Capacitance measuring circuit of a touch sensor and capacitive touch panel having the capacitance measuring circuit

Abstract

A capacitance measuring circuit of a touch sensor includes a voltage comparing part, a control part, a complex switch, a charging/discharging circuit part and a timer part. The voltage comparing part outputs a first comparing signal by comparing with a first reference voltage and a sensing voltage of a touch sensor and a second comparing signal by comparing with a second reference voltage and the sensing voltage, in response to a first control signal provided from an external device. The control part outputs a charging/discharging control signal based on the first and second comparing signals, in response to a second control signal provided from an external device. The complex switch is connected to each two terminals of the touch sensors, and is configured to set a path transmitting a sensing signal to the touch sensor and a path receiving a sensing signal sensing a capacitance variation amount of the touch sensor via the touch sensor.