Electrostatic capacitive touch sensor device
View Patent ↗An electrostatic capacitive touch sensor device includes sensing electrode provided at a plurality of positions, a high-frequency signal source that applies a high-frequency signal to the sensing electrode through a predetermined impedance element, a wiring portion that connects the sensing electrode and the impedance element, a shield portion provided to embrace the sensing electrodes and the connecting pattern, and a shield signal source that applies a shield signal to the shield portion and has the same phase and amplitude as the high-frequency signal source.
1. An electrostatic capacitive touch sensor device, comprising:
a first sensing electrode having a first electrostatic capacitance value that changes depending on a touch operation by an operator;
a second sensing electrode having a second electrostatic capacitance value that changes depending on a touch operation by the operator;
a wave signal source that outputs a wave signal;
a wiring that connects the wave signal source to the first and second sensing electrodes to provide the wave signal to the first and second sensing electrodes;
a first impedance element provided in the wiring at a position between the first sensing electrode and the wave signal source;
a second impedance element provided in the wiring at a position between the second sensing electrode and the wave signal source;
a first shield element that shields the wiring between the first sensing electrode and the first impedance element;
a second shield element that shields the wiring between the second sensing electrode and the second impedance element;
a first detector circuit connected to the first sensing electrode and the wave source signal, and outputting a first output signal that changes in accordance with changes in the electrostatic capacitance value of the first sensing electrode;
a second detector circuit connected to the second sensing electrode and the wave source signal, and outputting a second output signal that changes in accordance with changes in the electrostatic capacitance value of the second sensing electrode; and
a shield signal source connected to the wave signal source and to the first and second shield elements, and applying a shield signal to the first and second shield elements, the shield signal having a same phase and an amplitude as the wave signal, the shield signal source being directly connected to the wire at a position between the wave signal source and the first and second detector circuits.
2. The electrostatic capacitive touch sensor device according to claim 1 , wherein the shield signal source includes an output buffer circuit portion, and an output impedance value of the shield signal source is smaller than an output impedance value of the first and second impedance elements, respectively.
3. The electrostatic capacitive touch sensor device according to claim 2 , wherein the wave signal is a rectangular wave signal, the impedance element is a resistor, and the output buffer circuit portion is a C-MOS inverter element.