US3769465A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic servo in magnetic recording readout
Assignee: International Business Machines Corp
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Filing: 1971-12-20
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Granted: 1973-10-30
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Expires: 1991-12-20
Abstract
Abstract In high-density recording, a slight lateral movement between an information track and a readout transducer will cause either a failure to read out information from the track or incorrect read out of information. Instead of moving a transducer to a position centered over the track, a plurality of transducers are in a fixed position, and electronic gating is used to select the transducer presently centered over the track to be readout. Transducers used herein are the conventional magnetic heads or the newer magneto-optic transducers which utilize photodiodes as a final sense element. The alignment between tracks and transducers is detected by a plurality of transducers which monitor a guard band on the magnetic recording surface. The transducers monitoring the guard band detect the lateral edge of recorded information. The tracks on the magnetic surface will be a fixed position relative to this lateral edge. The detection of the lateral edge then permits the selection of the transducers which will be centered over each track on the magnetic recording surface.
Inventors
- 👤 A Wellbrock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:59
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/49; G11B5/4969; G11B11/00; G11B11/10; G11B11/105; G11B11/10532; G11B11/10541; G11B11/10543; G11B11/10547; G11B11/1055; G11B11/10556; G11B21/00; G11B7/00; G11B7/12; G11B7/14
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
141 words
Apparatus for selecting transducers aligned with information tracks on the surface of a magnetic storage medium, wherein each track is positioned a constant distance from a guard band parallel to the tracks on the storage medium, comprising: a plurality of magnetic transducers fixedly mounted adjacent the storage medium, each transducer being magnetically coupled with a portion of the medium which is a fraction of the width of a single track and more than one transducer being magnetically coupled with each track; means for detecting the lateral position of the information tracks relative to the fixed position of the transducers by monitoring the output signals from the transducers, the output of said detecting means being a lateral position signal; means responsive to the lateral position signal for selecting the transducer or transducers most nearly aligned with each information track for information readout.
Claim 2
Dependent Claim
141 words
Apparatus for selecting transducers aligned with information tracks on the surface of a magnetic storage medium, wherein each track is positioned a constant distance from a guard band parallel to the tracks on the storage medium, comprising: a plurality of magnetic transducers fixedly mounted adjacent the storage medium, each transducer being magnetically coupled with a portion of the medium which is a fraction of the width of a single track and more than one transducer being magnetically coupled with each track; means for detecting the lateral position of the information tracks relative to the fixed position of the transducers by monitoring the output signals from the transducers, the output of said detecting means being a lateral position signal; means responsive to the lateral position signal for selecting the transducer or transducers most nearly aligned with each information track for information readout.
Claim 3
Dependent Claim
23 words
The apparatus of claim 1, wherein said transducers are magneto-optic devices responding to the interaction between the magnetic stored information and radiant energy.
Claim 4
Dependent Claim
125 words
The apparatus of Claim 1, wherein the guard band contains a cyclic signal of a first amplitude, and the information tracks contain a cyclic signal of a Second amplitude whereby said detecting means comprises: means for rectifying the output from those transducers which are positioned adjacent an area where the guard band may reside depending upon lateral movement of the guard band and the information tracks, whereby the rectified output from transducers reading an information track will be a signal at a firSt level while the rectified output from transducers reading the guard band will be a signal at a second level; logic means responsive to the levels of rectified output for determining the position of the guard band and generating a lateral position signal.
Claim 5
Dependent Claim
117 words
The apparatus of claim 1, where in said information tracks are recorded at a signal frequency, and said guard band is recorded at a guard band frequency, and wherein said detecting means comprises: means for sensing the frequency of the signal from those transducers which are positioned adjacent an area where the guard band may reside depending upon lateral movement of the guard band and the information tracks, whereby said sensing means detects which transducers are reading the signal frequency and which transducers are reading the guard band frequency; logic means responsive to said sensing means for logically determining the position of the guard band relative to the magnetic transducers and there-upon generating a lateral position signal.
