Appeal 2007-0128
Reexamination Control 90/006,208
Patent 5,573,648
REEXAMINATION
A request for reexamination was filed on January 29, 2002 by Third Party
Requester Figaro Engineering for reexamination of U.S. Patent 5,573,648 (the
>648 patent) issued November 12, 1996 to Yousheng Shen, Franco Consadori and
D. George Field. The >648 patent is assigned to Atwood Mobile Products, Inc.,
hereinafter AAtwood.@
I. STATEMENT OF THE CASE
The invention relates to gas sensors. As explained in the background section
of the '648 patent, it is well known that carbon monoxide (CO), reacts with
moisture in the air at room temperature and forms protons, electrons and carbon
dioxide (CO2) in an oxidation reaction of CO. ('648, col. 1, ll. 24-30). Conversely,
it is also known that there is a moisture formation reaction where protons, electrons
and oxygen combine in a reduction reaction to form water. ('648, col. 1, ll. 31-36).
Through the use of these two reactions, prior art gas sensors utilizing a proton
conductor were able to detect the presence of carbon monoxide. The '648 patent
alleges however, that prior art sensors were complicated and required periodic
maintenance. ('648, col. 2, ll. 12-14 and 23-25).
Of the claims on appeal, only claims 1 and 79 are independent claims. Each
of the independent claims is directed towards electrochemical gas sensors for the
quantitative measurement of a gas in an ambient atmosphere. (Appeal Br.,
Appendix, preamble of claims 1 and 79). The gas sensors comprise a sensing
2
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