US4949329A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of effecting erasure of optical information media including varying duty cycle, laser power and focus offset
Assignee: Hoechst Celanese Chemical Co
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Filing: 1988-04-27
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Granted: 1990-08-14
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Expires: 2008-04-27
Abstract
Abstract Provided is a process for the erasure of information recorded in an optical information medium. The erasure is effected by irradiating the medium with a laser beam, with the duty cycle, laser power and focus offset having been adjusted from that used during writing such that upon the irradiation complete and clean erasure of the information is effected. It is preferred that the focus offset and laser power are adjusted the minimal amount possible and that the duty cycle is the parameter of the three for which the greatest adjustment is made. Control and adjustment of the three parameters in accordance with the present invention permits one to realize more accurate, efficient and clean erasure, even bit-by-bit erasure if desired, than has heretofore been possible.
Inventors
- 👤 Steven R. Furman
- 👤 James E. Kuder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:16
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/004; G11B7/0055
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
102 words
A process for the erasure of information recorded in an optical information medium by irradiating the medium with a laser beam, said optical information medium having an information layer with a melting point in the range of from about 50° C. to about 250° C., the improvement which comprises adjusting the (i) duty cycle; (ii) laser power; and (iii) focus offset of the laser from that used during writing such that the product of ##EQU3## ranges from about 3 to about 4, the adjustments being such that complete erasure of the information desired to be erased is effected substantially without additional writing.
Claim 2
Dependent Claim
102 words
A process for the erasure of information recorded in an optical information medium by irradiating the medium with a laser beam, said optical information medium having an information layer with a melting point in the range of from about 50° C. to about 250° C., the improvement which comprises adjusting the (i) duty cycle; (ii) laser power; and (iii) focus offset of the laser from that used during writing such that the product of ##EQU3## ranges from about 3 to about 4, the adjustments being such that complete erasure of the information desired to be erased is effected substantially without additional writing.
Claim 3
Dependent Claim
36 words
The process for erasure of claim 1, wherein the information recorded in the information layer of the optical information medium is in the form of pits, and the erasure effected is a levelling of the pits.
Claim 4
Dependent Claim
18 words
The process for erasure of claim 1, wherein the duty cycle is the parameter which is adjusted first.
Claim 5
Dependent Claim
19 words
The process for erasure of claim 1, wherein the information layer of the medium comprises a dimer acid polyamide.
Claim 6
Dependent Claim
21 words
The process for erasure of claim 4, wherein the information layer of the medium further comprises a dye or chromophoric material.
Claim 7
Dependent Claim
18 words
The process for erasure of claim 1, wherein the information layer of the medium comprises a polymeric material.
Claim 8
Dependent Claim
21 words
The process for erasure of claim 6, wherein the information layer of the medium further comprises a dye or chromophoric material.
Claim 9
Dependent Claim
20 words
The process for erasure of claim 1, wherein the information layer of the medium comprises a dye or chromophoric material.
Claim 10
Dependent Claim
19 words
The process for erasure of claim 6, wherein the information layer of the medium comprises a dimer acid polyamide.
Claim 11
Dependent Claim
14 words
The process for erasure of claim 1, wherein bit by bit erasure is effected.
Claim 12
Dependent Claim
27 words
The process for erasure of claim 1, wherein the width of erasure is substantially the same as the width of the bits of information to be erased.
Claim 13
Dependent Claim
18 words
The process for erasure of claim 1, wherein the laser beam is emitted from a AlGaAs diode laser.
Claim 14
Dependent Claim
12 words
The process for erasure of claim 1, wherein sector-by-sector erasure is effected.
Claim 15
Dependent Claim
15 words
The process for erasure of claim 10, wherein a single bit of information is erased.
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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) | 1993-08-13 | 1994-02-12 | 1994-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-13 | 1998-02-12 | 1998-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-13 | 2002-02-12 | 2002-08-14 | $7700.00 | Window Closed / Lapsed |