Patent US3882366A successfully refreshed from Google Patents.
US3882366A
Expired / Lapsed
US
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Motor speed control system
Assignee: 3M Co
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Filing: 1973-11-05
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Granted: 1975-05-06
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Expires: 1993-11-05
Abstract
Abstract Precise motor speed control is achieved in a system wherein the speed of a bi-directional motor is controlled by a servo means in response to a homopolar tachometer-generator voltage signal that indicates the speed and direction of rotation of the motor. The homopolar tachometer-generator includes a conductor that is symmetrical about the axis of rotation of the motor and is coupled to the motor shaft to uniformly intersect a provided unipolar magnetic field. Two pair of stationary brushes contact the conductor and serve to furnish a substantially ripple free voltage signal.
Inventors
- 👤 Kenneth Clunis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:15
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/18; G11B15/46; G11B15/54; G01; G01P; G01P13/00; G01P13/02; G01P13/04; G01P13/045; G01P3/00; G01P3/42; G01P3/44; G01P3/46; H; H02; H02K; H02K31/00; H02K31/02; H02K7/00; H02K7/20
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
209 words
A servo system that provides precise motor speed control Of a bi-directional motor and comprises: a control means for furnishing an electrical drive signal to said motor; a differential means for providing an error signal to said control means; and a homopolar generator serving as a tachometer for providing a signal indicative of the speed and rotation of the motor to said differential means and having: means for providing a unipolar magnetic field; a conductor coupled to the shaft of the motor for rotation in said magnetic field to uniformly intersect said field at all rotational positions; and at least two pair of stationary brushes for providing a signal to said differential means, which brushes include an outer pair electrically contacting the outside portion of one side of said conductor and an inner pair electrically contacting the inside portion of the same one side of said conductor, and the brushes of said outer pair are electrically connected together and the brushes of said inner pair are electrically connected together but one of the brushes from each pair is disposed to contact said conductor at a position radially opposite from the other brush of the pair in order that the output signal provided by said generator is substantially ripple free.
Claim 2
Dependent Claim
209 words
A servo system that provides precise motor speed control Of a bi-directional motor and comprises: a control means for furnishing an electrical drive signal to said motor; a differential means for providing an error signal to said control means; and a homopolar generator serving as a tachometer for providing a signal indicative of the speed and rotation of the motor to said differential means and having: means for providing a unipolar magnetic field; a conductor coupled to the shaft of the motor for rotation in said magnetic field to uniformly intersect said field at all rotational positions; and at least two pair of stationary brushes for providing a signal to said differential means, which brushes include an outer pair electrically contacting the outside portion of one side of said conductor and an inner pair electrically contacting the inside portion of the same one side of said conductor, and the brushes of said outer pair are electrically connected together and the brushes of said inner pair are electrically connected together but one of the brushes from each pair is disposed to contact said conductor at a position radially opposite from the other brush of the pair in order that the output signal provided by said generator is substantially ripple free.
Claim 3
Dependent Claim
16 words
A motor speed control system according to claim 1, wherein the conductor comprises a Faraday disk.
Claim 4
Dependent Claim
15 words
A motor speed control system according to claim 1, wherein the conductor comprises a cylinder.
Claim 5
Dependent Claim
39 words
A motor speed control system according to claim 1, wherein a resistive means is connected between each brush of said generator and said differential means to compensate for variation in the contact resistance between said brushes and said conductor.
Claim 6
Dependent Claim
29 words
A motor speed control system according to claim 4, wherein said resistive means is equal to at least 20 times the contact resistance between said brushes and said conductor.
Claim 7
Dependent Claim
220 words
A tape drive system wherein the tape is driven by a bi-directional motor, the speed of which is precisely controlled by a servo system that comprises: a control means for furnishing an electrical drive signal to said motor; a differential means for providing an error signal to said control means; and a homopolar generator serving as a tachometer for providing a signal indicative of the speed and rotation of the motor to said differential means and having: means for providing a unipolar magnetic field; a conductor coupled to the shaft of the motor for rotation in said magnetic field to uniformly intersect said field at all rotational positions; and at least two pair of stationary brushes for providing a signal to said differential means, which brushes include an outer pair electrically contacting the outside portion of one side of said conductor and an inner pair electrically contacting the inside portion of the same one side of said conductor, and the brushes of said outer pair are electrically connected together and the brushes of said inner pair are electrically connected together but one of the brushes from each pair is disposed to contact said conductor at a position radially opposite from the other brush of the pair in order that the output signal provided by said generator is substantially ripple free.
Claim 8
Dependent Claim
220 words
A tape drive system wherein the tape is driven by a bi-directional motor, the speed of which is precisely controlled by a servo system that comprises: a control means for furnishing an electrical drive signal to said motor; a differential means for providing an error signal to said control means; and a homopolar generator serving as a tachometer for providing a signal indicative of the speed and rotation of the motor to said differential means and having: means for providing a unipolar magnetic field; a conductor coupled to the shaft of the motor for rotation in said magnetic field to uniformly intersect said field at all rotational positions; and at least two pair of stationary brushes for providing a signal to said differential means, which brushes include an outer pair electrically contacting the outside portion of one side of said conductor and an inner pair electrically contacting the inside portion of the same one side of said conductor, and the brushes of said outer pair are electrically connected together and the brushes of said inner pair are electrically connected together but one of the brushes from each pair is disposed to contact said conductor at a position radially opposite from the other brush of the pair in order that the output signal provided by said generator is substantially ripple free.
Claim 9
Dependent Claim
15 words
A tape drive system according to claim 6, wherein the conductor comprises a Faraday disk.
Claim 10
Dependent Claim
14 words
A tape drive system according to claim 6, wherein the conductor comprises a cylinder.
Claim 11
Dependent Claim
38 words
A tape drive system according to claim 6, wherein a resistive means is connected between each brush of said generator and said differential means to compensate for variation in the contact resistance between said brushes and said conductor.
Claim 12
Dependent Claim
28 words
A tape drive system according to claim 9, wherein said resistive means is equal to at least 20 times the contact resistance between said brushes and said conductor.
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) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |