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AssigneePioneer Electronic Corporation
InventorsFumihiko Yokogawa, Seiichi Ohsawa
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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: 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)}.
A multi-layered recording disk with a plurality of data recording surfaces laminated therein, wherein data signals are recorded in each of the data recording surfaces in a band where, against a reproduction level obtained when a read light is on-focus to one of said data recording surfaces, a ratio of a reproduction level obtained when said read light is defocusing to a second one of said data recording surfaces is 1/N (N is a real number larger than 1), and a distance t between each of said data recording surfaces, numerical aperture NA of an objective lens guiding said read light to one of the data recording surfaces, wavelength .lambda. of said read light, an equivalent refractive index n between each of said data recording surfaces, and a number i representing the number of said laminated data recording surfaces satisfy the following relation:
A method of producing a multi-layered recording disk, said multi-layered recording disk having a plurality of data recording surfaces laminated therein, said method comprising the steps of:
A reproducing system for reproducing a data signal from a multi-layered recording disk, wherein said multi-layered recording disk has a plurality of data recording surfaces laminated therein, and data signals are recorded in each of the data recording surfaces in a band in which, against a reproduction level obtained when a read light is focusing to one of said data recording surfaces, a ratio of a reproduction level obtained when said read light is defocusing to a second one of said data recording surfaces is 1/N, wherein N is a real number larger than 1, and a distance t between each of said data recording surfaces, a numerical aperture NA of an objective lens guiding said read light to one of the data recording surfaces, a wavelength .lambda. of said read light, an equivalent refractive index n between each of said data recording surfaces, and a number i representing the number of said laminated data recording surfaces satisfy the following relation:
Dependencies are inferred from the claim text.