Patent ID: 6938475

Claim:
A device for establishing and/or monitoring a predetermined fill level in a container, comprising: a mechanical oscillatory structure mounted to the container at the height of the predetermined fill level, said mechanical oscillatory structure has at least one membrane-mounted oscillation bar, which in operation executes resonance oscillations perpendicular to its longitudinal axis; an electromechanical transducer associate with and adapted to excite said mechanical oscillatory structure to oscillate with resonant oscillations; and a receiver and evaluation unit connected to said electromechanical transducer, which uses a resonance frequency of said resonance oscillations to determine whether the predetermined fill level has been reached, or not, wherein: each membrane-mounted oscillation bar has a paddle formed at its terminal end away from said electromechanical transducer, the width of said paddle is maximum in a middle section and decreases in the direction toward its free end, and said paddle is slanted in its end region at an angle α between 20° and 55° to the longitudinal axis of the paddle such that the resonance frequency changes slowly with the immersion depth.