Touch location sensing system and method employing sensor data fitting to a predefined curve

Methods and devices for determining the location of a touch implement relative to a touch locating sensing device involve developing touch signals at a touch sensor in response to a touch implement on or near the touch surface. Data associated with the touch signals is fitted to a predefined curve. The predefined curve is preferably defined by a charged sphere near a conducting plane, the charged sphere representative of an end of the touch implement and the conducting plane representative of the touch surface. A location of the touch implement is determined relative to the touch surface using the predefined curve to which the data is fitted.