Method of measured variable/frequency conversion on the basis of the parametric effect (parametric measured variable/frequency converter) and device for non-contact estimation and detection of the distances of an object (parametric distance/frequency converter) for carrying out and proving the method

摘要

In the present patent application a measured variable/frequency converter in general and a distance/frequency converter in particular are described. The method is based upon changes in the natural frequency of a parametric system in which - under certain conditions - continuous oscillations are observed. As an example, the distance of a metallic or also non-metallic object can be measured without contact (distance estimation) with the aid of the parametric distance/frequency converter. The maximum distance to be measured can be varied within wide limits by means of corresponding selection of the active sensor surface. When using the system in the millimetre range, a slope of the transfer characteristic line of 0.1 nm/Hz is achievable. By a corresponding selection of the operating point, the sensor can be used as a proximity switch (distance detection). The parametric self-excitation is then initiated only when the distance falls below a threshold distance Ls. If both properties are combined, only those distances which are smaller than Ls are estimated.