Ex Parte Dewey

Board of Patent Appeals and Interferences

Jun 24, 2010

10823305 (B.P.A.I. Jun. 24, 2010)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte SCOTT DEWEY
____________

Appeal 2009-002523
Application 10/823,305
Technology Center 2800
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Decided: June 25, 2010
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Before JOHN C. MARTIN, THOMAS S. HAHN, and ELENI MANTIS
MERCADER, Administrative Patent Judges.

MANTIS MERCADER, Administrative Patent Judge.

DECISION ON APPEAL
Appeal 2009-002523
Application 10/823,305

STATEMENT OF THE CASE
Appellant appeals under 35 U.S.C. § 134(a) from the Final Rejection
of claims 1-20. We have jurisdiction under 35 U.S.C. § 6(b).
We affirm.

Appellant’s Invention
Appellant’s Figure 3 is reproduced below:

Figure 3 shows a fuel cell stack 24 having fuel cells 22 and the cell
monitoring system 20 which includes a giant magnetoresistive (GMR)
device 28 having a wheatstone bridge 26. The wheatstone bridge 26 uses
two non-shielded magnetoresistive resistors providing a greater differential
voltage at the output ports 32 and 34 in response to a magnetic field. Spec.
[0020].

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Appellant’s invention is directed to employing a giant
magnetoresistive (GMR) device 28 to determine the state of fuel cells 22 in a
fuel stack 24. See Spec. [0018] and Fig. 3.
Claim 1 is illustrative of the invention and reads as follows:
1. A monitoring system for monitoring the voltage potential of fuel
cells in a fuel cell stack, said system comprising:
a wheatstone bridge, said wheatstone bridge including at least one
giant magnetoresistive (GMR) resistor and two output ports;
a conductor positioned proximate to the wheatstone bridge;
a plurality of switches electrically coupled to the fuel cells and to the
conductor, said switches being selectively switched on and off to separately
and selectively couple each fuel cell in the fuel cell stack to the conductor
and generate a current flow therethrough, wherein a magnetic field generated
by the current flow through the conductor reduces the resistance of the GMR
resistor and unbalances the wheatstone bridge; and
a differencing amplifier electrically coupled to the output ports of the
wheatstone bridge, said differencing amplifier providing an output signal
indicative of the voltage potential of the selected fuel cell.

The Examiner’s Rejections
The Examiner’s Answer cites the following prior art references:
Thiele US 3,500,372 Mar. 10, 1970
Yoshino US 4,937,521 Jun. 26, 1990
Chen US 5,371,455 Dec. 6, 1994
Barbetta US 6,762,587 B1 Jul. 13. 2004
(effectively filed
Sep. 12, 2000)

1. The Examiner rejected claims 1-4, 6-10, 12-17, 19, and 20 under
35 U.S.C. § 103(a) as being unpatentable over Barbetta and Yoshino.
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2. The Examiner rejected claims 5, 11, and 18 under 35 U.S.C.
§ 103(a) as being unpatentable over Barbetta and Yoshino and further in
view of Chen and Thiele.

ISSUES
The pivotal issues before us are:
(1). with respect to claims 1-4, 6-10, 12-17, 19, and 20, whether the
Examiner’s articulated reasoning for modifying Barbetta in view of Yoshino
supports the legal conclusion of obviousness; and
(2). with respect to claims 5, 11, and 18 whether the Barbetta,
Yoshino, Chen, and Thiele combination teaches a fuel cell stack monitoring
wheatstone bridge GMR sensor including a polarity reverser.

FINDINGS OF FACT
The record supports the following relevant findings of fact (FF) by a
preponderance of the evidence:
1. Yoshino explicitly teaches that the current detecting device (col. 1, ll.
52-53) provides high accuracy in current detection.
2. Barbetta teaches a meter 13 (Fig. 1) which measures voltages of
individual cells or cell groups and communicates the measurements to
a monitor (col. 4, ll. 30-34).
3. Yoshino teaches a measuring device (Figs. 11-13; col. 8, ll. 32-66)
having a bridge circuit including a magnetoresistive sensor 1 for
accurately performing those measurements (col. 1, ll. 52-53).
Appellant does not deny that Yoshino’s bridge circuit is a wheatstone
bridge.
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4. Thiele discloses that fuel cell batteries occasionally reverse polarity
due to internal faults (col. 1, ll. 30-34).
5. Barbetta’s Figure 8 shows an embodiment of a multiplexer 2 (Fig. 7)
that includes a plurality of switches 1 for connecting individual cell or
grouped cell voltages 2 (Fig. 8) to a multiplexor output 3 (col. 6, ll.
37-40).
6. Yoshino indicates in Figure 12 that the current flow is in only one
direction in conductor 3 because polarity is significant for the
operational amplifiers 41, 42, as indicated by their + and – terminals
(col. 8, ll. 47-59).
7. Chen teaches automatic polarity detection and, if the polarity is
determined to be incorrect, polarity reversal (Fig. 1; col. 1, l. 50 to col.
2, l. 2).

