| 摘要 |
The invention relates to a capacitive proximity device (30, 40, 50, 60) for sensing a presence and/or absence of an object (32) in the proximity of an electronic device (34). The capacitive proximity device (30, 40, 50, 60) comprises: an emission electrode (TA) capacitively coupled to a receiver electrode ( ), an oscillator (17) for generating an emission-signal (ES) being an alternating electric field ( ) between the emission electrode (TA) and the receiving electrode ( ), and a sensing circuit (70, 72, 74, 76, 78) connected to the receiving electrode ( ). The sensing circuit receives a measured-signal (MS) from the receiver electrode ( ), and comprising a first synchronous detection circuit ( ) together with a low-pass filter (14) for generating an output-signal (OS) being proportional to a distance between the object and the electronic device. The sensing circuit further comprising noise-suppression means for reducing noise from the measured-signal (MS) before entering the first synchronous detection circuit. The inventors have found that additional noise-suppression techniques are required when applying the known capacitive sensors in a electronic device.
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