Appeal No. 1999-2126 Page 6
Application No. 08/857,938
have found it obvious to install such a regulator in the
structure of the primary reference.
We part company with the examiner, however, with regard to
the double-walled tube modification. Robinson ‘241 appears to
accomplish the same objective as the appellants’ invention,
that is, to supply liquid from the clean side to both the
outlet to the point of use and, through the regulator, to the
return line to the supply tank. This is done by placing the
outlet line at one end of the central tube and the regulator
and return line at the other end. While it is true that
Wilkinson, Gebert and Burhans all disclose filters having a
central double-walled tube with the contents of the annular
outer passage flowing to one outlet and the contents of the
inner passage flowing to another, it is not enough that a
double-walled tube exists in the art, for the mere fact that
the structure of Robinson ‘241 could be modified does not make
such a modification obvious unless the prior art suggests the
desirability of doing so. See In re Gordon, 733 F.2d 900, 902,
221 USPQ 1125, 1127 (Fed. Cir. 1984). In the present case, we
fail to perceive any teaching, suggestion or incentive which
would have led one of ordinary skill in the art to modify the
Page: Previous 1 2 3 4 5 6 7 8 9 Next
Last modified: November 3, 2007