Simultaneous time domain differential sensing and electric field sensing
AssigneeAlsentis, LLC
InventorDavid W. Caldwell
Life of this patent
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Abstract
Systems and methods for determining a touch input are provided. The systems and methods generally include measuring the peak voltage at an electrode over a measurement period and determining a touch input based on the peak voltage. The systems and methods can conserve computing resources by deferring digital signal processing until after a peak electrode capacitance has been sampled. The systems and methods are suitable for capacitive sensors using self-capacitance and capacitive sensors using mutual capacitance. The systems and methods are also suitable for capacitive buttons, track pads, and touch screens, among other implementations.
Claims18
A method comprising:
- strobing a first electrode having a capacitance with respect to a second electrode with a time-varying waveform over a first measurement period;
- strobing the first electrode with a time-varying waveform over a second measurement period;
- electrically coupling a processing unit to the first and second electrodes;
- registering a first touch signature in response to an object approaching one of the first or second electrode, the first touch signature occurring over a total time domain (T) between a first time and a second time, between a first capacitance and a second capacitance, wherein the first touch signature includes a rate of change (ds/dt) of the between the first and second capacitance in combination with at least one parameter of the first touch signature selected from the group consisting essentially, of an interval change in capacitance (ds) during the total time domain (T) where the interval change in capacitance (ds) is less than a total change in capacitance(S) for the first touch signature, an interval time domain (dt) corresponding to the interval change in capacitance (ds), wherein the interval time domain (dt) is less than the total time domain (T) for the first touch signature, and combinations thereof.
Dependencies are inferred from the claim text.