High accuracy differential pressure capacitive transducer

US4458537A · kind A · utility

Assignee

• Combustion Engineering, Inc. · US

Inventors

• Robert L. Bell · Calabasas, US
• Richard A. Lathlaen · Thousand Oaks, US

Key dates

• Filing date: May 11, 1981
• Grant date: Jul 10, 1984
• Expiry date: May 11, 2001

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L13/025
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A capacitive pressure transducer is disclosed in which a sensing diaphragm bearing an electrode is mounted to flex in response to applied fluid pressure relative to a reference member having an opposed electrode. A thin film or layer of dielectric material such as glass covers the reference member electrode and has formed therein a concavity matching the flexed curvature of the sensing diaphragm at its limit position. The dielectric layer has a high compressive strength and substantially enhances linearity by providing a substantially higher capacitance than the equivalent fluid-filled space. The transducer is retained within a transducer assembly under compressive preload, the assembly further including thermal strain relief means. Also disclosed are methods of making the transducer, which methods include thick film screen deposition techniques for forming concavities having preselected contours in the dielectric layer.