Ex Parte Shah et al

Patent Trial and Appeal Board

Feb 5, 2013

11115736 (P.T.A.B. Feb. 5, 2013)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________________
BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________________
Ex parte MINESH ASHOK SHAH, MAHADEVAN
BALASUBRAMANIAM, PHILIP PAUL BEAUCHAMP,
TODD ALAN ANDERSON, SAMHITA DASGUPTA,
DAVID MULFORD SHADDOCK, and EMAD ANDARAWIS
____________________
Appeal 2010-006172
Application 11/115,736
Technology Center 3700
____________________
Before MICHAEL L. HOELTER, SCOTT A. DANIELS, and
MITCHELL G. WEATHERLY, Administrative Patent Judges.
WEATHERLY, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Appellants appeal under 35 U.S.C. § 134 from the decision of the
Examiner rejecting claims 1-4 and 6-23. Claim 5 has been canceled. We
have jurisdiction under 35 U.S.C. § 6(b).
We reverse.
The claims are directed to systems and methods for sensing a
clearance between a rotating component and a stationary shroud of a rotating
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machine for example where “in the design of gas and steam turbines, it is
desirable to have a close tolerance between the tips of the rotor blades and
the surrounding static shroud.” Spec. para. [0002]. Claims 1 and 19,
reproduced below, are illustrative of the claimed subject matter:
1. A rotating machine, comprising:
a rotating component affixed to a shaft for rotation
within a stationary shroud;
a plurality of sensors disposed within the shroud,
each of the plurality of sensors being adapted to measure
a parameter indicative of an axial and a radial
displacement of the rotating component within the shroud
and to produce a signal that corresponds to the parameter;
and
a circuit that receives the signal from each of the
plurality of sensors and in response thereto calculates (a)
the axial displacement of the rotating component within
the shroud and (b) a radial displacement of the rotating
component relative to the shroud;
wherein the rotating component comprises a notch
to self calibrate at least one of the sensors against signal
drift.
19. A method for sensing a clearance between a
rotating component and a stationary shroud of a rotating
machine, comprising:
sensing a capacitance between the rotating
component and the shroud and producing a signal
corresponding to the sensed capacitance;
determining an axial displacement of the rotating
component within the shroud in response to the signal;
and
self calibrating at least one of the sensors
producing signal against signal drift using a notch in the
rotating component.
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REFERENCES
The Examiner relies upon the following evidence:
Luongo
Oates
Rickards
Hagi
Xia
US 4,573,358
US 4,644,270
US 5,119,036
US 6,152,685
US 6,401,460 B1
Mar. 4, 1986
Feb. 17, 1987
Jun. 2, 1992
Nov. 28, 2000
Jun. 11, 2002
Prinz US 2003/0215323 A1 Nov. 20, 2003
REJECTIONS
Appellants seek our review of the following rejections:
1. Claims 1, 3, 7, 8, 13 and 15 stand rejected under 35 U.S.C. § 103(a) as
being unpatentable over Oates and Luongo. Ans. 3-4.
2. Claims 1-3, 6, 8, 12-16, 19, 20, and 22 stand rejected under 35 U.S.C.
§ 103(a) as being unpatentable over Prinz and Luongo. Ans. 4-5.
3. Claim 4 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable over Oates, Luongo, and Hagi. Ans. 5-6.
4. Claims 1-3, 6, 8, 9, and 12-22 stand rejected under 35 U.S.C. § 103(a)
as being unpatentable over Prinz, Oates, Luongo. Ans. 6-7.
5. Claim 11 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable over Prinz, Oates, Luongo, and Rickards. Ans. 7.
6. Claim 23 stands rejected under 35 U.S.C. § 103(a) as being
unpatentable over Prinz, Oates, Luongo, and Xia. Ans. 7-8.
OPINION
Appellants proffer the same argument for reversing all six of the
Examiner’s rejections. Namely, that none of the references of record taken
alone or in combination describes the “notch to self calibrate at least one of
the sensors against signal drift” recited in independent claims 1, 12, and 13
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or the step of “self calibrating at least one of the sensors producing signal
against signal drift using a notch in the rotating component” recited in
independent claim 19. App. Br. 5-9. The Examiner cites Luongo as
describing the claimed notch in the form of Luongo’s indicia 16 that is
sensed by sensor R1. Ans. 4. The Examiner also cites Luongo as describing
