Linear absolute position sensing using capacitive sensing
AssigneeCypress Semiconductor Corporation
InventorGregory John Verge
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Abstract
The embodiments described herein are directed to systems and devices for electronically measuring the absolute position of one or more moving targets e.g., along the length of a metal beam using mutual capacitive sensing. The beam may be made of metal and may have a limited inset area to fit a position detection sensor device along its length. The moving targets may have no active elements and the position of multiple targets may be detected simultaneously along the beam. The systems and devices described herein do not utilize electronic position feedback and instead rely on an integrated ruler and minimize the total number of sensors required to support recalibration, thereby minimizing scan time (more sensors results in a linear increase in scan time).
Claims20
An apparatus comprising:
- a plurality of receive (Rx) sensors organized into a plurality of Rx columns, each Rx sensor of the plurality of Rx sensors driven by an Rx signal of a set of Rx signals;
- a transmit (Tx) sensor, the Tx sensor configured to couple to Rx sensors of one or more Rx columns in response to a target moving into proximity of the one or more Rx columns;
- a processing device operatively coupled to the memory, the processing device configured to:
- scan each of the plurality of Rx sensors;
- and
- determine a position of the target based on the scan of each of the plurality of Rx sensors using mutual capacitive sensing;
- and
- a guard channel coupled between the plurality of Rx columns and the Tx sensor to collapse electric field lines generated by the Tx sensor when the target is not present.
A system comprising:
- a measurement beam;
- one or more targets configured to move along the measurement beam;
- and
- a sensor device located within the measurement beam, the sensor device comprising:
- a plurality of receive (Rx) sensors organized into a plurality of Rx columns, each Rx sensor of the plurality of Rx sensors driven by an Rx signal of a set of Rx signals;
- a transmit (Tx) sensor, the Tx sensor configured to couple to Rx sensors of one or more Rx columns in response to a target of the one or more targets moving into proximity of the one or more Rx columns;
- a processing device configured to:
- scan each of the plurality of Rx sensors;
- and
- determine a position of the target based on the scan of each of the plurality of Rx sensors using mutual capacitive sensing;
- and
- a guard channel coupled between the plurality of Rx columns and the Tx sensor to collapse electric field lines generated by the Tx sensor when the target is not present.
Dependencies are inferred from the claim text.