A touch screen display circuit is disclosed which includes means for measuring
a voltage at two separate input terminals which represent a location on a touch
screen where pressure was applied. The display circuit includes means for defining
a time period during which the voltage is measured and means for converting the
measured voltage to a digital value. The means for measuring a voltage includes
an amplifier and a capacitor which are configured as an integrator. The means for
converting comprises a counter that measures an amount of time required for the
capacitor to dissipate its charge. A touch screen display system having a touch
screen which includes first and second sheets of conductive materials positioned
in a spaced apart relationship is disclosed. The touch screen display system utilizes
a means coupled to the first and second sheets for measuring a voltage at two separate
input terminals, a means for defining a time period during which the voltage is
measured and a means for converting the voltage to a digital value.