the “self calibrating” nature of the claimed notch to correct for “signal drift.”
Id. For example, regarding the rejection under § 103(a) of claims 1, 3, 7, 8,
and 13 as unpatentable over Oates and Luongo, the Examiner concludes:
Luongo notes that such reference sensor systems are common
to many turbine systems and are utilized for control purposes
(Luongo column 3, lines 21-22). Therefore, it would have been
obvious to one of ordinary skill in the art at the time the
invention was made to modify the system of Oates by
incorporating a reference sensor system utilizing a self-
calibrating indicia as taught by Luongo for the purpose of
providing a control signal for the system.
Id. The Examiner draws essentially the same conclusion for all rejections.
Id. at 5-7.
Appellants argue that Luongo fails to describe a notch “to self
calibrate the sensors against signal drift.” App. Br. 6. Rather, Appellants
contend that Luongo’s indicia 16 and R1 sensor generate a reference signal
used to reset counter 50. App. Br. 6-7 (citing Luongo, col. 3, ll. 15-20;
col. 4, ll. 15-20). Luongo’s counter 50 is then used along with other counters
and decode logic circuits to generate a gating signal that is unrelated to
calibrating any of Luongo’s sensors against sensor drift. App. Br. 7 (citing
Luongo, col. 4, ll. 21-47). The gated sensor signals in Luongo are
conditioned and then summed for a selected turbine blade “resulting in a
pulse train attributable only to the selected blade and which pulse train is
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provided to a novel detection means for determining blade tip vibration.”
Luongo, col. 3, ll. 29-32.
Appellants distinguish how the claimed notch acts to self calibrate the
sensors against signal drift without generating a reference signal from the
manner in which Luongo uses indicia 16 and sensor R1 to generate a
reference signal, by quoting a portion of the Specification as follows:
FIG. 3 illustrates a perspective view rotor 16 having seal
teeth 26 at the tip of the blades 16. The seal teeth 26 form a
continuous, and hence, capacitance measurements between the
teeth 26 and the sensor 24 would a produce nearly continuous
signal. However, due to electron drift, this signal may show a
steady shift, which may be wrongly correlated to radial and
axial displacements. According to one embodiment of the
present technique, the seal teeth 26 are provided with
diametrically opposite notches or grooves 27 and 31 to calibrate
this error. The radii of the notches 27 and 31 generally cover
the dimension of the capacitive probes and the height of these
notches is generally known apriori. The notches 27 and 31
introduce a spike in the signal produced by the capacitive
probes that can be used for self calibrating the sensing system
and ensure that measurements are not affected by signal drafts.
Reply Br. 2-3 (quoting Spec., para. [0025]). Thus, Appellants contend that
as the claimed notch rotates past each sensor, it causes a spike in the sensor’s
signal that eliminates the signal drift in the sensor’s signal that electron drift
induces. Appellants contend that a skilled artisan appreciates that the spike
induced in the sensor’s signal by the notch, is not itself a signal, and the
portion of the Specification quoted above conveys this concept. App. Br. 6;
Reply Br. 3. The Examiner has not identified evidence in Luongo or any
technical reasoning that Luongo uses such reference signals for self-
calibration of sensors against sensor drift. Appellants thus conclude that
Luongo fails to describe the claimed notch that eliminates the signal drift in
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the sensors that would otherwise occur if the notch were not present. We
agree. Because the Examiner’s factual finding is not adequately supported,
the Examiner’s conclusion of obviousness lacks rational underpinning. See
In re Kahn, 441 F.3d 977, 988 (Fed. Cir. 2006), cited with approval in KSR,
550 U.S. at 418 (“rejections on obvious 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”).
The Examiner has cited no other reference as describing the claimed
notch that renders the sensors self-calibrating against signal drift. Therefore,
we reverse the Examiner’s rejections of all claims.
DECISION
For the reasons stated above, we REVERSE the Examiner’s rejections
of claims 1-4 and 6-23.
REVERSED

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