Abstract: Proximity of a person causes a change in a capacitance value of a sensor capacitor having a pair of capacitive plates. The change is detected by charging the sensor capacitor by coupling the sensor to a voltage supply. The supply is disconnected from a tank capacitor during the charging. The charge is transferred from the sensor capacitor to a tank capacitor. The supply is disconnected from the tank capacitor during the charge transfer. The charging and charge transfer are repeated several times. The voltage of the tank capacitor is monitored. At least one value is determined which depends on the rate of change of the voltage of the tank capacitor. The capacitance of the tank capacitor may be several orders of magnitude higher than the capacitance of the sensor capacitor. The large tank capacitor acts as a part of a low-pass filter which effectively filters out signal noise.

Abstract: A storage system (500) comprises a storage unit (100), wherein said storage unit (100) has sites (S1a, S1b) for accommodating two or more of said objects (G1), said storage unit (100) further comprising one or more capacitive proximity sensors (50) arranged to detect the presence of said objects (G1) in the vicinity of said sites (S1a, S1b). The storage unit may be e.g. a shelving in a retail store. The filling ratio (N/Nmax) or the number (N) of objects on the shelves (90) may be monitored in real time. Consequently, out-of-shelf situations may be effectively avoided.

Abstract: A sensor (100) for capacitively detecting presence of conductive objects (BOD1) comprises a first signal electrode (10a), a second signal electrode (10b), and a base electrode structure (20), wherein the distance (s3) between said first signal electrode (10a) and said second signal electrode (10b) is smaller than or equal to 0.2 times the width (s1) of said first signal electrode (10a), and wherein at least a part of said base electrode structure (20) is between said first signal electrode (10a) and said second signal electrode (10).

Abstract: Proximity of a person causes a change in a capacitance value of a sensor capacitor having a pair of capacitive plates. The change is detected by charging the sensor capacitor by coupling the sensor to a voltage supply. The voltage supply is disconnected from a tank capacitor during the charging. The charge is transferred from the sensor capacitor to a tank capacitor. The voltage supply is disconnected from the tank capacitor during the charge transfer. The charging and charge transfer are repeated several times. The voltage of the tank capacitor is monitored. At least one value is determined which depends on the rate of change of the voltage of the tank capacitor. The capacitance of the capacitive sensor is typically low, typically in the order of 100 pF to 1 nF. The capacitance of the tank capacitor may be several orders of magnitude higher than the capacitance of the sensor capacitor. The large tank capacitor acts as a part of a low-pass filter which effectively filters out signal noise.