PASSIVE STYLUS AND GRIP SHADOW RECOGNITION

摘要

Various embodiments provide an object recognition process that is configured to detect a passive stylus and reject non-passive stylus objects on a touch screen, including an edge portion of the touch screen. In one embodiment, the object recognition process includes receiving sense signals from sense elements of a sense array in response to a touch object being on the sense array, selecting three sense signals from three respective sense elements, calculating a first sum of the strengths of the three selected signals, calculating a second sum of the strengths of two of the selected signals which are greater than the strength of one of the selected signals; and determining a type of the object (e.g., a passive stylus or a user hand's grip shadow) based on the first sum and the second sum.

主权项

1. A stylus sensor comprising:
reception circuitry which receives three signals having signal strengths S1, S2 and S3 respectively corresponding to three positions indicated by an object on a sensor surface, wherein the position corresponding to S2 is interposed between the positions corresponding to S1 and S3; and a processor coupled to the reception circuitry which, in operation,
(a) determines the object as a stylus if
i) S1+S2+S3b*S1 when S1b*S3 when S1≧S3); and(b) determines the object as not a stylus if
S1+S2+S3≧a*S2, and(S2+S3≦b*S1 when S1≦S3, orS2+S1≦b*S3 when S1≧S3).