Patent ID: 6373474
Filing Date: 2002-04-16
Classification: G06F

Abstract:
A real contact type touch panel apparatus in which a conductive surface disposed on a sensor panel is directly contacted by a finger or a conductor, the real contact type touch panel apparatus comprising: a voltage-floating system comprising the sensor panel having the conductive surface disposed thereon, a signal processing unit connected to the sensor panel, and a reference potential circuit connected to the signal processing unit; a non-floating system comprising an interface connected to an external apparatus, and a ground circuit; and an isolator for transmitting digital or analog electric information between the signal processing unit and the interface; wherein the reference potential circuit of the voltage-floating system is connected in series to the ground circuit of the non-floating system through an AC signal generator and an AC signal coupling capacitor, the AC signal coupling capacitor having a capacity of 5000 pF or less, the signal processing unit has an input circuit operating as a current/voltage conversion circuit comprising a transistor and a resonance circuit connected to an output of the transistor, the transistor having a base or gate grounded in an AC condition with respect to the current/voltage conversion circuit, an emitter or source into which an AC signal is input, and a collector or drain connected to the resonance circuit, and the resonance circuit comprises a coil and a capacitor.