US5386326A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Oscillating erase current circuit
Assignee: TECMAR TECHNOLOGIES Inc
•
Filing: 1993-02-25
•
Granted: 1995-01-31
•
Expires: 2013-02-25
Abstract
Abstract An oscillating erase current circuit for erasing information recorded on magnetic media. The inductance of an erase head is coupled with capacitors to form a tank circuit having a natural resonant frequency. The self-oscillating erase current circuit generates an oscillating signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of the tank circuit. Once enabled, the self-oscillating erase current circuit continuously oscillates without any external drive circuit.
Inventors
- 👤 Jefferson H. Harman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:10
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/02; G11B15/04; G11B5/00; G11B5/02; G11B5/024
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
103 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for transferring information to and from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; and oscillator means for causing said tank circuit to oscillate at said natural resonant frequency to apply an ac magnetic field to said magnetic media, wherein said oscillator means further comprises a self-oscillating circuit and feedback means for causing oscillation at a frequency determined by and equal to said natural resonant frequency of said tank circuit.
Claim 2
Dependent Claim
103 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for transferring information to and from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; and oscillator means for causing said tank circuit to oscillate at said natural resonant frequency to apply an ac magnetic field to said magnetic media, wherein said oscillator means further comprises a self-oscillating circuit and feedback means for causing oscillation at a frequency determined by and equal to said natural resonant frequency of said tank circuit.
Claim 3
Dependent Claim
19 words
The magnetic information recording system claimed in claim 1 wherein said self-oscillating circuit further comprises a push-pull amplifier oscillator.
Claim 4
Dependent Claim
18 words
The magnetic information recording system claimed in claim 2 wherein said feedback means further comprises said tank circuit.
Claim 5
Dependent Claim
52 words
The magnetic information recording system claimed in claim 3 wherein said oscillator means for causing said tank circuit to oscillate at said natural resonant frequency further comprises: means connected to said feedback means for maintaining oscillation at a frequency determined by and equal to said natural resonant frequency of said tank circuit.
Claim 6
Dependent Claim
19 words
The magnetic information recording system claimed in claim 4 wherein said means for maintaining oscillation further comprises amplification means.
Claim 7
Dependent Claim
116 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for transferring information to and from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; oscillator means for causing said tank circuit to oscillate at said natural resonant frequency to apply an ac magnetic field to said magnetic media; drive means operatively connected to said oscillator means for generating an input signal corresponding to an excitation frequency for driving said oscillator means; and feedback means for adjusting said drive means so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 8
Dependent Claim
116 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for transferring information to and from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; oscillator means for causing said tank circuit to oscillate at said natural resonant frequency to apply an ac magnetic field to said magnetic media; drive means operatively connected to said oscillator means for generating an input signal corresponding to an excitation frequency for driving said oscillator means; and feedback means for adjusting said drive means so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 9
Dependent Claim
64 words
The magnetic information recording system claimed in claim 6 wherein said feedback means further comprises: phase detection means for comparing the phase of said input signal with phase of said tank circuit to generate an error signal; and means for adjusting said drive means in response to said error signal so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 10
Dependent Claim
63 words
The magnetic information recording system claimed in claim 6 wherein said feedback means further comprises: detection means for measuring the magnitude of a current in said tank circuit and generating an error signal in response thereto; and means for adjusting said drive means in response to said error signal so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 11
Independent Claim
169 words
A method for erasing information recorded on magnetic media, comprising the steps of: generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of a tank circuit, wherein said step of generating an oscillatory signal further comprises the steps of: generating feedback signals in response to the natural resonance of said tank circuit; and applying said feedback signals to means for maintaining oscillation to generate said oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of said tank circuit such that self-oscillation occurs; providing an erase head with said oscillatory signal for erasing information recorded on said magnetic media; moving said magnetic media by said erase head; and subjecting said magnetic media to a rapidly fluctuating field produced by said oscillatory signal and movement of said magnetic media so that said rapidly fluctuating field is reduced in magnitude as the relative position between said magnetic media and said erase head is increased.
Claim 12
Independent Claim
169 words
A method for erasing information recorded on magnetic media, comprising the steps of: generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of a tank circuit, wherein said step of generating an oscillatory signal further comprises the steps of: generating feedback signals in response to the natural resonance of said tank circuit; and applying said feedback signals to means for maintaining oscillation to generate said oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of said tank circuit such that self-oscillation occurs; providing an erase head with said oscillatory signal for erasing information recorded on said magnetic media; moving said magnetic media by said erase head; and subjecting said magnetic media to a rapidly fluctuating field produced by said oscillatory signal and movement of said magnetic media so that said rapidly fluctuating field is reduced in magnitude as the relative position between said magnetic media and said erase head is increased.
Claim 13
Dependent Claim
53 words
The method claimed in claim 9 wherein said step of generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of a tank circuit further comprises the step of: combining the inductance of said erase head with capacitance means to form said tank circuit.
Claim 14
Dependent Claim
51 words
The method claimed in claim 10 wherein said step of generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of a tank circuit further comprises the step of: generating feedback signals in response to the natural resonance of said tank circuit.
Claim 15
Dependent Claim
52 words
The method claimed in claim 11 wherein said step of generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of a tank circuit further comprises the step of: applying said feedback signals to means for maintaining oscillation to generate said oscillatory signal.
Claim 16
Independent Claim
133 words
A method for erasing information recorded on magnetic media, comprising the steps of: generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of a tank circuit; providing an erase head with said oscillatory signal for erasing information recorded on said magnetic media; moving said magnetic media by said erase head; subjecting said magnetic media to a rapidly fluctuating field produced by said oscillatory signal and movement of said magnetic media so that said rapidly fluctuating field is reduced in magnitude as the relative position between said magnetic media and said erase head is increased; generating a drive signal corresponding to an excitation frequency for driving said oscillatory signal; and adjusting said excitation frequency to match said natural resonant frequency of said tank circuit.
Claim 17
Independent Claim
133 words
A method for erasing information recorded on magnetic media, comprising the steps of: generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of a tank circuit; providing an erase head with said oscillatory signal for erasing information recorded on said magnetic media; moving said magnetic media by said erase head; subjecting said magnetic media to a rapidly fluctuating field produced by said oscillatory signal and movement of said magnetic media so that said rapidly fluctuating field is reduced in magnitude as the relative position between said magnetic media and said erase head is increased; generating a drive signal corresponding to an excitation frequency for driving said oscillatory signal; and adjusting said excitation frequency to match said natural resonant frequency of said tank circuit.
Claim 18
Dependent Claim
61 words
The method claimed in claim 13 wherein said adjusting step further comprises the steps of: comparing a phase of said drive signal with a phase of a tank circuit output signal to generate an error signal; and adjusting said drive means in response to said error signal so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 19
Dependent Claim
57 words
The method claimed in claim 13 wherein said adjusting step further comprises the steps of: measuring a magnitude of a current in said tank circuit and generating an error in response thereto; and adjusting said drive means in response to said error signal so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 20
Dependent Claim
120 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for writing information to and reading information from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; and means for generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of said tank circuit to apply an ac magnetic field to said magnetic media; wherein said means for generating an oscillatory signal further comprises a self-oscillating circuit and feedback means for causing oscillation at a frequency determined by and equal to said natural resonant frequency of said tank circuit.
Claim 21
Dependent Claim
120 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for writing information to and reading information from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; and means for generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of said tank circuit to apply an ac magnetic field to said magnetic media; wherein said means for generating an oscillatory signal further comprises a self-oscillating circuit and feedback means for causing oscillation at a frequency determined by and equal to said natural resonant frequency of said tank circuit.
Claim 22
Dependent Claim
123 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for writing information to and reading information from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; means for generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of said tank circuit to apply an ac magnetic field to said magnetic media; means operatively connected to said oscillator means for generating an input signal corresponding to an excitation frequency for driving said oscillator means; and means for adjusting said excitation frequency to match said natural resonant frequency of said tank circuit.
Claim 23
Dependent Claim
123 words
A magnetic information recording system for transferring information to and from magnetic media, comprising: means for writing information to and reading information from said magnetic media; erase head inductance means; capacitance means coupleable with said erase head inductance means to form a tank circuit having a natural resonant frequency; means for generating an oscillatory signal having a frequency of oscillation determined by and therefore equal to the natural resonant frequency of said tank circuit to apply an ac magnetic field to said magnetic media; means operatively connected to said oscillator means for generating an input signal corresponding to an excitation frequency for driving said oscillator means; and means for adjusting said excitation frequency to match said natural resonant frequency of said tank circuit.
Claim 24
Dependent Claim
62 words
The magnetic information recording system claimed in claim 17 wherein said adjusting means further comprises: means for comparing the phase of said input signal with phase of said tank circuit to generate an error signal; and means for adjusting said drive means in response to said error signal so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 25
Dependent Claim
62 words
The magnetic information recording system claimed in claim 17 wherein said adjusting means further comprises: means for measuring the magnitude of a current in said tank circuit and generating an error signal in response thereto; and means for adjusting said drive means in response to said error signal so that said excitation frequency matches said natural resonant frequency of said tank circuit.
Claim 26
Dependent Claim
18 words
The magnetic information recording system claimed in claim 16 wherein said feedback means further comprises said tank circuit.
References Cited (Backward Citations)
US3666893A
Cited
US4063193A
Cited
US4274116A
Cited
US4280153A
Cited
US4504874A
Cited
US4511935A
Cited
US4466027A
Cited
US4616273A
Cited
US4779146A
Cited
US4802028A
Cited
US4829392A
Cited
US4918406A
Cited
US4953043A
Cited
US5168483A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-01-30 | 1998-08-01 | 1999-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-30 | 2002-08-01 | 2003-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-30 | 2006-08-01 | 2007-01-31 | $7700.00 | Window Closed / Lapsed |