Ex Parte Athari

Board of Patent Appeals and Interferences

Jan 7, 2010

10650246 (B.P.A.I. Jan. 7, 2010)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte FRANK ATHARI
____________

Appeal 2009-002507
Application 10/650,246
Technology Center 2800
____________

Decided: January 7, 2010
____________

Before MAHSHID D. SAADAT, THOMAS S. HAHN
and ELENI MANTIS MERCADER, Administrative Patent Judges.

SAADAT, Administrative Patent Judge.

DECISION ON APPEAL
Appellant appeals under 35 U.S.C. § 134(a) from a Final Rejection of
claims 2-13, which are all of the claims pending in this application as claim
1 has been canceled. We have jurisdiction under 35 U.S.C. § 6(b).
We affirm.
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STATEMENT OF THE CASE
Appellant’s invention relates to switching mode power supplies
(SMPS) and active electromagnetic interference (EMI) filters for such power
supplies and converters (Spec. 1:8-13). According to Appellant, a problem
with switching mode power supplies is that because of the high frequency of
the switching action of the semiconductor switches, EMI is generated and
radiated or conducted back to the power source (Spec. 1:17-20). Appellant
disposes an active EMI filter at the output of the switching stage that reduces
the physical size of the output EMI filtering and minimizes power loss
(Spec. 2:19-27).
Independent claim 8 is illustrative of the invention and reads as
follows:
8. A circuit arrangement comprising
a power transistor switching stage providing an output voltage
and
an active EMI filter having first and second input terminals and
first and second output terminals and a ground return line connected
to a ground return line terminal, the input terminals of the active EMI
filter being connected to receive the output voltage of the power
transistor switching stage and the output terminals of the active EMI
filter providing a filtered output voltage,
wherein the power transistor switching stage is a switch mode
power supply and the active EMI filter cancels common mode current
that flows between the input terminals and the output terminals,
substantially eliminating any current due to the common mode current
in the ground return line connected to the ground return line terminal.

The Examiner relies on the following prior art references in rejecting
the claims:
Ohkawa US 5,321,299 Jun. 14, 1994
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Sato US 5,731,689 Mar. 24, 1998
Suzuki US 6,067,243 May 23, 2000
Pelly US 6,636,107 B2 Oct. 21, 2003
(filed Mar. 23, 2001)
Kolar US 6,700,806 B2 Mar. 2, 2004
(effectively filed Jul. 12, 2001)

Claims 3-6 and 8-13 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Pelly in view of Kolar.
Claims 7 and 8 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Pelly in view of Sato.
Claim 2 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable over Pelly in view of Sato and Suzuki.
Claim 2 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable over Pelly in view of Kolar and Ohkawa.
Rather than repeat the arguments here, we make reference to the
Appeal Brief (filed May 20, 2008), the Reply Brief (filed Aug. 26, 2008),
and the Answer (mailed Jun. 26, 2008) for the respective positions of
Appellant and the Examiner. Since no claims are argued separately from the
others, we decide this Appeal on the basis of representative independent
claim 8. See 37 C.F.R. § 41.37(c)(1)(vii) (“When multiple claims subject to
the same ground of rejection are argued as a group by appellant, the Board
may select a single claim from the group of claims that are argued together
to decide the appeal with respect to the group of claims as to the ground of
rejection on the basis of the selected claim alone.”). Further, only those
arguments actually made by Appellant have been considered in this decision.
Arguments which Appellant did not make in the Briefs have not been
considered and are deemed waived. See id.
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ISSUES
With respect to the claim rejection over Pelly and Kolar, the Examiner
relies on Pelly for disclosing a switching stage and an active EMI filter
wherein the output of the EMI filter provides a filtered output voltage
canceling common mode current (Ans. 4). The Examiner further relies on
Kolar for teaching a transistor-based switching stage and concludes that
using the power transistors of Kolar in Pelly would have been obvious to one
of ordinary skill in the art (Ans. 4-5). Appellant argues that the references
provide no suggestion or motivation for the combination proposed by the
Examiner (App. Br. 7-8).
With respect to the rejection over Pelly and Sato, the Examiner again
relies on Sato for teaching a power transistor switching stage that was
indicated to be missing in Pelly (Ans. 6-7). Appellant contends that, similar
to Kolar, Sato provides no suggestion or motivation to one of ordinary skill
in the art for substituting the full bridge rectifier of Pelly with the power
transistors of Sato (App. Br. 8).
Thus, Appellant’s contentions and the Examiner’s arguments present
the following issues:
1. Has Appellant shown that the Examiner erred in combining the
teachings of Pelly with Kolar to arrive at the claimed invention?
2. Has Appellant shown that the Examiner erred in combining the
teachings of Pelly with Sato to arrive at the claimed invention?

FINDINGS OF FACT
The following findings of fact (FF) are relevant to the issues involved
in the appeal.
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Pelly
1. Pelly relates to an active filter for reducing the common mode
current in the ground wire of a motor drive circuit. (Abstract.)
2. As shown in Figure 3, Pelly discloses a circuit for diverting the
common mode current flow into the isolator capacitor 47 and the transistors
Q1 and Q2 away from the external ground wire connected to 43a. (Col. 6, ll.
61-65.)
3. Figure 3 of Pelly is shown below:

4. Similar to Figure 1, the embodiment shown in Figure 3 includes
an a-c source comprising an input terminal L and a neutral terminal N
connected to the a-c input terminals of a full wave bridge connected rectifier
40. (Col. 2, 30-34.)
Kolar
5. Kolar relates to a voltage generator system that converts a
three-phase power signal to a DC output voltage, which after filtering of
switching-frequency spectral components, has a sinusoidal profile of the
input current. (Col. 1, ll. 9-17.)
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6. Kolar discloses that each bridge arm of the controllable three-
phase bridge has identical structure and is connected to a control switch,
such as a power transistor, which can be switched off. (Col. 2, ll. 12-19.)
7. Kolar further discloses that one control switch may be switched
off in order to prevent current from flowing via that bridge arm, wherein the
bridge arm, in its on-state, has identical characteristics to the bridge arm of a
conventional diode bridge. (Col. 2, ll. 29-33.)
8. Kolar describes the advantage of controlling the conductance of
this type of circuit as reduction of the output voltage of the system in
comparison to conventional diode rectification, which results in reduced
power supply system reactions. (Col. 2, ll. 33-37.)
9. As shown in Figure 1, Kolar discloses control transistors 12
used as the control switches of the power supply system. (Col. 6, ll. 29-39.)
Sato
10. Sato discloses a voltage regulator 18, which includes a three-
phase full-wave rectifier 19 composed of power transistors 19a-19f. (Col.
11, ll. 7-12.)

PRINCIPLES OF LAW
Section 103 forbids issuance of a patent when “the differences
between the subject matter sought to be patented and the prior
art are such that the subject matter as a whole would have been
obvious at the time the invention was made to a person having
ordinary skill in the art to which said subject matter pertains.”
KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 406 (2007).
“‘The combination of familiar elements according to known methods
is likely to be obvious when it does no more than yield predictable results.’”
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Leapfrog Enters., Inc. v. Fisher-Price, Inc., 485 F.3d 1157, 1161 (Fed. Cir.
2007) (quoting KSR, 550 U.S. at 416). “One of the ways in which a patent’s
subject matter can be proved obvious is by noting that there existed at the
time of invention a known problem for which there was an obvious solution
encompassed by the patent’s claims.” KSR, 550 U.S. at 419-20. The KSR
Court further recognized that “[w]hen there is a design need or market
pressure to solve a problem and there are a finite number of identified,
predictable solutions, a person of ordinary skill has good reason to pursue
the known options within his or her technical grasp.” Id. at 421.

ANALYSIS
Rejection over Pelly and Kolar
Appellant’s arguments challenge combinability of Pelly and Kolar and
whether one of ordinary skill in the art would have used the power
transistors of Kolar in place of the full diode bridge of Pelly (App. Br. 7-8).
As asserted by the Examiner (Ans. 9), the full bridge rectifier of Pelly
provides a filtered d-c output signal based on switch mode conversion of an
a-c current mode input (FFs 1 and 3). Pelly further eliminates the common
mode current by using an active filter (FFs 1-3). Therefore, contrary to
Appellant’s assertion that nothing in the prior art teaches or suggests
providing an active EMI filter at the output of the power transistor switching
stage, we find that the Examiner has properly relied on Pelly for such
arrangement. We further agree with the Examiner’s finding that the
switching stage may comprise the power transistors taught by Kolar in place
of the full wave bridge of Pelly (Ans. 9).
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Initially, we find that Appellant’s arguments to be directed to each
reference separately, rather than the combined teachings of Pelly and Kolar
as a whole. Therefore, we are unpersuaded by Appellant’s contention (App.
Br. 7-8; Reply Br. 4-5) that the combination is improper because Kolar
includes no suggestion or description of a switching power supply placed
ahead of an active EMI filter. The teaching value of Kolar is in using power
transistors in the bridge arms of a controllable three-phase bridge that
produces a DC output voltage after filtering of switching-frequency spectral
components (FFs 5-6). The placement of the switching power supply ahead
of the active filter is taught by Pelly.
We also disagree with Appellant’s argument (App. Br. 8) that the
references can be combined only if a suggestion or motivation to combine
and a reasonable expectation of success are shown. Based on the principles
outlined in KSR, we also agree with the Examiner’s position (Ans. 10) that
using a well-known switching stage made of power transistors of Kolar in
place of the full wave bridge power supply of Pelly would have been
obvious. In other words, we find that the Examiner properly concluded (id.)
that one of ordinary skill in the art would have used the power transistors of
Kolar with the active filter of Pelly, because Kolar teaches that such
transistors may be used in place of conventional diode bridges (FFs 7 and 9)
in order to reduce power supply system reactions (FF 8).
Additionally, we find that Kolar discloses one of the different types of
circuits to be used as the switching stage of a power supply. As a result, the
Examiner’s asserted combination of the references amounts to no more than
the combination of familiar elements according to known methods, yielding
the predictable result of substituting the full wave bridge power supply of
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Pelly with the power transistor power supply of Kolar. As such, using
power transistors of Kolar presents one of the finite numbers of identified,
predictable solutions, within his or her technical grasp, that a person of
ordinary skill would pursue. Thus, we agree with the Examiner’s conclusion
that the combination of Pelly with Kolar would have rendered the subject
matter of claim 8 obvious.
Rejection over Pelly and Sato
Appellant challenges (App. Br. 8) the combinability of Pelly and Sato
by presenting arguments similar to those presented regarding Pelly and
Kolar, which are discussed above and found to be unpersuasive. Similar to
Kolar, Sato uses power transistors for a power supply (FF 10), which is one
of the available power supply circuits one of ordinary skill in the art may use
in place of the full wave bridge rectifier of Pelly. Therefore, we also agree
with the Examiner that the subject matter recited in claim 8 would have been
obvious over the combination of Pelly and Sato.

CONCLUSIONS
For the reasons discussed above and provided by the Examiner, we
conclude that Appellant has not shown error in the Examiner’s combination
of Pelly and Kolar or Pelly and Sato. Therefore, we sustain the 35 U.S.C.
§ 103(a) rejections of claims 3-6 and 8-13 over Pelly and Kolar and of
claims 7 and 8 over Pelly and Sato.
With respect to the rejection of claim 2 over the combination of these
references with Suzuki or Ohkawa, we observe that Appellant provides no
additional arguments and merely asserts (App. Br. 9) that neither Suzuki nor
Ohkawa remedies the deficiencies discussed above. Therefore, we also
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sustain the 35 U.S.C. § 103(a) rejection of claim 2 over the combination of
these references.

ORDER
The decision of the Examiner rejecting claims 2-13 is affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).

AFFIRMED

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