Capacitive sensor driving technique that enables hybrid sensing or equalization
First Claim
1. A processing system for a capacitive sensing device, the processing system comprising:
- a first module for the capacitive sensing device, wherein the first module is configured to drive a first electrode with a capacitive sensing signal comprising a plurality of sensing cycles linked by respective voltage transitions; and
a second module for the capacitive sensing device, wherein the second module is configured to drive a second electrode with an equalization pulse during at least one of the voltage transitions, wherein the first electrode is capacitively coupled to the second electrode via the capacitance;
wherein the second electrode is configured to perform at least one of capacitive sensing and display updating and is capacitively coupled to the first electrode, wherein the equalization pulse is out of phase with the capacitive sensing signal such that a voltage change of the equalization pulse is opposite the at least one voltage transition, and wherein a duration of the equalization pulse is less than a duration of one of the plurality of sensing cycles.
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Abstract
Embodiments described herein include an input device that drives an equalization signal onto an electrode that may be capacitively coupled to a sensor electrode used for capacitive sensing. The equalization signal may include a plurality of pulses that are synchronized to be out of phase with a capacitive sensing signal driven on the sensor electrode. For example, as the capacitive sensing signal transitions from a low voltage to a high voltage, the equalization signal transitions from a high voltage to a low voltage. Doing so increases the voltage difference between the electrodes and increases the slew rate of the capacitive sensing signal. In further embodiments, where the input device includes a display device, the equalization signal may be driven onto display electrodes that are used when updating a display.
253 Citations
21 Claims
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1. A processing system for a capacitive sensing device, the processing system comprising:
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a first module for the capacitive sensing device, wherein the first module is configured to drive a first electrode with a capacitive sensing signal comprising a plurality of sensing cycles linked by respective voltage transitions; and a second module for the capacitive sensing device, wherein the second module is configured to drive a second electrode with an equalization pulse during at least one of the voltage transitions, wherein the first electrode is capacitively coupled to the second electrode via the capacitance;
wherein the second electrode is configured to perform at least one of capacitive sensing and display updating and is capacitively coupled to the first electrode, wherein the equalization pulse is out of phase with the capacitive sensing signal such that a voltage change of the equalization pulse is opposite the at least one voltage transition, and wherein a duration of the equalization pulse is less than a duration of one of the plurality of sensing cycles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An input device comprising:
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a plurality of sensor electrodes that establish a sensing region of the input device; a processing system coupled to the plurality of sensor electrodes, the processing system is configured to; drive a first electrode of the plurality of sensor electrodes with a capacitive sensing signal comprising a plurality of sensing cycles linked by respective voltage transitions; drive a second electrode with an equalization pulse during at least one of the voltage transitions, wherein the second electrode is configured to perform at least one of capacitive sensing and display updating and is capacitively coupled to the first electrode, wherein the equalization pulse is out of phase with the capacitive sensing signal such that a voltage change of the equalization pulse is opposite the at least one voltage transition, and wherein a duration of the equalization pulse is less than a duration of one of the plurality of sensing cycles. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method of performing capacitive sensing, the method comprising:
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driving a capacitive sensing signal onto a first electrode, the capacitive sensing signal comprising a plurality of sensing cycles linked by respective voltage transitions; driving an equalization pulse onto a second electrode during at least one of the voltage transitions, wherein the second electrode is configured to perform at least one of capacitive sensing and display updating and is capacitively coupled to the first electrode, wherein the equalization pulse is out of phase with the capacitive sensing signal such that a voltage change of the equalization pulse is opposite the at least one voltage transition, and wherein a duration of the equalization pulse is less than a duration of one of the plurality of sensing cycles. - View Dependent Claims (20, 21)
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Specification