US3700985A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and circuit for driving inductive loads
Assignee: Memorex Corp
•
Filing: 1970-12-17
•
Granted: 1972-10-24
•
Expires: 1990-12-17
Abstract
Abstract The relative current in a pair of inductive loads is rapidly varied by maintaining a current in each load, so that when current is removed from one the rapid decay of current in that coil permits a substantial relative current differential since the other load need not rise from zero current due to the current pre-established therein. To further enhance the rapid current differential a choke in series with a low voltage supply provides a constant current source so that a large voltage spike is generated when the current goes to zero in one load thus enhancing the current buildup in the other load.
Inventors
- 👤 James E Applequist
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:37
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/56; H03K17/60; H03K17/64; H01; H01F; H01F7/00; H01F7/06; H01F7/08; H01F7/18; H01F7/1805
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
210 words
A circuit for providing a rapid change in the relative current between a pair of inductors comprising means for supplying a substantially constant current, a first circuit including a first of said inductors, first resistance means, and first switch means in series with said means for supplying a substantially constant current, a second circuit including a second of said inductors and a parallel circuit in series with said means for supplying a substantially constant current, said parallel circuit including a first a nd second series circuit, said first series circuit including second resistance means and second switch means and said second series circuit including third resistance and third switch means, said first and second resistance means having substantially the same resistance and said third reSistance means having a resistance substantially equal to the sum of said first and second resistance means, whereby closing said first, second and third switch means maintains the current in said second inductor greater than the current in said first inductor, opening only said second and third switch means provides a rapid increased in said first inductor current relative to said second inductor current, and opening only said first switch means provides a rapid increase in said second inductor current relative to said first inductor current.
Claim 2
Dependent Claim
210 words
A circuit for providing a rapid change in the relative current between a pair of inductors comprising means for supplying a substantially constant current, a first circuit including a first of said inductors, first resistance means, and first switch means in series with said means for supplying a substantially constant current, a second circuit including a second of said inductors and a parallel circuit in series with said means for supplying a substantially constant current, said parallel circuit including a first a nd second series circuit, said first series circuit including second resistance means and second switch means and said second series circuit including third resistance and third switch means, said first and second resistance means having substantially the same resistance and said third reSistance means having a resistance substantially equal to the sum of said first and second resistance means, whereby closing said first, second and third switch means maintains the current in said second inductor greater than the current in said first inductor, opening only said second and third switch means provides a rapid increased in said first inductor current relative to said second inductor current, and opening only said first switch means provides a rapid increase in said second inductor current relative to said first inductor current.
Claim 3
Dependent Claim
51 words
A circuit according to claim 1 wherein said first, second, and third switch means are transistors, connected to provide a closed circuit between the respective emitters and collectors when said transistors are in saturation and to provide an open circuit between the respective emitters and collectors when said transistors are cutoff.
Claim 4
Dependent Claim
24 words
A circuit according to claim 1 wherein said first and second inductors are the stator coils of first and second magnetic particle devices, respectively.
Claim 5
Dependent Claim
205 words
A circuit connectible to a DC voltage source supplying a substantially constant current for rapidly switching the relative current in inductive loads in response to control signals comprising first inductive load means, second inductive load means, first inductive load control means connected to said first inductive load means and to said DC voltage source for controlling the current in said first inductive load, second inductive load control means connected to said second inductive load means and to said DC voltage source for controlling the current in said second inductive load, said first and second inductive load control means responding to control signals in a steady state stop mode of operation to provide a predetermined first inductive load current and a predetermined second inductive load current and greater than said first inductive load current, and responding to control signals in a start mode of operation to reduce said second inductive load current to substantially zero, and responding to control signals in a steady state start mode of operation to re-establish said second inductive load current at a level less than said first inductive load current, and responding to control signals in a stop mode of operation to reduce said first inductive load current to substantially zero.
