Touch screen system and method of driving the same

A touch screen system comprising:na touch screen panel comprising a plurality of first lines, a plurality of second lines crossing the first lines, and a plurality of sensing cells formed at crossing regions of the first lines and the second lines;a driving circuit for sequentially applying a driving signal to the first lines;a first sensing circuit for receiving capacitance change information sensed by the first lines, and generating a first sensing signal corresponding to the capacitance change information;a selecting unit for selectively coupling the first lines to the driving circuit or the first sensing circuit;a second sensing circuit for receiving the capacitance change information sensed by the sensing cells from the second lines, and generating a second sensing signal corresponding to the capacitance change information; anda processing unit for receiving a sensing signal from the first sensing circuit and/or the second sensing circuit, and determining a detected touch position,wherein each of the first sensing circuit and the second sensing circuit comprises:nan amplifying unit coupled to a corresponding one of the first lines or a corresponding one of the second lines;a sample/hold circuit for sampling a signal output from the amplifying unit in a sampling period; andan analog digital converter for converting a signal output from the sample/hold circuit into the first sensing signal or the second sensing signal, and outputting the first sensing signal or the second sensing signal to the processing unit, andwherein a period of an electric field signal emitted by an active stylus is set as 4/3 of the sampling period.

A method of driving a touch screen system comprising a plurality of first lines, a plurality of second lines crossing the first lines, and a plurality of sensing cells formed at crossing regions of the first lines and the second lines, the method comprising:nsequentially applying a driving signal provided by a driving circuit to the plurality of first lines;coupling the first lines, excluding a first line to which the driving signal is applied, to a first sensing circuit or a ground power source;outputting first capacitance change information, sensed by a sensing cell among the sensing cells, to a corresponding one of the second lines coupled to the sensing cell when a finger contacts the sensing cell corresponding to the first line to which the driving signal is applied, and generating a sensing signal corresponding to the first capacitance change information; andoutputting second capacitance change information, sensed by another one of the first lines and another one of the second lines coupled to another one of the sensing cells, to a corresponding one of the first lines coupled to the another one of the sensing cells when an active stylus contacts or approaches the another sensing cell corresponding to the another first line coupled to the first sensing circuit, and generating another sensing signal corresponding to the second capacitance change information,wherein the first sensing circuit samples the capacitance change information provided to the first line in a sampling period, andwherein a phase of a signal sampled by the first sensing circuit is reversed every 2 sampling periods.