Source: http://www.google.com/patents/US7422838?dq=7,346,545
Timestamp: 2014-03-15 02:32:20
Document Index: 107361831

Matched Legal Cases: ['Application No. 61', 'Application No. 61', 'Application No. 62', 'Application No. 63', 'Application No. 60', 'Application No. 63', 'Application No. 4', 'Application No. 4', 'Application No. 4', 'Application No. 00', 'Application No. 11']

Patent US7422838 - Phase-change optical recording medium - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA phase-change optical recording medium is disclosed including a supporting substrate and the following contiguous layers formed on the supporting substrate in the order recited such as a first dielectric layer, a recording layer, a second dielectric layer, a metal/alloy layer, and an ultraviolet light...http://www.google.com/patents/US7422838?utm_source=gb-gplus-sharePatent US7422838 - Phase-change optical recording mediumAdvanced Patent SearchPublication numberUS7422838 B1Publication typeGrantApplication numberUS 09/569,501Publication dateSep 9, 2008Filing dateMay 11, 2000Priority dateJun 1, 1999Fee statusPaidAlso published asEP1058249A1Publication number09569501, 569501, US 7422838 B1, US 7422838B1, US-B1-7422838, US7422838 B1, US7422838B1InventorsKatsuyuki Yamada, Yuki Nakamura, Tatsuo Mikami, Eiji Noda, Kayo KatohOriginal AssigneeRicoh Company, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (38), Non-Patent Citations (13), Referenced by (1), Classifications (22), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetPhase-change optical recording mediumUS 7422838 B1Abstract A phase-change optical recording medium is disclosed including a supporting substrate and the following contiguous layers formed on the supporting substrate in the order recited such as a first dielectric layer, a recording layer, a second dielectric layer, a metal/alloy layer, and an ultraviolet light curing resinous layer. The recording layer is characterized by its uppermost recrystallization linear velocity ranging from about 5.0 m/sec to about 10.0 m/sec, which can be utilized in read/write/erase operations for the recording medium at linear velocities higher than the quad-speed as well.
The phase-change recording medium has been attracting much attention recently for its capabilities described above. It has been disclosed in U.S. Pat. No. 3,530,441 to provide chalcogenide alloys for forming recording materials such as Ge�Te, Ge�Te�Sn, Ge�Te�S, Ge�Se�S, Ge�Se�Sb, Ge�As�Se, In�Te, Se�Te and SeAs.
Also disclosed to improve stability and crystallization speed are Ge�Te alloy materials added with Au (Japanese Laid-Open Patent Application No. 61-219692), with Sn and Au (Japanese Laid-Open Patent Application No. 61-270190), or with Pd (Japanese Laid-Open Patent Application No. 62-19490). Further disclosed to improve write/readout repeated operation characteristics are Ge�Te�Se�Sb and Ge�Te�Sb alloys with specified compositions (Japanese Laid-Open Patent Applications Nos. 62-73438 and 63-228433). These alloy materials, however, have not proven satisfactory in achieving various desirable characteristics of the rewritable phase-change optical recording medium.
Another recording medium is proposed in Japanese Laid-Open Patent Application No. 63-251290, including a single recording layer with a crystallized state of substantially more than ternary composition. By �substantially more than ternary� is meant in the disclosure that the alloy system includes at least 90 atomic % of a ternary compound (e.g., In3SbTe2) in the recording layer. It is also stated in the disclosure that write/erasure characteristics are improved with the alloy composition. However, this composition still has shortcomings such as erasure ratio of relatively small magnitude and laser power yet to be reduced for write/erase operations.
In a similar manner, further recording media are proposed including respective recording layers, in which the one recording layer includes (In1−x Sbx)1−yMy with 0.55≦x≦0.80 and 0≦y≦0.20, as disclosed in Japanese Laid-Open Patent Application No. 60-177446, where M includes at least one which is selected from the group consisting Au, Ag, Cu, Pd, Pt, Al, Si, Ge, Ga, Sn, Te, Se and Bi; the other recording layer includes an alloy GeTe�Sb2Te3�Sb(excess), as disclosed in Japanese Laid-Open Patent Application No. 63-228433. However, this recording media composed of these alloy systems have not attained sufficient media characteristics such as the recording sensitivity and erasing ratio.
