US3930265A
Expired / Lapsed
US
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High density magnetic storage system
Assignee: Vrc California Inc
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Filing: 1974-06-07
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Granted: 1975-12-30
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Expires: 1994-06-07
Abstract
Abstract Apparatus and method for high track density magnetic recording and retrieval. A decoder-coupled five bit shaft register converts an incoming data bit stream to a converted data bit stream having successive groups of five bits corresponding to successive groups of four bits of the incoming stream, the converted stream having not more than two adjacent binary ''''1''s''''. A shift registercoupled NRZO encoder provides a self-clocking tri-frequency signal allowing a clocking window margin of one-half a converted bit cell. The tri-frequency signal has a primary frequency component and additional frequency components of one-half and one-third the primary frequency and is applied to an NRZO encoder coupled modulator. The modulator introduces flux reversals at double the primary frequency following the maintenance of the three-frequency signal in excess of one bit cell interval, enhancing the ratio of timing margin to maximum distance between flux reversals. Both fringing field effects on adjacent tracks and intersymbol interference between linearly adjacent bits of a magnetic recording medium are minimized in a storage system having a track density in excess of about 500 tracks per inch and a linear bit density on the order of 4000 bits per inch. An amplifier-coupled slope detector detects playback signal slope polarity changes to provide a coded output signal.
Inventors
- 👤 Noboru Kimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:54
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/14; G11B20/1403; G11B20/1423; G11B20/1426
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
182 words
In a high track density magnetic recording system in which digital information is represented by magnetic flux changes on a magnetic medium, apparatus for maintaining a high integrity recorded signal with high linear bit density comprising: means for converting an incoming bit stream to a converted bit stream comprising five bit cell fields, each of the five bit cell fields representing a corresponding ordered group of four bits from the incoming bit stream, the converted bit stream comprising a first bilevel signal having a first level and a second level, and having not more than two cells at the first level adjacent one another; means responsive to the converted bit stream for generating a second bilevel signal, the second bilevel signal changing from one level to the other level in response to the occurrence of the second level generated by the means for converting, thereby providing a self-clocking signal of known component frequency; and means coupled to the second bilevel signal generating means for providing a signal in response thereto having a modulated component for minimizing fringing field effects of nearby tracks.
Claim 2
Dependent Claim
182 words
In a high track density magnetic recording system in which digital information is represented by magnetic flux changes on a magnetic medium, apparatus for maintaining a high integrity recorded signal with high linear bit density comprising: means for converting an incoming bit stream to a converted bit stream comprising five bit cell fields, each of the five bit cell fields representing a corresponding ordered group of four bits from the incoming bit stream, the converted bit stream comprising a first bilevel signal having a first level and a second level, and having not more than two cells at the first level adjacent one another; means responsive to the converted bit stream for generating a second bilevel signal, the second bilevel signal changing from one level to the other level in response to the occurrence of the second level generated by the means for converting, thereby providing a self-clocking signal of known component frequency; and means coupled to the second bilevel signal generating means for providing a signal in response thereto having a modulated component for minimizing fringing field effects of nearby tracks.
Claim 3
Dependent Claim
30 words
The invention as set forth in claim 1 and in which the first level is a binary 1 and the second bilevel signal generating means comprises an NRZO coding circuit.
Claim 4
Dependent Claim
51 words
The invention as set forth in claim 1 and in which the means for providing a signal having a modulated component comprises means for reversing a recording head flux upon the maintenance of the second bilevel signal at a uniform level for an interval in excess of about one bit cell.
Claim 5
Dependent Claim
24 words
The invention as set forth in claim 3 and including means for reversing the recording head flux at intervals of about one-half bit cell.
Claim 6
Dependent Claim
52 words
The invention as set forth in claim 1 and further including means for reconstructing information from recorded magnetic flux patterns comprising: slope detector means for obtaining a signal representing a change in slope polarity in a signal responsive to the magnetic flux pattern; and means for attenuating modulation frequency flux reversal components.
