A Capacitive Touch Sensing Technique with Series-connected Sensing Electrodes

Touch sensing with multiple electrodes allows expressive touch interactions. The adaptability and flexibility of the sensor are important in efficiently prototyping touch based systems. The proposed technique uses capacitive touch sensing and simplifies the connections as the electrodes are connected in series via capacitors and the interface circuit is connected to the electrode array by just two wires. The touched electrode is recognized by measuring the capacitance changes while switching the polarity of the signal. We show that the technique is capable of detecting different touches through simulations and actual measurements. User tests show that ten electrodes are successfully recognized after user calibration. They also show the proposal's other novel capabilities of multi-touch (2-touch) and 'capacitor-free' design. Various forms of electrodes and applications are examined to elucidate the application range.