Capacitive position sensor system
AssigneeNXP B.V.
InventorThomas Suwald
Life of this patent
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Abstract
A capacitive position sensor system is provided for determining the position of an object, wherein the object is positioned within a sensitive area of the capacitive position sensor system and changes the capacitance of capacitors being arranged underneath the object.
Claims15
A capacitive position sensor system for determining the position of an object, wherein the object is positioned within a sensitive area of the capacitive position sensor system and changes the capacitance of capacitors being arranged underneath the object, the capacitive position sensor system comprising
- a first plurality of sensing elements, each sensing element comprising a first capacitor having a first electrode and a second electrode, wherein each first electrode is coupled via a switch to a voltage supply to form a switched capacitor filter, wherein the second electrodes are coupled to form a sensing line,
- a sensing unit, wherein the sensing unit is adapted to sense a voltage level representing the amount of charge being present on the sensing line, and
- a control unit, wherein the control unit is adapted to apply a drive signal to each of the switches being coupled to the first electrodes,
- wherein, in one integration cycle, a part of the switches being coupled to the first electrodes is closed so that a part of the first capacitors is driven by a first drive signal, wherein the sensing unit is adapted to sense the voltage level representing the sum of the amount of charge of the part of the first capacitors, wherein the number of the switches being closed is at least two,
- wherein the control unit is adapted to determine the position of the object by analyzing the results of a plurality of sensed voltage levels of a plurality of integration cycles.
A method of determining the position of an object, wherein the object is positioned within a sensitive area of the capacitive position sensor system and changes the capacitance of capacitors being arranged underneath the object, wherein the capacitive position sensor system comprises a first plurality of sensing elements, each sensing element comprising a first capacitor having a first electrode and a second electrode, wherein each first electrode is coupled via a switch to a voltage supply to form a switched capacitor filter, wherein the second electrodes are coupled to form a sensing line,
- the method comprising
- sensing, by a sensing unit, a voltage level representing the amount of charge being present on the sensing line,
- applying, by a control unit, a drive signal to each of the switches being coupled to the first electrodes,
- wherein, in one integration cycle, a part of the switches being coupled to the first electrodes is closed so that a part of the first capacitors is driven by a first drive signal, wherein the sensing unit is adapted to sense the voltage level representing the sum of the amount of charge of the part of the first capacitors, wherein the number of the switches being closed is at least two,
- determining, by the control unit, the position of the object by analyzing the results of a plurality of sensed voltage levels of a plurality of integration cycles.
Dependencies are inferred from the claim text.