US3696353A
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Timing track with discontinuity
Assignee: Unisys Corp
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Filing: 1971-08-04
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Granted: 1972-10-03
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Expires: 1991-08-04
Abstract
Abstract A method and circuit for deriving timing signal information required by present day rotating magnetic storage media from a single control track of N clock pulses, where the N Clock pulses are spaced in at least (N + 1) clock pulse periods or cycles, and where the trailing edge of each clock pulse coincides with the trailing edge of a pulse period or cycle. Conceptually, a comparison is continuously made between the time durations between the trailing edges of pairs of successive clock pulses and when the time durations differ by a predetermined amount, a sync pulse is generated corresponding to a pulse normally derived from a conventional sector track. A pulse train generator and a one-shot multivibrator employing an R-C timing network coordinated by a sync detection logic system are used to effect the comparison and generate the sync pulse.
Inventors
- 👤 Virgilio J Quiogue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:26
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/16
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
94 words
A method for generating timed reference signals synchronized to the rotation of a magnetic storage medium from a single control track thereon, said track including clock pulses of equal periods and a discontinuity in length equal to the clock pulse period located between series of said clock pulses, comprising the steps of reading said clock pulses from said control track of said rotating storage medium, comparing the time durations between corresponding edges of pairs of successive ones of said clock pulses, and generating a reference pulse responsive to a variance resulting from said comparison.
Claim 2
Independent Claim
94 words
A method for generating timed reference signals synchronized to the rotation of a magnetic storage medium from a single control track thereon, said track including clock pulses of equal periods and a discontinuity in length equal to the clock pulse period located between series of said clock pulses, comprising the steps of reading said clock pulses from said control track of said rotating storage medium, comparing the time durations between corresponding edges of pairs of successive ones of said clock pulses, and generating a reference pulse responsive to a variance resulting from said comparison.
Claim 3
Dependent Claim
109 words
The method of claim 1 wherein the steps of comparing includes the steps of grouping said clock pulses and discontinuity in a series of like numbers of period lengths said discontinuity occupying a predetermined position in a group, sampling each group as to the time duration from the trailing edge of the last pulse preceding said predetermined position and the trailing edge of the pulse in said predetermined position or the succeeding pulse of the discontinuity intervenes, measuring the time duration between the trailing edges of a pair of successive pulses following the predetermined location in each group, and testing the sampled time duration against the measured time duration.
Claim 4
Dependent Claim
61 words
The method of claim 2 wherein the steps of sampling and measuring both comprise generating pulses between the trailing edge of successive clock pulses and wherein the step of testing includes the step of extending the measuring pulse by a constant factor to generate a comparison pulse having a length greater than the measuring pulse but less than two measuring pulses.
Claim 5
Dependent Claim
32 words
The method of claim 3 further including the step of feeding back said comparison pulse for inhibiting the generation of a succeeding measuring pulse during the step of extending a measuring pulse.
Claim 6
Independent Claim
148 words
A method for generating both clock pulses and a reference pulse per revolution of a magnetic storage medium from a single control track thereon, said reference pulse being synchronized with the revolution of said medium regardless of variations in the rotational velocity of the medium, comprising the steps of recordIng on said control track N clock pulses in (N + 1) equal pulse periods, the trailing edge of each of said clock pulses coinciding with the trailing edge of a pulse period, resulting in a discontinuity in the pulses as to one pulse period, reading said clock pulses from said control track of said rotating storage medium, continuously comparing the time duration between the trailing edges of pairs of successive clock pulses, and generating a reference pulse when the time duration of one of said pairs of successive pulses exceeds the other by at least a predetermined amount.
Claim 7
Independent Claim
148 words
A method for generating both clock pulses and a reference pulse per revolution of a magnetic storage medium from a single control track thereon, said reference pulse being synchronized with the revolution of said medium regardless of variations in the rotational velocity of the medium, comprising the steps of recordIng on said control track N clock pulses in (N + 1) equal pulse periods, the trailing edge of each of said clock pulses coinciding with the trailing edge of a pulse period, resulting in a discontinuity in the pulses as to one pulse period, reading said clock pulses from said control track of said rotating storage medium, continuously comparing the time duration between the trailing edges of pairs of successive clock pulses, and generating a reference pulse when the time duration of one of said pairs of successive pulses exceeds the other by at least a predetermined amount.
Claim 8
Dependent Claim
148 words
The method of claim 5, wherein the step of comparing includes the steps of grouping said pulse periods into not less than three periods per group, said discontinuity being located in the first period of a group, generating first, second and third pulses for each of said groups, each generated first pulse having a length equal to the time duration between the trailing edges of the last clock pulse of the preceding group and the first clock pulse of said group, each generating second pulse having a length equal to the time duration between the trailing edges of the pulses in the second and third periods of said group, each of said generated third pulses having a length greater than said second generated pulse, but less than two generated second pulses, and testing said length of said first generated pulse against said length of said third generated pulse.
Claim 9
Independent Claim
32 words
The method of clam 6 including the step of feeding back said third generated pulse for inhibiting the generation of said second generated pulse during the generation of said third generated pulse.
Claim 10
Independent Claim
32 words
The method of clam 6 including the step of feeding back said third generated pulse for inhibiting the generation of said second generated pulse during the generation of said third generated pulse.
Claim 11
Independent Claim
98 words
An apparatus for generating timed synchronizing pulses from a rotating storage medium regardless of variations in the rotational velocity in said medium comprising a timing control track on said medium having recorded therein N clock pulses in (N + 1) equal pulse periods, resulting in a discontinuity in said pulses, means for reading said recorded clock pulses on said control track, means for precisely identifying the location of the discontinuity in the train of the read pulses, and means responsive to said identifying means for generating a reference pulse synchronized with a revolution of said magnetic storage medium.
Claim 12
Independent Claim
98 words
An apparatus for generating timed synchronizing pulses from a rotating storage medium regardless of variations in the rotational velocity in said medium comprising a timing control track on said medium having recorded therein N clock pulses in (N + 1) equal pulse periods, resulting in a discontinuity in said pulses, means for reading said recorded clock pulses on said control track, means for precisely identifying the location of the discontinuity in the train of the read pulses, and means responsive to said identifying means for generating a reference pulse synchronized with a revolution of said magnetic storage medium.
Claim 13
Dependent Claim
28 words
The apparatus of claim 8 wherein said identifying means includes means for comparing the time duration between like edges of pairs of successive ones of said clock pulses.
Claim 14
Dependent Claim
106 words
The apparatus of claim 8 wherein said identifying means includes means for dividing said pulse periods into groups of equal numbers of at least three equal periods, said discontinuity having a predetermined position in a group, means for generating first and second pulses for each of said group from like edges of successive clock pulses, said first generated pulse being initiated by the clock pulse immediately preceding said predetermined position, and said second generated pulse being initiated by the clock pulse immediately following said predetermined position, and means for comparing said first generated pulses of one group with said second generated pulse of the preceding group.
Claim 15
Dependent Claim
48 words
The apparatus of claim 10 wherein said comparing means includes means for generating a delayed pulse having a predetermined ratio in length to said second generated pulse, said delayed pulse being longer than said second generated pulse and less than the length of two said second generated pulses.
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) | 1975-10-03 | 1976-04-03 | 1976-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-03 | 1980-04-03 | 1980-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-03 | 1984-04-03 | 1984-10-03 | $7700.00 | Window Closed / Lapsed |