1. Field of the Invention
The invention relates to an electrostatic capacity type touch sensor.
2. Description of the Related Art
Conventionally, an electrostatic capacity type touch sensor is known as a data input device for various types of electronic devices such as a cellular phone, a portable audio device, a portable game device, a television, a personal computer and so on.
This type of electrostatic capacity type touch sensor performs touch detection by detecting a capacitance change of a capacitor that a touch sensor pad has by a touch or approach of a human finger, a tip of a pen or the like (hereafter, referred to as a human finger or the like) to the touch sensor pad.
A relevant technique is disclosed in the Japanese Patent Application Publication No. 2005-190950.
Since the electrostatic capacity type touch sensor detects a capacitance change of a capacitor that a touch sensor pad has, when a capacitance of a parasitic capacitor formed between a sensor line connected to the touch sensor pad and other signal line changes, there occurs a problem that the touch sensor detects the capacitance change.
For example, there is a case that an LED (the abbreviation of a Light Emitting Diode) is disposed on a touch sensor pad to light the LED in response to a touch detection.
In this case, when a sensor line connected to the touch sensor pad and a LED signal line are disposed close, a parasitic capacitor is formed between these. Then, when the capacitance of this parasitic capacitor changes due to a change of the electric state of the LED signal line (e.g. floating→L level→floating, floating→H level→floating), the electrostatic capacity type touch sensor detects the capacitance change of this parasitic capacitor, thereby causing a problem that the sensor output is unstable.