CAPACITIVE PROXIMITY SENSOR

摘要

PURPOSE: To obtain a capacitive proximity sensor suitable for various applications and having various shapes and sizes. CONSTITUTION: The capacitive proximity sensor 10 comprises a sensing electrode 11, a guard electrode 12 and an insulator 13 for isolating therebetween. Such a sensor 10 is formed of a double surface circuit board. The other sensor is formed in a frame or annular shape formed of a conductive mesh. The electrodes 11, 12 are commonly driven by a radio frequency(RF) signal. The capacitance between the electrode 11 and the circumstance is changed as an object approaches, and the change of the capacitance can be sensed by measuring the change of the RF of the current flowing from the electrode 11. The electrode 12 serves as a role of shielding the electrode 11 from the object of one side of the sensor 10. When both the electrodes are commonly driven, no current flows therebetween. Therefore, the change of the capacity of the guard electrode affects no influence at all.