Ex Parte Mirafzal et al

Board of Patent Appeals and Interferences

May 31, 2012

11541623 (B.P.A.I. May. 31, 2012)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________________

Ex parte BEHROOZ MIRAFZAL and CRAIG WINTERHALTER
____________________

Appeal 2010-003399
Application 11/541,623
Technology Center 2800
____________________

Before ST. JOHN COURTENAY, III, THU A. DANG, and JAMES R.
HUGHES, Administrative Patent Judges.

DANG, Administrative Patent Judge.

DECISION ON APPEAL

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I. STATEMENT OF THE CASE
Appellants appeal under 35 U.S.C. § 134(a) from a Final Rejection of
claims 1-5 and 8-22 (App. Br. 2). Claims 6 and 7 are objected to as
including allowable subject matter but are dependent upon a rejected
independent claim (id.). We have jurisdiction under 35 U.S.C. § 6(b).
We affirm.

A. INVENTION
Appellants’ invention is directed to an integrated direct current (DC)
link inductor and current sensor winding including at least two primary legs
having link windings and at least one secondary leg having a common mode
current sensor winding; wherein, the differential mode current through the
two primary legs flow in opposite directions (Figs. 1 and 2; Abstract; and
Spec. ¶ [0029]).

B. ILLUSTRATIVE CLAIM
Claim 9 is exemplary:
9. A method, comprising:

receiving, in a core, magnetic flux induced by differential
mode currents in a positive current path and a negative current
path through a DC link, wherein current in the positive current
path flows in a different direction from current in the negative
current path;

receiving, in the core, resultant magnetic flux induced by
a common mode current in the DC link, wherein the common
mode current corresponds to a difference between
magnitudes of the differential mode currents; and

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sensing the resultant magnetic flux.

C. REJECTIONS
The prior art relied upon by the Examiner in rejecting the claims on
appeal is:
Seiersen US 5,335,163 Aug. 02, 1994
Hegg US 5,694,014 Dec. 02, 1997
Briere US 6,898,092 B2 May 24, 2005
Henze US 2005/0259371 Al Nov. 24, 2005

Claims 9, 15, and 18 stand rejected under 35 U.S.C. § 102(b) as being
anticipated by Briere.
Claims 1-4, 10, and 17 stand rejected under 35 U.S.C. § 103(a) as
being unpatentable over Briere in view of Seiersen.
Claims 5, 8, 11, and 12 stand rejected under 35 U.S.C. § 103(a) as
being unpatentable over Briere in view of Seiersen and Henze.
Claims 13, 14, 16, and 20 stand rejected under 35 U.S.C. § 103(a) as
being unpatentable over Briere in view of Henze.
Claim 19 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable over Briere in view of Henze and APA.
Claims 21 and 22 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Briere in view of Henze and Hegg.

II. ISSUE
The dispositive issue before us is whether the Examiner has erred in
finding that Briere teaches “receiving, in a core, magnetic flux induced by
differential mode currents in a positive current path and a negative current
path through a DC link, wherein current in the positive current path flows in
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a different direction from current in the negative current path” (claim 9,
emphasis added).

III. FINDINGS OF FACT
The following Findings of Fact (FF) are shown by a preponderance of
the evidence.
The Invention
1. According to Appellants, the invention concerns an integrated
DC link inductor and current sensor winding having differential mode
currents ix and iy, which have different directions and represent the currents
present or absent a current leak (Spec. ¶ [0029]). The common mode
current, however, represents the difference between the magnitude of ix and
iy, indicating a net loss or gain of current on the two current paths 38 and 40
(id.). The difference in magnitude arises as a result of a ground fault, where
some of the current ix flowing into the load 20 leaks to ground rather than
flowing back out of the load as iy (id.).
Briere
2. Briere discloses a converter system 200, including a power
converter 102 and an EMI filter circuit, having a common mode circuit 212
that senses the common-mode current ICM flowing between the power
converter 102 and a voltage source 101 (Fig. 3; col. 4, l. 65-col. 5, l. 3).
3. When the differential currents in paths (225, 227 and 226, 228)
from the power source through the common mode circuit to the load cancel
one another out, no common-mode current ICM exists, and thereby, no signal
in the tertiary winding 313 is produced (Fig. 4; col. 5, ll. 47-51). However,
when the presence of the common mode AC current, ICM, is detected, a
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resultant differential voltage is produced across the tertiary winding 313
(Fig. 4; col. 5, ll. 51-55). Thus, the common mode filter circuit 212 having a
transformer acts as a common-mode current sense element detecting the
presence of common-mode AC current, ICM, and producing a resultant
differential voltage across the tertiary winding 313 (id.).
Seiersen
4. Seiersen discloses a three leg transformer core having two
primary windings on the outer legs; wherein, the flux in the central leg will
be the total of or the difference between the flux of the outer legs (col. 3, ll.
45-53).

IV. ANALYSIS
Claims 9, 15, and 18
Appellants provide similar arguments with respect to independent
claims 9 and 15 (App. Br. 5-10). Appellants do not provide arguments with
respect to dependent claim 18 (id.). Accordingly, we select claim 9 as being
representative of claim 9, 15, and 18. See 37 C.F.R. § 41.37(c)(1)(vii).
Appellants contend that Briere does not teach “‘wherein current in the
positive current path flows in a different direction from current in the
negative current path’” (App. Br. 6 (quoting claim 9)) because “the positive
and negative path common-mode currents ICMl and ICM2, are illustrated as
flowing in the same direction, and do not, as the Examiner contends, flow in
different directions” (App. Br. 7). Appellants argue that the negative “path
[through the neutral terminals (109a and 109b)] … complet[es] the circuit
between the power source 101 and the load” and, therefore, the Examiner’s
finding that the “reverse path through the common mode circuit (212) from
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the load to the negative power source terminal (226)” completes the circuit
is incorrect (id.). Thus, “the Examiner’s assertion that … current flows in
different directions in the positive and negative paths of the common mode
circuit (212) is explicitly contradicted by Briere” (id.).
However, the Examiner finds that “[a]s is commonly understood in
the art, current will flow from the power source at terminal 225 in the
direction of the load during a normal operation” and “[u]pon reaching the
load, current will return in the opposite direction and arrive at terminal 226
when no other unwanted paths to ground are present such as those created
by impedances” (Ans. 9-10). The Examiner notes that “[t]he currents ICMl
and ICM2 as seen below represent currents that result due to an unwanted path
to ground and cause an imbalance between the current flowing in the
positive current line and the negative current line” (Ans.10). Thus, “[t]he
currents ICMl and ICM2 represent the currents that result after a fault condition
or path to ground has occurred” and “[p]rior to the fault condition, the
normal operation current flows in equal and opposite paths and no common
mode signal is detected as taught in … Briere” (Ans. 12).
In the Reply Brief, Appellants assert that the Examiner has made the
aforementioned findings “made without any citation to any portion of
Briere” (Reply Br. 3).
Appellants’ argument that the negative “path [through the neutral
terminals (109a and 109b)] … complet[es] the circuit between the power
source 101 and the load” is not commensurate in scope with the specific
language of claim 9 (App. Br. 7). In particular, claim 9 does not recite such
“completing the circuit between the power source … and the load” as
Appellants argue.
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Regarding the Appellants’ argument that the Examiner has “made [his
findings] without any citation to any portion of Briere” (Reply Br. 3), we
note that the Examiner has made reference to recited portions of Briere to
support his findings on pages 3, 4, and 12 of the Answer.
We give the claim its broadest reasonable interpretation consistent
with the Specification. See In re Morris, 127 F.3d 1048, 1054 (Fed. Cir.
1997). However, we will not read limitations from the Specification into the
claims. In re Van Geuns, 988 F.2d 1181, 1184 (Fed. Cir. 1993).
Claim 9 does not place any limitation on what “differential mode
currents” (claim 9) means, includes, or represents, other than the currents
flow in different directions in a positive and negative current path. The
Specification makes the distinction between differential mode currents and
the common mode current, in that the common mode current represents the
difference between the differential mode currents in the presence of a ground
fault; wherein, absent a current leak to ground, the differential mode currents
are equal and opposite and the common mode current is zero (FF 1). Thus,
we give “differential mode currents” (claim 9) its broadest reasonable
interpretation as the current that exists in the positive and negative current
path absent a current leak, as consistent with the Specification and as
specifically defined in claim 9.
Briere discloses a converter system including an EMI filter circuit
having a common mode circuit that senses the common-mode current ICM
flowing between the power converter and a voltage source (FF 2). From the
Examiner’s recited portion of Briere (Ans. 12), when the differential
currents in the paths from the power source through the common mode
circuit to the load cancel one another out, no common mode current ICM
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Examiner’s finding that the differential “current flows in equal and opposite
paths and no common mode signal is detected” (Ans. 12) which is consistent
with the Specification (FF 1) and the claim. That is, we find that “wherein
[differential mode] current in the positive current path flows in a different
direction from [differential mode] current in the negative current path”
(claim 9) reads on Briere’s differential currents in paths from the power
source to the load.
Accordingly, we find that Appellants have not shown that the
Examiner erred in rejecting claim 9 under 35 U.S.C. § 102(b) over Briere;
and independent claim 15 and claim 18 depending from claim 15 which
have been grouped therewith.
Claims 1-4, 10, and 17
Appellants provide arguments with respect to independent claim 1
(App. Br. 10-13). Appellants do not provide arguments with respect to
dependent claims 2-4, 10, and 17. Accordingly, we select claim 1 as being
representative of claims 1-4, 10, and 17.
Appellants contend that since Briere teaches “producing an offset
current (Ioffset) [through the tertiary winding] in response to the presence of
the first common-mode current and/or the second common-mode current
which flow in the same direction,” “the tertiary winding … of Briere cannot
be read as conducting a common mode current generated by a difference in
currents flowing in different directions in the two DC link windings” (App.
Br. 11-12). Appellants argue that “modification of the system of Briere
would destroy the principle of operation of the reference, because the system
of Briere requires sensing of a magnetic flux to occur before the current is
passed through the load to aid in preventing the common-mode current ICM
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from flowing through the power delivery system 101 adjacent to a load”
(App. Br. 12). Appellants contend further that “Seiersen fails to obviate the
deficiencies of Briere” (id.).
However, the Examiner finds that “the currents ICMl and ICM2 of Briere
do not represent the normal operation current that flows when no fault
connections to ground are present, but the difference in currents flowing in
different directions in the two windings that result when an erroneous path to
ground occurs on one or both of the current conducting lines” (Ans. 15).
The Examiner finds further that “Seiersen teaches the difference of or total
flux between the primary windings will be present on the center leg …
making it perfectly suitable to implement the magnetic flux relationship
required by the transformer … of Briere, which requires two primary legs to
create a total flux on a tertiary winding” (id.).
As noted supra, Briere discloses that when the differential currents in
the paths from the power source through the common mode circuit to the
load cancel one another out, no common mode current ICM exists, and
thereby, no signal in the tertiary winding is produced (FF 3). Yet, when
there is a difference in the differential currents, the common mode current
ICM exists and a signal is produced in the tertiary winding (id.). We find that
the tertiary winding is the current sensor winding that conducts the common
mode current which is generated by a difference in the differential currents
that flow in different directions. That is, we find that “the current sensor
winding conducts a common mode current generated by a difference in
currents flowing in different directions in the two DC link windings” (claim
1) reads on Briere’s tertiary winding.
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In addition, Seiersen discloses that for a three leg transformer core
having two primary windings on the outer legs, the flux in the central leg
will be the total of or the difference between the flux of the outer legs (FF 4).
We find that current sensor winding around the central leg (secondary leg)
comprises a flux that represents the difference between the flux of the two
outer legs (primary legs). That is, we also find that “the current sensor
winding conducts a common mode current generated by a difference in
currents flowing in different directions in the two DC link windings” (claim
1) also reads on Seiersen’s transformer.
Though Appellants contend that “modification of the system of Briere
would destroy the principle of operation of the reference” (App. Br. 12), we
agree with the Examiner’s conclusion that “Seiersen teaches the difference
of or total flux between the primary windings will be present on the center
leg … making it perfectly suitable to implement the magnetic flux
relationship required by the transformer … of Briere, which requires two
primary legs to create a total flux on a tertiary winding” (Ans. 15).
Since Seiersen discloses a transformer having two primary legs and a
secondary leg with a current sensor, we conclude that the combination of
one known element (Briere’s common mode circuit having two primary
windings and a current sensor winding) with another (Seiersen’s
transformer, having three legs wherein the center leg includes a current
sensor) would have yielded predictable results to one of ordinary skill in the
art at the time of the invention. That is, we find that a common mode circuit,
having two primary windings and a current sensor winding as taught by
Briere in addition to Seiersen’s transformer having three legs where the
center leg includes a current sensor, is no more than a simple arrangement of
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old elements, with each performing the same function it had been known to
perform, yielding no more than one would expect from such an arrangement.
See KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 417 (2007).
The skilled artisan would “be able to fit the teachings of multiple
patents together like pieces of a puzzle” since the skilled artisan is “a person
of ordinary creativity, not an automaton.” Id. at 420-21. In arguing that the
“the system of Briere requires sensing of a magnetic flux to occur before the
current is passed through the load” (App. Br. 12), we find that Appellants
have not presented persuasive evidence that combining Briere’s teaching of
three windings in the common mode circuit with transformer having three
legs of Seiersen was “uniquely challenging or difficult for one of ordinary
skill in the art” or “represented an unobvious step over the prior art.” See
Leapfrog, Inc. v. Fisher-Price, Inc., 485 F.3d 1157, 1162 (Fed. Cir. 2007)
(citing KSR, 550 U.S. at 418-19)
Accordingly, we find that Appellants have not shown that the
Examiner erred in rejecting claim 1 under 35 U.S.C. § 103(a) over Briere in
view of Seiersen; and claims 2-4, 10, and 17 depending from claims 1, 9,
and 15.
Claims 5, 8, 11-14, 16, and 19-22
Appellants argue that claims 5, 8, 11-14, 16, and 19-22 are patentable
over the cited prior art for the same reasons asserted with respect to claims 1,
9, and 15 (App. Br. 14-17).
As noted supra, however, we see no deficiencies in Briere with
respect to parent claims 1, 9, and 15. We therefore affirm the Examiner’s
rejection of claims 5, 8, 11, and 12 over Briere in further view of Seiersen
and Henze; of claims 13, 14, 16, and 20 over Briere in further view of
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Henze; of claim 19 over Briere in further view of Henze and APA; and of
claims 21 and 22 over Briere in further view of Henze and Hegg.

V. CONCLUSION AND DECISION
The Examiner’s rejection of claims 9, 15, and 18 under 35 U.S.C. §
102(b) and claims 1-5, 8, 10-14, 16, 17, and 19-22 under 35 U.S.C. § 103(a)
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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