Claim 7
Dependent Claim
76 words
A high track density magnetic recording system comprising: means responsive to an incoming signal having an average information density per bit cell interval for providing an information coded self-clocking signal having a reduced average information density per bit cell interval comprising a conversion circuit for providing the reduced average information density and coupled to an encoder providing the self-clocked signal; and means for selectively modulating the information coded signal for limiting intersymbol interference between adjacent tracks.
Claim 8
Dependent Claim
76 words
A high track density magnetic recording system comprising: means responsive to an incoming signal having an average information density per bit cell interval for providing an information coded self-clocking signal having a reduced average information density per bit cell interval comprising a conversion circuit for providing the reduced average information density and coupled to an encoder providing the self-clocked signal; and means for selectively modulating the information coded signal for limiting intersymbol interference between adjacent tracks.
Claim 9
Dependent Claim
28 words
The invention as set forth in claim 6 and in which the information coded signal providing means comprises a 5/4 conversion circuit coupled to a non-return-to-zero type encoder.
Claim 10
Dependent Claim
37 words
The invention as set forth in claim 6 and in which the modulation means comprises means for altering the information coded signal when the signal is maintained at a single level in excess of a given interval.
Claim 11
Dependent Claim
55 words
The invention as set forth in claim 6 and in which the first signal responsive means comprises means for providing a signal having not more than two adjacent bit cell intervals at a first binary signal level and means responsive thereto for providing a binary signal reversing in response to the first binary signal level.
Claim 12
Dependent Claim
173 words
A high track density magnetic recording system having apparatus for obtaining a high integrity recorded signal comprising: a conversion circuit for converting an incoming data bit stream having an associated cloCking window margin to a converted data bit stream comprising five bit cell fields, each of the five bit cell fields representing a corresponding ordered group of four bits from the incoming bit stream, the converted bit stream comprising a binary signal having not more than two adjacent binary 1''s; an NRZO coding circuit for providing a signal having three component flux reversal frequencies in response to the binary signal having not more than two adjacent binary 1''s and providing an enhanced associated clocking window margin for increasing the signal integrity of the system; and a modulation circuit coupled to the NRZO encoding circuit for providing a signal having a modulation frequency component upon the maintenance of an NRZO coded signal at a single binary level in excess of a given interval for limiting intersymbol interference between adjacent tracks and enhancing signal integrity.
Claim 13
Dependent Claim
173 words
A high track density magnetic recording system having apparatus for obtaining a high integrity recorded signal comprising: a conversion circuit for converting an incoming data bit stream having an associated cloCking window margin to a converted data bit stream comprising five bit cell fields, each of the five bit cell fields representing a corresponding ordered group of four bits from the incoming bit stream, the converted bit stream comprising a binary signal having not more than two adjacent binary 1''s; an NRZO coding circuit for providing a signal having three component flux reversal frequencies in response to the binary signal having not more than two adjacent binary 1''s and providing an enhanced associated clocking window margin for increasing the signal integrity of the system; and a modulation circuit coupled to the NRZO encoding circuit for providing a signal having a modulation frequency component upon the maintenance of an NRZO coded signal at a single binary level in excess of a given interval for limiting intersymbol interference between adjacent tracks and enhancing signal integrity.
Claim 14
Dependent Claim
101 words
The invention as set forth in claim 10 and in which the conversion circuit comprises a five bit shift register having an input for receiving an incoming data bit stream, a decoding matrix communicataing with the shift register and a counter coupled to the shift register such that a fifth count state of the counter causes the matrix to force a bit configuration of each of the five bit cells of the shift register to a coded five bit cell field configuration such that a bit stream composed of five bit cell fields contains not more than two adjacent binary 1''s.
