Capacitive sensor and sensing method
First Claim
1. A capacitive sensing method, comprising:
- alternately charging/discharging a capacitive sensing electrode of a capacitive sensor for predetermined times under an active mode and charging/discharging the capacitive sensing electrode during a fixed period under a standby mode while an object is not coupled to the capacitive sensing electrode, wherein the capacitive sensing electrode has a first capacitance while the object is not coupled to the capacitive sensing electrode;
generating a switch signal while the object is coupled to the capacitive sensing electrode under the standby mode such that the capacitive sensing electrode has a second capacitance larger than the first capacitance; and
switching the standby mode to the active mode according to the switch signal.
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Abstract
A capacitive sensing method is provided. The capacitive sensing method includes the step of alternately charging/discharging a capacitive sensing electrode of a capacitive sensor for predetermined times under an active mode and charging/discharging the capacitive sensing electrode during a fixed period under a standby mode while an object is not coupled to the capacitive sensing electrode, in which the capacitive sensing electrode has a first capacitance while the object is not coupled to the capacitive sensing electrode. The capacitive sensing method also includes the step of generating a switch signal while the object is coupled to the capacitive sensing electrode under the standby mode such that the capacitive sensing electrode has a second capacitance larger than the first capacitance and the step of switching the standby mode to the active mode according to the switch signal.
18 Citations
20 Claims
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1. A capacitive sensing method, comprising:
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alternately charging/discharging a capacitive sensing electrode of a capacitive sensor for predetermined times under an active mode and charging/discharging the capacitive sensing electrode during a fixed period under a standby mode while an object is not coupled to the capacitive sensing electrode, wherein the capacitive sensing electrode has a first capacitance while the object is not coupled to the capacitive sensing electrode; generating a switch signal while the object is coupled to the capacitive sensing electrode under the standby mode such that the capacitive sensing electrode has a second capacitance larger than the first capacitance; and switching the standby mode to the active mode according to the switch signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A capacitive sensor, comprising:
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at least one capacitive sensing electrode, the capacitive sensing electrode having a first capacitance while an object is not coupled to the capacitive sensing electrode, the capacitive sensing electrode having a second capacitance larger than the first capacitance while an object is coupled to the capacitive sensing electrode; a current source for charging the capacitive sensing electrode; a multiplexer for conducting the capacitive sensing electrode and the current source or conducting the capacitive sensing electrode and a ground, such that the capacitive sensing electrode is charged by the current source or discharged to the ground; a first charging/discharging control module for controlling the multiplexer under an active mode so as to charge/discharge the capacitive sensing electrode for predetermined times; a second charging/discharging control module for controlling the multiplexer under a standby mode so as to charge/discharge the capacitive sensing electrode during a fixed period; and a controller for alternately controlling the first charging/discharging control module and the second charging/discharging control module under the active mode and the standby mode, such that capacitive sensing electrode is alternately charged/discharged under the active mode and the standby mode. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A capacitive sensor, comprising:
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a plurality of capacitive sensing electrodes, wherein while an object is not coupled to any of the capacitive sensing electrodes, each of the capacitive sensing electrodes has a first capacitance, and while the object is coupled to one of the capacitive sensing electrodes, the coupled capacitive sensing electrode has a second capacitance larger than the first capacitance; a current source for sequentially charging the capacitive sensing electrodes; a multiplexer for sequentially conducting the capacitive sensing electrodes and the current source or conducting the capacitive sensing electrodes and a ground, such that the capacitive sensing electrodes are charged by the current source or discharged to the ground; a first charging/discharging control module for controlling the multiplexer under an active mode so as to sequentially charge/discharge the capacitive sensing electrodes for predetermined times; a second charging/discharging control module for controlling the multiplexer under a standby mode so as to sequentially charge/discharge the capacitive sensing electrodes during a fixed period; and a controller for alternately controlling the first charging/discharging control module and the second charging/discharging control module under the active mode and the standby mode, such that capacitive sensing electrodes are sequentially and alternately charged/discharged under the active mode and the standby mode.
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Specification