Claim 6
Dependent Claim
117 words
The apparatus of Claim 1, wherein said detecting means comprises: means for sensing the signal from those transducers which are positioned adjacent an area where the guard band may reside depending upon lateral movement of the guard band and information tracks, whereby said sensing means detects which transducers are positioned over information tracks and which transducers are positioned over the guard band; means responsive to said sensing means for generating a lateral position signal indicative of the position of the guard band relative to the transducers; said sensing means having a sensitivity deadband region so that changes in lateral position of the tracks must be significant before said generating means will generate a new lateral position signal.
Claim 7
Dependent Claim
189 words
Apparatus for electronically servoing transducers so that each information track on a magnetic storage medium is always read out by a transducer aligned with the track comprising: a guide track on the storage medium; information tracks recorded on the magnetic storage medium parallel to the guide track, each information track having a fixed position relative to said guide track; an array of transducers fixedly mounted adjacent the storage medium for reading out the signals recorded on the storage medium; the width of each transducer being such that at least three transducers are required to completely span a single track, and the array of transducers together completely spans all possible lateral positions of the information tracks and guide track; means responsive to said transducers for detecting whether each transducer is aligned with an information track or a guide track; means responsive to said detecting means for generating a lateral position signal based upon the position of the guide track relative to said transducers as detected by said detecting means; means responsive to the lateral position signal for selecting the transducer means presently aligned with and centered over each information track.
Claim 8
Dependent Claim
189 words
Apparatus for electronically servoing transducers so that each information track on a magnetic storage medium is always read out by a transducer aligned with the track comprising: a guide track on the storage medium; information tracks recorded on the magnetic storage medium parallel to the guide track, each information track having a fixed position relative to said guide track; an array of transducers fixedly mounted adjacent the storage medium for reading out the signals recorded on the storage medium; the width of each transducer being such that at least three transducers are required to completely span a single track, and the array of transducers together completely spans all possible lateral positions of the information tracks and guide track; means responsive to said transducers for detecting whether each transducer is aligned with an information track or a guide track; means responsive to said detecting means for generating a lateral position signal based upon the position of the guide track relative to said transducers as detected by said detecting means; means responsive to the lateral position signal for selecting the transducer means presently aligned with and centered over each information track.
Claim 9
Dependent Claim
79 words
The apparatus of claim 6, wherein the guide track contains a cyclic signal of a first amplitude, and the information tracks contain a cyclic signal of a second amplitude whereby said detecting means comprises: means for rectifying the output from each transducer, so that the rectified output from transducers reading an information track will be a signal at a first level while the rectified output from transducers reading the guide track will be a signal at a second level.
Claim 10
Dependent Claim
58 words
Apparatus of claim 6, wherein said information tracks are recorded at a signal frequency, and said guide track is recorded at a guide frequency, and wherein said detecting means comprises: means for sensing the frequency of the signal from each transducer to detect which transducers are reading the signal frequency and which transducers are reading the guide frequency.
Claim 11
Dependent Claim
83 words
The apparatus of Claim 6, wherein said information tracks are recorded at a predetermIned frequency and said guide track is recorded at the same frequency with a phase shift relative to the signal recorded on the information track, and wherein said detecting means comprises: means for sensing the phase of the frequency signal from each transducer to detect which transducers are reading out a frequency signal from the information tracks and which transducers are reading out a frequency signal from the guide track.
Claim 12
Dependent Claim
67 words
The apparatus of claim 6, wherein said detecting means comprises: means for sensing the signal from each transducer to detect which transducers are positioned over information tracks, and which transucers are positioned over the guide track, said sensing means having a sensitivity dead-band region so that changes in lateral position of the tracks must be significant before said generating means will generate a new lateral position signal.
