| 摘要 |
The invention relates to an evaluation circuit for a capacitive sensor for detecting the distance, the speed, or the position of an object, comprising a reference capacitance (1) and two measuring capacitances (21, 22), wherein a square wave voltage (3) is applied to the reference capacitance (1) and the measuring capacitances (21, 22) via a resistor, and a pulse (7) which has a variable duration is obtained with the aid of a logic linking unit (4) and which duration represents a measure of the respective measuring capacitance (21, 22), wherein the reference capacitance (1) is connected to the input of a first switching stage (41) and the measuring capacitances (21, 22) are connected to the inputs of further switching stages (42, 43), wherein at least one measuring capacitance (21, 22) has a capacitive coupling (15) to an auxiliary electrode (8), wherein the switching stages (42, 43) are part of a logic linking unit (4) which is designed so that reaching the threshold voltage of a first switching stage (41) determines the activation time of an output signal (7) and reaching the threshold voltage of a further switching stage (42, 43) determines the deactivation time of the output signal (7), and the output of the logic linking unit (4) is connected to the input of an integration stage (5), wherein a charging capacitor (Ca) is charged or discharged via the output of the integration stage (5). The invention also relates to a capacitive sensor and an actuator with said capacitive sensor. |
