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US 8,710,827 B2Granted
Processing circuitry for use with a position sensor
AssigneeSagentia Limited
InventorVictor Evgenievich Zhitomirsky
Life of this patent
Estimating the term…
Abstract
A position encoder is described that generates a signal whose phase varies with a position to be determined. A phase detector determines a first phase measurement of the sensor signal during a first mode and a second phase measurement of said sensor signal during a second mode. The phase detector then differences the first and second phase measurements to obtain a phase difference measurement, which it uses to determine an indication of the position to be sensed. A controller controls a signal generator in order to set a start phase of signals generated in at least one of the first and second modes so that the timings at which said sensor signal crosses a reference level are substantially the same.
Claims24
An apparatus for use with a position sensor, the apparatus comprising:
- a signal generator configured to generate signals for driving the position sensor so that a cyclically varying sensor signal is obtained from the position sensor whose phase varies with the position to be sensed;
- a controller configured to control the signal generator to switch between a first mode in which the phase of said sensor signal varies with said position according to a first function and a second mode in which the phase of said sensor signal varies with said position according to a second function that is different than said first function;
- and
- a phase detector configured:
- i) to determine a first phase measurement of said sensor signal during said first mode, said first phase measurement depending upon a time between a start of the first mode and when said sensor signal crosses a reference level;
- ii) to determine a second phase measurement of said sensor signal during said second mode, said second phase measurement depending upon a time between a start of the second mode and when said sensor signal crosses a reference level;
- iii) to obtain a difference between the first and second phase measurements to obtain a phase difference measurement;
- and iv) to output an indication of the position to be sensed determined using said phase difference measurement,
- wherein said controller is configured to control said signal generator in order to change a start phase of signals generated by said signal generator in at least one of said first and second modes so that the timings at which said sensor signal crosses said reference level relative to the corresponding start times of said first and second modes are substantially the same, and
- wherein said controller is configured to control said signal generator to switch repeatedly between said first and second modes and wherein said start phase of signals generated by said signal generator for a current first mode is based on a phase measurement obtained by said phase detector in a previous first mode.
7 more elements
An apparatus for use with a position sensor, the apparatus comprising:
- a signal generator configured to generate signals for driving the position sensor so that a cyclically varying sensor signal is obtained from the position sensor whose phase varies with the position to be sensed;
- a controller configured to control the signal generator to switch between a first mode in which the phase of said sensor signal varies with said position according to a first function and a second mode in which the phase of said sensor signal varies with said position according to a second function that is different than said first function;
- and
- a phase detector configured:
- i) to determine a first phase measurement of said sensor signal during said first mode, said first phase measurement depends depending upon a time between a start of the first mode and when said sensor signal crosses a reference level;
- ii) to determine a second phase measurement of said sensor signal during said second mode, which said second phase measurement depending upon a time between a start of the second mode and when said sensor signal crosses a reference level;
- iii) to obtain a difference between the first and second phase measurements to obtain a phase difference measurement;
- and iv) to output an indication of the position to be sensed determined using said phase difference measurement,
- wherein said controller is configured to control said signal generator in order to change a start phase of signals generated by said signal generator in at least one of said first and second modes so that the timings at which said sensor signal crosses said reference level relative to the corresponding start times of said first and second modes are substantially the same,
- wherein said controller is configured to control the signal generator so that during said first mode the phase of said sensor signal varies with said position according to a first linear function and so that during said second mode the phase of said sensor signal varies with said position according to a second different linear function, and
- wherein said controller is configured to control the signal generator so that during said first mode the phase of said sensor signal varies with said position according to a linear function with a positive gradient and so that during said second mode the phase of said sensor signal varies with said position according to a linear function with a negative gradient.
8 more elements
Dependencies are inferred from the claim text.