Claim 6
Dependent Claim
205 words
A circuit connectible to a DC voltage source supplying a substantially constant current for rapidly switching the relative current in inductive loads in response to control signals comprising first inductive load means, second inductive load means, first inductive load control means connected to said first inductive load means and to said DC voltage source for controlling the current in said first inductive load, second inductive load control means connected to said second inductive load means and to said DC voltage source for controlling the current in said second inductive load, said first and second inductive load control means responding to control signals in a steady state stop mode of operation to provide a predetermined first inductive load current and a predetermined second inductive load current and greater than said first inductive load current, and responding to control signals in a start mode of operation to reduce said second inductive load current to substantially zero, and responding to control signals in a steady state start mode of operation to re-establish said second inductive load current at a level less than said first inductive load current, and responding to control signals in a stop mode of operation to reduce said first inductive load current to substantially zero.
Claim 7
Dependent Claim
43 words
A current according to claim 4 wherein said first inductive load control means comprises first resistance means and first switch means responsive to a first control signal, said first inductive load, said first resistance means and said first switch means connected in series.
Claim 8
Dependent Claim
84 words
A circuit according to claim 5 wherein said second inductive load control means comprises a first branch circuit comprising second resistance means and second switch means responsive to a second control signal, said second inductive load, said second resistance means and said second switch means connected in series, and a second branch circuit comprising a third resistance means and third switch means responsive to a third control signal, said second inductive load, said third resistance means and said third switch means connected in series.
Claim 9
Dependent Claim
26 words
A circuit according to claim 6 wherein said switch means comprises solid-state switching device means for providing open or closed circuits in response to control signals.
Claim 10
Dependent Claim
45 words
A circuit according to claim 7 wherein said first resistance means has a resistance close to the resistance of said second resistance means and said third resistance means has a resistance close to the sum of the resistance of said first and second resistance means.
Claim 11
Dependent Claim
42 words
A circuit according to claim 7 wherein said solid-state switching device means comprise transistors each having an emitter, base and collector, said emitters and bases providing switching action as the base voltage is controlled to vary said transistors between cutoff and saturation.
Claim 12
Dependent Claim
24 words
A circuit according to claim 9 wherein said DC Voltage source is connectable between the junction of said load inductors and said switching transistors.
Claim 13
Dependent Claim
21 words
A circuit according to claim 10 wherein said inductive loads are the stator coils of first and second magnetic particle devices.
Claim 14
Dependent Claim
164 words
A circuit for providing a rapid change in the relative current between a pair of inductors comprising a first load inductor, a second load inductor, a choke, means for connecting one end of said load inductors together through said choke to a first polarity of a source of DC voltage, first resistance means, means for connecting the second end of said first load inductor to said first resistance means, first switch means connected between said first resistance means and the second polarity of said source of DC voltage, second resistance means, means for connecting the second end of said second load inductor to said second resistance means, second switch means connected between said second resistance means and the second polarity of said source of DC voltage, third resistance means, means for connecting the second end of said second load inductor to said third resistance means, third switch means connected between said third resistance means and the second polarity of said source of DC voltage.
Claim 15
Dependent Claim
164 words
A circuit for providing a rapid change in the relative current between a pair of inductors comprising a first load inductor, a second load inductor, a choke, means for connecting one end of said load inductors together through said choke to a first polarity of a source of DC voltage, first resistance means, means for connecting the second end of said first load inductor to said first resistance means, first switch means connected between said first resistance means and the second polarity of said source of DC voltage, second resistance means, means for connecting the second end of said second load inductor to said second resistance means, second switch means connected between said second resistance means and the second polarity of said source of DC voltage, third resistance means, means for connecting the second end of said second load inductor to said third resistance means, third switch means connected between said third resistance means and the second polarity of said source of DC voltage.
Claim 16
Dependent Claim
34 words
A circuit according to claim 12 wherein said switch means comprise first, second and third transistors each having a base, emitter and collector, the emitter and collector of each transistor providing the switching action.
Claim 17
Dependent Claim
51 words
A circuit according to claim 13 further comprising a zener diode having one side connected to said polarity of the DC voltage three diodes having a first side thereof connected to the other side of zener diode, and the remaining side of said diodes connected to each of said transistors, respectively.
Claim 18
Dependent Claim
25 words
A circuit according to claim 13 wherein said first and second load inductors are the stator coils of first and second magnetic particle devices, respectively.
References Cited (Backward Citations)
US3388300A
Cited
US3315092A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |