Capacitive position sensor
First Claim
1. A capacitive position sensor comprising:
- a substrate;
a single resistive sensing element forming a continuous resistor supported by the substrate in an angular route; and
three spaced-apart terminals disposed along the single resistive sensing element to couple to separate sensing channels, wherein signals from the three spaced-apart terminals are representative of a position of a touch along the single resistive sensing element;
each sensing channel being operable to generate a signal indicative of a capacitance for a respective terminal coupled to the sensing channel, the position of the touch along the single resistive sensing element being determinable by performing operations comprising;
determining a section of the single resistive sensing element corresponding to the touch, the determined section being between a first terminal and an adjacent second terminal;
subtracting a signal of a respective sensing channel coupled to a third terminal from each of signals taken from respective sensing channels coupled to the first and the second terminals to generate first and second reduced signals; and
determining the position of the touch within the determined section using a ratiometric analysis of the first and second reduced signals.
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Accused Products
Abstract
A capacitive position sensor for detecting the position of an object, typically an operator'"'"'s finger, relative to a resistive sensing element, wherein 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. In this way, 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.
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Citations
20 Claims
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1. A capacitive position sensor comprising:
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a substrate; a single resistive sensing element forming a continuous resistor supported by the substrate in an angular route; and three spaced-apart terminals disposed along the single resistive sensing element to couple to separate sensing channels, wherein signals from the three spaced-apart terminals are representative of a position of a touch along the single resistive sensing element; each sensing channel being operable to generate a signal indicative of a capacitance for a respective terminal coupled to the sensing channel, the position of the touch along the single resistive sensing element being determinable by performing operations comprising; determining a section of the single resistive sensing element corresponding to the touch, the determined section being between a first terminal and an adjacent second terminal; subtracting a signal of a respective sensing channel coupled to a third terminal from each of signals taken from respective sensing channels coupled to the first and the second terminals to generate first and second reduced signals; and determining the position of the touch within the determined section using a ratiometric analysis of the first and second reduced signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A capacitive position sensor comprising:
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a substrate; a resistive sensing element forming a continuous resistor supported by the substrate in an angular route; three spaced-apart terminals disposed along the resistive sensing element to couple to separate sensing channels, wherein the signals from the three terminals are representative of a position of a touch along the resistive sensing element; and three sensing channels, each electrically coupled to respective spaced apart terminals, the sensing channels configured to implement a charge transfer technique to generate the signals; each sensing channel being operable to generate a signal indicative of capacitance for a respective terminal coupled to the sensing channel, the position of the touch along the resistive sensing element being determinable by performing operations comprising; determining a section of the resistive sensing element corresponding to the touch, the determined section being between a first terminal and an adjacent second terminal; subtracting a signal of a respective sensing channel coupled to a third terminal from each of signals taken from respective sensing channels coupled to the first and the second terminals to generate first and second reduced signals; and determining the position of the touch within the determined section using a ratiometric analysis of the first and second reduced signals. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A capacitive position sensor comprising:
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a substrate; a resistive sensing element forming a continuous resistor supported by the substrate and forming a path; and three spaced-apart terminals disposed along the resistive sensing element to couple to separate sensing channels to provide signals representative of a touch position on the path responsive to charge transfer signals; each sensing channel being operable to generate a signal indicative of capacitance for a respective terminal coupled to the sensing channel, the position of the touch along the resistive sensing element being determinable by performing operations comprising; determining a section of the resistive sensing element corresponding to the touch, the determined section being between a first terminal and an adjacent second terminal; subtracting a signal of a respective sensing channel coupled to a third terminal from each of signals taken from respective sensing channels coupled to the first and the second terminals to generate first and second reduced signals; and determining the position of the touch within the determined section using a ratiometric analysis of the first and second reduced signals. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification