The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 18, 1995
Filed:
Mar. 25, 1991
Antonius H Holtslag, Eindhoven, NL;
Derk Visser, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A method of and an apparatus for writing and reading and/or erasing a multilayer record carrier (1) having a guide plane (2) and a plurality of recording planes (4) are described, using a guide beam (5) which cooperates with the guide plane (2) and a scanning beam (6) for at least writing in the recording planes (4). During writing the position of the scanning focus (36) formed by the scanning beam (6) is coupled to the focus (11) of the guide beam (5) which is actively controlled by using guide information which is present in the guide plane (2). During reading the scanning beam (6) is actively controlled by its own servosystem (20-28).