Touch screen device

A touch screen device comprising:

• a touch screen;
• and
• a touch pen transmitting a plurality of pen output signals to the touch screen,
• wherein the touch pen adjusts the pen output signals according to pressure applied thereto when the touch pen contacts the touch screen,
• during a touch screen driving period, the touch pen outputs the pen output signal in synchronization with a touch electrode driving signal of the touch screen, the touch electrode driving signal being supplied for detecting a position of a touch input,
• the touch pen output signal includes a first pen output signal and a second pen output signal,
• the first pen output signal includes N number of pulses where a first voltage and a second voltage higher than the first voltage are repeated;
• the second pen output signal includes N number of pulses where the first voltage and a third voltage are repeated,
• the third voltage is adjusted within a range from the first voltage to the second voltage according to the pressure, and
• the touch screen senses pressure information according to a voltage difference between the second voltage and the third voltage, and
• the touch pen comprises:
• an alternating current (AC) signal generator outputting a first AC signal;
• a delayer delaying the first AC signal;
• a comparator comparing the delayed first AC signal with a reference voltage to output a second AC signal;
• and
• a signal processor outputting a pen output variable signal for adjusting the pen output signals according to a comparison result obtained by comparing phases of the first and second AC signals.