Patent ID: 9658095
Date: 2017-05-23
CPC Classifications: G01F

Claim:
1. Capacitive fill level sensor ( 10 ) for measuring the fill level (H 1 , H 2 ; H 1 ′, H 2 ′) of a medium ( 16 ) in a container ( 14 ), having an electrode unit ( 12 ), which has a strip-shaped measurement electrode ( 22 ), a strip-shaped counter electrode ( 24 ) and a strip-shaped first shielding electrode ( 26 , 28 , 40 ), wherein the first shielding electrode ( 26 , 28 , 40 ) surrounds the measurement electrode ( 22 ) at least partially, wherein a first AC voltage source ( 60 ) having a predefined frequency and amplitude is present, which is applied to the ground ( 62 ) and to which the first shielding electrode ( 26 , 28 , 40 ) is connected such that a shielding capacitor ( 54 , 56 , 58 ) formed between the first shielding electrode ( 26 , 28 , 40 ) and the measurement electrode ( 22 ) has a shielding capacitance that is proportional to the length of the first shielding electrode ( 26 , 28 , 40 ), wherein a second AC voltage source ( 66 ) of the same frequency and with predefined second amplitude is present, wherein the second amplitude is in phase opposition to the first amplitude, which is applied to the ground ( 62 ) and to which the counter electrode ( 24 ) is connected such that a measurement capacitor ( 52 ) formed between the counter electrode ( 24 ) and the measurement electrode ( 22 ) has a measurement capacitance, which is proportional to the fill level (H 1 , H 2 ; H 1 ′, H 2 ′) and wherein the measurement electrode voltage ( 72 ) applied to the measurement electrode ( 22 ) in relation to the ground ( 62 ) is used to determine the fill level (H 1 , H 2 ; H 1 ′, H 2 ′).