Claim 15
Dependent Claim
87 words
The invention as set forth in claim 10 and in which the NRZO encoder comprises an EXCLUSIVE OR gate having an input coupled to a least significant bit output of the shift register, an output of the EXCLUSIVE OR gate coupled to a FLIP-FLOP and a complementary output of the FLIP-FLOP coupled to another input of the EXCLUSIVE OR gate, such that a change in polarity of an uncomplemented output of the shift register occurs only upon the occurrence of a zero during a bit cell interval.
Claim 16
Dependent Claim
102 words
The invention as set forth in claim 10 and in which the modulation circuit comprises: a FLIP-FLOP coupled to the NRZO encoder for providing a delayed NRZO signal; an EXCLUSIVE OR gate, an input of which is coupled to the delayed NRZO signal and another input coupled to the NRZO signal for providing an ouput representing the logical intersection of the NRZO signal with the delayed NRZO signal; means coupled to the delayed NRZO signal and the logical intersection signal for providing the delayed NRZO signal except during the occurrence of the intersection signal during which time a modulation frequency is applied.
Claim 17
Dependent Claim
43 words
The invention as set forth in claim 13 and in which the delayed NRZO signal is delayed by one bit cell interval with respect to the NRZO signal and in which the modulation component introduces flux reversals at about one-half bit cell intervals.
Claim 18
Dependent Claim
120 words
A high track density information storage system having a data recovery circuit comprising: means for providing an amplified electrical signal in response to a movement of a playback head with respect to a magnetic medium; filter means responsive to the electrical signal providing means for passing amplified electrical signal components within a tri-frequency bandwidth; and slope detection means coupled to the filter means for providing an output signal related to changes in slope polarity of the filtered signal comprising: means providing a truncated signal in response to the filtered signal; means for shifting the truncated signal with respect to the filtered signal; and comparator means for detecting crossings of the filtered signal with respect to the shifted and truncated signal.
Claim 19
Dependent Claim
120 words
A high track density information storage system having a data recovery circuit comprising: means for providing an amplified electrical signal in response to a movement of a playback head with respect to a magnetic medium; filter means responsive to the electrical signal providing means for passing amplified electrical signal components within a tri-frequency bandwidth; and slope detection means coupled to the filter means for providing an output signal related to changes in slope polarity of the filtered signal comprising: means providing a truncated signal in response to the filtered signal; means for shifting the truncated signal with respect to the filtered signal; and comparator means for detecting crossings of the filtered signal with respect to the shifted and truncated signal.
Claim 20
Dependent Claim
59 words
The invention as set forth in claim 15 and further comprising resistance means coupled to the comparator means for reducing the magnitude of the shifted and truncated signal applied to the comparator with respect to the filtered signal to eliminate cross-over detectioN by the comparator between the shifted and truncated signal and modulation frequency components of the filtered signal.
Claim 21
Dependent Claim
98 words
A high track density magnetic recording system having apparatus for obtaining a high integrity recorded signal comprising: a conversion circuit for converting an incoming data bit stream to a converted data bit stream, the converted data bit stream having not more than two adjacent bits at a first binary level; means responsive to the converted data bit stream for providing a three-frequency signal having a primary frequency component and additional frequency components of one-half and one-third the primary frequency; and means for modulating the three-frequency signal to reduce peak shifting and to reduce intersymbol interference between adjacent tracks.
Claim 22
Dependent Claim
98 words
A high track density magnetic recording system having apparatus for obtaining a high integrity recorded signal comprising: a conversion circuit for converting an incoming data bit stream to a converted data bit stream, the converted data bit stream having not more than two adjacent bits at a first binary level; means responsive to the converted data bit stream for providing a three-frequency signal having a primary frequency component and additional frequency components of one-half and one-third the primary frequency; and means for modulating the three-frequency signal to reduce peak shifting and to reduce intersymbol interference between adjacent tracks.
Claim 23
Dependent Claim
41 words
The invention as set forth in claim 17 and in which the means for modulating the three-frequency signal comprises means for introducing modulation components after the three-frequency signal is maintained at a single level in excess of one bit cell interval.
