Touchpad having increased noise rejection, decreased moisture sensitivity, and improved tracking
First Claim
1. A method for decreasing noise in a capacitance sensitive touchpad to thereby improve accuracy of operation, said method comprising the steps of:
- (1) disposing a time aperture filter between at least one sense electrode and at least one measurement circuit, wherein the time aperture filter opens prior to an electrode transition of at least one sense electrodes, and remains open for a selectable time aperture window period; and
(2) draining remaining charge from the time aperture filter after the time aperture filter closes, to a reference circuit, thereby preventing the remaining charge from reaching the at least one measurement circuit.
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Accused Products
Abstract
An improved touchpad and measurement circuitry for enabling input to a computer or other electronic device. The system includes an X electrode, a Y electrode, a common sensing electrode, and a “water” electrode, wherein these four separate electrodes can be implemented in various physical configurations to obtain the desired effects, wherein moisture and water droplets can be identified and compensated for so as not to interfere with the input of data, wherein noise rejection is achieved by using a time aperture filtering method, wherein an improved scanning technique focuses scanning around an identified input object, wherein an adaptive motion filter responds to the speed and acceleration of an object being tracked, and wherein the measurement circuitry has an increased dynamic range enabling the touchpad to operate with greater tolerances to manufacturing variances.
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Citations
57 Claims
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1. A method for decreasing noise in a capacitance sensitive touchpad to thereby improve accuracy of operation, said method comprising the steps of:
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(1) disposing a time aperture filter between at least one sense electrode and at least one measurement circuit, wherein the time aperture filter opens prior to an electrode transition of at least one sense electrodes, and remains open for a selectable time aperture window period; and
(2) draining remaining charge from the time aperture filter after the time aperture filter closes, to a reference circuit, thereby preventing the remaining charge from reaching the at least one measurement circuit. - View Dependent Claims (2, 3, 4, 5)
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6. A capacitance sensitive touchpad that filters noise on a sense electrode from reaching measurement circuitry which detects an electrode event that is indicative of the presence of an object on a surface of the touchpad, said noise filtering touchpad comprising:
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at least one sense electrode which is driven by at least one drive frequency, and which generates at least one electrode event when an object on the surface of the touchpad causes a change in capacitance on the at least one sense electrode;
at least one measurement circuit that receives an electrical signal from the at least one sense electrode, wherein the at least one measurement circuit is capable of detecting the at least one electrode event; and
a time aperture filter disposed between the at least one sense electrode and the at least one measurement circuit, wherein the time aperture filter is capable of passing the electrical signal that is indicative of the electrode event, while preventing noise on the at least one sense electrode from reaching the at least one measurement circuit to thereby improve performance by decreasing sensitivity of the measurement circuit to noise. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A capacitance sensitive touchpad that is capable of compensating for the presence of liquid or moisture on a surface of the touchpad, thereby enabling the touchpad to operate in humid or wet environments, said touchpad comprising:
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a common sensing electrode disposed in a first plane;
an array of first electrodes disposed in a second plane which are arranged generally parallel to each other, wherein the second plane is parallel to the first plane, and wherein the array of first electrodes is driven to the common sensing electrode;
an array of second electrodes disposed in a third plane which are arranged generally parallel to each other, wherein the third plane is parallel to the first plane, wherein the array of second electrodes is driven to the common sensing electrode, and wherein the array of second electrodes is disposed in a direction which is perpendicular to a direction of the array of first electrodes;
a water electrode disposed in a fourth plane, wherein the fourth plane is parallel to the first plane, and wherein the water electrode is capable of capacitively coupling to droplets of water on the surface of the touchpad; and
at least one measurement circuit which receives signals from the array of the first electrodes and the array of second electrodes to thereby determine whether a detected object on the surface of the touchpad is a liquid which increases measured capacitance, or a pointing object such as a finger which decreases measured capacitance. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method for minimizing the effect of moisture or liquid which is disposed on a surface of a capacitance sensitive touchpad, thereby enabling the touchpad to operate in humid or wet environments, said method comprising the steps of:
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(1) providing a first electrode array, a second electrode which is in a same plane as the first electrode array but disposed perpendicularly relative to a direction thereof, a common sensing electrode in the same plane, and a water electrode which is also in the same plane;
(2) providing at least one measurement circuit which receives signals from the first electrode array and the second electrode array;
(3) driving the first electrode array and the second electrode array to the common sensing electrode;
(4) determining whether a detected object on the surface of the touchpad is a liquid which increases measured capacitance, or a pointing object such as a finger which decreases measured capacitance; and
(5) utilizing the capacitive coupling of the water electrode to droplets of liquid on the surface of the touchpad to eliminate an effect of the liquid on touchpad measurements. - View Dependent Claims (19, 20, 21, 22, 23)
