Ex Parte Tsung

Board of Patent Appeals and Interferences

Dec 27, 2004

09870770 (B.P.A.I. Dec. 27, 2004)

The opinion in support of the decision being entered today was not written
for publication and is not binding precedent of the Board.
Paper No. 20
UNITED STATES PATENT AND TRADEMARK OFFICE
____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________
Ex parte WEI-JIUNG TSUNG
____________
Appeal No. 2004-1530
Application No. 09/870,770
____________
HEARD: December 12, 2004
____________
Before FRANKFORT, STAAB, and McQUADE, Administrative Patent Judges.
STAAB, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on an appeal from the final rejection of
claims 1-9, all the claims currently pending in the application.
Appellant’s invention pertains to a differential gear assembly
having an optimized number of gear teeth on the side gears and the
pinion mate gears. A further understanding of the invention can be
Appeal No. 2004-1530
Application No. 09/870,770
2
derived from a reading of exemplary claim 1, which reads as
follows:
1. A differential assembly comprising:
a rotatable differential case;
a pair of side gears rotatably mounted within said
differential case; and
a set of spaced apart differential pinion mate gears rotatably
supported by apinion shaft and drivingly engaging said side gears
to allow differential rotation therebetween;
wherein a sum of a first number of teeth of any one of said
side gears and a second number of teeth of any one of said pinion
mate gears is less than nineteen.
As evidence of obviousness, the examiner relies upon
appellant’s admitted prior art (AAPA) as set forth in the
application specification at page 1, line 15, through page 2, line
12; and page 6, line 14, through page 7, line 13.
Claims 1-9 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over AAPA.
Reference is made to appellant’s main and reply briefs (Paper
Nos. 10 and 12) and to the final rejection and examiner’s answer
(Paper Nos. 6 and 11) for the respective positions of appellant and
the examiner regarding the merits of this rejection. In addition,
Appeal No. 2004-1530
Application No. 09/870,770
1These include a publication entitled “Passenger Car Drive
Axle Gear Design” by GLEASON WORKS (Exhibit A) and what appears
to be excerpts from a book entitled “Handbook of Gears,” pages
T44-T45 (Exhibit B).
2The declaration in question is incorrectly identified as an
affidavit. The examiner has indicated in the advisory letter
mailed September 10, 2003 (Paper No. 15) that the reply brief and
declaration have been entered and considered.
3
appellant relies upon certain exhibits1 appended to the main brief
and the declaration of Todd Smith2 appended to the reply brief as
evidence of the state of the art at the time of appellant’s
invention.
Discussion
In rejecting the appealed claims under 35 U.S.C. § 103(a), the
examiner correctly found that the appealed claims differ from AAPA
only in the claim limitations regarding number of teeth on the side
gears and the number of teeth on pinion mate gears, and in the
relationships between these numbers (e.g., the sum of and/or the
difference between these numbers). Regarding these limitations,
the examiner takes the following position:
Applicant has also admitted in the disclosure from line
14 of page 6 of the specification until line 13 on page 7
of the specification that it was known to one skilled in
the art at the time the invention was made that gear
strength for any single pitch diameter is proportional to
the number of teeth. Therefore, the number of teeth on
the side gear and the number of teeth on the pinion gear
are both result-effective variables.
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Application No. 09/870,770
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It has previously been held that it is not inventive
to discover optimum ranges of [sic] by routine
experimentation where the general conditions of the claim
are disclosed in the prior art. In re Aller, 220 F.2d
454, 456, 105 USPQ 233, 235 (CCPA 1955). The particular
variable must first be recognized as being result-
effective before the determination of optimum ranges of
the variables may be characterized as routine
experimentation. In re Antoine, 559 F.2d 618, 195 USPQ 6
(CCPA 1977). Because it has been shown that the number
of teeth on any one of the side gears and the number of
teeth on any one of the pinion gears are result-effective
variables, it would have been obvious to one of ordinary
skill in the art at the time the invention was made to
optimize these tooth numbers in the differential admitted
to be prior art by applicant by selecting them such that:
A. the sum [of] the number of teeth of the side gear and
the number of teeth of the pinion mate gear is less than,
or alternatively, no greater than nineteen; B. the
difference between the number of teeth of the side gear
and the number of teeth of the pinion mate gear is no
greater than three; and C. the number of teeth of the
side gear and the number of teeth of the pinion mate gear
each is no greater that eleven. [Final rejection, page
3].
In the present case, appellant’s independent claims differ
from AAPA in that they call for, among other things, the number of
teeth on the side gear and the number of teeth on the pinion mate
gear to be such that the sum of these numbers is either less than
nineteen (claims 1 and 4) or no greater than nineteen (claims 5, 7
and 9). These limitations are consistent with appellant’s
disclosure at the bottom of page 2 of the specification that the
combination of side gear and pinion side gear should have numbers
of teeth optimized to provide improved power density and reduced
Appeal No. 2004-1530
Application No. 09/870,770
3In that appellant does not appear to challenge the
(continued...)
5
size. Given appellant’s purpose for selecting a combination of
side gear and pinion mate gear, and the lack of any teaching in
AAPA of selecting the number of teeth on the side gear and the
number of teeth of the pinion mate gear so that the combination
thereof achieves a desired result, we cannot accept the examiner’s
position that it would have been obvious to modify AAPA in a manner
to arrive at the subject matter of appellant’s independent claims.
In this regard, the examiner’s theory of obviousness based on the
principle of discovering the optimum value of a variable does not
apply here because the variable in question (i.e., the sum of the
number of teeth on the side gear and the number of teeth on the
pinion mate gear) has not been shown by the examiner to be
recognized in the art as being a result effective variable. In re
Antoine, 559 F.2d 618, 621, 195 USPQ 6, 8-9 (CCPA 1977).
In what may be termed an alternative theory of obviousness,
the examiner takes Official Notice “of the fact that the
relationship between the number of teeth on the side gear and the
number of teeth on the pinion mate gear, whether expressed as a
sum, a difference, or a ratio, determines the rate of rotation of a
wheel that has lost traction” (final rejection, page 4).3 On this
Appeal No. 2004-1530
Application No. 09/870,770
3(...continued)
examiner’s taking of Official Notice in this regard, we accept
the examiner’s statement as being a fair representation of what
is well-known to those of ordinary skill in the art.
6
basis, the examiner concludes that “it would have been obvious to
one of ordinary skill in the art to optimize the number of teeth of
the pinion mate gear and the side gear in the differential admitted
to be prior art such that the limitations of claims 1-9 are met”
(final rejection, page 4).
This alternative theory of obviousness likewise is not well
taken. It is not clear to us, and the examiner has not adequately
explained, why one of ordinary skill in the art would have any
interest or incentive whatsoever in selecting a combination of side
gear and pinion mate gear for a differential to provide a
particular rate of rotation of a wheel that has lost traction.
This is especially so in that it is common practice to explicitly
design differential gearing to have “limited slip” capabilities so
that when a wheel losses traction, the opposite wheel does not
freely spin. Thus, even in view of the examiner’s taking of
Official Notice, there is no teaching aside from the hindsight
knowledge first gained from reading appellant’s disclosure for
modifying AAPA in a manner that would have resulted in the claimed
Appeal No. 2004-1530
Application No. 09/870,770
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subject matter. It follows that we also cannot sustain the
standing rejection based on the examiner’s alternative rationale.
The decision of the examiner finally rejecting the appealed
claims is reversed.
REVERSED
CHARLES E. FRANKFORT )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
LAWRENCE J. STAAB ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
JOHN P. McQUADE )
Administrative Patent Judge )
LJS/lp
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Application No. 09/870,770
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LINIAK, BERENATO, LONGACRE & WHITE
6550 ROCK SPRING DRIVE, STE. 240
BETHESDA, MD 20817