Further, there are disclosed optical recording media provided with respective recording layers including alloy systems such as, a Ge�Te�Sb alloy added with N, described in Japanese Laid-Open Patent Application No. 4-163839; a Te�Ge�Se alloy formed such that at least one of constituent elements thereof is incorporated as a nitride, described in Japanese Laid-Open Patent Application No. 4-52188; and a Te�Ge�Se alloy adsorbed with N, described in Japanese Laid-Open Patent Application No. 4-52189. The optical recording media composed of these alloy systems, however, have not acquired satisfactory characteristics for the recording media.
SUMMARY Accordingly, it is an object of the present disclosure to provide a rewritable CD-RW disk, having most, if not all, of the advantages and features of similar employed optical recording disks, while eliminating many of the aforementioned disadvantages.
BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing, wherein;
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, there is illustrated a phase-change optical recording medium disclosed herein, including a supporting substrate 1, and the following layers formed contiguously on the supporting substrate in the order recited, such as a first dielectric layer 2, a recording layer 3, a second dielectric layer 4, a metal/alloy layer 5, and an overcoat layer 6. Further, a printed layer 7 and a hard coat layer 8 may be formed on the overcoat layer 6 and the mirror face of the substrate, respectively.
The results obtained from the measurements are typically illustrated in FIG. 2, in which a recrystallization linear velocity is defined as the point �A� on the horizontal axis, which approximately corresponds to the point dividing higher reflective values from lower ones on the graph. It may be noted that these higher and lower reflective values result from recrystallized and amorphous portions, respectively, on the irradiated disk area.
The N species is preferably incorporated into the recording layer chemically bonded to at least one of Ag, In, Sb and Te. When the chemical bond is formed with Te, such as exemplified by, for example, Te�N and Sb�Te�N, pronounced effects can be obtained on the improvement in the number of repeated overwrite cycles.
Such chemical bonds as above may be analyzed by spectroscopic methods such as, for example, FT-IR and XPS. In the FT-IR spectra, for example, the Te�N bond yields an absorption peak in the range of 500-600 cm−1 spectral range, while the Sb�Te�N exhibits an absorption peak in the 600-650 cm−1 range.
EXAMPLES Examples 1 Through 8 A phase-change recording medium was fabricated on a 1.2 millimeter thick polycarbonate substrate which was provided with pregrooved guide tracks of 0.5 micron width and 35 nanometers depth. The following constituent layers were formed consecutively on the substrate in the order recited in a single sheet-type sputtering apparatus with a seven seconds tact time. These constituent layers were a first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer of metal or alloy. Thereafter, a hard coat layer and an overcoating layer were formed on the substrate and the reflective layer, respectively, using an ultraviolet curing resinous material disposed by spin coating, whereby a phase-change recording medium was fabricated. For forming the first and second dielectric layers, the combination of ZnS and SiO2 was used; and for forming the reflective layer, an aluminum alloy was used.
Comparative Example 1 A further phase-change recording medium was fabricated in a manner similar to Example 1, with the exception that other compositions such as shown in Table 1 were used for forming the constituent layers. Subsequently, the thus fabricated phase change recording medium was subjected to the measurements for determining the disk characteristics described above.
Example 9 A phase-change recording medium was fabricated in a manner similar to Example 4, with the exception that the first dielectric layer was formed with two constituent layer such as a ZnS�SiO2 (20 mol. %) layer 20 nm thick and another ZnS�SiO2 (10 mol. %) layer formed further thereon. Subsequently, the thus fabricated phase change recording medium was subjected to the measurements for determining disk characteristics described above.
Example 10 A phase-change recording medium was fabricated in a manner similar to Example 8, with the exception that an aluminum alloy layer 20 nm thick was formed on the second dielectric layer with a silver layer 50 nm formed further thereon.
Example 11 The plurality of phase-change recording media fabricated in Examples 1 through 4 were subjected to the measurements for determining disk characteristics under the conditions of the aforementioned ratio Pe4/Pw4 of 0.5 for the quad-CD speed writing and the ratio Pe8/Pw8 of 0.46 for octad-CD speed writing. The results from the measurements indicate that the jitter values were reduced after octad-speed overwrite operations with the respective phase-change recording media.
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