Patent US4991944A successfully refreshed from Google Patents.
Patent US3704349A successfully refreshed from Google Patents.
US3704349A
Expired / Lapsed
US
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Magnetic recording system
Assignee: Canon Inc
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Filing: 1971-01-18
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Granted: 1972-11-28
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Expires: 1991-01-18
Abstract
Abstract An improved magnetic recording system is provided which uses an amplitude-modulated high frequency bias. A first high frequency bias or carrier is amplitude-modulated by a second bias component or modulating wave having a frequency higher than the highest frequency of the input signal but lower than that of the first bias component, and the amplitude-modulated high frequency bias is superposed upon the input signal. The deterioration of the input signal, especially its high frequency component by the prior art unmodulated high frequency bias may be eliminated so that the flat reproduction characteristic may be obtained over the wide range of the input signal. In addition, the improved system requires only the minimum number of component parts.
Inventors
- 👤 Takeshi Goshima
- 👤 Yutaka Kohtani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:49
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
128 words
A magnetic recording system for recording a signal upon a magnetic recording medium comprising means for providing an input signal to be recorded, a high-frequency signal source, a modulating signal source for providing a modulating signal having a substantially constant frequency which is lower than said high frequency signal but higher than the highest frequency of said input signal to be recorded, amplitude-modulating means coupled to said high frequency source and said modulating signal source for providing an amplitudemodulated high frequency bias signal by modulating said high frequency signal with said modulating signal, means for superposing upon said input signal to be recorded said amplitude-modulated high frequency bias signal, and means for applying said superposed signals to an electromagnetic transducer means in contact with a magnetic recording medium.
Claim 2
Dependent Claim
128 words
A magnetic recording system for recording a signal upon a magnetic recording medium comprising means for providing an input signal to be recorded, a high-frequency signal source, a modulating signal source for providing a modulating signal having a substantially constant frequency which is lower than said high frequency signal but higher than the highest frequency of said input signal to be recorded, amplitude-modulating means coupled to said high frequency source and said modulating signal source for providing an amplitudemodulated high frequency bias signal by modulating said high frequency signal with said modulating signal, means for superposing upon said input signal to be recorded said amplitude-modulated high frequency bias signal, and means for applying said superposed signals to an electromagnetic transducer means in contact with a magnetic recording medium.
Claim 3
Dependent Claim
44 words
A magnetic recording system according to claim 1 wherein said high frequency signal source and said modulating signal source provide sinusoidal waves so that the amplitude-modulated high frequency bias signal is a sinusoidal high frequency signal whose envelope is symmetrically increased and decreased repetetively
Claim 4
Dependent Claim
24 words
A magnetic recording system according to claim 2 wherein said amplitude modulator means comprises means for providing a percentage modulation which is about 100%.
Claim 5
Dependent Claim
197 words
A magnetic recording device for recording a signal upon a magnetic recording medium characterized by a first oscillator for generating a high frequency signal having a frequency higher than that of an input signal to be recorded, a second oscillator for generating a modulating wave having a frequency lower than that of said high frequency signal and higher than the highest frequency of said input signal to be recorded, an amplitude modulator electrically coupled to said first and second oscillators for amplitude-modulating said high frequency signal generated by said first oscillator by said modulating wave to thereby produce an output bias signal, a circuit for applying said input signal to be recorded, a superposition circuit electrically coupled to said amplitude modulator and said signal applying circuit for superposing tHe output of said amplitude modulator upon the output of said signal applying circuit, and an electromagnetic transducer means in contact with a magnetic recording medium, the output of said superposition circuit being applied to said electromagnetic transducer means so that the electrical signal from said superposition circuit may be converted into the magnetic signal so as to be recorded upon said magnetic recording medium as the remanent magnetism.
Claim 6
Dependent Claim
197 words
A magnetic recording device for recording a signal upon a magnetic recording medium characterized by a first oscillator for generating a high frequency signal having a frequency higher than that of an input signal to be recorded, a second oscillator for generating a modulating wave having a frequency lower than that of said high frequency signal and higher than the highest frequency of said input signal to be recorded, an amplitude modulator electrically coupled to said first and second oscillators for amplitude-modulating said high frequency signal generated by said first oscillator by said modulating wave to thereby produce an output bias signal, a circuit for applying said input signal to be recorded, a superposition circuit electrically coupled to said amplitude modulator and said signal applying circuit for superposing tHe output of said amplitude modulator upon the output of said signal applying circuit, and an electromagnetic transducer means in contact with a magnetic recording medium, the output of said superposition circuit being applied to said electromagnetic transducer means so that the electrical signal from said superposition circuit may be converted into the magnetic signal so as to be recorded upon said magnetic recording medium as the remanent magnetism.
Claim 7
Dependent Claim
55 words
A magnetic recording device according to claim 4 wherein said superposition circuit has a filter for isolating said input signal to be recorded, which is interposed between the output terminal of said signal applying circuit and said amplitude modulator, and a bias signal isolating filter, both of said filters being coupled to said transducer means.
Claim 8
Dependent Claim
38 words
A magnetic recording system according to claim 4 wherein said first and second oscillators produce*sinusoidal waveform signals, and the output of said first oscillator is amplitude-modulated at a percentage modulation of about 100 percent by said amplitude modulator.
References Cited (Backward Citations)
US2876294A
Cited
US3262124A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-28 | 1976-05-29 | 1976-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-28 | 1980-05-29 | 1980-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-28 | 1984-05-29 | 1984-11-28 | $7700.00 | Window Closed / Lapsed |