Determining Touch Locations and Forces Thereto on a Touch and Force Sensing Surface
First Claim
1. A method for decoding multiple touches and forces thereof on a touch sensing surface, said method comprising the steps of:
- scanning a plurality of channels aligned on an axis for determining self capacitance values of each of the plurality of channels;
comparing the self capacitance values to determine which one of the channels has a local maximum self capacitance value;
scanning a plurality of nodes of the at least one channel having the local maximum self capacitance value for determining mutual values of the nodes;
comparing the mutual values to determine which one of the nodes has the largest mutual capacitance value, wherein the node having the largest mutual capacitance value on the local maximum self capacitance value channel is a potential touch location; and
determining a force at the potential touch location from a change in the mutual capacitance values of the node at the potential touch location during no touch and during a touch thereto.
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Abstract
A projected capacitive touch and force sensor capable of detecting multiple touches thereto and forces thereof is coupled with a digital device having multi-touch and force decoding capabilities. Once a touch has been established, a force thereof may be assigned to the touch based upon the magnitude of change of capacitance values determined during scans of the projected capacitive touch and force sensor. The touch forces applied to the touch sensor from the associated tracked touch points may be utilized in further determining three dimensional gesturing, e.g., X, Y and Z positions and forces, respectively.
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Citations
37 Claims
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1. A method for decoding multiple touches and forces thereof on a touch sensing surface, said method comprising the steps of:
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scanning a plurality of channels aligned on an axis for determining self capacitance values of each of the plurality of channels; comparing the self capacitance values to determine which one of the channels has a local maximum self capacitance value; scanning a plurality of nodes of the at least one channel having the local maximum self capacitance value for determining mutual values of the nodes; comparing the mutual values to determine which one of the nodes has the largest mutual capacitance value, wherein the node having the largest mutual capacitance value on the local maximum self capacitance value channel is a potential touch location; and determining a force at the potential touch location from a change in the mutual capacitance values of the node at the potential touch location during no touch and during a touch thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for determining gesturing motions and forces thereof on a touch sensing surface having a visual display, said system comprising:
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a first plurality of electrodes arranged in a parallel orientation having a first axis, wherein each of the first plurality of electrodes comprises a self capacitance; a second plurality of electrodes arranged in a parallel orientation having a second axis substantially perpendicular to the first axis, the first plurality of electrodes are located over the second plurality of electrodes and form a plurality of nodes comprising overlapping intersections of the first and second plurality of electrodes, wherein each of the plurality of nodes comprises a mutual capacitance; a flexible electrically conductive cover over the first plurality of electrodes, wherein a face of the flexible electrically conductive cover forms the touch sensing surface; a plurality of deformable spacers between the flexible electrically conductive cover and the first plurality of electrodes, wherein the plurality of deformable spacers maintains a distance between the flexible electrically conductive cover and the first plurality of electrodes; a digital processor and memory, wherein digital outputs of the digital processor are coupled to the first and second plurality of electrodes; an analog front end coupled to the first and second plurality of electrodes; an analog-to-digital converter (ADC) having at least one digital output coupled to the digital processor; wherein values of the self capacitances are measured for each of the first plurality of electrodes by the analog front end, the values of the measured self capacitances are stored in the memory; values of the mutual capacitances of the nodes of at least one of the first electrodes having at least one of the largest values of self capacitance are measured by the analog front end, the values of the measured mutual capacitances are stored in the memory; and the digital processor uses the stored self and mutual capacitance values for determining a gesturing motion and at least one force associated therewith applied to the touch sensing surface. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification