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US 11,599,222 B2Granted
Detection device
AssigneeAlps Alpine Co., Ltd.
InventorTatsumi Fujiyoshi
Life of this patent
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Abstract
This detection device includes a sensor electrode, a shield electrode, which has a parasitic capacitance between the sensor electrode and the shield electrode and is driven by an AC voltage, a detection circuit, which is electrically connected to the sensor electrode and the shield electrode and detects the electrostatic capacitance of the sensor electrode, a capacitor, which is connected in series between the sensor electrode and the detection circuit, and a bias unit, which biases the potential of the sensor electrode via a resistor.
Claims7
A detection device comprising:
- a sensor electrode, an operating body causing an electrostatic capacitance of the sensor electrode to change;
- a shield electrode driven by an alternating-current voltage, the shield electrode having a parasitic capacitance formed between the sensor electrode and the shield electrode;
- a detection circuit electrically connected to the sensor electrode and the shield electrode, and configured to detect the electrostatic capacitance of the sensor electrode;
- a capacitor connected in series between the sensor electrode and the detection circuit;
- and
- a bias unit that biases a potential of the sensor electrode via a resistor,
- wherein the detection circuit includes a differential amplifier having a non-inverting input terminal and an inverting input terminal, the shield electrode being connected to the non-inverting input terminal, while the sensor electrode is connected to the inverting input terminal only via the capacitor.
4 more elements
Dependencies are inferred from the claim text.