Patent EP0432731A2 successfully refreshed from Google Patents.
EP0432731A2
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Information recording medium and information recording and reproducing method and apparatus
Assignee: Hitachi Ltd
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Filing: 1990-12-11
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Granted: —
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Expires: 2010-12-11
Abstract
Abstract An information recording medium (32) which comprises two or more energy beam absorbing layers (2, 4) which are formed at different positions across the thickness within the depth of focus of the energy beam, and an energy beam transmitting layer (3) interposed between said energy beam absorbing layers (2, 4). A method for recording and reproducing information by applying an energy beam to an information recording medium (32) mentioned above, characterized in that the information recording is accomplished in response to the energy beam power which varies or the pulse waveform which varies, or both. An apparatus for reproducing information which comprises a means (30) to encode information into recording signals and a means (31) to drive the irradiating energy beam. The information recording medium (32) has a high recording density and a large recording capacity owing to its capability of multi-valued recording.
Inventors
- 👤 Shigenori Okamine
- 👤 Tetsuya Nishida
- 👤 Shinkichi Horigome
- 👤 Motoyasu Terao
- 👤 Norio Ohta
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:28
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/004; G11B7/0045
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
60 words
An information recording medium (32) capable of information recording and reproduction upon irradiation with an energy beam, characterized by two or more energy beam absorbing layers (2, 4) which are formed at different positions across the thickness within the depth of focus of the energy beam, said energy beam absorbing layers (2, 4) recording information according to their respective absorptions.
Claim 2
Dependent Claim
28 words
An information recording medium (32) according to claim 1, characterized in that said energy beam absorbing layers (2, 4) hold an energy beam transmitting layer (3) between them.
Claim 3
Dependent Claim
45 words
An information recording medium (32) according to claim 1 or 2, characterized by an energy beam transmitting layer (3) formed on the side on which the energy beam is incident or on the side opposite to the side on which the energy beam is incident.
Claim 4
Dependent Claim
35 words
An information recording medium (32) according to claims 1 to 3, characterized in that the energy beam absorbing layers (2, 4) are arranged such that the adjacent energy beam absorbing layers differ in energy absorption.
Claim 5
Dependent Claim
30 words
An information recording medium (32) according to claims 1 to 4, characterized by a plurality of energy beam absorbing layers (2, 4) which differ in melting point or crystallization temperature.
Claim 6
Dependent Claim
38 words
An information recording medium (32) according to claims 1 to 5, characterized by an energy beam reflecting layer (12) formed on the side opposite to that side of the recording film on which the energy beam is incident.
Claim 7
Dependent Claim
56 words
An information recording medium (32) according to claims 1 to 6, characterized in that the energy beam transmitting layer has a thickness d defined by λ/(4 n ) ≦αµρ¨ d ≦αµρ¨ 2λ/ n , where λ denotes the wavelength of the incident energy beam and n denotes the refractive index of the energy beam transmitting layer.
Claim 8
Dependent Claim
39 words
An information recording medium (32) according to claims 1 to 7, characterized in that the energy absorbing layer contains at least one element selected from Se, Te, As, Sb and Ge, Bi, Sn, Pb, Al, Ga, In and Tl.
Claim 9
Dependent Claim
39 words
An information recording medium (32) according to claims 1 to 8, characterized in that the energy beam transmitting layer is made of a dielectric material which is at least one kind selected from oxides, nitrides, sulfides, selenides and carbides.
Claim 10
Independent Claim
87 words
A method for recording and reproducing information by applying an energy beam to an information recording medium (32) having two or more energy beam absorbing layers (2, 4) which are formed at different positions across the thickness within the depth of focus of the energy beam, said energy beam absorbing layers (2, 4) holding an energy beam transmitting layer (3) between them, characterized in that the information recording is accomplished in response to the energy beam power which varies or the pulse waveform which varies, or both.
Claim 11
Dependent Claim
28 words
An information recording method according to claim 10, characterized in that the change is made at different positions in the direction across the thickness of the recording film.
Claim 12
Dependent Claim
24 words
An information recording method according to claim 10 or 11, characterized in that the change is made in different modes of the recording film.
Claim 13
Independent Claim
47 words
A method for recording and reproducing information according to claims 10 to 12, characterized in that the information reproduction is accomplished by dividing the level of readout signals into three or more different zones so that the individual zones correspond to three or more values of information.
Claim 14
Independent Claim
47 words
A method for recording and reproducing information according to claims 10 to 13, characterized in that the information reproduction is accomplished by dividing the waveform of readout signals into three or more different patterns so that the individual patterns correspond to three or more values of information.
Claim 15
Independent Claim
99 words
An apparatus for recording information by applying an energy beam to an information recording medium 32, characterized by two or more energy beam absorbing layers (2, 4) at different positions across the thickness within the depth of focus of the energy beam and also has an energy beam transmitting layer (3) between the energy beam absorbing layers (2, 4), which comprises a means (30) to encode binary recording signals into ternary or multi-valued signals and a means (31) to change the power or pulse width or both of the irradiating energy beam in accordance with the multi-valued recording signals.
Claim 16
Dependent Claim
52 words
An apparatus for reproducing information according to claim 15, characterized by a means to detect the level of the readout signals, a means to generate timing for the detection of the level of readout signals, and a means to reproduce ternary or multi-valued signals and decode the multi-valued signals into binary signals.
References Cited (Backward Citations)
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