Active stylus pen and touch sensing system including the same

A touch sensing system, comprising:

• a touch screen;
• a touch driving device configured to apply an uplink signal and a touch sensor driving signal to the touch screen;
• and
• an active stylus pen configured to generate a pen driving signal synchronized with the touch sensor driving signal and to output the generated pen driving signal to the touch screen,
• wherein the active stylus pen includes:
• a housing connected to an electrical ground;
• a conductive tip protruding outwardly beyond the housing, the conductive tip being operable to contact the touch screen;
• a conductor layer at least partially surrounding an outer surface of the housing with a first electrical insulator layer interposed therebetween;
• a pen driving circuit configured to receive the uplink signal and the touch sensor driving signal from the touch screen, and to output the pen driving signal to the touch screen through the conductive tip, the pen driving circuit being housed within the housing;
• and
• a switch configured to electrically couple the conductor layer to the pen driving circuit during a reception section of a touch period, and to electrically decouple the conductor layer from the pen driving circuit during a transmission section of the touch period.

A method, comprising:

• applying an uplink signal and a touch sensor driving signal to a touch screen during a touch period;
• contacting the touch screen by a conductive tip of an active stylus pen;
• receiving, by a pen driving circuit housed within a housing of the active stylus pen, the uplink signal and the touch sensor driving signal during a reception section of the touch period;
• generating, by the pen driving circuit, a pen driving signal synchronized with the touch sensor driving signal;
• outputting the generated pen driving signal to the touch screen during a transmission section of the touch period;
• and
• controlling a switch to electrically couple a conductor layer that at least partially surrounds the housing of the active stylus pen to the pen driving circuit during the reception section of the touch period, and to electrically decouple the conductor layer from the pen driving circuit during the transmission section of the touch period.