Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2000-08-15
2002-01-22
Angebranndt, Martin (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S945000, C369S275200, C369S275500, C428S064200, C428S064500, C428S064600
Reexamination Certificate
active
06340555
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an information recording medium for recording information therein when receiving an energy beam and also to an information recording and reproducing apparatus which uses the information recording medium. More particularly, the present invention concerns an erasable optical disk such as a phase change type optical disk or a magneto-optical disk and also concerns an information recording and reproducing apparatus capable of reproducing information from the erasable optical disk and a read-only optical disk.
This type of technique is disclosed in JP-A-272032 in which two metallic layers are provided so that first one of the two first and second metallic layers closer to a recording layer is set to be lower in thermal conductivity than the other second metallic layer, the first metallic layer is disposed as opposed to the second metallic layer, and the recording layer is disposed between the first and second metallic layers.
Further disclosed in a Proceeding of International Symposium on Optical Memory, 1995, pp. 151 and 152 is the fact that a semiconductor thin film of Si or the like material having a large transmittance is used in place of the aforementioned first metallic layer.
In general, reproduction compatibility conditions of the information recording and reproducing apparatus with the read-only optical disk are that the stabilities of tracking servo, focusing servo, etc. should be taken into consideration, a medium reflectivity be 15% or more, and the modulation of a reproduced signal be 50% or more when the quality of the reproduced signal is taken into consideration.
Known as one of information recording media satisfying the above conditions is such an information recording medium using a metal such as Au having a high reflectivity as shown in a paper entitled “A CD-compatible erasable disc”, by J. H. Coombs, et al., in Proceedings of Topical Meeting on Optical Data Storage, 1994, pp. 94-106. Also known as another information recording medium is an information recording and reproducing system for recording, on such an information recording medium, information modulated based on the same modulation system as the read-only optical disk or an information reproducing system therefor. An optical recording disk is disclosed in JP-A-6-76361.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an information recording medium which can provide a good recording sensitivity and produce a good reproduced signal, and also to provide an information recording and reproducing apparatus using the above information recording medium, which can have a high reliability at the time of recording and reproducing information.
In accordance with a first aspect of the present invention, there is provided an information recording medium which comprises a recording layer for recording information in the form of a recording mark based on atomic array change and/or electronic state change caused by irradiation of an energy beam, the recording mark being reproduced by irradiating the energy beam on the recording mark; and first and second metallic layers formed as opposed to an energy beam incident side of the recording layer and having different compositions, and wherein first one of the first and second metallic layers disposed closer to the recording layer contains Al, Cu, Ag, Au, Pt and Pd as its main components and a sum of contents of these atoms is 60% or more.
In the present invention, the second metallic layer contains Al, Cu, Ag, Au, Pt and Pd as its main components and a sum of contents of these atoms is larger than that of the first metallic layer.
In accordance with a second aspect of the present invention, there is provided an information recording and reproducing apparatus for reproducing information from an information recording medium, which apparatus comprises the information recording medium of the aforementioned first aspect including a recording layer for recording information in the form of a recording mark based on atomic array change and/or electronic state change caused by irradiation of an energy beam, the recording mark being reproduced by irradiating the energy beam on the recording mark, and also including first and second metallic layers formed as opposed to an energy beam incident side of the recording layer and having different compositions, wherein first one of the first and second metallic layers disposed closer to the recording layer contains Al, Cu, Ag, Au, Pt and Pd as its main components and a sum of contents of these atoms is 60% or more; a laser beam irradiating circuit for reproducing the recording mark from the information recording medium; and an address information detecting circuit for detecting address information from an electrical signal obtained by reproducing an address information mark provided on the information recording medium.
In accordance with a third aspect of the present invention, there is provided an information recording and reproducing apparatus for recording and reproducing information in and from an information recording medium, which apparatus comprises the information recording medium of the aforementioned first aspect including a recording layer for recording information in the form of a recording mark based on atomic array change and/or electronic state change caused by irradiation of an energy beam, the recording mark being reproduced by irradiating the energy beam on the recording mark, and also including first and second metallic layers formed as opposed to an energy beam incident side of the recording layer and having different compositions, wherein first one of the first and second metallic layers disposed closer to the recording layer contains Al, Cu, Ag, Au, Pt and Pd as its main components and a sum of contents of these atoms is 60% or more; a laser beam irradiating circuit for recording and reproducing the recording mark on and from the information recording medium; and a recorded signal modulating circuit and a recorded signal demodulating circuit for performing the recording operation of the recording marks having lengths associated with an information signal.
In accordance with yet a fourth aspect of the present invention, there is provided an information recording and reproducing apparatus in which a protective layer of a recording medium is made up of 2 first and second layers. The first protective layers is made of (ZnS)
80
(SiO
2
)
20
(molar ratio). However, the first protective layer may be made of preferably a mixture composition (15-20 mol % of SiO
2
) of ZnS and SiO
2
having a mixture ratio different from the above case or a mixture composition of ZnS and 10-40 mol % of oxide which will be given below, though its recording sensitivity and jitter become somewhat bad when compared with the above case. The oxide to be mixed in the above case is preferably SiO
2
, SiO, TiO
2
, Al
2
O
3
, Y
2
O
3
, CeO, La
2
O
3
, In
2
O
3
, GeO, GeO
2
, PbO, SnO, SnO
2
, Bi
2
O
3
, TeO
2
, WO
2
, WO
3
, SC
2
O
3
, Ta
2
O
5
or ZrO
2
. Usable as the material of the protective layer in addition to the above is an oxide such as Si—O—N material or Si—Al—O—N material, or Cr—O material such as Cr
2
O
3
, CrO or Co—O material such as Co
2
O
3
, CoO, an nitride such as TaN, AlN, Si—N material such as Si
3
N
4
, Al—Si—N material (e.g., AlSiN
2
), or Ge—N material a sulfide such as ZnS, Sb
2
S
3
, CdS, In
2
S
3
, Ga
2
S
3
, GeS, SnS
2
, PbS or Bi
2
S
3
, a selenide such as SnSe
2
, Sb
2
Se
3
, CdSe, ZnSe, In
2
Se
3
, Ga
2
Se
3
, GeSe, GeSe
2
, SnSe, PbSe or Bi
2
Se
3
, a fluoride such as CeF
3
, MgF
2
or CaF
2
, a composition close to the above material, or a mixture of the above materials. It is highly profitable that the protective layer comprise multi-layers of the protective layers of the ZnS-based material and a third protective layer of material other than the above ZnS-based material. In this case, the material other than the above ZnS-based material is preferably any one of an oxide, a nitride or a fluoride.
In addition to the above mater
Andoo Keikichi
Fukui Yukio
Hirotsune Akemi
Miyamoto Makoto
Miyauchi Yasushi
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