Multi-layered recording disk and recording/reproducing system using the same
US5608715A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 20, 1995 |
| Grant date | Mar 4, 1997 |
| Priority date | — |
| Expiry date | Jul 20, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A multi-layered disk which can improve a data recording density and also can record signals and allow reading and reproduction of the recorded signals in good conditions and a recording system as well as a reproducing system using the same and a multi-layered recording disk in which a plurality of data recording surfaces are laminated. In a band wherein, against an MTF level obtained when a read light is on-focus to one of the data recording surfaces, an MTF level obtained when the read light is defocusing to other data recording surfaces is 1/N (N is a real number larger than 1), data signals are recorded in each of the data recording surfaces. A distance t between each data recording surface, numerical aperture NA of an objective lens guiding a read light to any of the data recording surfaces, a wavelength.lambda. of the read light, an equivalent refractive index n between each data recording surface, and a number i of laminated data recording surfaces satisfy the following relation: EQU 1.4 n.lambda./(NA).sup.2 .gtoreq.t.gtoreq.7.5 n.sup.3 .lambda./{(n.sup.2 -1)(NA).sup.4 (i-1)}.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.