EP0034938A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A servo system and method for positioning a read/write transducer relative to a storage medium and a recording medium for use in such a system and method
Assignee: Nortel Networks Inc
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Filing: 1981-02-23
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Granted: —
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Expires: 2001-02-23
Abstract
Abstract An embodded servo track following system and method for positioning a transducer (10) relative to a storage medium (13) to read and write data on the medium such as a magnetic disc. The system includes positioning means (15) energizable for moving the transducer to preselected recording positions relative to the storage medium. A plurality of side-by-side closely spaced alternately arranged odd and even servo tracks are embedded or recorded on the medium such that a pair of the odd and even servo tracks identifies a preselected position or informational data track on the medium therebetween. Each of the odd and even tracks generates a waveform having a net DC component. The DC component of the odd and even tracks are equal in magnitude but opposite in polarity such that the DC components of the odd and even tracks cancel each other when the transducer is disposed therebetween. Servo control circuit means is provided for sensing the output of the transducer and selectively energizing the positioning means to null the output of the transducer and thereby centre the transducer between a preselected odd and even track pair (e.g. on line 36).
Inventors
- 👤 Theodore Arthur Oliver
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 20:36
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59633; G11B5/5965
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
288 words
A servo system for positioning a read/write transducer (10) relative to a storage medium (13) to read data stored in any of a plurality of adjacent recording tracks on the medium, said servo system comprising: positioning means (15) energizable to move the read/write transducer in variable amounts of motion relative to the storage medium so as to align the transducer with any selected one of the different recording tracks on the storage medium; drive means (21) for providing relative movement between the storage medium and the read/write transducer thereby enabling the transfer of data between the medium and, with the transducer aligned with a given recording track, the read/write transducer at the position of that recording track; a plurality of laterally aligned, closely-spaced, alternately arranged, odd and even servo tracks (30) recorded on the medium with one such servo track disposed between each of said recording tracks(31), such that any two such alternating odd and even servo tracks on opposite sides of any given recording track denote the position of that recording track on the medium, each of said odd and even servo tracks when transduced generating a waveform having a net DC component, the DC components of said odd and even servo tracks being equal in magnitude but opposite in polarity whereby said DC components of an adjacent pair of said odd and even servo tracks counterbalance each other when the read/write transducer is directly aligned with the recording track therebetween; servo control means (38, 150, 151) for sensing the output of the read/write transducer and continuously selectively energizing said positioning means to null the output of said read/write transducer and thereby centre the same upon the recording track disposed between said odd and even servo tracks.
Claim 2
Dependent Claim
288 words
A servo system for positioning a read/write transducer (10) relative to a storage medium (13) to read data stored in any of a plurality of adjacent recording tracks on the medium, said servo system comprising: positioning means (15) energizable to move the read/write transducer in variable amounts of motion relative to the storage medium so as to align the transducer with any selected one of the different recording tracks on the storage medium; drive means (21) for providing relative movement between the storage medium and the read/write transducer thereby enabling the transfer of data between the medium and, with the transducer aligned with a given recording track, the read/write transducer at the position of that recording track; a plurality of laterally aligned, closely-spaced, alternately arranged, odd and even servo tracks (30) recorded on the medium with one such servo track disposed between each of said recording tracks(31), such that any two such alternating odd and even servo tracks on opposite sides of any given recording track denote the position of that recording track on the medium, each of said odd and even servo tracks when transduced generating a waveform having a net DC component, the DC components of said odd and even servo tracks being equal in magnitude but opposite in polarity whereby said DC components of an adjacent pair of said odd and even servo tracks counterbalance each other when the read/write transducer is directly aligned with the recording track therebetween; servo control means (38, 150, 151) for sensing the output of the read/write transducer and continuously selectively energizing said positioning means to null the output of said read/write transducer and thereby centre the same upon the recording track disposed between said odd and even servo tracks.
Claim 3
Dependent Claim
49 words
A servo system as claimed in Claim 1 in which each of said odd and even servo tracks comprises a serial array of transitions recorded on the recording medium, the DC components of said odd and even servo tracks being coded in the timing and order of the transitions.
Claim 4
Dependent Claim
23 words
A servo system as claimed in Claim 1 in which both of said odd and even servo tracks comprise a 110110110... MFM code.
Claim 5
Dependent Claim
85 words
A servo system as claimed in Claim 2 in which each of said odd and even servo tracks comprises an array of equally spaced transition-pairs, each of said transition pairs comprising first and second equally spaced oppositely directed transitions, each of said transition pairs disposed in said even serve track having an identical order and each of said transition pairs disposed in said odd servo track having an order iden-` tically opposite of the order of said transition pairs disposed in said even servo track.
Claim 6
Dependent Claim
42 words
A servo system as claimed in Claim 4 in which the spacing between said transitions of said transition pairs is λ 1 and the spacing between said transition pairs is X 2 , X 2 being greater in.magnitude than λ 1 .
Claim 7
Dependent Claim
42 words
A servo system as claimed in any of the preceding claims in which the odd and even servo tracks are both provided with more than one frequency, the same frequencies being used to write both of said odd and even servo tracks.
Claim 8
Dependent Claim
36 words
A servo system as claimed in Claim 6 in which the odd and even servo tracks are both provided with first and second frequencies having differing wavelengths, said second frequency being impressed upon said first frequency.
