| 摘要 |
The invention concerns apparatus for processing signals induced by a stylus applied to a digitizing tablet. The tablet produces four signals, A, B, C, and D, indicative of four currents, induced at four different points on the tablet, by the stylus. The four signals indicate the position of the stylus. The invention derives stylus position based solely on two difference pairs (A-D) and (B-C). Further, the computation of the difference-pairs suppresses common-mode noise, which otherwise interferes with computation of stylus position.
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