Claim 24
Dependent Claim
22 words
The invention as set forth in claim 18 and in which the modulation means introduces a modulation signal double the primary frequency.
Claim 25
Dependent Claim
79 words
A high track density magnetic recording system having apparatus for obtaining a high integrity recording signal comprising: means responsive to an ordered incoming data bit stream for providing a three-frequency signal, the three-frequency signal having a primary frequency and frequency components of one-half and one-third the primary frequency; and modulation means coupled to the three-frequency signal providing means for reversing the three-frequency to reduce the maximum distance between flux reversals, thereby reducing peak shift and intersymbol interference adjacent tracks.
Claim 26
Dependent Claim
79 words
A high track density magnetic recording system having apparatus for obtaining a high integrity recording signal comprising: means responsive to an ordered incoming data bit stream for providing a three-frequency signal, the three-frequency signal having a primary frequency and frequency components of one-half and one-third the primary frequency; and modulation means coupled to the three-frequency signal providing means for reversing the three-frequency to reduce the maximum distance between flux reversals, thereby reducing peak shift and intersymbol interference adjacent tracks.
Claim 27
Dependent Claim
29 words
The invention as set forth in claim 20 and in which: the modulation means comprises means for reversing the three-frequency signal at an even multiple of the primary frequency.
Claim 28
Dependent Claim
35 words
The invention as set forth in claim 21 and in which: the modulation means comprises means for modulating the three-frequency signal upon maintenance of the three-frequency signal at a single level for one-bit cell interval.
Claim 29
Dependent Claim
86 words
A high density magnetic recording system comprising: a modulation circuit responsive to an information coded self-clocking three-frequency signal of the type having a primary frequency and frequency components of one-half and one-third of the primary frequency, the modulation means for reversing the three-frequency signal to reduce the maximum distance between flux reversals, thereby reducing peak shifting and intersymbol interference, the modulation circuit comprising means for reversing the three-frequency signal after maintenance of the three-frequency signal at a single level in excess of approximately one bit cell.
Claim 30
Dependent Claim
86 words
A high density magnetic recording system comprising: a modulation circuit responsive to an information coded self-clocking three-frequency signal of the type having a primary frequency and frequency components of one-half and one-third of the primary frequency, the modulation means for reversing the three-frequency signal to reduce the maximum distance between flux reversals, thereby reducing peak shifting and intersymbol interference, the modulation circuit comprising means for reversing the three-frequency signal after maintenance of the three-frequency signal at a single level in excess of approximately one bit cell.
Claim 31
Dependent Claim
24 words
The invention as set forth in claim 23 and in which the three-frequency signal is modulated at an even multiple of the primary frequency.
Claim 32
Dependent Claim
96 words
The invention as set forth in claim 23 and in which the modulation circuit comprises: means for delaying the three-frequency signal for one bit cell interval with respect to the three-frequency signal; means for providing a signal representing the logical intersection of the three-frequency signal and the delayed three-frequency signal; and means responsive to the three-frequency signal and the logical intersection signal for providing a three-frequency output signal except during the occurrence of the intersection signal during which time the output signal is modulated at an even multiple of one flux reversal per bit cell interval.
Claim 33
Dependent Claim
202 words
In a high density magnetic recording system in which digital information is represented by magnetic flux changes on a magnetic medium, apparatus for maintaining a high integrity recorded signal with high linear bit density comprising: means for converting an incoming bit stream to a converted bit stream comprising fields having a fixed integral number Of bits, each of the fields representing a corresponding ordered group of bits of less than the fixed integral number from the incoming bit stream, the converted bit stream comprising a first bi-level signal having a first level and a second level, and having not more than two bit cells at the first level adjacent one another; means responsive to the converted bit stream for generating a second bi-level signal, the second bi-level signal changing from one level to the other level in response to the occurrence of the second level generated by the converting means, for providing a self-clocking tri-frequency signal having components limited to a primary frequency and one-half and one-third the primary frequency; and means coupled to the second bi-level signal generating means for providing a signal in response thereto having a modulated component for minimizing intersymbol interference between linearly adjacent bits and adjacent tracks.
