Electrostatic capacity type touch sensor

摘要

The invention provides an electrostatic capacity type touch sensor that is not influenced by a parasitic capacitor formed between a sensor line connected to a touch sensor pad and other signal line and provides a stable sensor output. A sensor line connected to a touch sensor pad is connected to a non-inverting input terminal (+) of a charge amplifier. An LED is disposed in the touch sensor pad, and the cathode of the LED is connected to an LED signal line. Since the LED signal line is disposed adjacent to the sensor line, a parasitic capacitor is formed between the LED signal line and the sensor line. In order to keep the capacitance of this parasitic capacitor constant, a pull-up resistor is connected to the LED signal line. The LED signal line is biased to a power supply potential Vdd by the pull-up resistor.

主权项

1. An electrostatic capacity type touch sensor, comprising:
a touch sensor pad; a sensor line connected to the touch sensor pad; a charge amplifier having a first input connected to the sensor line and outputting an output voltage corresponding to a change of a capacitance at the touch sensor pad; a signal line disposed adjacent to the sensor line that connects a vibration motor associated with the touch sensor pad that indicates touch detection to a drive transistor that drives the signal line between a first potential and a second potential in correspondence with the output voltage of the charge amplifier, wherein the vibration motor is connected between the first potential and the signal line; a parasitic capacitor formed between the sensor line and the signal line; and a bias resistor connected in parallel with the vibration motor associated with the touch sensor pad that biases the signal line to a first potential so as to avoid floating of the signal line.