Push amount detecting sensor and touch input device

A touch input device comprising:

• a push detecting sensor that includes:
• a touch panel that includes a piezoelectric sensor that outputs a push signal corresponding to a displacement amount when a surface of the touch panel is pushed;
• a touch detecting sensor that outputs a touch detection signal when the surface of the touch panel is touched;
• a push amount calculating circuit that is coupled to the touch detecting sensor and receives the touch detection signal;
• and
• a switching element that controls the push amount calculating unit, based on a state of the touch detection signal, to switch between integrating a difference between the push signal and a reference potential to generate a push amount detection signal and resetting the reference potential,
• wherein the switching element controls the push amount calculating circuit to integrate the difference between the push signal and the reference potential when the state of the touch detection signal indicates an operation state in which the touch panel is being touched, and
• wherein the switching element controls the push amount calculating circuit to reset the reference potential when the state of the touch detection signal switches to an untouched state of the touch panel to stabilize the reference potential,
• wherein the touch input device is configured to output the touch detection signal together with the push amount detection signal.