Claim 34
Dependent Claim
202 words
In a high density magnetic recording system in which digital information is represented by magnetic flux changes on a magnetic medium, apparatus for maintaining a high integrity recorded signal with high linear bit density comprising: means for converting an incoming bit stream to a converted bit stream comprising fields having a fixed integral number Of bits, each of the fields representing a corresponding ordered group of bits of less than the fixed integral number from the incoming bit stream, the converted bit stream comprising a first bi-level signal having a first level and a second level, and having not more than two bit cells at the first level adjacent one another; means responsive to the converted bit stream for generating a second bi-level signal, the second bi-level signal changing from one level to the other level in response to the occurrence of the second level generated by the converting means, for providing a self-clocking tri-frequency signal having components limited to a primary frequency and one-half and one-third the primary frequency; and means coupled to the second bi-level signal generating means for providing a signal in response thereto having a modulated component for minimizing intersymbol interference between linearly adjacent bits and adjacent tracks.
Claim 35
Dependent Claim
51 words
The invention as set forth in claim 26 and in which the means for providing a signal having a modulated component comprises means for reversing a recording head flux upon the maintenance of the second bi-level signal at a uniform level for an interval in excess of about one bit cell.
Claim 36
Dependent Claim
24 words
The invention as set forth in claim 27 and including means for reversing the recorded head flux at intervals of about one-half bit cell.
Claim 37
Dependent Claim
33 words
The invention as set forth in claim 26 and including means for reversing the recording head flux during selected time intervals at a frequency of at least two flux reversals per bit cell.
Claim 38
Dependent Claim
118 words
A high track density magnetic recording system comprising: means responsive to an incoming signal having an average information density per bit cell interval for providing an information coded three-frequency self-clocking signal, the three-frequency self-clocking signal reversing at one, two and three bit cell intervals, the self-clocking signal having a reduced average information density per bit cell interval with respect to the incoming signal and comprising a conversion circuit for providing the reduced average information density and coupled to an encoder providing the self-clocking signal; and means for selectively modulating the information encoded signal for enhancing the ratio of clocking window margin to maximum time between flux reversals to reduce peak shifting and limit intersymbol interference between adjacent tracks.
Claim 39
Dependent Claim
118 words
A high track density magnetic recording system comprising: means responsive to an incoming signal having an average information density per bit cell interval for providing an information coded three-frequency self-clocking signal, the three-frequency self-clocking signal reversing at one, two and three bit cell intervals, the self-clocking signal having a reduced average information density per bit cell interval with respect to the incoming signal and comprising a conversion circuit for providing the reduced average information density and coupled to an encoder providing the self-clocking signal; and means for selectively modulating the information encoded signal for enhancing the ratio of clocking window margin to maximum time between flux reversals to reduce peak shifting and limit intersymbol interference between adjacent tracks.
Claim 40
Dependent Claim
38 words
The invention as set forth in claim 30 and in which: the modulating means comprises means for reversing the self-clocking signal in response to maintenance of the self-clocking signal at the same level for one bit cell interval.
Claim 41
Dependent Claim
49 words
The invention as set forth in claim 30 and in which the modulation means comprises means for providing a signal reversing at one-half bit cell intervals between level changes in the self-clocking signal, following the maintenance of the self-clocking signal at a single level for one bit cell interval.
Claim 42
Dependent Claim
89 words
The invention as set forth in claim 30 and comprising: means for delaying the self-clocking signal for one bit cell interval with respect to the self-clocking signal; means for providing a signal representing the logical intersection of the self-clocking and the delayed self-clocking signal; and means responsive to the self-clocking signal and the logical intersection signal for providing a self-clocking output signal except during the occurrence of the intersection signal during which time the output signal is modulated at an even multiple of one flux reversal per bit cell.
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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) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |