Correction of memory effect errors in force-based touch panel systems
First Claim
1. A method for determining a touch location on a touch screen, comprising:
- detecting one or more touch force responsive sensor signals characterized by an initial response to a step change in a touch force, the initial response being augmented by a monotonic increase in the sensor signals over a period of time;
preparing a correction value reflective of the monotonic increase in the sensor signals; and
determining the touch location using the correction value;
wherein the monotonic increase tends to an asymptotic value according to a weighted sum of one or more exponentially decreasing functions of time while a constant touch force is maintained, the one or more functions characterized by one or more distinct time constants, and preparing the correction value further comprises modeling the difference between the monotonically increasing response and the asymptotic value according to the weighted sum of the one or more exponentially decreasing functions of time.
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Accused Products
Abstract
A method and system are provided to correct one or more sensor signals having errors induced by a viscoelastic effect. The errors may be characterized using a combination of linear or non linear functions. The characterization of the errors may be used to reduce the errors from the sensor signals. In one aspect of the invention, the errors associated with a viscoelastic effect are reduced from the sensor signals by filtering the sensor signals, scaling the output of the filter circuit to produce correction factors and subtracting the correction factors from the sensor signals. Corrected sensor signals may be used to determine the location of a touch on a touch screen with improved accuracy.
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Citations
68 Claims
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1. A method for determining a touch location on a touch screen, comprising:
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detecting one or more touch force responsive sensor signals characterized by an initial response to a step change in a touch force, the initial response being augmented by a monotonic increase in the sensor signals over a period of time; preparing a correction value reflective of the monotonic increase in the sensor signals; and determining the touch location using the correction value; wherein the monotonic increase tends to an asymptotic value according to a weighted sum of one or more exponentially decreasing functions of time while a constant touch force is maintained, the one or more functions characterized by one or more distinct time constants, and preparing the correction value further comprises modeling the difference between the monotonically increasing response and the asymptotic value according to the weighted sum of the one or more exponentially decreasing functions of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for determining a touch location on a touch screen using a plurality of touch sensors mechanically coupled to a touch surface, comprising:
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detecting at least a first touch force responsive sensor signal having a deviation from a proportional response to a touch force caused by viscoelasticity; preparing a correction value reflective of the deviation caused by viscoelasticity by modeling the deviation as a weighted sum of one or more exponentially decreasing functions of time and preparing a correction value reflective of the deviation so modeled; and determining the touch location using the correction value. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for determining a touch location on a touch screen using a plurality of touch sensors mechanically coupled to a touch surface, comprising:
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detecting one or more force responsive sensor signals having errors induced by a viscoelastic effect; correcting the one or more sensor signals by characterizing the errors in the one or more sensor signals and reducing the viscoelastic induced errors; and determining the touch location using the corrected sensor signals; wherein characterizing the errors in the one or more sensor signals comprises characterizing the errors using an exponential function. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33)
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34. A touch screen system, comprising:
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a touch surface; a plurality of touch sensors, the touch sensors physically coupled to the touch surface and producing sensor signals in response to a touch force applied to the touch surface; and a control system, coupled to the touch sensors, the control system configured to detect one or more sensor signals having one or more errors induced by a viscoelastic effect, correct the one or more sensor signals by reducing the viscoelastic induced errors, and determine a touch location using the corrected sensor signals; wherein the control system is configured to characterize the errors in the one or more sensor signals as an exponential function. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42)
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43. A touch screen display system, comprising:
- a touch screen system, including;
a touch surface; a plurality of touch sensors, the touch sensors physically coupled to the touch surface and producing sensor signals in response to a touch force applied to the touch surface; a control system, coupled to the touch sensors, the control system configured to detect one or more sensor signals having errors induced by a viscoelastic effect, correct the one or more sensor signals by reducing the viscoelastic induced errors, and determine a touch location using the corrected sensor signals, the control system characterizing the errors in the one or more sensor signals using an exponential function; and a display for displaying information through the touch screen system. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51)
- a touch screen system, including;
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52. A display system, comprising:
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a touch screen system, including a touch surface; a plurality of touch sensors, the touch sensors physically coupled to the touch surface and producing sensor signals in response to a touch force applied to the touch surface; a control system, coupled to the touch sensors, the control system configured to detect one or more sensor signals having errors induced by a viscoelastic effect, correct the one or more sensor signals by reducing the viscoelastic induced errors, and determine a touch location using the corrected sensor signals, the control system characterizing the errors in the one or more sensor signals using an exponential function; and a processor coupled to the display and the touch screen system for processing data to be displayed on the display and information received from the touch screen system. - View Dependent Claims (53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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63. A system for determining a touch location on a touch screen, comprising:
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means for detecting one or more touch force responsive sensor signals characterized by an initial response to a step change in a touch force, the initial response being augmented by a monotonic increase in the sensor signals over a period of time; means for preparing a correction value reflective of the monotonic increase in the sensor signals; and means for determining the touch location using the correction value; wherein the monotonic increase tends to an asymptotic value while the touch force is maintained, and means for preparing the correction value further comprises means for modeling the difference between the monotonically increasing response and the asymptotic value as a weighted sum of one or more exponentially decreasing functions of time. - View Dependent Claims (64)
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65. A system for determining a touch location on a touch screen using a plurality of touch sensors mechanically coupled to a touch surface, comprising:
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means for detecting at least a first touch force responsive sensor signal having a deviation from a proportional response to a touch force caused by viscoelasticity; means for preparing a correction value reflective of the deviation caused by viscoelasticity, the means for preparing the correction value including means for modeling the deviation as a weighted sum of one or more exponentially decreasing functions of time and means for preparing a correction value reflective of the deviation so modeled; and means for determining the touch location using the correction value. - View Dependent Claims (66, 67)
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68. An article of manufacture comprising a program storage medium readable by a computer, the medium tangibly embodying one or more programs of instructions executable by one or more computers to perform a method for determining a touch location on a touch screen, the method comprising;
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detecting one or more force responsive sensor signals having errors induced by a viscoelastic effect; correcting the one or more sensor signals by characterizing the errors in the one or more sensor signals and reducing the viscoelastic induced errors; and determining the touch location using the corrected sensor signal; wherein characterizing the errors in the one or more sensor signals comprises characterizing the errors using an exponential function.
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Specification