US5296995A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of magnetically recording and reading data, magnetic recording medium, its production method and magnetic recording apparatus
Assignee: Hitachi Ltd
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Filing: 1993-01-04
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Granted: 1994-03-22
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Expires: 2013-01-04
Abstract
Abstract The present invention uses a magnetic recording medium equipped with those magnetically readable recording servo pits which are preformed on a magnetic recording medium and have different magnetic characteristics from those of a recording magnetic film, detects magnetically a tracking signal or preformat signals such as sync signals, address signals, and the like, from the magnetic flux distribution (leakage magnetic field) occurring at edges of each of the servo pits using a magnetic head, makes servo control of the position of the magnetic head by the detected tracking signal and records or reads magnetically the data along the center of a track. In the magnetic recording medium of the present invention, magnetically readable, wobbled servo pits or sync pits, track address pits and data pits are preformed on the magnetic recording medium, these pit portions have locally different magnetic characteristics from those of the recording magnetic film and have a magnetic film structure wherein saturated magnetization is smaller than at other portions or the magnetic film is removed locally. These preformed pits can be read magnetically by detecting the local magnetic field (leakage magnetic field) generated at their edges by the magnetic head.
Inventors
- 👤 Seiji Yonezawa
- 👤 Keiji Kataoka
- 👤 Hajime Fukke
- 👤 Tsuneo Terasawa
- 👤 Keizo Kato
- 👤 Harukazu Miyamoto
- 👤 Klaus Kinstatter
- 👤 Masaru Ito
- 👤 Norio Ohta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:27
CPC Classifications
G; G09; G09B; G09B5/00; G09B5/06; G09B5/065; B; B82; B82Y; B82Y10/00; G11; G11B; G11B19/00; G11B19/02; G11B20/00; G11B20/10; G11B20/12; G11B20/1217; G11B20/1252; G11B27/00; G11B27/02; G11B27/031; G11B27/034; G11B27/10; G11B27/102; G11B27/105; G11B27/19; G11B27/28; G11B5/00; G11B5/012; G11B5/48; G11B5/54; G11B5/55; G11B5/5521; G11B5/5526; G11B5/58; G11B5/596; G11B5/59633; G11B5/62; G11B5/74; G11B5/743; G11B5/82; G11B5/84; G11B5/855; G11B2020/1259; G11B2220/00; G11B2220/20; G11B2220/21; G11B2220/211; G11B2220/25; G11B2220/2537
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
175 words
A method of recording and reading data comprising: using a magnetic recording medium having a magnetic film storing data in such a form as to be capable of recording and reading magnetically the data and equipped with a plurality of servo areas for detecting tracking signals, disposed periodically along tracks and with a plurality of servo pits preformed in each of said servo areas and having magnetic characteristics different from those of said magnetic film; magnetically the magnetic film in a direction of data recording; detecting the magnetic field occurring at edges of each of said preformed servo pits when a magnetic head scans each of said servo areas to obtain said tracking signals; and recording or reading said data, by said magnetic head, between said servo areas while making tracking control on the basis of said tracking signals with said magnetic head moving along the center of said tracks; wherein said magnetic recording medium is a magnetic recording medium whose preformed servo pits are formed by removing a base film below said magnetic film.
Claim 2
Independent Claim
175 words
A method of recording and reading data comprising: using a magnetic recording medium having a magnetic film storing data in such a form as to be capable of recording and reading magnetically the data and equipped with a plurality of servo areas for detecting tracking signals, disposed periodically along tracks and with a plurality of servo pits preformed in each of said servo areas and having magnetic characteristics different from those of said magnetic film; magnetically the magnetic film in a direction of data recording; detecting the magnetic field occurring at edges of each of said preformed servo pits when a magnetic head scans each of said servo areas to obtain said tracking signals; and recording or reading said data, by said magnetic head, between said servo areas while making tracking control on the basis of said tracking signals with said magnetic head moving along the center of said tracks; wherein said magnetic recording medium is a magnetic recording medium whose preformed servo pits are formed by removing a base film below said magnetic film.
Claim 3
Dependent Claim
78 words
A magnetic recording medium having a ferromagnetic recording film to which magnetically readable data are recorded, wherein servo areas for detecting tracking signals are periodically provided along tracks and each of said servo areas has preformed servo pits having different magnetic characteristics from those of said magnetic film, and a groove being provided between said tracks, wherein said preformed servo pits in each of said servo areas are formed by removing a base film below said magnetic film.
Claim 4
Dependent Claim
78 words
A magnetic recording medium having a ferromagnetic recording film to which magnetically readable data are recorded, wherein servo areas for detecting tracking signals are periodically provided along tracks and each of said servo areas has preformed servo pits having different magnetic characteristics from those of said magnetic film, and a groove being provided between said tracks, wherein said preformed servo pits in each of said servo areas are formed by removing a base film below said magnetic film.
Claim 5
Independent Claim
120 words
A method of producing a magnetic recording medium having a ferromagnetic recording film to which magnetically readable data are recorded, wherein servo areas for detecting tracking signals are periodically provided along tracks and each of said servo areas has preformed servo pits having different characteristics from those of said magnetic film, said method comprising the steps of: preparing a mask having patterns of servo pits to be provided in advance in said servo areas using an elongated shape laser beam spot; exposing a resist disposed on said magnetic film through said mask; and removing said resist corresponding to said patterns; wherein said servo pits are preformed by removing locally a base film below said magnetic film corresponding to said patterns.
Claim 6
Independent Claim
120 words
A method of producing a magnetic recording medium having a ferromagnetic recording film to which magnetically readable data are recorded, wherein servo areas for detecting tracking signals are periodically provided along tracks and each of said servo areas has preformed servo pits having different characteristics from those of said magnetic film, said method comprising the steps of: preparing a mask having patterns of servo pits to be provided in advance in said servo areas using an elongated shape laser beam spot; exposing a resist disposed on said magnetic film through said mask; and removing said resist corresponding to said patterns; wherein said servo pits are preformed by removing locally a base film below said magnetic film corresponding to said patterns.
Claim 7
Independent Claim
107 words
A method of recording and reading data comprising: using a magnetic recording medium including a substrate having preformed pits thereon and a magnetic film storing data in such a form as to be capable of recording and reading magnetically the data, the magnetic film overlying a surface of the substrate including the preformed pits; magnetizing the magnetic film in a direction of data recording; detecting the magnetic field occurring at edges of each of the preformed pits when a magnetic head scans the magnetic recording medium to obtain a control signal; and recording or reading data, by the magnetic head on the basis of the control signal.
Claim 8
Independent Claim
107 words
A method of recording and reading data comprising: using a magnetic recording medium including a substrate having preformed pits thereon and a magnetic film storing data in such a form as to be capable of recording and reading magnetically the data, the magnetic film overlying a surface of the substrate including the preformed pits; magnetizing the magnetic film in a direction of data recording; detecting the magnetic field occurring at edges of each of the preformed pits when a magnetic head scans the magnetic recording medium to obtain a control signal; and recording or reading data, by the magnetic head on the basis of the control signal.
Claim 9
Dependent Claim
39 words
A method according to claim 4, wherein at least portions of the magnetic film overlying preformed pits have magnetic characteristics different from other portions of the magnetic film overlying the surface of the substrate without overlying the preformed pits.
Claim 10
Dependent Claim
15 words
A method according to claim 5, wherein the substrate is made by a replication process.
Claim 11
Dependent Claim
45 words
A method according to claim 5, wherein the magnetic recording medium includes a base film interposed between the magnetic film and the surface of the substrate only at the portions of the magnetic film overlying the surface of the substrate without overlying the preformed pits.
Claim 12
Dependent Claim
21 words
A method according to claim 5, wherein the magnetic film overlies the entire surface of the substrate including the preformed pits.
Claim 13
Dependent Claim
98 words
A method according to claim 5, wherein the preformed pits are disposed periodically along tracks in servo areas for detecting tracking signals and the magnetic field occurring at edges of each of the preformed pits is detected when the magnetic head scans each of the servo areas to obtain a tracking signal as the control signal, the step of recording or reading data including recording or reading data by the magnetic head between the servo areas while making tracking control on the basis of the tracking signal with the magnetic head moving along the center of the tracks.
Claim 14
Dependent Claim
85 words
A method of recording and reading data according to claim 9, wherein said magnetic recording medium is a magnetic recording medium wherein said preformed servo pits in each of said servo areas consists of at least one pair of wobbled servo pits provided in a wobbling arrangement with respect to the center of said track, and said tracking signal is detected from the difference of the outputs obtained by detecting the magnetic field occurring at each of said wobbled servo pits by said magnetic head.
Claim 15
Dependent Claim
78 words
A method of recording and reading data according to claim 9, wherein said magnetic recording medium is magnetic recording medium wherein said preformed servo pits in each of said servo areas consists of a set of bit trains having mutually different frequencies, components having said mutually different frequencies are detected from outputs obtained by scanning said set of pit lines by said magnetic head and said tracking signal is detected from the difference of the signals thus detected.
Claim 16
Dependent Claim
84 words
A method of recording and reading data according to claim 9, wherein said magnetic recording medium is magnetic recording medium including first areas having preformed data pits having different magnetic characteristics from those of said magnetic film between said servo areas and second areas having recording areas between said servo areas, said recording areas being capable of recording data using said magnetic head, and said data pits are read by detecting the magnetic field occurring at said preformed data pits by said magnetic head.
Claim 17
Dependent Claim
41 words
A method of recording and reading data according to claim 9, wherein the length of said preformed servo pit in a direction at right angles to said track is substantially equal to that of the recording portion of said magnetic head.
Claim 18
Dependent Claim
17 words
A method according to claim 9, wherein the preformed servo pits are of circular or rectangular shape.
Claim 19
Dependent Claim
54 words
A magnetic recording medium comprising a substrate having preformed pits therein and a magnetic film overlying a surface of the substrate including the pits preformed therein so as to enable a magnetic field occurring at edges of each of the preformed pits to be detected by a magnetic head scanning the magnetic recording medium.
Claim 20
Dependent Claim
54 words
A magnetic recording medium comprising a substrate having preformed pits therein and a magnetic film overlying a surface of the substrate including the pits preformed therein so as to enable a magnetic field occurring at edges of each of the preformed pits to be detected by a magnetic head scanning the magnetic recording medium.
Claim 21
Dependent Claim
41 words
A magnetic recording medium according to claim 15, wherein at least portions of the magnetic film overlying preformed pits have magnetic characteristics different from other portions of the magnetic film overlying the surface of the substrate without overlying the preformed pits.
Claim 22
Dependent Claim
54 words
A magnetic recording medium according to claim 16, wherein the magnetic film stores data in such a form as to be capable of recording and reading magnetically the data, the preformed pits being disposed periodically along tracks in servo areas for detecting tracking signals, the preformed pits in the servo areas being servo pits.
Claim 23
Dependent Claim
42 words
A magnetic recording medium according to claim 17, wherein said preformed servo pits in each of said servo areas consist of at least a pair of wobbled servo pits provided in a wobbling arrangement with respect to the center of said track.
Claim 24
Dependent Claim
30 words
A magnetic recording medium according to claim 17, wherein said preformed servo pits in each of said servo areas consist of one set of pit lines having mutually different frequencies.
Claim 25
Dependent Claim
50 words
A magnetic recording medium according to claim 17, which includes first areas having preformed data pits having different magnetic characteristics from those of said magnetic film between said servo areas and second areas having recording areas to which data can be recorded by a magnetic head between said servo areas.
Claim 26
Dependent Claim
16 words
A magnetic recording medium according to claim 17, wherein a groove is provided between said tracks.
Claim 27
Dependent Claim
43 words
A magnetic recording medium according to claim 16, wherein a base film is interposed between the surface of the substrate and the magnetic film only at the portion of the magnetic film overlying the surface of the substrate without overlying the preformed pits.
Claim 28
Dependent Claim
23 words
A magnetic recording medium according to claim 16, wherein the magnetic film overlies the entire surface of the substrate including the preformed pits.
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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) | 1997-03-21 | 1997-09-20 | 1998-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-21 | 2001-09-20 | 2002-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-21 | 2005-09-20 | 2006-03-22 | $7700.00 | Window Closed / Lapsed |