Claim 13
Dependent Claim
109 words
Method for reading information in data tracks and at least one guide track on a storage medium with transducers for transducing the information from the tracks comprising the steps of: transducing a plurality of tracks with a plurality of transducers wherein more than one transducer is aligned within the boundaries of each track and is transducing each track at any given time; detecting the alignment between tracks on the medium and the transducers from the signals generated by the transducers by detecting which transducers are transducing the guide track; using the signals generated by the transducers in a predetermined manner dependent upon the detected alignment between tracks and transducers.
Claim 14
Dependent Claim
109 words
Method for reading information in data tracks and at least one guide track on a storage medium with transducers for transducing the information from the tracks comprising the steps of: transducing a plurality of tracks with a plurality of transducers wherein more than one transducer is aligned within the boundaries of each track and is transducing each track at any given time; detecting the alignment between tracks on the medium and the transducers from the signals generated by the transducers by detecting which transducers are transducing the guide track; using the signals generated by the transducers in a predetermined manner dependent upon the detected alignment between tracks and transducers.
Claim 15
Dependent Claim
29 words
Method of claim 11 wherein said using step comprises the step of selecting the signal generated by one transducer aligned with each track as determined by said detecting step.
Claim 16
Dependent Claim
36 words
Method of claim 11 wherein said using step comprises the steps of selecting at least one transducer aligned with each track as determined by said detecting step and inhibiting those transducers that overlap two adjacent tracks.
Claim 17
Dependent Claim
65 words
A method of claim 11 wherein said detecting step comprises the steps of: monitoring the signals generated by the transducers for a guide signal from a guide track; identifying those transducers that are generating the guide signals; determining the boundary of the guide track from the position of those transducers identified as generating the guide signal, and thereby detecting the alignment between tracks and transducers.
Claim 18
Dependent Claim
143 words
Apparatus for decoding data signals from a mixture of guide and data signals generated by a plurality of transducers reading a guide track and data tracks on a magnetic storage medium comprising: said plurality of transducers positioned so that more than one transducer is aligned within the boundaries of each track and is transducing each track at any given time; a first group of said transducers positioned relative to an area of the medium where either the guide track or data tracks may reside; means responsive to said first group of transducers for identifying those transducers transducing the guide track and thereby detecting the position of the guide track and generating an alignment signal; means responsive to the alignment signal for separating out the data signal for each track from the mixture of guide and data signals generated by the plurality of transducers.
Claim 19
Dependent Claim
143 words
Apparatus for decoding data signals from a mixture of guide and data signals generated by a plurality of transducers reading a guide track and data tracks on a magnetic storage medium comprising: said plurality of transducers positioned so that more than one transducer is aligned within the boundaries of each track and is transducing each track at any given time; a first group of said transducers positioned relative to an area of the medium where either the guide track or data tracks may reside; means responsive to said first group of transducers for identifying those transducers transducing the guide track and thereby detecting the position of the guide track and generating an alignment signal; means responsive to the alignment signal for separating out the data signal for each track from the mixture of guide and data signals generated by the plurality of transducers.
Claim 20
Dependent Claim
105 words
The apparatus of claim 15 wherein said identifying means comprises: means for sensing the presence of a guide signal in the signal generated by each transducer of said first group; a second means for sensing the presence of a data signal in the signal generated by each transducer of said first group; means responsive to both of said sensing means for comparing signals from adjacent transducers in said first group to detect the boundary of the guide track from the presence of a guide signal from one transducer and the presence of a data signal from the adjacent transducer and thereby generate the alignment siGnal.
Claim 21
Dependent Claim
42 words
The apparatus of claim 15 wherein said separating means comprises; means responsive to the alignment signal for gating the data signal for each track from the one transducer most nearly aligned with the track as the output data signal for that track.
Claim 22
Dependent Claim
58 words
The apparatus of claim 15 wherein said separating means comprises; means responsive to the alignment signal for passing data signals for each track from all the transducers aligned completely within the boundaries of each data track; means responsive to the alignment signal for inhibiting the passage of signals from transducers that overlap the boundary between adjacent data tracks.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |