DENSO CORPORATION

Patent Trials and Appeals Board

Jun 4, 2021

2020000844 (P.T.A.B. Jun. 4, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
14/168,388 01/30/2014 Sho YAMADA RYM-2635-1391 4993
23117 7590 06/04/2021
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON, VA 22203
EXAMINER
O TOOLE, COLLEEN J
ART UNIT PAPER NUMBER
2849
NOTIFICATION DATE DELIVERY MODE
06/04/2021 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
PTOMAIL@nixonvan.com
pair_nixon@firsttofile.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________________

Ex parte SHO YAMADA, YOSUKE WATANABE,
JUNICHI FUKUTA, and
TSUNEO MAEBARA
____________________

Appeal 2020-000844
Application 14/168,3881
Technology Center 2800
____________________

Before JAMES C. HOUSEL, MICHELLE N. ANKENBRAND, and
JULIA HEANEY, Administrative Patent Judges.

HOUSEL, Administrative Patent Judge.

DECISION ON APPEAL
A. STATEMENT OF THE CASE
Appellant filed an appeal under 35 U.S.C. § 134(a) from the
Examiner’s final decision rejecting claims 6, 7, 15, 16, and 29–31, which
constitute all the claims pending in this application. We have jurisdiction
under 35 U.S.C. § 6(b).2
We REVERSE.

1 We use the word Appellant to refer to “applicant” as defined in 37 C.F.R.
§ 1.42. Appellant identifies Denso Corporation as the real party in interest.
Appeal Brief (“Appeal Br.”) filed May 17, 2019, 3.
2 Our Decision additionally refers to the Specification (“Spec.”) filed
January 30, 2014, the Final Office Action (“Final Act.”) dated February 26,
2019, the Examiner’s Answer (“Ans.”) dated September 20, 2019, and the
Reply Brief (“Reply Br.”) filed November 13, 2019.
Appeal 2020-000844
Application 14/168,388

2
The subject matter on appeal relates to an electronic apparatus that
includes a plurality of switching elements, a plurality of resonance
suppression resistors, an on-drive circuit, an off-drive circuit, a plurality of
diodes, and a control circuit that is connected to the diodes and controls a
drive power circuit on the basis of a forward voltage of the diodes (see, e.g.,
claims 6 and 15). The Specification explains that an insulated gate bipolar
transistor (“IGBT”) is a switching element driven by controlling the voltage
of its gate. Spec. 1:29–30. A gate drive circuit can include on-drive
elements for applying electric charge to the gate and off-drive elements for
releasing the electric charge from the gate. Id. at 1:30–2:12.
The Specification explains that when a large current capacity
switching element is required, a plurality of IGBTs having a small current
capacity can be connected in parallel. Id. at 2:17–21. However, capacitor
and inductor components are present in such an arrangement, which
generates resonance. Id. at 2:31–3:5. The Specification describes using
resonance suppression resistors to suppress the resonance. Id. at 3:5–10.
However, the Specification further explains that when the resistance of an
off-drive resistor is smaller than the resistance of the resonance suppression
resistors, the current flowing out of the gates of the small-current capacity
IGBTs cannot be sufficiently increased and it is difficult to shorten the
period in which electric charge is released from the gates of the small-
current-capacity IGBTs. Id. at 3:23–31. According to the Specification, this
causes a loss. Id. at 3:31–33.
In view of the above, the Specification describes an electronic
apparatus that can apply electric charge or allow the release of electric
charge from the control terminals of switching elements without being
Appeal 2020-000844
Application 14/168,388

3
influenced by resonance suppression resistors because a resistance of an on-
drive resistor or an off-drive resistor is smaller than the resistance of
resonance suppression resistors. Id. at 4:3–9. The Specification explains
that such an arrangement can shorten the time required for IGBTs to be
turned and suppresses loss. Id. at 13:26–14:3. The Specification also
explains using a control circuit that controls a drive power circuit on the
basis of forward voltage of diodes suppresses variation of gate voltage when
the electric charge is being released from the gates of IGBTs. Id. at 14:11–
19.
Independent claim 6 is illustrative and is reproduced below from the
Claims Appendix to the Appeal Brief.
6. An electronic apparatus, comprising:
a plurality of switching elements each of which has an
input terminal, an output terminal and a control terminal, the
input terminals having a common connection, and the output
terminals having a common connection, and each of which is
driven by controlling voltage at the control terminal;
a plurality of resonance suppression resistors each of
which has a first end and a second end, the first ends being
connected to the respective control terminals of the switching
elements, and the second ends having a common connection;
an on-drive circuit which has at least one on-drive
resistor and is connected to a drive power circuit, and which is
supplied with voltage from the drive power circuit and applies
electric charge to the control terminals of the switching
elements via the on-drive resistor to turn on the switching
elements;
an off-drive circuit which has an off-drive resistor and
releases electric charge from the control terminals of the
switching elements via the off-drive resistor to turn off the
switching elements;
a plurality of diodes each of which has an anode and a
cathode, the anodes being connected to a switching elements
Appeal 2020-000844
Application 14/168,388

4
side of the respective resonance suppression resistors, and the
cathodes being connected to an opposite side of the switching
elements side of the respective resonance suppression resistors;
and
a control circuit which is connected to the diodes and
controls the drive power circuit on the basis of forward voltage
of the diodes to adjust output voltage of the drive power circuit,
wherein
a resistance of the off-drive resistor is set to be smaller
than a resistance of the resonance suppression resistors,
the off-drive circuit releases electric charge from the
control terminals of the switching elements not via the
resonance suppression resistors,
the off-drive circuit is connected to a common-
connecting point of the resonance suppression resistors and
releases electric charge from the control terminals of the
switching elements via the diodes,
if the forward voltage of the diodes is larger than a
predetermined voltage, the control circuit steps down the output
voltage of the drive power circuit in accordance with the
forward voltage of the diodes, and
if the forward voltage of the diodes is smaller than the
predetermined voltage, the control circuit steps up the output
voltage of the drive power circuit in accordance with the
forward voltage of the diodes.
REJECTIONS ON APPEAL
The Examiner maintains, and Appellant requests our review of, the
following grounds of rejection under 35 U.S.C. § 103:
I. Claims 6, 29, and 30 as unpatentable over Ishii,3 Hoshi,4
and Wagoner;5

3 Ishii, US 5,977,814, issued Nov. 2, 1999 (“Ishii”).
4 Hoshi et al., US 6,271,708 B1, issued Aug. 7, 2001 (“Hoshi”).
5 Wagoner et al., US 2014/0015571 A1, published Jan. 16, 2014.
Appeal 2020-000844
Application 14/168,388

5
II. Claim 7 as unpatentable over Ishii, Hoshi, Wagoner, and
Kimata;6
III. Claims 15 and 31 as unpatentable over Hoshi, Kayama,7
and Wagoner; and
IV. Claim 16 as unpatentable over Hoshi, Kayama, Wagoner,
and Kimata. Final Act. 2–9.

B. DISCUSSION
Rejection I
The Examiner finds that Ishii discloses an electronic apparatus having
a switching element, a resonance suppression resistor, an on-drive circuit,
and an off-drive circuit. Final Act. 2–3. The Examiner finds Ishii does not
teach a plurality of switching elements and a plurality of resonance
suppression resistors. Id. at 3. The Examiner finds Hoshi discloses a
plurality of switching elements and a plurality of resonance suppression
resistors. Id. The Examiner concludes it would have been obvious to
modify Ishii in view of Hoshi to use a plurality of switching elements and
that the combination would result in a plurality of diodes. Id.
The Examiner finds that the combination of Ishii and Hoshi does not
teach a control circuit. Id. at 4. The Examiner finds:
Wagoner teaches a control circuit (Figure 2) which is connected
to the diodes and controls the drive power circuit on the basis of
forward voltage of the diodes to adjust output voltage of the drive
power circuit ([0019], where the input parameters are gate
voltage and ambient temperature and diodes have a threshold
voltage that is substantially in inverse proportion to the change

6 Kimata, US 5,986,484, issued Nov. 16, 1999 (“Kimata”).
7 Kayama, US 5,227,655, issued July 13, 1993 (“Kayama”).
Appeal 2020-000844
Application 14/168,388

6
of the surrounding temperature (see, for example, [0114] of U.S.
Patent Application Publication 2010/0039364)).
Id. at 7. The Examiner finds that Wagoner’s control circuit would perform
the claimed controls for output voltage of a drive power circuit based on
whether a forward voltage of diodes is larger or smaller than a
predetermined voltage. Id. The Examiner concludes it would have been
obvious to modify the combination of Ishii and Hoshi to use Wagoner’s
control circuit to prevent current and voltage transients on an IGBT. Id.
Appellant contends that the portions of Wagoner the Examiner cites
(i.e., Figure 2 and paragraph 19) do not disclose a control circuit connected
to diodes. Appeal Br. 15. Appellant also argues there is nothing in these
portions of Wagoner that discloses controlling the output voltage of a drive
power circuit based on whether a forward voltage of diodes is larger or
smaller than a predetermined voltage, as claim 6 recites. Id. The Examiner
responds to Appellant’s arguments by essentially repeating the findings and
conclusion in the rejection regarding Wagoner and by stating that Wagoner’s
control unit would be connected to Ishii’s diodes. Ans. 8–9.
Appellant’s arguments are persuasive. Wagoner’s paragraph 19
discloses that an
adaptive current regulator 22 may adjust the gate drive currents
provided to the gate (G) of the IGBT 10 based on input
parameters such as, for example, the collector voltage 24 (Vc),
the rate of collector voltage change 26 (dVc/dt), the collector
current 28 Ic), the gate voltage 30 (Vg), the rate of gate voltage
change 32 (dVg/dt), the ambient temperature 34 (Tamb), the gate
current feedback 36 (Ifbk), the emitter current 38 (Ie), the rate of
emitter current change 40 (dIe/dt), and the like.
Appeal 2020-000844
Application 14/168,388

7
Wagoner’s Figure 2 depicts a block diagram that includes adaptive current
regulator 22 and the various possible input parameters described in
paragraph 19. However, neither Figure 2 nor paragraph 19 discloses or
suggests that Wagoner’s adaptive current regulator 22 is connected to diodes
and performs a control on the basis of a forward voltage of the diodes, as
claim 6 recites. The cited portions of Wagoner also do not disclose or
suggest that adaptive current regulator 22 controls the output voltage of a
drive power circuit based on whether a forward voltage of the diodes is
larger or smaller than a predetermined voltage, as claim 6 recites.
The Examiner’s citation to paragraph 114 of U.S. Patent Application
Publication 2010/0039364 does not remedy this deficiency. As noted above,
the Examiner cites this reference to support the Examiner’s position that
“diodes have a threshold voltage that is substantially in inverse proportion to
the change of the surrounding temperature.” Final Act. 4; Ans. 9. Paragraph
114 of U.S. Patent Application Publication 2010/0039364 states that a
“diode D3 may have a threshold voltage that is substantially in inverse
proportion to the change of the surrounding temperature.” This statement,
however, does not support the Examiner’s position because it states that a
diode may have a threshold voltage that is related to the surrounding
temperature, not that a diode necessarily has such a relationship. This
paragraph also does not clearly suggest that the “threshold voltage” it
discusses is the same as the forward voltage for a diode, as claim 6 requires.
The Examiner’s reasoning also does not sufficiently explain how the
threshold voltage described in paragraph 114 is equivalent to the forward
voltage of a diode, as claim 6 recites.
Appeal 2020-000844
Application 14/168,388

8
To the extent a relationship exists between the input parameters that
Wagoner discloses (e.g., gate voltage and/or ambient temperature) and the
forward voltage for a diode, the Examiner has not established such a
relationship on this record or articulated sufficient reasoning with some
rational underpinning why it would have been obvious to combine Ishii,
Hoshi, and Wagoner and to further include the claimed control circuit in
view of such a relationship. KSR Int’l. Co. v. Teleflex Inc., 550 U.S. 398,
418 (2007). When one considers the disclosures of the applied references
and these deficiencies, the Examiner’s conclusion that the proposed
combination would have resulted in the claimed invention can only be
viewed as being based on impermissible hindsight. Id. at 421 (citing
Graham v. John Deere Co., 383 U.S. 1, 36 (1966) (warning against a
“temptation to read into the prior art the teachings of the invention in
issue”)); In re McLaughlin, 443 F.2d 1392, 1395, (CCPA 1971) (“Any
judgment on obviousness is in a sense necessarily a reconstruction based
upon hindsight reasoning, but so long as it takes into account only
knowledge which was within the level of ordinary skill at the time the
claimed invention was made and does not include knowledge gleaned only
from applicant’s disclosure, such a reconstruction is proper.”).
For the reasons discussed above, we do not sustain the Examiner’s
§ 103 rejection of claims 6, 29, and 30 as unpatentable over Ishii, Hoshi, and
Wagoner.

Rejection III
The Examiner finds Hoshi teaches an electronic apparatus that
includes a plurality of switching elements, an on-drive circuit, and an off-
Appeal 2020-000844
Application 14/168,388

9
drive circuit. Final Act. 6. The Examiner finds that Hoshi does not teach a
plurality of resonance suppression resistors, but finds that Kayama does. Id.
at 6–7. The Examiner concludes that it would have been obvious to modify
Hoshi in view of Kayama to use a plurality of resonance suppression
resistors. Id. at 7.
The Examiner further finds that Hoshi and Kayama do not teach a
control circuit. Id. The Examiner concludes that it would have been
obvious to modify Hoshi and Kayama in view of Wagoner to include the
claimed control circuit, based on reasoning similar to that set forth in the
rejection over Ishii, Hoshi, and Wagoner. Id. at 7–8; Ans. 9–128.
Appellant argues that the cited portions of Wagoner do not disclose a
control circuit connected to diodes or controlling the output voltage of a
drive power circuit based on whether a forward voltage of diodes is larger or
smaller than a predetermined voltage, as claim 15 recites. Appeal Br. 16–
17. For the reasons discussed above with regard to the rejection of claim 6,
Appellant’s arguments identify a reversible error in this rejection.
Accordingly, we do not sustain the Examiner’s § 103 rejection of
claims 15 and 31 as unpatentable over Hoshi, Kayama, and Wagoner.

8 The Examiner also cites Wagoner’s paragraph 42 on page 11 of the
Answer. Although paragraph 42 describes advantages for Wagoner’s
adaptive current regulator 22 (e.g., fast switching times and efficient power
consumption properties), this paragraph also does not disclose or suggest
that adaptive current regulator 22 performs control on the basis of a forward
voltage of a diode. Further, paragraph 42 teaches that “[t]he elimination of
the zener diodes generally provides a reliability improvement since zener
diodes are susceptible to reliability issues.”
Appeal 2020-000844
Application 14/168,388

10
Rejections II and IV
The Examiner does not rely on Kimata in the rejections of claims 7
and 16 to remedy the deficiencies discussed above with regard to the
rejections of claims 6 and 15. Therefore, we do not sustain the Examiner’s
§ 103 rejections of claims 7 and 16.

CONCLUSION
Upon consideration of the record and for the reasons set forth above
and in the Final Office Action and the Examiner’s Answer, the Examiner’s
decision to reject claims 6, 7, 15, 16, and 29–31 under 35 U.S.C. § 103 is
reversed.
In summary:

Claim(s)
Rejected
35
U.S.C. § Reference(s)/Basis Affirmed Reversed
6, 29, 30 103 Ishii, Hoshi, Wagoner 6, 29, 30
7 103 Ishii, Hoshi, Wagoner, Kimata 7
15, 31 103 Hoshi, Kayama, Wagoner 15, 31
16 103 Hoshi, Kayama, Wagoner, Kimata 16
Overall
Outcome
6, 7, 15, 16,
29–31

REVERSED