: Expired due to Term

• Current Assignee: LaserCard Corp. (Assa Abloy AB)
• Original Assignee: Drexler Technology Corporation (Assa Abloy AB)
• Inventors: Drexler, Jerome, Bouldin, Eric W.
• Primary Examiner(s): Schilling, Richard L.
• Application Number:
  US06/161,342
• Time in Patent Office: 501 Days
• Field of Search: 430/246, 430/251, 430/616, 430/346, 430/416, 430/414, 430/495, 430/16, 430/229, 430/231, 430/945, 430/964, 346/1.1, 346/76 L, 346/135.1
• US Class Current: 430/616
• CPC Class Codes: G03C 5/40 Chemically transforming developed images G03C5/50 takes precedence
• CPC Class Codes: G03C 8/06 Silver salt diffusion transfer
• CPC Class Codes: G11B 7/0045 Recording G11B7/006, G11B7/0065 take precedence
• CPC Class Codes: G11B 7/013 for discrete information, i.e. where each information unit is stored in a distinct discrete location , e.g. digital information formats within a data block or sector
• 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 7/251 comprising inorganic materials dispersed in an organic matrix
• CPC Class Codes: G11B 7/261 Preparing a master, e.g. exposing photoresist, electroforming
• CPC Class Codes: G11B 7/28 Re-recording, i.e. transcribing information from one optical record carrier on to one or more similar or dissimilar record carriers
• CPC Class Codes: G11C 13/048 using other optical storage elements
• CPC Class Codes: Y10S 430/146 Laser beam
• CPC Class Codes: Y10S 430/165 Thermal imaging composition

Abstract

A reflective laser recording and data storage medium, for direct reading after writing, formed from a photosensitive silver-halide emulsion including silver precipitating nuclei. A single step negative silver diffusion transfer process is used to develop silver nuclei of the latent image and dissolve unexposed silver halide elsewhere, forming silver ion complexes. These complexes are transported by diffusion transfer to the developing silver nuclei sites where silver is precipitated and adsorbed to form a high concentration of non-filamentary particles at a surface of a low melting temperature dielectric matrix which is highly reflective of light and electrically non-conducting.

Claims

1. A method of making a reflective laser recording medium from an unexposed photosensitive silver-halide emulsion layer incorporating a surface layer of high volume concentration silver precipitating nuclei having a size primarily less than five hundredths of a micron therein, the emulsion being disposed on a substrate with the nuclei layer disposed in said emulsion comprising,

defining laser recording area in the silver-halide emulsion,

contacting the unexposed and undeveloped photosensitive silver-halide emulsion layer incorporating the surface layer of silver precipitating nuclei with an aqueous monobath comprising a weak silver-halide developing agent and a rapid-acting silver-halide solvent for reacting with unexposed and undeveloped silver halide to form soluble silver ion complexes which are transported by diffusion transfer to the silver precipitating nuclei within said emulsion layer where the silver of said silver ion complexes is precipitated and adsorbed on said nuclei in the presence of said developer acting as a reducing agent, to the extent that a layer of aggregate and individual silver particles is formed exhibiting reflectivity of at least 15%.