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24. A method for providing improved performance of a capacitance sensitive touchpad according to an acceleration and speed of an object whose presence is detected on the touchpad surface, said method comprising the steps of:
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(1) detecting a speed of the object on the touchpad surface;
(2) determining whether the speed of the object is above or below a speed threshold;
(3) increasing a precision of the touchpad when the speed of the object is determined to be below a speed threshold by utilizing an adaptive motion filter; and
(4) decreasing a precision of the touchpad when the speed of the object is determined to be above a speed threshold by utilizing the adaptive motion filter. - View Dependent Claims (25, 26, 27, 28)
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29. A method for providing improved performance of a capacitance sensitive touchpad according to an acceleration of an object whose presence is detected on the touchpad surface, said method comprising the steps of:
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(1) detecting an acceleration of the object on the touchpad surface;
(2) determining whether the acceleration of the object is above or below an acceleration threshold;
(3) increasing a precision of the touchpad when the acceleration of the object is determined to be below the acceleration threshold by utilizing an adaptive motion filter; and
(4) decreasing a precision of the touchpad when the acceleration of the object is determined to be above the acceleration threshold by utilizing the adaptive motion filter. - View Dependent Claims (30, 31)
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32. A method for providing improved performance of a capacitance sensitive touchpad by improving a scanning scheme whereby an object is detected, identified and then tracked as it moves across a touchpad surface, said method comprising the steps of:
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(1) utilizing a wide scanning mode when no objects are detected on the touchpad surface, wherein all electrodes are driven to an active mode so that the presence of an object can be detected at any location on the touchpad;
(2) detecting an object that touches the touchpad surface by observing a decrease in capacitance between electrodes and the common sense electrode in a vicinity of a location of the object; and
(3) utilizing a focused scanning mode to thereby concentrate position determining activities in the vicinity of the location of the object. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39)
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40. A method for providing improved power conservation of a capacitance sensitive touchpad by improving a scanning scheme whereby an object is detected, identified and then tracked as it moves across a touchpad surface, said method comprising the steps of:
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(1) utilizing a wide scanning mode when no objects are detected on the touchpad surface, wherein all electrodes are driven to an active mode so that the presence of an object can be detected at any location on the touchpad;
(2) detecting an object that touches the touchpad surface by observing a decrease in capacitance between electrodes and the common sense electrode in a vicinity of a location of the object; and
(3) utilizing a focused scanning mode to thereby concentrate position determining activities in the vicinity of the location of the object, and consequently deactivate power that is going to electrodes that are not in the vicinity of the location of the object.
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41. A method for improving a dynamic range of measurement circuitry for a capacitance sensitive touchpad, said method comprising the steps of:
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(1) decreasing noise within an analog-to-digital converter to thereby enable lower resolution data bits to be utilized in position calculations by the measurement circuitry;
(2) increasing a number of samples that are measured; and
(3) making measurement calculations utilizing at least two lower resolution data bits from the A/D converter. - View Dependent Claims (42)
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43. A method for optimizing touchpad performance by improving object detection scanning, said method comprising the steps of:
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(1) utilizing a wide scanning mode when no objects are detected on a touchpad surface;
(2) detecting an object that touches the touchpad surface; and
(3) utilizing a narrow scanning mode to thereby concentrate position determining functions near a position of the object as determined by the wide scanning mode. - View Dependent Claims (44, 45, 46, 47, 48)
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49. A method for providing improved performance of a capacitance sensitive touchpad by improving a scanning scheme whereby an object is detected, identified and then tracked as it moves across a touchpad surface, said method comprising the steps of:
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(1) utilizing a wide scanning mode when no objects are detected on a touchpad surface, wherein all electrodes are driven to an active mode so that the presence of an object can be detected at any location on the touchpad;
(2) detecting an object that touches the touchpad surface by observing a decrease in capacitance between electrodes and the common sense electrode in a vicinity of a location of the object; and
(3) utilizing a focused scanning mode to thereby concentrate position determining activities in the vicinity of the location of the object. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56)
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57. A method for providing improved power conservation of a capacitance sensitive touchpad by improving a scanning mode, said method comprising the steps of:
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(1) utilizing a wide scanning mode when no objects are detected on the touchpad surface, wherein all electrodes are driven to an active mode so that the presence of an object can be detected at any location on the touchpad;
(2) detecting an object that touches the touchpad surface by observing a decrease in capacitance between electrodes and the common sense electrode in a vicinity of a location of the object; and
(3) utilizing a focused scanning mode to thereby concentrate position determining activities in the vicinity of the location of the object, and consequently deactivate power that is going to electrodes that are not in the vicinity of the location of the object.
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Specification