Capacitive sensing system using active shielding and operating method thereof
AssigneePixart Imaging Inc.
InventorsYU-SHENG LIN, CHIN-HUA HU, YUHAN CHEN
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Abstract
There is provided a capacitive sensing system including multiple sensor electrodes, an insulating layer and a single active shielding metal. The single active shielding metal has an overlapped region with each of the multiple sensor electrodes. The insulating layer is arranged between the single active shielding metal and the multiple sensor electrodes. When one of the multiple sensor electrodes is driven by a driving signal, the rest of the multiple sensor electrodes are grounded or receive an active shielding signal, and the single active shielding metal receives the active shielding signal.
Claims20
A capacitive sensing system, comprising:
- an electrode layer, comprising:
- a first electrode, connected to a first sensor line;
- and
- a second electrode, connected to a second sensor line;
- a single shielding layer, having an overlapped region with the first electrode and the second electrode, respectively, and
- an input capacitor, coupled to the single shielding layer, and arranged to have a capacitance identical to one of the first electrode and the second electrode having a larger ground capacitance.
A capacitive sensing system, comprising:
- a sensor chip;
- an input capacitor, connected to the sensor chip;
- and
- an electrode layer, comprising:
- a first electrode, configured to be coupled to the sensor chip via a first sensor line;
- and
- a second electrode, configured to be coupled to the sensor chip via a second sensor line;
- and
- a single shielding metal, coupled to the input capacitor, and having an overlapped region with the first electrode and the second electrode, respectively,
- wherein the input capacitor is arranged to have a capacitance identical to one of the first electrode and the second electrode having a larger ground capacitance, and
- the first electrode and the second electrode have identical areas.
An operating method of a capacitive sensing system, the capacitive sensing system comprising a sensor chip, a first electrode, a second electrode and a single shielding metal which has an overlapped region with the first electrode and the second electrode respectively and coupled to the sensor chip via an input capacitor, and the operating method comprising:
- charging the first electrode and the single shielding metal within a first time interval, wherein the first electrode and the single shielding metal have identical charging waveforms within the first time interval;
- charging the second electrode and the single shielding metal within a second time interval, wherein the second electrode and the single shielding metal have identical charging waveforms within the second time interval;
- and
- performing, by the sensor chip, a hand off detection on a vehicle steering wheel according to the charging waveforms within the first time interval and the second time interval.
Dependencies are inferred from the claim text.