Capacitive pressure sensors with high linearity by optimizing electrode boundaries

US5792957A · kind A · utility

Assignee

• Endress+Hauser Inc. · DE

Inventors

• Ernst Luder · Stuttgart, DE
• Traugott Kallfass · Bornsteiner Straße, DE
• Hubert Benzel · Neckartenzlingen, DE
• Joerg Schaepperle · Stuttgart, DE

Key dates

• Filing date: Jul 19, 1994
• Grant date: Aug 11, 1998
• Expiry date: Jul 19, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L9/0075
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In a first variant of this pressure sensor with a substrate and a diaphragm which are joined together parallel to each other in a defined spaced relationship, forming a chamber sealed at least at the edge, the chamber-side surface of the diaphragm is completely covered with a diaphragm electrode. The chamber-side surface of the substrate supports a reference electrode consisting of an outer portion, which extends along the edge of the chamber and whose capacitance is virtually pressure-independent, and a pressure-dependent central portion, which is located at the center of the substrate and is connected with the outer portion via a connecting portion. The remainder of the substrate surface is covered with a measuring electrode spaced from the reference electrode by a constant distance. In a second circular variant and in a third, rectangular variant, the reference electrode consists of an outer portion, which extends along the edge of the chamber and whose capacitance is virtually pressure-independent, and two pressure-dependent central portions, which are each located in one half of the substrate symmetrically with respect to the substrate center and are connected with the outer p…