Ex parte Kanai

Board of Patent Appeals and Interferences

Sep 21, 2000

08329687 (B.P.A.I. Sep. 21, 2000)

The opinion in support of the decision being entered today was not written
for publication in a law journal and is not binding precedent of the Board.
Paper No. 28
UNITED STATES PATENT AND TRADEMARK OFFICE
____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________
Ex parte TAKEO KANAI
____________
Appeal No. 1997-2340
Application No. 08/329,687
____________
HEARD: September 14, 2000
____________
Before FLEMING, LALL, and BARRY, Administrative Patent Judges.
BARRY, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal under 35 U.S.C. § 134 from
the rejection of claims 1-9. We reverse.
BACKGROUND
The invention at issue in this appeal relates to over-
voltage protection. Asynchronous inputs and short circuits
generate over-voltage in the windings of generators and
motors. Over-voltage protection devices use parallel current
Appeal No. 1997-2340 Page 2
Application No. 08/329,687
paths including VBO free thyristors to protect against the
over-
voltage. The thyristors are switched on, i.e., fired, by a
gate or fire by themselves, i.e., self-fire, to relieve over-
voltage.
Randomness between the self-firing voltages of the
individual thyristors and temperature variations can cause
current flow to become concentrated in one of the parallel
circuits. To prevent such a condition, heretofore,
temperature control and VB0 free thyristors having identical
characteristics had to be used in over-voltage protection
devices. Consequently, such devices were bulky and costly.
In contrast, a sensor in the inventive protection device
detects the self-firing of a thyristor in any one of its
parallel current paths. Upon such detection, a gate fires all
the other thyristors. Firing all the thyristors allows
current to flow through all the current paths thereby
distributing the excessive current between the various paths.
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Application No. 08/329,687
The distribution relieves the over-voltage before any
components are damaged.
Claim 6, which is representative for our purposes,
follows:
6. A switching circuit protection method
comprising the steps of:
detecting the self-firing of at least one
switching element due to an over-voltage in a
switching circuit having multiple parallel circuits;
applying a firing pulse to all the switching
elements in the switching circuit in response to the
detected self-firing; and
firing all un-fired switching elements at the
same time due to the firing pulse.
Besides the appellant’s admitted prior art (AAPA), the
references relied on in rejecting the claims follow:
Mitsuoka 4,697,219 Sep. 29, 1987
Takahashi 4,796,146 Jan.
3, 1989.

