The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 26, 1989
Filed:
Jul. 12, 1989
Milton W Mathias, Colorado Springs, CO (US);
Douglas W Wilda, Ambler, PA (US);
Honeywell Inc., Minneapolis, MN (US);
Abstract
An absolute pressure transducer includes a hollow glass tube supporting across one end thereof a differential pressure responsive semiconductor plate having piezoresistive elements diffused therein and an evacuated sealed chamber within the tube exposed to the plate. A method for making the transducer and providing the evacuated chamber within the tube adjacent to the plate includes the steps of mounting the plate across the end of the tube to form a first fluid-tight seal therewith, inserting a loose glass plug within the tube to define the chamber, exposing the interior of the tube to a vacuum, concurrently heating the tube in the vicinity of the plug to allow the heated tube wall to constrict around the plug in response to the internal vacuum and to fuse with the plug to form a second fluid-tight seal therewith and allowing the tube and plug to cool to trap the vacuum in the chamber. A pressure transmitter uses the transducer with electrical connections to the piezoresistive elements in a fluid filled system for applying an external pressure to the plate to produce an output signal from the elements representative of the differential pressure between the evacuated chamber and the external pressure.