| 摘要 |
An object sensing system ( 50 ), and method, employing electric field sensing, also known as quasi-electrostatic sensing and which may be termed cross capacitive sensing, is described. The system ( 50 ) includes at least one electrode arrangement ( 30 ), each electrode arrangement ( 30 ) includes one electric field sensing reception electrode ( 32 ) and two electric field sensing transmission electrodes ( 34, 36 ). One of the electric field sensing transmission electrodes ( 36 ) is driven with an alternating voltage ( 130 ) including at least some antiphase portions, for example an inverted signal, in comparison to an alternating voltage ( 120 ) with which the other electric field sensing transmission electrode ( 34 ) is driven. This improves the spatial precision of object sensing performed by detecting changes in the current induced in the electric field reception electrode ( 32 ). In one arrangement the two electric field sensing transmission electrodes ( 34, 36 ) are in the form of annular rings arranged around the electric field sensing reception electrode ( 32 ).
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