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CN103959651A 以具有用于驱动防护环的数字输出的微控制器来测量电容性传感器的电容 有权

以具有用于驱动防护环的数字输出的微控制器来测量电容性传感器的电容
摘要：
围绕每一电容性传感器板提供防护环(320)且将所述防护环充电到实质上与所述电容性传感器板上的电压相同的电压。所述防护环减小由所述电容性传感器板与邻近电路导体、接地平面及电源平面之间的电压电位差引起的所述电容性传感器板的寄生电容。使用两个数字输出(724，728)及相关联的分压器电阻器(708，710)将防护环电压驱动到实质上与所述电容性传感器板上的所述电压相同的电压。
摘要（英）：

A guard ring (320) is provided around each capacitive sensor plate and charged to substantially the same voltage as a voltage on the capacitive sensor plate. The guard ring reduces parasitic capacitances of the capacitive sensor plate caused by differences in voltage potentials between the capacitive sensor plate, and adjacent circuit conductors, ground planes and power planes. Two digital outputs (724, 728) and associated voltage divider resistors (708, 710) are used to drive the guard ring voltage to substantially the same voltage as the voltage on the capacitive sensor plate.

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