CHARGE SENSING APPARATUS OF TOUCH PANEL THAT REMOVED AN OFFSET CHARGE AND LOW FREQUENCY NOISE THEREOF, REDUCING LOW FREQUENCY NOISE GENERATED BY NOISE INCLUDED IN SIGNAL ITSELF AND A TOUCH OF PANEL AND CONDUCTOR

摘要

PURPOSE: A charge sensing apparatus of touch panel that removed an offset charge and low frequency noise is provided to guarantee sufficient sensitivity to catch a small change of charge and minimizing the noise.;CONSTITUTION: A charge sensing apparatus of touch panel(100) comprises a signal transmitting unit(110), a capacitance sensor(120), a signal receiver(130), a noise eliminator(140), and an automatic compensator(160). The signal transmitting unit outputs by generating sensing signal that includes information about the sampling point. The capacitance sensor receives the sensing signal through an input terminal. The capacitance sensor outputs the first charge and the second charge repetitively in order, through an output terminal. The automatic compensator, by using the charge outputted, generates a plurality of offset control signals to set offset charge quantity. The automatic compensator outputs by generating the first modified charge and the second modified charge, responding to the offset control signals; the first modified charge is calculated by removing offset charge from the first charge and the second modified charge is calculated by removing offset charge from the second charge. The signal receiver outputs the first cumulated voltage and the second cumulated voltage by sampling the first modified charge and the second modified charge in N times respectively, and controlling gain. The noise eliminator calculates the difference of the first cumulated voltage and the second cumulated voltage, after receiving the first cumulate voltage and the second cumulate voltage sequentially. The noise eliminator outputs the low frequency noise removed voltage difference which is generated by touching the conductor on the touch panel.;COPYRIGHT KIPO 2013;[Reference numerals] (110) Signal transmitting unit; (131) Sampling unit; (133) First charge accumulation unit; (134) Second charge accumulation unit; (135) Gain controller; (143) CDS controller; (145) CDC unit; (160) Automatic compensator