| 摘要 |
Proximity of a body, which may be a user's finger, to an electrode pair (100, 104) is sensed by a charge transfer capacitive measurement approach. The electrode pair (100, 104) thus act as a key (10) that can be arrayed with other electrode pairs to form a keypad, keyboard, linear slider control, or liquid level sensor. In one embodiment of the invention, each key is associated with an alternating voltage source (101) and a pair of electrodes (100, 104) mounted on or within a solid dielectric substrate (103) or panel so as to be separated from each other by a gap. The voltage source (101) is connected to a driven electrode (100), a sampling charge detector (402) is connected to a second, receiving, electrode (104), and the output of the charge detector is, in turn, fed into an amplifier (403) and a charge measurement means (407). Disturbances in coupling between the two electrodes (100, 104) are detected through the solid substrate or panel material (103) when a substance or object approaches or contacts the panel. The receiving electrode (104) is a low-impedance node during the sampling phase of the process, which aids in keeping the sensor from being affected by wiring length or extraneous objects near an output lead.
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