Claims 1-9 stand rejected under 35 U.S.C. § 103 as obvious
over AAPA in view of Takahashi and Mitsuoka. Rather than
repeat the arguments of the appellant or examiner in toto, we
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Application No. 08/329,687
refer the reader to the briefs and answer for the respective
details thereof.
OPINION
In deciding this appeal, we considered the subject matter
on appeal and the rejection advanced by the examiner.
Furthermore, we duly considered the arguments and evidence of
the appellant and examiner. After considering the totality of
the record, we are persuaded that the examiner erred in
rejecting claims 1-9. Accordingly, we reverse.
We begin by noting the following principles from In re
Rijckaert, 9 F.3d 1531, 1532, 28 USPQ2d 1955, 1956 (Fed. Cir.
1993).
In rejecting claims under 35 U.S.C. § 103, the
examiner bears the initial burden of presenting a
prima facie case of obviousness. In re Oetiker, 977
F.2d 1443, 1445, 24 USPQ2d 1443, 1444 (Fed. Cir.
1992).... "A prima facie case of obviousness is
established when the teachings from the prior art
itself would appear to have suggested the claimed
subject matter to a person of ordinary skill in the
art." In re Bell, 991 F.2d 781, 782, 26 USPQ2d
1529, 1531 (Fed. Cir. 1993) (quoting In re Rinehart,
531 F.2d 1048, 1051, 189 USPQ 143, 147 (CCPA 1976)).
If the examiner fails to establish a prima facie
case, the rejection is improper and will be
Appeal No. 1997-2340 Page 5
Application No. 08/329,687
overturned. In re Fine, 837 F.2d 1071, 1074, 5
USPQ2d 1596, 1598 (Fed. Cir. 1988).
With these principles in mind, we address the examiner's
rejection and the appellant's argument.
The examiner's rejection follows in pertinent part.
The prior art figure does not show a detect means
for detecting the voltage or current of the
switching thyristors in order to send a firing pulse
to all of the switching elements to protect the
thyristor(s) which is(are) conductive.
Takahashi shows in figure 1 series connected
thyristors 1N, 12, 13 with a voltage detect circuit
in parallel to each thyristor (4N ... 41) and a
digital circuit for combining and comparing the
voltage sense responses for determining an out of
range voltage for any of the individual thyristors
an sending a signal h to simultaneously fire all of
the thyristors into conduction to avoid an
application of overvoltages across some of the
thyristors.
Mitsuoka shows in figure 5 a current sensor 13
for measuring the current through the thyristor 1
and parallel components for detecting an abnormal
signal, causing the conduction of the thyristor lla
and llb to protect the thyristor 1.
(Paper No. 16 at 3.) The appellant argues, "the prior art
does not disclose or suggest the claimed detecting of self-
firing." (Appeal Br. at 7.)
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Application No. 08/329,687
“‘[T]he main purpose of the examination, to which every
application is subjected, is to try to make sure that what
each claim defines is patentable. [T]he name of the game is
the claim ....’” In re Hiniker Co., 150 F.3d 1362, 1369,
47 USPQ2d 1523, 1529 (Fed. Cir. 1998) (quoting Giles S. Rich,
The Extent of the Protection and Interpretation of
Claims--American Perspectives, 21 Int'l Rev. Indus. Prop. &
Copyright L. 497, 499, 501 (1990)). Furthermore, “[c]laims
are not interpreted in a vacuum, but are part of and are read
in light of the specification.” Slimfold Mfg. Co. v. Kinkead
Indus., Inc., 810 F.2d 1113, 1116,
1 USPQ2d 1563, 1566 (Fed. Cir. 1987) (citing Hybritech Inc. v.
Monoclonal Anti-bodies, Inc., 802 F.2d 1367, 1385, 231 USPQ
81, 94-95 (Fed. Cir. 1986); In re Mattison, 509 F.2d 563, 565,
184 USPQ 484, 486 (CCPA 1975)). Here, claim 1-5 specify in
pertinent part the following limitations: "detect means for
detecting the self-firing of any of the switching elements in
the switching circuit due to the over-voltage ...."
Similarly, claim 6 specifies in pertinent part the following
limitations: "detecting the self-firing of at least one
switching element due to an over-voltage in a switching
Appeal No. 1997-2340 Page 7
Application No. 08/329,687
circuit having multiple parallel circuits ...." Also
similarly, claims 7-9 specify in pertinent part the following
limitations: "a detection circuit which detects a self-firing
of either the switching element of said first current path or
the switching element of said second current path ...."
The specification defines self-firing as follows.
"[E]ven when there is no ON command, VBO free thyristors 11,
12, 21, 22, 31, and 32 can fire by themselves and prevent
over-voltage." (Spec. at 2.) Reading the limitations in light
of the specification, claims 1-9 require detecting the self-
turning-on of a switching element absent an ON command.
The examiner fails to show a suggestion of the
