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:
Jul. 31, 2001
Filed:
Oct. 06, 1998
Peter M. Livingston, Palos Verdes Estates, CA (US);
TRW Inc., Redondo Beach, CA (US);
Abstract
A method and device for determining concentration and rate of change of concentration of a gas having ability to act as crystal etchant, such as hydrofluoric acid (HF) or deuterium fluoric acid (DF) gas. A crystal,is placed in a chamber and subjected to erosion by the gas. The crystal resonant frequency, changeable during the crystal erosion, is determined and a crystal resonant frequency change is calculated to determine the concentration of the gas. The crystal,is preferably an AT-cut quartz crystal. The step of obtaining the crystal resonant frequency is preferably performed in a Colpitts oscillator. The step of calculating the gas concentration, proportional to the change in the crystal resonant frequency, may also encompass calculating a change and rate of change in the gas concentration, and averaging the calculated gas concentration. The crystal,is preferably inserted in a crystal holder,and mounted on an electronic box,which holds the oscillator board. The crystal,is partially protected with a cover,and is easily replaceable.