US4371960A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measurement of disc servo head/data head misalignment
Assignee: Seagate Technology LLC
•
Filing: 1980-12-24
•
Granted: 1983-02-01
•
Expires: 2000-12-24
Abstract
Abstract Compensation for radial misalignment between a data head and a servo head is provided. At least one pair of servo data tracks having a servo null there between are written on each data surface. The servo head is moved to a corresponding servo track null and the offset of the data head from its servo track null is measured iteratively by injecting voltages generated by a digital-to-analog converter into the servo head servo loop to progressively decrease the offset of the data head from its servo null until the data head is positioned over the servo null. The digital value of the digital-to-analog converter input is then stored in a digital memory for later use in fine positioning of the data head over a data track by means of retrieving the digital value from memory, converting it to a voltage through the digital-to-analog converter and injecting it into the servo head servo loop.
Inventors
- 👤 Gerald C. Kroiss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:46
CPC Classifications
G; G11; G11B; G11B21/00; G11B21/02; G11B21/10; G11B21/106
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
203 words
In a method of compensating for radial offset between a disk drive's servo head and a data head wherein at least one track of data surface servo data is written on a data surface and at least one track of servo surface servo data is written on a servo surface in vertical alignment with said data surface servo data, an auxiliary demodulator is connected with the data head to develop a position error signal from said data surface servo data and a standard demodulator is connected with the servo head in a servo loop for developing a position error signal from said at least one track of servo surface servo data, the improvement comprising: A. measuring the position error signal due to the radial offset between the servo head and the data head as developed by the standard demodulator connected to the servo head; B. converting this signal into a digital value; and C. storing it in a digital memory for later compensating for said radial offset in fine positioning of a data head over a data track center by retrieving said digital value from memory, converting it to a voltage via a digital-to-analog converter and injecting said voltage into the servo loop.
Claim 2
Dependent Claim
203 words
In a method of compensating for radial offset between a disk drive's servo head and a data head wherein at least one track of data surface servo data is written on a data surface and at least one track of servo surface servo data is written on a servo surface in vertical alignment with said data surface servo data, an auxiliary demodulator is connected with the data head to develop a position error signal from said data surface servo data and a standard demodulator is connected with the servo head in a servo loop for developing a position error signal from said at least one track of servo surface servo data, the improvement comprising: A. measuring the position error signal due to the radial offset between the servo head and the data head as developed by the standard demodulator connected to the servo head; B. converting this signal into a digital value; and C. storing it in a digital memory for later compensating for said radial offset in fine positioning of a data head over a data track center by retrieving said digital value from memory, converting it to a voltage via a digital-to-analog converter and injecting said voltage into the servo loop.
Claim 3
Dependent Claim
102 words
The improvement of claim 1 wherein the measuring of said position error signal due to said offset comprises: D. servoing said servo head toward its servo track center (null); E. inspecting the error signal from the auxiliary demodulator connected to the data head to determine if said signal is approximately zero; F. injecting a voltage into the servo loop to offset said servo head from its servo track center and to reduce the magnitude of the error signal from said auxiliary demodulator; and G. repeating Steps E and F until the error signal from said auxiliary demodulator is reduced to approximately zero.
Claim 4
Dependent Claim
70 words
The improvement of claim 2 wherein Step B includes inputting a digital value into a digital-to-analog converter, the output of which is connected into the servo loop; and wherein the digital value which causes the error signal from the auxiliary demodulator to be reduced to zero comprises the digital value of the position error signal due to said offset as developed by the standard demodulator connected to the servo head.
Claim 5
Dependent Claim
58 words
The improvement of claim 1 wherein Steps A and B comprise: H. servoing the data head over its servo track center; and I. inputting the error signal from the standard demodulator connected to the servo head into an analog-to-digital converter, the output of which comprises the digital value of the position error signal due to said radial offset.
References Cited (Backward Citations)
US3994016A
Cited
US4135217A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-31 | 1986-08-02 | 1987-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-31 | 1990-08-02 | 1991-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-31 | 1994-08-02 | 1995-02-01 | $7700.00 | Window Closed / Lapsed |