Abstract: A method for classifying input to a multi-touch sensitive digitizer that is obtained from a body part as inputs invalid for user interaction and inputs valid for user interaction comprises: identifying a plurality of discrete regions of input to a digitizer sensor; determining spatial relation between at least two of the regions; and classifying one of the at least two regions as either valid input region or invalid input region based on the spatial relation determined between the at least two regions.

Abstract: A digitizer system comprises at least one object incorporating an electronic tag configured for radiating at least one modulated signal and at least one second signal; a digitizer sensor configured for detecting the at least one second signal while the object is positioned on or over the digitizer sensor; and circuitry configured for identifying the object based on modulation of the at least one modulated signal and for determining a position of the object on or over the digitizer based on the detected second signal on a portion of the digitizer sensor.

Abstract: A system for determining information regarding at least one object, comprising: a sensor sensitive to capacitive coupling; at least one object adapted to create a capacitive coupling with the sensor when at least one signal is input to the sensor; a detector adapted to measure at least one output signal of said sensor associated with the at least one object, wherein the output signal associated with the at least one object is an object information code.