Patent US3665485A successfully refreshed from Google Patents.
US3665485A
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Method and system for high density recording of information on premagnetized magnetic tape
Assignee: PETTER INSTRUMENT CO Inc
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Filing: 1969-06-11
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Granted: 1972-05-23
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Expires: 1989-06-11
Abstract
Abstract A method and system for recording information on a premagnetized magnetic media, such as a magnetic tape, employs an unsymmetrical write current wave form. When recording to produce a transition from the direction of magnetization of the media to the reverse direction, the current through the recording head is initially increased to a relatively large value for a short interval and then reduced to a lesser value, comprising respectively an overdrive or step pulse of relatively high current amplitude followed by a pedestal level, or lower amplitude of recording current is maintained until the next transition is recorded. When recording a transition from the now established opposite direction of magnetization to that of the premagnetized direction, the recording current is initially increased to a large value, but of opposite polarity, for a short interval, comprising a return step pulse, after which the current is reduced to zero until the next transition is recorded. There results high recording densities wherein the recorded transitions may be read with high resolution and without undesirable interference, the reading of both switching and return transitions with either forward or reverse motion of the tape producing output pulses of substantially identical shape and of substantially identical timing.
Inventors
- 👤 Charles B Pear Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:16
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G11B20/10046; G11B20/10194; G11B5/00; G11B5/02; G11B5/09
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
132 words
A method for recording binary information in a premagnetized magnetic recording medium wherein information is recorded as a transition of the direction of magnetization of the medium between the premagnetized and reverse directions of magnetization, comprising the steps of: generating a switching field during a switching interval for switching the magnetization of the medium from the premagnetized direction to a reversed direction for recording information as a switching flux transition in the medium, generating a return magnetic field during a return interval for switching the magnetization of the medium from the reverse to the premagnetized direction for recording information as a return flux transition in the medium, and terminating or substantially terminating the return magnetic field after recording the return flux transition and in advance of recording the next switching flux transition.
Claim 2
Independent Claim
132 words
A method for recording binary information in a premagnetized magnetic recording medium wherein information is recorded as a transition of the direction of magnetization of the medium between the premagnetized and reverse directions of magnetization, comprising the steps of: generating a switching field during a switching interval for switching the magnetization of the medium from the premagnetized direction to a reversed direction for recording information as a switching flux transition in the medium, generating a return magnetic field during a return interval for switching the magnetization of the medium from the reverse to the premagnetized direction for recording information as a return flux transition in the medium, and terminating or substantially terminating the return magnetic field after recording the return flux transition and in advance of recording the next switching flux transition.
Claim 3
Dependent Claim
33 words
A recording method as recited in claim 1 further comprising: controlling the value of the switching magnetic field to limit the switched direction of magnetization to less than full saturation of the medium.
Claim 4
Dependent Claim
88 words
A recording method as recited in claim 1 further comprising: generating a switching magnetic field of relatively large value for a short time interval comprising a first portion of said switching interval and reducing the switching magnetic field to a smaller value for the duration of said switching interval, and generating a return magnetic field of relatively large value for a short time interval comprising a first portion of said return interval and reducing the return magnetic field to zero value for the duration of sAid return interval.
Claim 5
Dependent Claim
45 words
A recording method as recited in claim 3 further comprising: generating a return magnetic field during said first portion of the return interval of equal value but opposite sense to that of said switching magnetic field generated during said first portion of the switching interval.
Claim 6
Dependent Claim
221 words
In a method for recording binary information in a premagnetized magnetic recording medium wherein the medium is transported past magnetic transducer means responsive to an electrical recording current supplied thereto for generating a magnetic field for controlling the direction of magnetization of the medium and information is recorded as transitions of the direction of magnetization of the medium between the premagnetized and reverse directions, the improved recording method for high density recording of information comprising: generating an electrical switching pulse during a switching interval in response to information to be recorded, supplying the switching pulse to the transducer means for establishing a switching magnetic field to switch the direction of magnetization in a corresponding region of the medium from the premagnetized direction to a reverse direction for recording the information as a switching flux transition in the medium, generating an electrical return pulse during a return interval in response to subsequent information to be recorded, supplying the return pulse to the transducer means for establishing a return magnetic field to return the direction of magnetization from the switched direction to the premagnetized direction for recording information as a return flux transition in the medium, and terminating or substantially terminating the return pulse after recording the return flux transition and in advance of supplying a subsequent switching pulse to the transducer means.