limitations in the prior art. “Obviousness may not be
established using hindsight or in view of the teachings or
suggestions of the inventor.” Para-Ordnance Mfg. v. SGS
Importers Int’l, 73 F.3d 1085, 1087, 37 USPQ2d 1237, 1239
(Fed. Cir. 1995)(citing W.L. Gore & Assocs., Inc. v. Garlock,
Inc., 721 F.2d 1540, 1551, 1553, 220 USPQ 303, 311, 312-13
(Fed. Cir. 1983)). “The mere fact that the prior art may be
Appeal No. 1997-2340 Page 8
Application No. 08/329,687
modified in the manner suggested by the Examiner does not make
the modification obvious unless the prior art suggested the
desirability of the modification.”
In re Fritch, 972 F.2d 1260, 1266, 23 USPQ2d 1780, 1783-84
(Fed. Cir. 1992) (citing In re Gordon, 733 F.2d 900, 902, 221
USPQ 1125, 1127 (Fed. Cir. 1984)). “It is impermissible to
use the claimed invention as an instruction manual or
‘template’ to piece together the teachings of the prior art so
that the claimed invention is rendered obvious.” Id. at 1266,
23 USPQ2d at 1784, (citing In re Gorman, 933 F.2d 982, 987, 18
USPQ2d 1885, 1888 (Fed. Cir. 1991)).
Here, the examiner admits that AAPA does not teach
detecting the self-turning-on of a switching element absent an
ON command. He specifically admits, "[t]he prior art figure
does not show a detect means for detecting the voltage or
current of the switching thyristors in order to send a firing
pulse to all of the switching elements to protect the
thyristor(s) which is(are) conductive." (Paper No. 16 at 3.)
The examiner fails to show that Takahashi and Mitsuoka remedy
the defect of AAPA.
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Application No. 08/329,687
Although Takahashi teaches detecting, it does not detect
the self-turning-on of a switching element absent an ON
command. To the contrary, "a partial turn-off phenomenon
itself is detected ...." Col. 7, ll. 11-12. The reference
describes the phenomenon as follows.
In more detail, when many thyristors are turned off,
reverse voltages are required to be applied across
the corresponding thyristors during long enough
intervals that all of the thyristors can withstand
forward voltages subsequently applied thereto. In
case these reverse voltage intervals are
insufficient, when a forward voltage is applied
across the thyristors, some thyristors can withstand
the forward voltage, but the remaining thyristors
fail to perform forward recovery, i.e., recover
their features to withstand the forward voltage,
with the result that they maintain their conductive
states. This phenomenon is a so-called partial
turn-off phenomenon.
Col. 1, ll. 28-40. In summary, Takahashi detects partial
turn-off of some thyristors rather than their self-turning-on.
For its part, although Mitsuoka teaches detecting, it
does not detect the self-turning-on of a switching element
absent an ON command. To the contrary, "the main current path
of the GTO 1 is provided with a current detector 13 for
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Application No. 08/329,687
detecting the value of the main current of the GTO 1. The
output of this current detector 13 is applied to a control
circuit 14. This control circuit 14 is a circuit which serves
to selectively activate the sub snubber circuits 2a and 2b in
accordance with the magnitude of the main current value of the
GTO 1." Col. 3, ll. 14-20. In summary, the reference detects
the magnitude of the main current of a thyristor rather than
its self-turning-on.
Because Takahashi detects partial turn-off of some
thyristors and Mitsuoka detects the magnitude of the main
current of a thyristor, we are not persuaded that teachings
from the prior art would have suggested the limitations of
"detect means for detecting the self-firing of any of the
switching elements in the switching circuit due to the over-
voltage;" "detecting the self-firing of at least one switching
element due to an over-voltage in a switching circuit having
multiple parallel circuits;" or "a detection circuit which
detects a self-firing of either the switching element of said
first current path or the switching element of said second
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Application No. 08/329,687
current path ...." The examiner fails to establish a prima
facie case of obviousness. Therefore, we reverse the
rejections of claims 1-9 as obvious over AAPA in view of
Takahashi and Mitsuoka.
CONCLUSION
In summary, the rejection of claims 1-9 under 35 U.S.C.
§ 103 as obvious over AAPA in view of Takahashi and Mitsuoka
is reversed.
REVERSED
MICHAEL R. FLEMING )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
PARSHOTAM S. LALL ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
LANCE LEONARD BARRY )
Administrative Patent Judge )
Appeal No. 1997-2340 Page 12
Application No. 08/329,687
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