US5470628A
Expired / Lapsed
US
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Optical recording medium
Assignee: TDK Corp
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Filing: 1994-11-14
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Granted: 1995-11-28
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Expires: 2014-11-14
Abstract
Abstract An optical recording medium has a mask layer 4, an intermediate dielectric layer 5, a recording layer 6, and a reflective layer 8 on a transparent substrate 2. The recording layer 6 contains a recording material which changes its crystallographic structure upon exposure to recording light for recording information. The mask layer 4 contains a mask material which increases its light transmittance when melted and has a complex refractive index (n 0 -ik 0 ), of which the real part n 0 drops by 1.0 or less and the imaginary part k 0 drops by 0.25-1.0 when the mask material converts from a crystalline state to an amorphous or microcrystalline state. Signals can be reproduced from the medium with high C/N without resorting to reading light of shorter wavelength or an optical pickup objective lens having a larger numerical aperture and even when the linear velocity of the medium relative to recording and reproducing light is low.
Inventors
- 👤 Junji Tominaga
- 👤 Susumu Haratani
- 👤 Tokuhiko Handa
- 👤 Ryo Inaba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:30
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/252; G11B7/004; G11B7/0045; G11B7/00454; G11B7/0055; G11B7/00557; G11B7/242; G11B7/243; G11B2007/24302; G11B2007/24306; G11B2007/24308; G11B2007/2431; G11B2007/24312; G11B2007/24314; G11B2007/24316; G11B7/257; G11B2007/25705; G11B2007/25706; G11B2007/25708; G11B2007/2571; G11B2007/25713; G11B2007/25715; G11B2007/25716; G11B7/253; G11B7/2531; G11B7/2533; G11B7/2534; G11B7/254; G11B7/2542; G11B7/258; G11B7/2595; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10S430/00; Y10S430/146
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
112 words
An optical recording medium comprising a mask layer, an intermediate dielectric layer, a recording layer, and a reflective layer on a transparent substrate in the described order, wherein said recording layer contains a recording material which changes its crystallographic structure upon exposure to recording light for recording information, and said mask layer contains a mask material which increases its light transmittance when melted, and said mask layer has a complex refractive index (n 0 -ik 0 ), of which the real part n 0 has a drop of up to 1.0 and the imaginary part k 0 has a drop of 0.25 to 1.0 when the mask material becomes amorphous or microcrystalline.
Claim 2
Dependent Claim
112 words
An optical recording medium comprising a mask layer, an intermediate dielectric layer, a recording layer, and a reflective layer on a transparent substrate in the described order, wherein said recording layer contains a recording material which changes its crystallographic structure upon exposure to recording light for recording information, and said mask layer contains a mask material which increases its light transmittance when melted, and said mask layer has a complex refractive index (n 0 -ik 0 ), of which the real part n 0 has a drop of up to 1.0 and the imaginary part k 0 has a drop of 0.25 to 1.0 when the mask material becomes amorphous or microcrystalline.
Claim 3
Dependent Claim
60 words
The optical recording medium of claim 1 wherein provided that the minimum of a relative linear velocity at which a material can convert to an amorphous or microcrystalline state after exposure to a light beam is designated a non-crystallizing linear velocity, the non-crystallizing linear velocity of said mask layer is higher than the non-crystallizing linear velocity of said recording layer.
Claim 4
Dependent Claim
21 words
The optical recording medium of claim 2 wherein the non-crystallizing linear velocity of said recording layer is 2.4 to 4.5 m/s.
Claim 5
Dependent Claim
65 words
The optical recording medium of claim 1 wherein provided that the minimum of a relative linear velocity at which a material can convert to an amorphous or microcrystalline state after exposure to a light beam is designated a non-crystallizing linear velocity, the relative linear velocity of the medium relative to recording and reproducing light is less than the non-crystallizing linear velocity of said mask layer.
Claim 6
Dependent Claim
21 words
The optical recording medium of claim 4 wherein the non-crystallizing linear velocity of said recording layer is 2.4 to 4.5 m/s.
Claim 7
Dependent Claim
110 words
The optical recording medium of claim 1 wherein said mask material contains A, B, C, MI, and MII wherein A is at least one of silver and gold, B is indium, C is at least one of tellurium and selenium, MI is at least one of antimony and bismuth, and MII is at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, manganese, tungsten and molybdenum, the atomic ratio of the respective elements in the mask material being represented by the formula: [(A.sub.a B.sub.b C.sub.1-a-b).sub.c MI.sub.1-c ].sub.1-d MII.sub.d wherein letters a, b, c and d are in the ranges: 0.01≦a<0.50, 0.01≦b<0.50, 0.30≦c≦0.70, and 0.001≦d≦0.20.
Claim 8
Dependent Claim
16 words
The optical recording medium of claim 6 wherein said mask layer further contains a dielectric material.
Claim 9
Dependent Claim
16 words
The optical recording medium of claim 1 wherein said mask layer further contains a dielectric material.
Claim 10
Dependent Claim
30 words
The optical recording medium of claim 8 wherein in said mask layer, the dielectric material occupies up to 25% by volume of the total of the mask and dielectric materials.
Claim 11
Dependent Claim
110 words
The optical recording medium of claim 1 wherein said recording material contains A, B, C, MI, and MII wherein A is at least one of silver and gold, B is indium, C is at least one of tellurium and selenium, MI is at least one of antimony and bismuth, and MII is at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, manganese, tungsten and molybdenum, the atomic ratio of the respective elements in the recording material being represented by the formula: [(A.sub.e B.sub.f C.sub.1-e-f).sub.g MI.sub.1-g ].sub.1-h MII.sub.h wherein letters e, f, g and h are in the ranges: 0.01≦e<0.50, 0.01≦f<0.50, 0.30≦g≦0.70, and 0.001≦h≦0.20.
Claim 12
Dependent Claim
16 words
The optical recording medium of claim 10 wherein said recording layer further contains a dielectric material.
Claim 13
Dependent Claim
30 words
The optical recording medium of claim 11 wherein in said recording layer, the dielectric material occupies up to 25% by volume of the total of the recording and dielectric materials.
Claim 14
Dependent Claim
17 words
The optical recording medium of claim 1 wherein said mask layer is 7 to 100 nm thick.
Claim 15
Dependent Claim
18 words
The optical recording medium of claim 1 wherein said intermediate dielectric layer is 10 to 200 nm thick.
Claim 16
Dependent Claim
22 words
The optical recording medium of claim 1 which further includes a lower dielectric layer between the transparent substrate and the mask layer.
Claim 17
Dependent Claim
43 words
The optical recording medium of claim 15 wherein said lower dielectric layer has a thickness of [λ R /(2n 3 )]±50 nm wherein the reproducing light has a wavelength λ R and said lower dielectric layer has a refractive index n 3 .
Claim 18
Dependent Claim
22 words
The optical recording medium of claim 1 which further includes an upper dielectric layer between the recording layer and the reflective layer.
Claim 19
Dependent Claim
21 words
The optical recording medium of claim 1 which further includes a protective layer containing an organic material on the reflective layer.
Claim 20
Dependent Claim
26 words
The optical recording medium of claim 1 wherein the recording layer includes an unrecorded region which is crystalline and recorded marks which are amorphous or microcrystalline.
Claim 21
Dependent Claim
26 words
The optical recording medium of claim 1 wherein the recording layer includes an unrecorded region which is amorphous or microcrystalline and recorded marks which are crystalline.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-11-27 | 1999-05-29 | 1999-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-27 | 2003-05-29 | 2003-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-27 | 2007-05-29 | 2007-11-28 | $7700.00 | Window Closed / Lapsed |