Patent ID: 9678597
Date: 2017-06-13
CPC Classifications: G06F

Claim:
1. A signal processing circuit connected to one of a plurality of conductors of a position detection sensor having a self-capacitance, the signal processing circuit including a capacitor circuit and configured to detect a change in capacitance between the conductor and a pointer as a change in voltage in the capacitor circuit, the signal processing circuit further comprising: a gate circuit which, in operation, controls a connection between the capacitor circuit and the conductor; a voltage supply control circuit which, in cooperative operation with the gate circuit, temporarily sets, to a defined voltage level, a first end of the gate circuit to which the conductor is connected, and sets a defined potential difference between the first end of the gate circuit and a second end of the gate circuit to which the capacitor circuit is connected, and an analog-digital conversion circuit which, in operation, converts a voltage signal form the capacitor circuit to a digital signal, wherein a first voltage signal produced in the capacitor circuit during detection of a position pointed to by the pointer and a second voltage signal, which is produced in the capacitor circuit due to the defined potential difference between the first and second ends of the gate circuit, are generated in a time divided manner and supplied to the analog-digital conversion circuit, and first and second digital signals that correspond respectively to the first and second voltage signals are generated, and the first digital signal is corrected using the second digital signal corresponding to the self-capacitance.