EP0305876A2
Expired / Lapsed
EP
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Stepper motor shaft position sensor
Assignee: Honeywell International Inc
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Filing: 1988-08-24
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Granted: —
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Expires: 2008-08-24
Abstract
Abstract A stepper motor shaft position sensor differentiates the current provided when the stepper motor is excited as by a step command voltage. The differentiated current is, in effect, a signature indicative of whether or not the motor shaft has taken a step. If the differentiated current falls below a predetermined level within a predetermined interval the motor shaft has taken a step as indicated by a sensor output at a predetermined logic level. Otherwise, the sensor output is at another predetermined logic level indicating that a step has not been taken and the motor is in a stalled condition. The sensor output is applied to a utilizing means which provides a continuous verification of the stepper motor shaft position.
Inventors
- 👤 Terry J. Ahrendt
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 05:52
CPC Classifications
H; H02; H02P; H02P8/00; H02P8/36
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
135 words
With a stepper motor of the type which is energized by a motor shaft step command signal to provide a motor current, and including means for sensing the motor current to determine if the motor shaft has taken a step in response to the step command signal, the improvement comprising: means for differentiating the sensed motor current and for providing a differentiated signal; means for providing a reference signal at a predetermined level; means for providing a signal during a predetermined interval; means for comparing the differentiated signal and the reference signal at the predetermined level and for providing a comparison signal; and means connected to the comparing means and to the predetermined interval signal means and responsive to the signals therefrom for providing a signal indicative of the step status of the motor shaft.
Claim 2
Dependent Claim
135 words
With a stepper motor of the type which is energized by a motor shaft step command signal to provide a motor current, and including means for sensing the motor current to determine if the motor shaft has taken a step in response to the step command signal, the improvement comprising: means for differentiating the sensed motor current and for providing a differentiated signal; means for providing a reference signal at a predetermined level; means for providing a signal during a predetermined interval; means for comparing the differentiated signal and the reference signal at the predetermined level and for providing a comparison signal; and means connected to the comparing means and to the predetermined interval signal means and responsive to the signals therefrom for providing a signal indicative of the step status of the motor shaft.
Claim 3
Dependent Claim
34 words
The improvement as described by claim 25, including: means connected to the means for providing a signal indicative of the step status of the motor shaft for verifying the position of the motor shaft.
Claim 4
Dependent Claim
80 words
The improvement as described by claim 25, wherein the means connected to the comparing means and to the predetermined interval signal means and responsive to the signals therefrom for providing a signal indicative of the step status of the motor shaft includes: means for providing the signal indicative of the step status of the motor at a first logic level when the motor shaft has taken a step and at a second logic level when the motor shaft is stalled.
Claim 5
Dependent Claim
25 words
The improvement as described by claim 27, wherein: the first logic level is a logic "high" and the second logic level is a logic "low".
Claim 6
Dependent Claim
46 words
The improvement as described by claim 28, wherein: the signal indicative of the step status of the motor is at the logic "high" when the differentiated signal falls below the predetermined level during the predetermined interval, with said input signal otherwise being at the logic "low".
Claim 7
Dependent Claim
52 words
The improvement as described by claim 25, wherein the means for differentiating the sensed motor current and for providing a differentiated signal includes: a first operational amplifier connected to the means for sensing the motor current; and a second operational amplifier connected to the first operational amplifier and providing the differentiated signal
Claim 8
Dependent Claim
17 words
The improvement as described by claim 30, including: operational amplifier means connected to the second operational amplifier.
Claim 9
Dependent Claim
46 words
The improvement as described by claim 31, wherein the means for providing a reference signal at a predetermined level includes: a variable resistor having one leg connected to a voltage source of one polarity and another leg connected to a voltage source of an opposite polarity.
Claim 10
Dependent Claim
27 words
The improvement as described by claim 32, wherein the comparing means includes: an operational amplifier connected to the variable resistor and connected to the operational amplifier means.
Claim 11
Dependent Claim
65 words
The improvement as described by claim 25, wherein the means for providing a signal during a predeterminal interval includes: a first monostable multivibrator; a clock for providing driving pulses; the first monostable multivibrator connected to the clock and driven by the pulses therefrom; and a second monostable multivibrator connected to the first monostable multivibrator and driven thereby for providing the signal during the predetermined interval.
References Cited (Backward Citations)
No citation records indexed.
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