Force a displacement sensor with a capacitive transducer

US5750904A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Gunter Doemens · Holzkirchen, DE
• Markus Gilch · Moosburg an der Isar, DE

Key dates

• Filing date: Feb 11, 1997
• Grant date: May 12, 1998
• Expiry date: Feb 11, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L1/142
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The force or extension sensor has a measuring capacitor (Mk) whose electrode structures (Es1, Es2), of comb-like design and interengaging, can be moved parallel to one another via two securing points (Bp1, Bp2) as a function of the force (F) to be measured or of the extension (.di-elect cons.) to be measured. The total capacitance of the measuring capacitor (Mk) is determined by parallel connection of individual electrode pairs. The variation in the total capacitance of the measuring capacitor (Mk) due to variation of the electrode separations (d1) gives information regarding the force (F) to be measured or the extension (.di-elect cons.) to be measured. A change in the electrode separations due to thermally induced extensions is compensated by providing, in the electrical series circuit connected to the measuring capacitor (Mk), an identically designed compensating capacitor (Kk) arranged orthogonally to the measuring capacitor (The), the securing points (Bp3, Bp4) of this compensating capacitor (Kk) are selected such that thermally induced variations in the electrode separation (d1, d3) of the measuring capacitor (Mk) and of the compensating capacitor (Kk) have opposite signs.