Claim 7
Dependent Claim
221 words
In a method for recording binary information in a premagnetized magnetic recording medium wherein the medium is transported past magnetic transducer means responsive to an electrical recording current supplied thereto for generating a magnetic field for controlling the direction of magnetization of the medium and information is recorded as transitions of the direction of magnetization of the medium between the premagnetized and reverse directions, the improved recording method for high density recording of information comprising: generating an electrical switching pulse during a switching interval in response to information to be recorded, supplying the switching pulse to the transducer means for establishing a switching magnetic field to switch the direction of magnetization in a corresponding region of the medium from the premagnetized direction to a reverse direction for recording the information as a switching flux transition in the medium, generating an electrical return pulse during a return interval in response to subsequent information to be recorded, supplying the return pulse to the transducer means for establishing a return magnetic field to return the direction of magnetization from the switched direction to the premagnetized direction for recording information as a return flux transition in the medium, and terminating or substantially terminating the return pulse after recording the return flux transition and in advance of supplying a subsequent switching pulse to the transducer means.
Claim 8
Dependent Claim
35 words
A recording method as recited in claim 5 further comprising controlling the amplitude of the switching pulse to limit the switched direction of magnetization in each region to less than full saturation of the medium.
Claim 9
Dependent Claim
49 words
A recording method as recited in claim 6 further comprising generating a step pulse at the initiation of each switching pulse and exceeding the controlled amplitude thereof to effect an overdrive of the switching magnetic field to produce a rapid switching flux transition at the beginning of each region.
Claim 10
Dependent Claim
20 words
A recording method as recited in claim 7 further comprising controlling the amplitude and duration of the switching step pulse.
Claim 11
Dependent Claim
55 words
A recording method as recited in claim 8 further comprising generating a return pulse of equal amplitude and duration to the switching step pulse, and supplying the return pulse to the transducer means for establishing a return magnetic field of opposite sense to the switching magnetic field produced in response to the switching step pulse.
Claim 12
Dependent Claim
214 words
In a system for recording binary information on a premagnetized magnetic recording medium wherein there are provided magnetic transducer means responsive to electrical recording current pulses supplied thereto for generating a magnetic field for controlling the direction of magnetization of the medium, and wherein information is recorded as the transition of the direction of magnetization of the medium between the premagnetized and reverse directions, the improvement comprising: means for generating an electrical switching pulse in response to information to be recorded and for supplying the electrical switching pulse to the transducer means for establishing a switching magnetic field for switching the direction of magnetization of the medium from the premagnetized to the reverse direction for recording information as a switching flux transition in the medium, means for generating an electrical return pulse in response to information to be recorded and for supplying the electrical switching pulse to the transducer means for establishing a return magnetic field for returning the direction of magnetization of the medium froM the switched to the premagnetized direction for recording information as a return flux transition in the medium, and said return pulse generating means reducing the value of the return pulse to zero after recording the return flux transition and in advance of recording the next switching flux transition.
Claim 13
Dependent Claim
214 words
In a system for recording binary information on a premagnetized magnetic recording medium wherein there are provided magnetic transducer means responsive to electrical recording current pulses supplied thereto for generating a magnetic field for controlling the direction of magnetization of the medium, and wherein information is recorded as the transition of the direction of magnetization of the medium between the premagnetized and reverse directions, the improvement comprising: means for generating an electrical switching pulse in response to information to be recorded and for supplying the electrical switching pulse to the transducer means for establishing a switching magnetic field for switching the direction of magnetization of the medium from the premagnetized to the reverse direction for recording information as a switching flux transition in the medium, means for generating an electrical return pulse in response to information to be recorded and for supplying the electrical switching pulse to the transducer means for establishing a return magnetic field for returning the direction of magnetization of the medium froM the switched to the premagnetized direction for recording information as a return flux transition in the medium, and said return pulse generating means reducing the value of the return pulse to zero after recording the return flux transition and in advance of recording the next switching flux transition.
Claim 14
Dependent Claim
86 words
A recording system as recited in claim 10 wherein: said switching pulse generating means includes means for generating an electrical switching pulse of relatively large value for a short time interval comprising a first portion thereof and for reducing the switching pulse to a smaller value for the duration thereof, and said return pulse generating means generates an electrical return pulse of relatively large value for a short time interval corresponding to that of the first portion of the electrical switching pulse but of opposite sense.
Claim 15
Dependent Claim
44 words
A recording system as recited in claim 11 wherein said electrical switching pulse means includes means for controlling the amplitude thereof following the first portion of a switching pulse to limit the switched direction of magnetization to less than full saturation of the medium.
Claim 16
Dependent Claim
45 words
A recording system as recited in claim 12 wherein: said switching pulse and said return pulse generating means include means for independently controlling the amplitude and duration of said switching pulse in the first portion thereof and of the corresponding, but opposite sense return pulse.
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) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |