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. 21, 2003
Filed:
Sep. 16, 1999
Wenjun Yang, Sunnyvale, CA (US);
Peter C. Hsi, Fremont, CA (US);
RAE Systems, Inc., Sunnyvale, CA (US);
Abstract
A photo-ionization detector (PID) employs combinations of ion mobility spectrometry, ionization energy discrimination, and chemical filtering to identify the presence and quantity of specific gases. One such PID introduces a gas sample into an ionization chamber at an end of a drift tube. UV light from a PI source ionizes ionizable molecules contained in the gas sample. The PI source includes either multiple UV lamps, each having a specific energy level for discriminating between potential constituents of the gas sample or one multiple-energy level UV lamp with different light bandwidth window zones and a zone selector. A shutter grid separates the ionization chamber from the drift tube. When the shutter grid is open, an electric field in the drift tube attracts ions that travel against the flow of a drift gas until a collector electrode at the end of the drift tube captures the ions. A time required for the ions to travel the length of the drift tube is characteristic of the type of ion. Thin mesh electrodes in the drift tube sustain a uniform electric field so that groups of ions traveling down the drift tube to create well defined current pulses at the collector electrode.