CAPACITANCE MEASURING CIRCUIT OF A TOUCH SENSOR AND CAPACITIVE TOUCH PANEL HAVING THE CAPACITANCE MEASURING CIRCUIT

摘要

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.

主权项

1. A capacitance measuring circuit of a touch sensor, comprising:
a voltage comparing part outputting 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; a control part outputting 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; a complex switch connected to each two terminals of the touch sensors, and 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, in response to a third control signal provided from an external device; a charging/discharging circuit part charging a touch sensor selected by the complex switch from the first reference voltage to the second reference voltage or discharging the touch sensor selected by the complex switch from the second reference voltage to the first reference voltage, in response to the charging/discharging control signal; and a timer part receiving a third control signal and a fourth control signal provided from an external device, respectively measuring charging time and discharging time of the charging/discharging circuit part, respectively measuring entire charging time and entire discharging time, and outputting a corresponding output signal.