Anisotropic, resistance-based determination of a position of an object with respect to a touch screen element
First Claim
1. A touch sensitive position sensor comprising:
- a substrate defining a touch sensitive platform;
a first resistive bus-bar on the substrate;
a second resistive bus-bar substantially parallel to the first resistive bus-bar on the substrate;
a third resistive bus-bar substantially parallel to the first resistive bus-bar and the second resistive bus-bar on the substrate, the third resistive bus-bar being between the first resistive bus-bar and the second resistive bus-bar;
wherein the first resistive bus-bar extends between a first and a second electrode, the second resistive bus-bar extends between a third and a fourth electrode, and the third resistive bus-bar extends between a fifth and a sixth electrode;
a first, second, third, fourth, fifth, and sixth drive channel associated with respective ones of the first, second, third, fourth, fifth, and sixth electrodes;
each drive channel being operable to generate an output signal dependent on the resistance between the respective first, second, third, fourth, fifth, and sixth electrode and a position of an object;
an anisotropic conductive area having a non-zero resistance arranged between the first, second and third resistive bus-bars such that currents induced in the anisotropic conductive area flow preferentially towards the first, second, and third resistive bus-bars; and
a processor operable to generate an estimate for the position of the object by comparing the output signals from the fifth and sixth drive channels and a sum of the output signals selected from one of the first and second drive channels or the third and fourth drive channels;
wherein processor is configured to estimate the position of the object in a first direction running between the resistive bus-bars from a ratiometric analysis of a sum of the output signals from the fifth and sixth drive channels and the sum of the selected output signals.
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Abstract
A touch sensitive position sensor for detecting the position of an object in two dimensions is described. The position sensor has first and second resistive bus-bars spaced apart with an anisotropic conductive area between them. Electric currents induced in the anisotropic conductive area by touch or proximity flow preferentially towards the bus-bars to be sensed by detection circuitry. Because induced currents, for example those induced by drive circuitry, flow preferentially along one direction, pin-cushion distortions in position estimates are largely constrained to this single direction. Such one-dimensional distortions can be corrected for very simply by applying scalar correction factors, thereby avoiding the need for complicated vector correction.
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Citations
8 Claims
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1. A touch sensitive position sensor comprising:
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a substrate defining a touch sensitive platform; a first resistive bus-bar on the substrate; a second resistive bus-bar substantially parallel to the first resistive bus-bar on the substrate; a third resistive bus-bar substantially parallel to the first resistive bus-bar and the second resistive bus-bar on the substrate, the third resistive bus-bar being between the first resistive bus-bar and the second resistive bus-bar; wherein the first resistive bus-bar extends between a first and a second electrode, the second resistive bus-bar extends between a third and a fourth electrode, and the third resistive bus-bar extends between a fifth and a sixth electrode; a first, second, third, fourth, fifth, and sixth drive channel associated with respective ones of the first, second, third, fourth, fifth, and sixth electrodes;
each drive channel being operable to generate an output signal dependent on the resistance between the respective first, second, third, fourth, fifth, and sixth electrode and a position of an object;an anisotropic conductive area having a non-zero resistance arranged between the first, second and third resistive bus-bars such that currents induced in the anisotropic conductive area flow preferentially towards the first, second, and third resistive bus-bars; and a processor operable to generate an estimate for the position of the object by comparing the output signals from the fifth and sixth drive channels and a sum of the output signals selected from one of the first and second drive channels or the third and fourth drive channels; wherein processor is configured to estimate the position of the object in a first direction running between the resistive bus-bars from a ratiometric analysis of a sum of the output signals from the fifth and sixth drive channels and the sum of the selected output signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification