Ex parte Fordyce

Board of Patent Appeals and Interferences

Dec 12, 1997

08037767 (B.P.A.I. Dec. 12, 1997)

Application for patent filed March 26, 1993.1
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THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today
(1) was not written for publication in a law journal and
(2) is not binding precedent of the Board.
Paper No. 22
UNITED STATES PATENT AND TRADEMARK OFFICE
____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________
Ex parte GRAHAM T. FORDYCE
____________
Appeal No. 96-2551
Application 08/037,7671
____________
ON BRIEF
____________
Before HAIRSTON, KRASS, and MARTIN, Administrative Patent Judges.
MARTIN, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 from the
examiner's final rejection of claims 1-3, 5-9 and 11-14 under the
second paragraph of 35 U.S.C. § 112 and of claims 10 and 15 under
Appeal No. 96-2551
Application 08/037,767
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§ 102(b). No claims have been indicated as allowable. We reverse
both grounds of rejection.
The claimed subject matter is a gate drive for rapidly
turning on and off a high current capacity power switch, such as
an insulated gate bipolar transistor in an inverter operated in a
pulse-width modulated mode of operation. Claim 1 reads as
follows:
1. A drive circuit for a power switching
device, comprising:
a transformer having a primary winding and a
secondary winding across which secondary pulses of first
and second polarities and first and second magnitudes
are developed when input pulses of opposing polarities
are provided to the primary winding;
a full-wave rectifier bridge having first and
second nodes coupled to the secondary winding and third
and fourth nodes;
first and second capacitors connected in series
between the third and fourth nodes;
first and second controlled switches coupled
between a control electrode of the power switching
device and the first and second capacitors,
respectively, each controlled switch having a control
electrode coupled to the secondary winding of the
transformer;
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Application 08/037,767
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wherein control current is drawn from the control
electrode of the power switching device through the
second controlled switch to the second capacitor in
response to the development of a secondary pulse of the
second polarity and the second magnitude, at which point
charging current is provided to the first and second
capacitors from the secondary winding of the
transformer; and
wherein the control current is provided by the
first capacitor to the control electrode of the
power switching device through the first
controlled switch in response to the
development of a secondary pulse of the
first polarity and the first magnitude,
the first capacitor being discharged
thereby until a voltage magnitude of the
first capacitor discharges below the first
magnitude of the secondary pulse of the
first polarity and the first magnitude, at
which point charging current is provided
to the first capacitor from the secondary
winding of the transformer.
A. The § 112 rejection
The § 112 rejection was applied against claim 2 for the
first time as a new ground of rejection in the examiner's Answer.
Appellant's reply brief was refused entry by the examiner on the
ground that it was not limited to the new ground of rejection.
Appellant filed a petition arguing that the reply brief is
responsive to the § 112 rejection of claim 2 and to a number of
arguments presented for the first time in the Answer. In a
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Application 08/037,767
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decision on petition mailed April 30, 1996, the Deputy Director of
Group 2500 held that the reply brief is entitled to consideration
only to the extent it concerns the § 112 rejection of claim 2 and
the "capacitor charging/discharging" example used for the first
time at page 9 of the Answer. Accordingly, we have considered the
reply brief only to this extent.
The examiner contends claim 1 fails to particularly
point out and distinctly claim the invention for several reasons.
Regarding the limitation "secondary pulses of first and second
polarities and first and second magnitudes," the examiner offers
two criticisms. The first is that the phrase "secondary pulses of
first and second polarities" is a complete description of both of
the pulses shown in Figure 5, with the result that the further
recitation of "first and second magnitudes" implies two additional
types of pulses, which have no support in the specification
(Answer at 6). We do not agree. While it is true that the phrase
"secondary pulses of first and second polarities" implies that the
pulses have amplitudes, the further recitation that these pulses
have first and second magnitudes does not imply anything not shown
in that figure. Instead, it merely makes explicit what is already
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Application 08/037,767
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implicit, i.e., that pulses have magnitudes, which is akin to
reciting first and second circular openings having first and
second diameters. Furthermore, the language in question provides
antecedent basis for the limitation "below the first magnitude" in
the second "wherein" clause. Consequently, we agree with
appellant that it is not improper to recite that the secondary
pulses have first and second polarities and first and second
magnitudes.
The examiner's second criticism of the limitation
"secondary pulses of first and second polarities and first and
second magnitudes" is that it is "misdescriptive" because it
implies that the magnitude of the pulses of the first polarity can
be different from the magnitude of the pulses of the second
polarity, when the magnitudes are depicted as being the same in
Figure 5 and there is no indication in the specification that they
can have different magnitudes. He further contends it is well
known that pulse sources, such as source 20 of Figure 4,
conventionally provide pulses that are equally spaced and have
equal width and magnitude. Even assuming that all of these
allegations are correct, they do not establish that claim 1
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violates the second paragraph of § 112 by claiming more than
appellant regards as his invention. See In re Borkowski, 422 F.2d
904, 909-10, 164 USPQ 642, 645-46 (CCPA 1970):
The examiner's approach to determining whether
appellants' claims satisfy the requirements of § 112
appears to have been to study appellants' disclosure, to
formulate a conclusion as to what he (the examiner)
regards as the broadest invention supported by the
disclosure, and then to determine whether appellants'
claims are broader than the examiner's conception of
what "the invention" is. We cannot agree that § 112
permits of such an approach to claims. The first
sentence of the second paragraph of §112 is essentially
a requirement for precision and definiteness of claim
language. If the scope of subject matter embraced by a
claim is clear, and if the applicant has not otherwise
indicated that he intends the claim to be of a different
scope [footnote 3: "See In re Prater, 56 CCPA 1381, 415
F.2d 1393, 162 USPQ 541 (1969), where the applicant did
indicate an intended scope different from our
interpretation"], then the claim does particularly point
out and distinctly claim the subject matter which the
applicant regards as his invention. [Emphasis in
original.]
As the examiner has not explained why the scope of the claim
language is unclear or why he believes the applicant has indicated
that he intends to limit his claims to pulses having the same
Appeal No. 96-2551
Application 08/037,767
If the examiner believes the breadth of the claim language2
is such that it lacks either written description or enabling
support, he should have rejected the claim under the first
paragraph of § 112 rather than the second. See Borkowski, 422
F.2d at 909, 164 USPQ at 646:
[I]f the "enabling" disclosure of a specification is not
commensurate in scope with the subject matter
encompassed by a claim, that fact does not render the
claim imprecise or indefinite or otherwise not in
compliance with the second paragraph of § 112; rather,
the claim is based on an insufficient disclosure
[footnote omitted](§ 112, first paragraph) and should be
rejected on that ground. See In re Fuetterer, 50 CCPA
1453, 319 F.2d 259, 138 USPQ 217 (1963); In re Kamal, 55
CCPA 1409, 398 F.2d 867, 158 USPQ 320 (1968); and In re
Wakefield, 164 USPQ [636, 422 F.2d 897 (CCPA 1970)],
decided concurrently herewith. [Emphasis in original.]
See also In re Cormany, 477 F.2d 998, 999-1000, 177 USPQ 450, 451
(CCPA 1973) (indefiniteness of claim language and inadequate
support for it in the specification are distinct questions under
the second and first paragraphs, respectively, of 35 U.S.C.
§ 112); and In re Miller, 441 F.2d 689, 693, 169 USPQ 597, 600
(CCPA 1971)("Even if it is not true, as appellant asserts, that it
is generally understood in the art that omission of temperature
from such a recitation indicates that room temperature is intended
and the claims are therefor broader than they otherwise would be,
breadth is not to be equated with indefiniteness, as we have said
many times.").
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amplitude, the rejection based on the second paragraph of § 112
cannot be sustained. 2
The examiner also finds fault with claim 1's second
"wherein" clause to the extent it recites that "a voltage
magnitude on the first capacitor discharges below the first
Appeal No. 96-2551
Application 08/037,767
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magnitude of the secondary pulse of the first polarity and the
first magnitude." This "wherein" clause describes the effect of
activating the "first controlled switch [Q3] in response to the
development of a secondary pulse of the first [i.e., negative]
polarity and the first magnitude." The examiner contends the
passage in question is "not understood" because
[i]t is not seen possible that either the "first
capacitor" or the "second capacitor" can discharge.
When either a positive or a negative pulse is provided
from the secondary winding (turning on either Q3 or Q4,
respectively), a positive voltage is provided between
nodes 30 and 32 due to rectifier [diodes] D1-D4 and
diodes D5 and D6. With a positive voltage being applied
across nodes 30 and 32, and thus across the "first
capacitor" and the "second capacitor," the "first
capacitor" cannot discharge. [Answer at 7; emphasis in
original.]
This analysis ignores the fact that the diodes do not conduct
immediately upon receipt of a negative or a positive secondary
pulse and turn-on of control transistor Q3 or Q4. The diodes do
not begin to conduct until after some charge has been transferred
via Q3 or Q4 between the capacitors and control electrode 24 of
transistor Q1. See the specification at page 3, line 20 to page
4, line 7, and page 12, lines 7-8. The examiner has not
explained, and it is not apparent to us, why appellant's circuit
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cannot operate in this manner. Thus, it is clear that the claimed
discharging of the first capacitor (C4, C5) occurs after Q3 begins
to conduct but before D2, D3, D5, and D6 begin to conduct.
Consequently, we will not sustain the § 112 rejection of claim 1
or the § 112 rejection of dependent claim 2, which was rejected
for the same reasons as claim 1.
The examiner contends that dependent claim 3, which
specifies that the precharging means of claim 2 "comprises a third
controlled switch coupled between a voltage source and the first
capacitor" (examiner's emphasis) is misdescriptive of transistor
Q5, whose base-emitter path is used to precharge the first
capacitor (C4, C5) (Spec. at page 14, lines 20-26). According to
the examiner, the claim language would be understood to mean that
the switched terminals of the switch (i.e., the emitter and
collector of a transistor) are connected between the voltage
source and the first capacitor, which whereas in the disclosed
arrangement only one of the switched terminals (the emitter) and
the control terminal (the base) are connected between the voltage
source and the first capacitor. We agree with appellant that
since the claim does not specify which terminals of the controlled
Appeal No. 96-2551
Application 08/037,767
This connection is recited dependent claim 5.3
The contention in the final Office action (at 3) that4
"first capacitor" in claim 3 should be changed to "control
electrodes of the first and second controlled switches" was not
repeated in the Answer and is therefore presumed to have been
withdrawn.
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switch are to be connected between the voltage source and the
first capacitor, it is broad enough to read on connecting the base
and emitter terminals in this manner. The examiner also argues
that because only the base and emitter are involved in precharging
the first capacitor, Q5 is effectively operating as a diode rather
than as the "controlled switch" required by the claim. This
argument fails because Q5 actually functions as an emitter-
collector switch, albeit for a purpose not set forth in claim 3,
i.e., for applying a high potential to the control electrodes of
transistors Q3 and Q4 (Spec. at sentence bridging pages 14 and
15). The claim does not require that the precharging of the3
first capacitor be responsive to switching of the controlled
switch. As a result, we will not sustain the § 112 rejection of
claim 3.4
For the foregoing reasons, we are also reversing the
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Application 08/037,767
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§ 112 rejection of claims 5-9, which were rejected "for the
reasons discussed in claims 1 and 3," of claim 11, which was
rejected "for similar reasons as discussed above with respect to
claim 3," and of claims 12-14, which were rejected "for the
reasons discussed above with claim 11" (Answer at 5).
B. The § 102(b) rejection of claims 10 and 15.
Claims 10 and 15 are directed to precharging of the
first capacitor, which, as noted above in the discussion of claim
3, is performed by transistor Q5. Those claims read as follows:
10. In a drive circuit for a power switching
device wherein the drive circuit includes a transformer
having a primary winding and a secondary winding across
which a secondary pulse is developed when an input pulse
is provided to the primary winding at a particular time,
means coupled to the secondary winding for rectifying
the secondary pulse, a capacitor connected across the
rectifying means and a controlled switch having a
control electrode coupled to the secondary winding of
the transformer and first and second main current path
electrodes, the first main current path electrode
coupled to the capacitor and the second main current
electrode coupled to a control electrode of the power
switching device, the improvement comprising:
means coupled to the first capacitor and operable
before the particular time for precharging the
capacitor.
15. In a drive circuit for a power transistor
having main current path electrodes one of which is
coupled to a power source wherein the drive circuit
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Application 08/037,767
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includes a pulse transformer having a primary winding
and a secondary winding across which positive and
negative secondary pulses are developed when positive
and negative input pulses are provided to the primary
winding following a particular time, means coupled to
the secondary winding for rectifying the secondary
pulses, first and second series-connected capacitors
connected to the rectifying means and first and second
controlled switches each having a control electrode
coupled to the secondary winding of the transformer and
main current path electrodes coupled between the
capacitors and a control electrode of the power
transistor, the improvement comprising:
means coupled to the first capacitor and operable
before the particular time for precharging the first
capacitor including a third controlled switch coupled
between the power source and the first capacitor; and
means coupled between the power transistor and the
third controlled switch for detecting an overcurrent
condition in the power transistor wherein the third
controlled switch is responsive to such overcurrent
detection to turn off the power transistor.
The examiner reads the limitations of claim 10, which is the
broader of the two claims, on Landseadel as follows:
(a) "transformer" - transformer 26;
(b) "rectifying means" - rectifier circuit 36;
(c) "capacitor" - capacitors 46 and/or 48;
(d) "controlled switch" - MOSFET 14 or 22;
(e) "means for precharging" - resistor 54.
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The only point in dispute is whether the means for precharging,
i.e., resistor 54, precharges one of the capacitors prior to
application of an input pulse to the primary winding of the
transformer, as required by the claim. The examiner contends that
"prior to the transformer receiving pulses, resistor 54 will cause
capacitor 46 to have a charge of approximately zero volts" (final
Office action at 4). Most of appellant's discussion of the
rejection concerns whether the examiner is correct to construe the
term "precharge" as broad enough to read on discharging a
capacitor to approximately zero volts. However, whether or not
the examiner is correct on this point, the rejection fails
because, as appellant correctly notes in an alternative argument
at page 16 of the brief: "The circuit of Landseadel cannot
precharge the capacitor until the power supply, and specifically
the transformer, receives an input. Prior to this time there is
no voltage with which to charge a capacitor." Appellant is
correct in this regard because the transformer, rectifier circuit
36 and capacitors 46 and 48 are part of a DC power supply 24,
which produces DC power supply voltages only when the transformer
primary is receiving AC power (col. 2, lines 31-51). As a result,
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prior to the application of the first AC "pulse" to the primary
winding of the transformer, resistor 54 is unable to transfer
charge to or from either of the two capacitors. For this reason,
the rejection of claim 10 is reversed.
The rejection of claim 15, which like claim 10 requires
"precharging" to occur prior to application of the first pulse to
the primary winding of the transformer, is reversed for the same
reason. It is also reversed for an additional reason argued by
appellant (Br. at 18), which is that the final Office action fails
to address the claimed "means . . . for detecting an overcurrent
condition in the power transistor wherein the third controlled
switch is responsive to such overcurrent detection to turn off the
power transistor." Nor was this limitation addressed in the
Answer, which improperly treats claim 15 as standing or falling
with claim 10 (Answer at 10) even though it is separately argued
in the brief.
For the foregoing reasons, the § 102(b) rejection of
claims 10 and 15 is reversed.
REVERSED
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KENNETH W. HAIRSTON )
Administrative Patent Judge )
)
)
)
ERROL A. KRASS ) BOARD OF PATENT
Administrative Patent Judge ) APPEALS AND
) INTERFERENCES
)
)
JOHN C. MARTIN )
Administrative Patent Judge )
Jeffery S. Makeever
Patent Department #441-3
Sundstrand Corporation
4949 Harrison Avenue
P.O. Box 7003
Rockford, IL 61125-7003