CAPACITANCE-TYPE SENSOR

摘要

The distance between a subject to be detected and a sensor is accurately measured by reducing differences among sensor output fluctuation quantities, differences among sensor initial capacities, and the like, and the subject to be detected is highly accurately detected.  The capacitance-type sensor is provided with sensor electrodes (1-5) constituting a sensor electrode group (6), and a pair of guard electrodes (28a, 28b).  Each of the sensor electrodes (1-5) is driven by having a sensor potential or a guard potential applied thereto, and the guard electrodes (28a, 28b) are driven by having a guard potential applied thereto.  Since the guard electrodes (28a, 28b) are driven with the guard potential, even when the sensor electrodes (1, 5) on the outermost sides of the sensor electrode group (6) are active, the differences among the output fluctuation quantities and those among the initial capacities of the sensor electrodes (1-5) constituting the sensor electrode group (6) are substantially uniformized.