Closed path capacitive position sensor
First Claim
1. A capacitive position sensor for detecting a position of an object comprising:
- a single resistive sensing element comprising one continuous resistor that forms a closed sensing path;
a plurality of at least three terminals disposed along the single resistive sensing element at different locations along the closed sensing path, each of the plurality of terminals coupled to a respective one of a plurality of sensing channels;
a plurality of at least three sensing channels that are each connected to a respective one of the plurality of terminals, wherein each sensing channel is operable to generate a signal indicative of capacitance between the respective one of the plurality of terminals and a system ground; and
a processor operable to determine a particular one of the plurality of sensing channels over which the object is positioned and a position of the object within the particular one of plurality of sensing channels by comparing the signals from the plurality of sensing channels, andwherein the processor is further operable to determine the position of the object within the determined particular one of the plurality of sensing channels by a ratiometric analysis of signals taken from the terminals spanning the determined particular one of the plurality of sensing channels, andwherein the processor is further operable to subtract a signal taken from a further terminal from each of the signals taken from the terminals spanning the determined particular one of the plurality of sensing channels prior to performing the ratiometric analysis.
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Accused Products
Abstract
A capacitive position sensor for detecting the position of an object relative to a resistive sensing element. The sensing element comprises a sensing path that has terminals connected along it that subdivide the sensing path into multiple sections. Each terminal is coupled to its own sensing channel, each of which generates a signal that is sensitive to the capacitance between its terminal and a system ground. The signals are fed to a processor for analysis. The processor determines over which section the object is positioned by comparing the signals from the sensing channels, and determines the position of the object within that section by comparing the signals from the terminals spanning that section. The sensing path can be formed in a closed loop, such as a circle for a scroll dial, in which the operator'"'"'s finger position and movement can be uniquely determined in a straightforward manner.
44 Citations
16 Claims
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1. A capacitive position sensor for detecting a position of an object comprising:
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a single resistive sensing element comprising one continuous resistor that forms a closed sensing path; a plurality of at least three terminals disposed along the single resistive sensing element at different locations along the closed sensing path, each of the plurality of terminals coupled to a respective one of a plurality of sensing channels; a plurality of at least three sensing channels that are each connected to a respective one of the plurality of terminals, wherein each sensing channel is operable to generate a signal indicative of capacitance between the respective one of the plurality of terminals and a system ground; and a processor operable to determine a particular one of the plurality of sensing channels over which the object is positioned and a position of the object within the particular one of plurality of sensing channels by comparing the signals from the plurality of sensing channels, and wherein the processor is further operable to determine the position of the object within the determined particular one of the plurality of sensing channels by a ratiometric analysis of signals taken from the terminals spanning the determined particular one of the plurality of sensing channels, and wherein the processor is further operable to subtract a signal taken from a further terminal from each of the signals taken from the terminals spanning the determined particular one of the plurality of sensing channels prior to performing the ratiometric analysis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A control panel incorporating a capacitive position sensor for detecting a position of an object comprising;
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a single resistive sensing element comprising one continuous resistor that forms a closed sensing path; a plurality of at least three terminals disposed along the single resistive sensing element at different locations along the closed sensing path, each of the plurality of terminals coupled to a respective one of a plurality of sensing channels; a plurality of sensing channels that are each connected to a respective one of the plurality of terminals, wherein each sensing channel is operable to generate a signal indicative of capacitance between the respective one of the plurality of terminals and a system ground; and a processor operable to determine a particular one of the plurality of sensing channels over which the object is positioned and a position of the object within the particular one of plurality of sensing channels by comparing the signals from the plurality of sensing channels, and wherein the processor is further operable to determine the position of the object within the determined particular one of the plurality of sensing channels by a ratiometric analysis of signals taken from the terminals spanning the determined particular one of the plurality of sensing channels, and wherein the processor is further operable to subtract a signal taken from a further terminal from each of the signals taken from the terminals spanning the determined particular one of the plurality of sensing channels prior to performing the ratiometric analysis. - View Dependent Claims (14)
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15. An apparatus having a control panel incorporating a capacitive position sensor for detecting a position of an object comprising:
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a single resistive sensing element comprising one continuous resistor that forms a closed sensing path; a plurality of at least three terminals disposed along the single resistive sensing element at different locations along the closed sensing path, each of the plurality of terminals coupled to a respective one of a plurality of sensing channels; a plurality of sensing channels that are each connected to a respective one of the plurality of terminals, wherein each sensing channel is operable to generate a signal indicative of capacitance between the respective one of the plurality of terminals and a system ground; and a processor operable to determine a particular one of the plurality of sensing channels over which the object is positioned and a position of the object within the particular one of plurality of sensing channels by comparing the signals from the plurality of sensing channels, and wherein the processor is further operable to determine the position of the object within the determined particular one of the plurality of sensing channels by a ratiometric analysis of signals taken from the terminals spanning the determined particular one of the plurality of sensing channels, and wherein the processor is further operable to subtract a signal taken from a further terminal from each of the signals taken from the terminals spanning the determined particular one of the plurality of sensing channels prior to performing the ratiometric analysis. - View Dependent Claims (16)
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Specification