PRINCIPLES OF LAW
The Examiner’s rejection for obviousness must set forth articulated
reasoning that possesses a rational underpinning supporting the legal
conclusion of obviousness. In re Kahn, 441 F.3d 977, 988 (Fed. Cir. 2006).
The Supreme Court stated that “‘rejections on obviousness grounds cannot
be sustained by mere conclusory statements; instead, there must be some
articulated reasoning with some rational underpinning to support the legal
conclusion of obviousness.’” KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398,
418 (2007) (quoting Kahn, 441 F.3d at 988).
The test for obviousness is what the combined teachings of the
references would have suggested to the artisan. Accordingly, one cannot
show nonobviousness by attacking references individually where the
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rejection is based on a combination of references. In re Keller, 642 F.2d
413, 426 (CCPA 1981).

ANALYSIS
Claims 1-4, 6-10, 12-17, 19, and 20
Appellant argues (App. Br. 8), inter alia, that the Examiner has failed
to explain why one skilled in the art would combine the current detecting
device of Yoshino into the fuel cell voltage detecting device of Barbetta.
We are unconvinced by Appellant’s argument.
The Examiner articulated as a rationale to combine the references “the
benefit of accurately reading current/voltage of each cell whilst ensuring
isolation existed between the cell’s high voltage and the measurement
electronics, particularly since Barbetta’s sensor is connected to a conductive
trace” (Ans. 6-7). Thus, the Examiner has essentially provided two
rationales for the combination. The first being accuracy and the second
being isolation. Without deciding whether the second rationale is sufficient
to support the combination, we find that the first rationale of accuracy does
support the combination. Yoshino explicitly teaches that the current
detecting device (FF 1) provides high accuracy in current detection.
Accordingly, one skilled in the art would have been motivated to replace
Barbetta’s meter 13 (Fig. 1), which measures voltages of individual cells or
cell groups and communicates the measurements to a monitor (FF 2), with
the wheatstone bridge measuring device of Yoshino (FF 3), which has a
magnetoresistive sensor 1, for accurately performing those measurements.
Thus, the Examiner has provided, in the rejection, articulated reasoning
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possessing a rational underpinning that supports the legal conclusion of
obviousness. See Kahn, 441 F.3d at 988.
For the foregoing reasons, we will sustain the rejection of claims 1-4,
6-10, 12-17, 19, and 20.
Claims 5, 11, and 18
Appellant argues (App. Br. 11) that Chen does not teach or suggest a
polarity reverser in a monitoring circuit for monitoring the voltage across
fuel cells in the fuel cell stack where the polarity reverser reverses the
voltage polarity from fuel cells so that the current sent to the conductor
positioned in close proximity to a wheatstone bridge always flows in the
same direction.
The combination of Barbetta and Yoshino as discussed supra,
includes the fuel cell stack as taught by Barbetta and the wheatstone
monitoring sensor of Yoshino. As noted by Appellant (Reply Br. 3), the
Examiner found (Ans. 28-29) that Barbetta’s multiplexer switches of Figure
8 are capable of accomplishing polarity reversal of the voltages in fuel cell
stack 10, although the switches are not described as being used in that
manner (FF 5). Thiele was used by the Examiner (Ans. 29) for disclosing
the problem that fuel cell batteries occasionally reverse polarity (FF 4). The
Examiner further found (Ans. 30) that Yoshino indicates in Figure 12 that
the current flow is in only one direction in conductor 3 because polarity is
significant for the comparators 40-42, as indicated by their + and –
terminals, and that polarity reversal would either damage the comparators or
garble the output (FF 6). Appellant has not asserted any error in these
findings regarding Yoshino. The Examiner (Ans. 31), correctly, relies on
Chen for a teaching of automatic polarity detection and, if the polarity is
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determined to be incorrect, automatic polarity reversal (FF 7). Appellant’s
argument that “a reverse-polarity detection circuit is not a polarity reverser”
(Reply Br. 4) is therefore unpersuasive.
Based on the foregoing teachings, the Examiner concluded that it
would have been obvious to protect Yoshino’s wheatstone bridge
comparators and output in the above combination of Barbetta and Yoshino
by automatically detecting the polarity of Barbetta’s fuel cell voltages and
reversing their polarity if they are determined to have the wrong polarity, a
potential problem recognized by Thiele. Appellant has not asserted any
error in combining the reference teachings in the above manner, instead
faulting the references individually for failing to disclose the claimed
polarity reverser in a monitoring circuit. The test for obviousness is what
the combined teachings of the references would have suggested to the
artisan. Accordingly, one cannot show nonobviousness by attacking
references individually where the rejection is based on a combination of
references (i.e., the Examiner conclued that the combination teaches a
polarity reverser in a monitoring circuit for monitoring the voltage across
fuel cells in the fuel cell stack where the polarity reverser reverses the
voltage polarity from fuel cells so that the current sent to the conductor
positioned in close proximity to a wheatstone bridge always flows in the
same direction). See Keller, 642 F.2d at 426.
Accordingly, we will also sustain the rejection of claims 5, 11, and 18.

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CONCLUSIONS OF LAW
(1). With respect to claims 1-4, 6-10, 12-17, 19, and 20, the
Examiner’s articulated reasoning for modifying Barbetta in view of Yoshino
supports the legal conclusion of obviousness; and
(2). with respect to claims 5, 11, and 18, the Barbetta, Yoshino, Chen,
and Thiele combination teaches a fuel cell stack monitoring wheatstone
bridge GMR sensor including a polarity reverser.

DECISION
The Examiner’s decision rejection of claims 1-20 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).

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AFFIRMED

ELD

MILLER IP GROUP, PLC
GENERAL MOTORS CORPORATION
42690 WOODWARD AVENUE
SUITE 200
BLOOMFIELD HILLS, MI 48304

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