Claim 9
Dependent Claim
54 words
A servo system as claimed in any of the preceding claims in which the storage medium includes a plurality of informational data sectors (31) and a plurality of servo data sectors (30), said informational data sectors and said servo data sectors being alternately spaced relative to the direction of motion caused.by said drive means.
Claim 10
Dependent Claim
32 words
A servo system as claimed in Claim 8 which includes means for generating gating signals defining the positions of said plurality of informational data sectors and said plurality of servo data sectors.
Claim 11
Dependent Claim
72 words
A servo system as claimed in any of the preceding claims in which the servo control means comprises a position-signal producing means connected to the read/write transducer for producing a position signal from the output of said transducer, and further including a velocity transducer for providing a velocity signal representative of the velocity of the read/write transducer as the read/write transducer is moved to different recording track positions by said positioning means
Claim 12
Dependent Claim
91 words
A servo system as claimed in Claim 10 in which the servo control means further includes a summing means (131) for receiving said position signal (130), said velocity signal (136) and a velocity profile signal (135) from a controller, the least significant bit of said velocity profile signal being greater than the maximum value of said position signal whereby whenever said velocity profile signal is present said velocity profile signal dominates said position signal causing said summing means to energize said positioning means to move the.read/wr,ite transducer to a predetermined position.
Claim 13
Dependent Claim
159 words
A recording medium for use in an embedded servo track system that positions a read/write transducer to read data stored on the medium, said recording medium having a plurality of defined informational data sectors (31) and a plurality of recorded servo data sectors (30), said plurality of servo data sectors comprising a plurality of generally parallel, closely-spaced, alternately arranged, odd and even servo tracks recorded on the medium such that a laterally-adjacent pair of said servo tracks comprises one odd and one even servo track spaced apart sufficiently to define a preselected information track location on the medium therebetween, each of said odd and even tracks servo generating a waveform having a net DC component, said DC components of any pair of odd and even such tracks being equal in magnitude but opposite in polarity whereby said DC components of any two adjacent odd and even servo tracks will counterbalance each other when the read/write transducer is centered therebetween.
Claim 14
Dependent Claim
159 words
A recording medium for use in an embedded servo track system that positions a read/write transducer to read data stored on the medium, said recording medium having a plurality of defined informational data sectors (31) and a plurality of recorded servo data sectors (30), said plurality of servo data sectors comprising a plurality of generally parallel, closely-spaced, alternately arranged, odd and even servo tracks recorded on the medium such that a laterally-adjacent pair of said servo tracks comprises one odd and one even servo track spaced apart sufficiently to define a preselected information track location on the medium therebetween, each of said odd and even tracks servo generating a waveform having a net DC component, said DC components of any pair of odd and even such tracks being equal in magnitude but opposite in polarity whereby said DC components of any two adjacent odd and even servo tracks will counterbalance each other when the read/write transducer is centered therebetween.
Claim 15
Independent Claim
210 words
A method for positioning a read/write transducer relative to a storage medium to read data stbred in recording tracks on the medium, the method comprising the steps of: driving the storage medium to provide relative movement between the storage medium and the read/write transducer thereby enabling the transfer of data between the medium and the transducer; using pairs of generally parallel odd and even servo tracks recorded on the medium to continuously control the position of the read/write transducer and maintain it in alignment with a desired such recording track disposed between an odd and an even servo track comprising a pair thereof, each of said odd and even servd tracks representing a waveform having a net DC component, any pair of DC components of said odd and even servo tracks being equal in magnitude but opposite in polarity whereby said DC components of a pair of said odd and even servo tracks offset each other when the read/write transducer is centered therebetween; continuously sensing the output of the read/write transducer to monitor servo track data; and continuously positioning the read/write transducer to seek a null of the monitored servo track output of the transducer thus centering the transducer on the recording track located between odd and even servo tracks.
Claim 16
Independent Claim
210 words
A method for positioning a read/write transducer relative to a storage medium to read data stbred in recording tracks on the medium, the method comprising the steps of: driving the storage medium to provide relative movement between the storage medium and the read/write transducer thereby enabling the transfer of data between the medium and the transducer; using pairs of generally parallel odd and even servo tracks recorded on the medium to continuously control the position of the read/write transducer and maintain it in alignment with a desired such recording track disposed between an odd and an even servo track comprising a pair thereof, each of said odd and even servd tracks representing a waveform having a net DC component, any pair of DC components of said odd and even servo tracks being equal in magnitude but opposite in polarity whereby said DC components of a pair of said odd and even servo tracks offset each other when the read/write transducer is centered therebetween; continuously sensing the output of the read/write transducer to monitor servo track data; and continuously positioning the read/write transducer to seek a null of the monitored servo track output of the transducer thus centering the transducer on the recording track located between odd and even servo tracks.
Claim 17
Dependent Claim
47 words
A method as claimed in Claim 13 in which both of said odd and even servo tracks comprise a serial array of transitions in the recording medium, the DC components of said odd and even servo tracks being coded in the timing and order of the transitions.
Claim 18
Dependent Claim
51 words
A method as claimed in Claim 14 which includes the steps of: providing alternately spaced informational data and servo data sectors on the recording medium; providing a cylinder identification in said informational data sectors; and reading said cylinder identification on the fly when the read/write transducer is traversing the recording medium.
Claim 19
Dependent Claim
27 words
A method as claimed in Claim 13 or Claim 14 or Claim 15 in which both of said odd and even servo tracks comprise a 110110110...MFM code..
References Cited (Backward Citations)
No citation records indexed.
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