Patent ID: 7403127

Claim:
A device for establishing and/or monitoring a predetermined fill level of a liquid in a container, comprising: a mechanical oscillatory structure including a membrane and two mutually separated oscillation bars formed on said membrane and adapted to execute oscillations perpendicular to their longitudinal axis, said mechanical oscillatory structure oscillating with a first resonance frequency, when it is immersed in liquid, and with a second resonance frequency, when it is out of the liquid, and said mechanical oscillatory structure being placed at the height of said predetermined fill level such that at least said oscillation bars are immersed in the liquid, if said predetermined fill level has been reached; an electromechanical transducer for exciting the oscillatory structure to oscillate and for changing oscillations of said oscillatory structure into an electrical received signal; and a receiver- and evaluation-unit for establishing and/or monitoring, based on a frequency of said electrical received signal, whether the predetermined fill level has been reached, wherein: said oscillation bars have a shape in which a mass moment of inertia of a liquid quantity, which moves with the oscillating oscillation bars immersed within the liquid is greater than 0.2 times a mass moment of inertia of the oscillation bars.