TOUCHSCREEN WITH Z-VELOCITY ENHANCEMENT

A system and a method are disclosed for detecting an interaction, such as physical contact, with a touch-sensitive screen. The screen comprises a plurality of cells each associated with a signal value, such as a capacitance, that is modified based on the proximity of an object to the screen. During a first time interval, a first signal value associated with a cell is captured and during a second time interval a second signal value associated with the cell is captured. A difference is computed by subtracting the second signal value from the first signal value. The difference is used to classify the proximity of the object to the screen. For example, the object is classified as approaching the screen if the difference is positive and non-zero or the object is classified as moving away from the screen if the difference is negative and non-zero.