Frequency-selective vibration sensor

摘要

The invention relates to a frequency-selective vibration sensor with a vibration sensing device (1) which is constructed on a silicon substrate (2) and has silicon tongues (9) as vibration-sensitive structures with staggered natural frequencies. The silicon tongues (9) are worked out of the silicon substrate with the aid of a suitable etching technique, for example anisotropic etching, anisotropic and electrochemical etching, isotropic etching for a short time or even a combination of these etching techniques. The output signals are picked up by means of piezoresistors (6) and preamplified in a preferably integrated preamplifier circuit (11a). In order to be able to use such vibration sensors flexibly and to achieve cost-effective manufacture, it is proposed according to the invention also to provide on the silicon substrate (2) a measurement transformer (11b), preferably to integrate it in turn. This measurement transformer can have a timing element (23), a threshold value switch (25) and/or a timing integral element (21) and, in addition, if appropriate an output relay (22, 24). The vibration sensing device (1) is connected via an interface (14, 16) to an evaluation circuit (15) which has a multiplex measuring circuit (26, 27, 28). The voltages which are brought about by the tongues (9) can be individually interrogated with this multiplex measuring circuit, sorted according to maximum and peak values and displayed. The vibration sensor serves preferably... Original abstract incomplete. <IMAGE>