| 摘要 |
PCT No. PCT/SI94/00013 Sec. 371 Date Jan. 30, 1996 Sec. 102(e) Date Jan. 30, 1996 PCT Filed Jul. 25, 1994 PCT Pub. No. WO95/04261 PCT Pub. Date Feb. 9, 1995Selfadjusting capacitive level switch for a non-contact or contact sensing of media or objects comprising a sensor (S6), on a dielectric body (db) of which between an opposite plate (op) and a plate (p) a screening plate (sp) is mounted. Starting from the plate (p) there are alternately mounted additional screening plates (sp1, . . . , spn+1) connected through a resistor (r1) to the screening plate (sp) and additional plates (p1, . . . , pn). Groups of additional plates (p1, . . . , pn+1) are connected through resistors to the inverting input of an operational amplifier (1). At the beginning of each oscillation halfperiod the potential of the plates (p, p1, . . . , pn) has a phase opposite to the phase of the screening plates (sp, sp1, . . . , spn+1). The level switch detects electrically very poorly conductive materials with the relative permittivity near to 1 even through a thick, electrically well conductive deposit on its sensor.
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