Information carrier

US3990084A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Hansjoachim Hamisch · Berlin, DE
• Hans Kaiser

Key dates

• Filing date: Nov 25, 1974
• Grant date: Nov 2, 1976
• Expiry date: Nov 25, 1994

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S430/146
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

An article for the recording and storage of information includes a support and a layer for storing information provided on the support. The layer is amorphous and composed of a mixture which includes an element of the group bismuth, antimony and selenium and a different element of the group selenium and tellurium. Information may be recorded on the layer by burning away selected regions thereof with high-energy radiation such as a laser beam. A preferred mixture includes bismuth and selenium with the weight ratio of bismuth to selenium being between about 1:2.5 and 1:3.5 for radiation having a wavelength corresponding to visible blue light and with the proportion of selenium being increased for longer wavelengths such as those corresponding to visible green and red light. The layer has a thickness which corresponds to a fraction of the wavelength of the radiation used for recording and the layer is optically opaque. A coating of lacquer may be applied over the layer prior to and/or subsequent to the recording operation so as to protect the layer. The layer is advantageously formed by vapor-depositing the elements selected from the above-mentioned groups onto the support simultaneou…