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:
Jan. 15, 1980
Filed:
Aug. 14, 1978
Earl K Davis, Tempe, AZ (US);
Kent W Hansen, Scottsdale, AZ (US);
Scot W Taylor, Tempe, AZ (US);
Robert M Wentworth, Phoenix, AZ (US);
Motorola, Inc., Schaumberg, IL (US);
Abstract
An inexpensive glass capacitive pressure sensor. Conductive capacitor electrodes are disposed on two flat glass plates, one serving as a diaphragm, the other as a substrate. The electrodes are positioned in a spaced apart, substantially parallel relationship to form the plates of a parallel plate capacitor. The glass plates are sealed together with a sealing glass mixture to bound a volume between the conductors. The volume is at a reference pressure, preferably a substantial vacuum. Differences between the pressure to be measured and this reference pressure cause a flexing of the glass diaphragm which is detected by measuring the capacitance between the two electrodes. A suitable sealing glass mixture which provides a hermetic seal between the glass plates is comprised of, in weight percent, 8-10 SiO.sub.2, 1-2 Al.sub.2 O.sub.3, 55-60 PbO, 7-9 PbF.sub.2, 7-10 ZnO, 4-6 CdO, and 10-15 B.sub.2 O.sub.3. The sealing glass mixture must be vacuum fined to permit hermetic sealing within a vacuum.