SENSOR DEVICE, AND SENSOR SYSTEM AND ELECTRONIC DEVICE USING THE SENSOR DEVICE

A sensor device which detects a positional relationship between an first member and second member, includes a signal source generating an electrical signal, a first electrode receiving the electrical signal and storing an electrical charge at a first part on the first member, a second electrode inducing an electrical charge at the second part on the second member, a third electrode inducing an electrical charge at the third part on the second member, a fourth electrode inducing an electrical charge at the fourth part on the first member, a reference electrode disposed at a fifth part on the second member to be connected to a reference voltage point, a fifth electrode inducing an electrical charge at the sixth part on the first member, and a differential amplifier amplifying a voltage difference between the fourth electrode and the fifth electrode and outputting a difference signal.