US5680272A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital servo control system for use in disk drives
Assignee: QED INTELLECTUAL PROPERTY SERVICES Ltd
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Filing: 1995-06-01
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Granted: 1997-10-21
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Expires: 2015-06-01
Abstract
Abstract A servo control system provides adaptive compensation for a variety of tracking and seek problems found in disk drives. The servo control system is ideally implemented in digital form for accuracy, speed and compactness. A first embodiment includes two modes, a tracking (or position) mode and a seek (or velocity) mode, each mode employing a variety of compensation functions. A second embodiment includes a single comprehensive control system which functions during both tracking and seek operations.
Inventors
- 👤 Ronald James Kadlec
- 👤 Thomas James Frederick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:13
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59605; G11B5/59622; G11B21/00; G11B21/02; G11B21/08; G11B21/081; G11B21/083; G11B21/085; G11B21/10; G11B5/54; G11B5/55; G11B5/5521; G11B5/5526; G11B5/553; G11B5/5534; G11B5/5547; G11B5/59616; G11B5/59633; G11B5/5965
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
189 words
In an information storage device having a recording medium and a reading device, an arrangement for controlling the reading device's position relative to a requested location relative to the recording medium throughout a seek operation in which the distance between the reading device and the requested location is reduced, the arrangement comprising: a) means for controlling the position of the reading device relative to the recording medium by processing position-related signals, the position-related signals being related to at least the position of the reading device relative to the recording medium, wherein: 1) the means for controlling operates using a plurality of parameters which operate on the position-related signals during the processing, wherein values of the parameters remain substantially constant within each of a plurality of periods of the seek operation but vary among the periods; and 2) the means for controlling includes means for changing the values of the parameters so as to reduce errors in how the position-related signals represent quantities which relate to the position of the reading device relative to the recording medium, the changing being substantially in accordance with the periods of the seek operation.
Claim 2
Dependent Claim
189 words
In an information storage device having a recording medium and a reading device, an arrangement for controlling the reading device's position relative to a requested location relative to the recording medium throughout a seek operation in which the distance between the reading device and the requested location is reduced, the arrangement comprising: a) means for controlling the position of the reading device relative to the recording medium by processing position-related signals, the position-related signals being related to at least the position of the reading device relative to the recording medium, wherein: 1) the means for controlling operates using a plurality of parameters which operate on the position-related signals during the processing, wherein values of the parameters remain substantially constant within each of a plurality of periods of the seek operation but vary among the periods; and 2) the means for controlling includes means for changing the values of the parameters so as to reduce errors in how the position-related signals represent quantities which relate to the position of the reading device relative to the recording medium, the changing being substantially in accordance with the periods of the seek operation.
Claim 3
Dependent Claim
56 words
The arrangement of claim 1, wherein: the means for controlling operates in fixed point arithmetic; and the means for changing the values of the parameters reduces the errors by changing resolution of the parameters in accordance with periods of the seek operation so as to allow different quantities to be represented in the fixed point arithmetic.
Claim 4
Dependent Claim
35 words
The arrangement of claim 1, wherein the plurality of parameters include: a plurality of parameter value sets, each parameter value set providing a different degree of resolution for mathematical quantities in the means for controlling.
Claim 5
Dependent Claim
44 words
The arrangement of claim 1, wherein: the means for changing the values of the parameters includes means for changing the values of the parameters to increasingly finer resolution parameter value sets as the distance between the reading device and the requested location is reduced.
Claim 6
Dependent Claim
46 words
The arrangement of claim 1, wherein: the means for changing the values of the parameters includes means for changing the values of the parameters to increasingly finer resolution parameter value sets as the velocity of the reading device with respect to the recording medium is reduced.
Claim 7
Dependent Claim
30 words
The arrangement of claim 1, wherein the plurality of parameters include: a coarse resolution parameter value set; a mid resolution parameter value set; and a fine resolution parameter value set.
Claim 8
Dependent Claim
47 words
The arrangement of claim 1, wherein the means for changing the values of the parameters includes: a position threshold decoder for comparing (1) a measured positional error signal to (2) one or more distance threshold values, to contribute to a determination of the values of the parameters.
Claim 9
Dependent Claim
46 words
The arrangement of claim 1, wherein the means for changing the values of the parameters includes: a velocity threshold decoder for comparing (1) an estimated head velocity to (2) one or more velocity threshold values, to contribute to a determination of the values of the parameters.
Claim 10
Dependent Claim
78 words
The arrangement of claim 1, wherein the means for changing the values of the parameters includes: a position threshold decoder for comparing (1) a measured positional error signal to (2) one or more distance threshold values, to contribute to a determination of the values of the parameters; and a velocity threshold decoder for comparing (1) an estimated head velocity to (2) one or more velocity threshold values, to contribute to the determination of the values of the parameters.
Claim 11
Dependent Claim
70 words
The arrangement of claim 9, wherein the means for changing the values of the parameters includes: means for determining which of the position threshold decoder and the velocity threshold decoder provides an output which favors the coarse resolution parameter value set over the mid resolution parameter value set and fine resolution parameter value set, or which favors the mid resolution parameter value set over the fine resolution parameter value set.
Claim 12
Dependent Claim
98 words
The arrangement of claim 1, wherein the means for changing the values of the parameters includes: a) means for determining whether a measured distance between the reading device and the requested location is: 1) greater than about 100 data track separation distances; 2) between about 10 and about 100 data track separation distances; or 3) less than about 10 data track separation distances; and b) means for choosing: 1) a coarse resolution parameter value set; 2) a mid resolution parameter value set; or 3) a fine resolution parameter value set; respectively, in response to the means for determining.
Claim 13
Dependent Claim
30 words
The arrangement of claim 1, wherein the means for controlling further includes: a state space observer including some of the parameters whose values are changed by the means for changing.
Claim 14
Dependent Claim
30 words
The arrangement of claim 1, wherein the means for controlling further includes: an integral controller operating using some of the parameters whose values are changed by the means for changing.
Claim 15
Dependent Claim
59 words
The arrangement of claim 1, wherein: the means for changing the values of the parameters constitutes means for increasing a bandwidth of the controlling means so that the controlling means responds more quickly to changes in a measured distance between (1) the reading device and (2) the requested location, as the measured distance is reduced during the seek operation.
Claim 16
Dependent Claim
34 words
The arrangement of claim 1, wherein: the means for controlling constitutes means for processing position-related signals which include measured positional error signals representative of the distance between the reading device and the requested location.
Claim 17
Dependent Claim
31 words
The arrangement of the claim 1, wherein the means for controlling constitutes means for processing position-related signals including an estimated velocity of the reading device with respect to the recording medium.
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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) | 2000-10-20 | 2001-04-21 | 2001-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-10-20 | 2005-04-21 | 2005-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-10-20 | 2009-04-21 | 2009-10-21 | $7700.00 | Window Closed / Lapsed |