Patent US3586953A successfully refreshed from Google Patents.
US3586953A
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US
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Stepper motor control system
Assignee: Fairchild Semiconductor Corp
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Filing: 1967-09-22
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Granted: 1971-06-22
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Expires: 1987-09-22
Abstract
Abstract A stepper motor drive system includes a shaft carrying an encoder which develops a binary-coded signal representative of 12 discrete shaft positions on either side of a reference position. Binary-coded signals representative of the desired position of the motor and the shaft position signals are applied to a digital comparator and direction logic circuit which develops output pulses until the motor advances to bring the shaft position signals and the input signals into coincidence. The comparator also develops CW or CCW signals indicating the direction of rotation of the motor in order to reach the desired position in the shortest direction. An electromagnetic detent on the motor shaft is controlled by the comparator to lock the motor shaft in the final desired position. To prevent overshoot of the motor past a desired position n and subsequent oscillation about that position, an auxiliary comparator responsive to the shaft encoder signals and the input signals develops a simulated coincidence signal when the motor reaches the n- 1 or n+ 1 position, depending upon whether it is rotating CW or CCW, respectively, and this latter signal is utilized to excite the motor momentarily in the reverse direction to check its momentum. Shortly before the motor reaches the final desired position, a forward direction pulse is applied to the motor to drive it to that position.
Inventors
- 👤 Carl O Markkanen
- 👤 Dale B Blackwell
- 👤 George A Knaust
- 👤 Christian R Kropac
- 👤 John M Mccall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 21:26
CPC Classifications
B; B41; B41J; B41J19/00; B41J19/18; B41J19/20; B41J19/202; G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/27; G05B19/29; G05B19/291; G05D; G05D3/00; G05D3/12; G05D3/14; G05D3/18; G05D3/183; H; H02; H02P; H02P8/00; H02P8/32; G05B2219/00; G05B2219/30; G05B2219/34; G05B2219/34064; G05B2219/42; G05B2219/42212
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
138 words
A system for operating a stepper motor to a preselected position in response to an encoded digital signal comprising: a multichannel input circuit for supplying encoded groups of parallel digital control pulses for a motor to be controlled; means adapted to be driven by a motor to be controlled for generating after each step an encoded group of parallel digital position-representative pulses; a coincidence comparator coupled to said input circuit and to said generating means and effective to develop an output pulse upon each successive comparison of said pulse groups when said Two pulse groups do not correspond; circuit means responsive to said output pulse for developing and applying a corresponding pulse to a stepper motor to be controlled; and means responsive to correspondence between said two pulse groups for disabling said circuit means to stop the motor.
Claim 2
Independent Claim
138 words
A system for operating a stepper motor to a preselected position in response to an encoded digital signal comprising: a multichannel input circuit for supplying encoded groups of parallel digital control pulses for a motor to be controlled; means adapted to be driven by a motor to be controlled for generating after each step an encoded group of parallel digital position-representative pulses; a coincidence comparator coupled to said input circuit and to said generating means and effective to develop an output pulse upon each successive comparison of said pulse groups when said Two pulse groups do not correspond; circuit means responsive to said output pulse for developing and applying a corresponding pulse to a stepper motor to be controlled; and means responsive to correspondence between said two pulse groups for disabling said circuit means to stop the motor.
Claim 3
Dependent Claim
36 words
A system for operating a stepper motor to a preselected position in accordance with claim 1 in which said generating means includes a drum having a plurality of encoded position-representative holes and a photoelectric hole-sensing apparatus.
Claim 4
Dependent Claim
30 words
A system for operating a stepper motor to a preselected position in accordance with claim 2 in which said holes are arranged in angularly spaced axial rows of code groups.
Claim 5
Dependent Claim
48 words
A system for operating a stepper motor to a preselected position in accordance with claim 2 in which said drum also includes a peripheral ring of equally spaced timing holes and photoelectric sensing means therefor and in which said pulse-developing circuit means is controlled by said sensing means.
Claim 6
Dependent Claim
43 words
A system for operating a stepper motor to a preselected position in accordance with claim 1 which includes a source of timing signals and in which said pulse-developing circuit means is jointly responsive to said timing signals and to said comparator output signal.
Claim 7
Dependent Claim
49 words
A system for operating a stepper motor to a preselected position in accordance with claim 1 which includes a source of timing signals and a circuit jointly responsive to said timing signals and to said comparator output signal for controlling the application of said position-representative signal to said comparator.
Claim 8
Dependent Claim
76 words
A system for operating a stepper motor to a preselected position in accordance with claim 1 in which the motor is provided with a drive shaft and including an electromagnetic detent rigidly coupled to the motor shaft and having an angular positioning accuracy substantially greater than that of the stepper motor and means for energizing said detent only when the stepper motor has arrived at its preselected position, accurately to hold the motor in such position.
Claim 9
Dependent Claim
90 words
A system for operating a stepper motor to a preselected position in accordance with claim 1 in which the motor is provided with a drive shaft and including an electromagnetic detent rigidly coupled to the motor shaft and having an angular positioning accuracy substantially greater than that of the stepper motor and means responsive to said output signal to energize said detent and for energizing selected windings of the motor with direct current of a magnitude less than that of said pulses to lock the motor in the selected position.
Claim 10
Independent Claim
97 words
A system for accurately positioning a stepper motor in a preselected position in response to a series of electrical pulses comprising: an input circuit for supplying a series of electrical pulses to a stepper motor to be controlled; a normally deenergized electromagnetic detent including a stator and a rotor rigidly connected to be driven by said controlled stepper motor and having an angular positioning accuracy substantially greater than that of the stepper motor; and control means for energizing said detent substantially at the conclusion of said series of pulses to lock the motor in the selected position.
Claim 11
Independent Claim
97 words
A system for accurately positioning a stepper motor in a preselected position in response to a series of electrical pulses comprising: an input circuit for supplying a series of electrical pulses to a stepper motor to be controlled; a normally deenergized electromagnetic detent including a stator and a rotor rigidly connected to be driven by said controlled stepper motor and having an angular positioning accuracy substantially greater than that of the stepper motor; and control means for energizing said detent substantially at the conclusion of said series of pulses to lock the motor in the selected position.
Claim 12
Dependent Claim
42 words
A system for accurately positioning a stepper motor in a preselected position in accordance with claim 9 in which said stator and said rotor have a plurality of complementary precision teeth which upon energization of the detent are locked in registering positions.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |