CHARGE SENSING APPARATUS OF TOUCH PANEL THAT REMOVED LOW FREQUENCY NOISE WHICH ACCUMULATES WITHOUT AMPLIFYING QUANTITY OF ELECTRIC CHARGE UPON TOUCH STATUS OF A TOUCH PANEL

摘要

PURPOSE: A charge sensing apparatus of touch panel that removed low frequency noise is provided to guarantee sufficient sensitivity to catch a small change of charge and minimizing the noise by reducing the low frequency noise.;CONSTITUTION: A charge sensing apparatus(100) of touch panel comprises a signal transmitting unit(110), a capacitance sensor(120), a signal receiver(130), a noise eliminator(140), and an AD(Analog to Digital) converter(150). The signal transmitting unit outputs by generating sensing signal including the information about the sampling point. The capacitance sensor comprises an input terminal and an output terminal. The input terminal receives the sensing signal. The output outputs the first charge and the second charge repetitively in order, when the conductor touches the touch panel by responding to the received sensing signal. 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. The AD converter outputs the voltage difference transmitted to digital signal.;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) CDS unit