Patent US4855951A successfully refreshed from Google Patents.
US4855951A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for erasing recording in a PHB memory
Assignee: Hitachi Ltd
•
Filing: 1987-10-23
•
Granted: 1989-08-08
•
Expires: 2007-10-23
Abstract
Abstract A desired portion of information stored in the form of holes using hole burning phenomena is erased by irradiating a desired portion of a recording medium with light so as to erase desired holes. In this way it is possible to erase selectively only desired information among information stored in a PHB memory and further to rewrite information in the portion, where information has been erased.
Inventors
- 👤 Yasushi Tomioka
- 👤 Shuji Imazeki
- 👤 Motoyasu Terao
- 👤 Masahiro Ojima
- 👤 Yoshio Taniguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:22
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/004; G11B7/0045; G11B7/00453; G11B7/0055; G11B7/242; G11B7/244; G11B7/246; G11B7/248; G11B7/249
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
74 words
A method for erasing recording in a PHB memory, wherein a desired portion of a recording medium, in which a plurality of holes are formed by hole burning, is irradiated with light so that among said plurality of holes only the holes, which are irradiated with said light, are selectively erased for the purpose of erasing a desired portion of information stored in the form of said plurality of holes in said recording medium.
Claim 2
Independent Claim
74 words
A method for erasing recording in a PHB memory, wherein a desired portion of a recording medium, in which a plurality of holes are formed by hole burning, is irradiated with light so that among said plurality of holes only the holes, which are irradiated with said light, are selectively erased for the purpose of erasing a desired portion of information stored in the form of said plurality of holes in said recording medium.
Claim 3
Dependent Claim
19 words
A method for erasing recording in a PHB memory according to claim 1, wherein said light is infrared radiation.
Claim 4
Dependent Claim
25 words
A method for erasing recording in a PHB memory according to claim 2, wherein the wavelength of said infrared radiation is longer than 0.7 μm.
Claim 5
Dependent Claim
24 words
A method for erasing recording in a PHB memory according to claim 1, wherein said recording medium is prepared by dispersing 1,4-dihydroxyanthraquinone in polyvinylalcohol.
Claim 6
Dependent Claim
77 words
A method for erasing recording in a PHB memory according to claim 1, wherein said recording medium comprises a first material, in which hole burning can be effected by irradiating it with a first light beam, and a second material having a light absorption wavelength region, which is different from that of said first material, and erasure is effected by irradiating said recording medium with a second light beam, which can be absorbed by said second material.
Claim 7
Dependent Claim
19 words
A method for erasing recording in a PHB memory according to claim 5, wherein said first material is phthalocyanine.
Claim 8
Dependent Claim
20 words
A method for erasing recording in a PHB memory according to claim 5, wherein said second material is a dye.
Claim 9
Dependent Claim
26 words
A method for erasing recording in a PHB memory according to claim 5, wherein said first light beam is produced by a variable wavelength dye laser.
Claim 10
Dependent Claim
24 words
A method for erasing recording in a PHB memory according to claim 5, wherein said second light beam is produced by a GaAlAs laser.
Claim 11
Dependent Claim
43 words
A method for erasing recording in a PHB memory according to claim 1, wherein erasure is effected by irradiating said recording medium with a second light having a continuous wavelength region including a wavelength of a first light used for said hole burning.
Claim 12
Dependent Claim
20 words
A method for erasing recording in a PHB memory according to claim 10, wherein said second light is white light.
Claim 13
Dependent Claim
50 words
A method for erasing recording in a PHB memory according to claim 10, wherein said second light is a laser light and said erasure is effected by irradiating continuously said recording medium with said second light while sweeping in wavelength the wavelength region for which information is to be erased.
Claim 14
Dependent Claim
56 words
A method for erasing recording in a PHB memory according to claim 12, wherein said first and second light beams are produced by variable wavelength dye lasers and said erasure is effected by irradiating said recording medium while sweeping in wavelength continuously the wavelength region of said second light beam comprised between 510 and 515 nm.
Claim 15
Dependent Claim
19 words
A method for erasing recording in a PHB memory according to claim 10, wherein said recording medium includes 1,4-dihydroxyanthraquinone.
Claim 16
Dependent Claim
28 words
A method for erasing recording in a PHB memory according to claim 10, wherein said holes are formed in a wavelength region comprised between 400 and 550 μm.
Claim 17
Dependent Claim
26 words
A method for erasing recording in a PHB memory according to claim 10, wherein said first light beam is produced by a variable wavelength dye laser.
Claim 18
Dependent Claim
51 words
A method for erasing recording in a PHB memory according to claim 1, wherein said PHB memory has a metastable state in which information is stored in the form of said plurality of holes in said recording medium, said metastable state being retained until said PHB memory is irradiated for erasure.
References Cited (Backward Citations)
US3896420A
Cited
US4101976A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-07 | 1993-02-06 | 1993-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-07 | 1997-02-06 | 1997-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-07 | 2001-02-06 | 2001-08-08 | $7700.00 | Window Closed / Lapsed |