Patent ID: 9389724
Filing Date: 2016-07-12
CPC Classification: G06F

Claim Text:
1. A touch sensitive system comprising: a touch panel comprising a transparent capacitive sensing medium including a first set of electrodes and a second set of electrodes arranged to form a matrix and an insulating layer arranged between the first set of electrodes and the second set of electrodes, the matrix having a plurality of nodes defined by areas on a touch surface of the transparent capacitive sensing medium where the first set of electrodes and the second set of electrodes traverse one another; a stylus electrode arranged in a stylus housing; a stylus drive unit configured to provide a stylus drive signal to the stylus electrode; a touch panel sense unit configured to generate, for each stylus drive signal provided to the stylus electrode, if capacitively coupled to an electrode in the touch panel, touch panel response signals, each of the touch panel response signals comprising a differentiated representation of the stylus drive signal, the differentiated representation of the stylus drive signal being an output signal of a differentiation circuit, the output signal being substantially a derivative with respect to time of an input signal received by the differentiation circuit, the input signal being indicative of the stylus drive signal, an amplitude of each of the response signals being responsive to the coupling capacitance between the stylus electrode and at least one electrode in the touch panel, the amplitude of the response signals being substantially linearly proportional to the coupling capacitance; a measurement unit configured to measure or receive input indicative of the amplitude of the touch panel response signals and to determine therefrom the position of the stylus, if present, on the touch surface.