Ex Parte RE.36,571 et al

Board of Patent Appeals and Interferences

Jul 12, 2012

90010671 (B.P.A.I. Jul. 12, 2012)

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.
90/010,671 09/11/2009 RE.36,571 RE36571REX 6187
27964 7590 07/13/2012
HITT GAINES P.C.
P.O. BOX 832570
RICHARDSON, TX 75083
EXAMINER
HEYMAN, JOHN S
ART UNIT PAPER NUMBER
3992
MAIL DATE DELIVERY MODE
07/13/2012 PAPER
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.
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
_____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
______________

Ex parte LINEAGE POWER CORPORATION
______________

Appeal 2012-008610
Reexamination Control No. 90/010,671
Reissue Patent 36,5711
Technology Center 3900
______________

Before JOHN C. MARTIN, KEVIN F. TURNER, and STEPHEN C. SIU,
Administrative Patent Judges.

MARTIN, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal by the Lineage Power Corporation (hereinafter
“Appellant”), the owner and real party in interest of Reissue Patent 36,571

1 Issued February 15, 2000, to inventor Allen Frank Rozman for reissue of
Patent 5,528,482, which was filed on April 8, 1994, and issued on June 18,
1996. The ‘482 patent identifies itself as a continuation of Application No.
08/054,918, filed April 29, 1993, which issued as Patent 5,303,138.
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(hereinafter “Rozman ’571”),2 under 35 U.S.C. §§ 134(b) and 306 from the
Examiner’s rejection of claims 1-60, which are all of the pending claims.
We have jurisdiction under 35 U.S.C. §§ 6(b) and 306.
We AFFIRM.

I. STATEMENT OF THE CASE
A. Related Litigation and Appeal
This reexamination proceeding was initiated by a request for ex parte
reexamination (hereinafter “Request”) filed on September 11, 2009, on
behalf of an anonymous third party requester by James M. Smith of
Hamilton, Brook, Smith & Reynolds, P.C.
The Rozman ‘571 patent was involved in a lawsuit styled Lineage
Power Corp. v. SynQor, Inc., Civil Action No. 2:08-CV-9-TJW-CE) (E. D.
Texas, Marshall Division), which has been dismissed with prejudice. See
Br. 3, para. II; and “Lineage Power Corporation’s Disclosure of Asserted
Claims and Infringement Contentions Under P.R. 3-1” (Ex. I to Request)
at 1.
Appellant also identifies as a related appeal a pending appeal in
Reexamination Control No. 95/001,231, an inter partes reexamination
proceeding directed to Patent 6,191,964.3 Br. 3, para. II.

2 Appeal Brief filed January 20, 2012 (hereinafter “Br.”) at 3, para. I.
3 This patent, which issued to Jeffrey J. Boylan and Allen Frank Rozman on
February 20, 2001, is titled,” Circuit and Method for Controlling a
(Continued on next page.)
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B. The Rozman ‘571 Invention
The claims of the Rozman ‘571 patent relate to switching-type power
converters and more particularly to forward and flyback converters that
employ a clamp-mode topology. Specification 1:16-18. The claimed
converters employ “self synchronized” or “synchronous” rectifiers, which
use MOSFET-type rectifying devices whose control terminals are driven by
voltages of the windings of a power transformer in order to provide
rectification of the output of the transformer. Id. at 1:21-25.
Figure 1 of Rozman ‘571 is reproduced below.

Figure 1 is a schematic of a prior art forward converter having “a
synchronous rectifier including the MOSFET rectifying devices 105 and
106.” Id. at 2:17-29.

Synchronous Rectifier Converter.”
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A DC voltage input Vin, at input 100, is connected to the primary
winding 110 of the power transformer by a MOSFET power switch 101. Id.
at 2:24-26. The secondary winding 102 is connected to an output lead 103
through an output filter inductor 104 and the synchronous rectifier, which
includes MOSFET rectifying devices 105 and 106, each of which includes a
body diode 108 and 107, respectively. Id. at 2:26-30.
Figure 2 of Rozman ‘571 is reproduced below.

Figure 2 is a voltage waveform of the secondary transformer winding of the
prior art converter of Figure 1. Id. at 1:60-61. During conduction interval T1
of power switch 101, the secondary winding voltage Vns1 charges the gate of
MOSFET 106 to bias it on (i.e., conducting) for the entire interval T1. Id. at
2:45-48. When power switch 101 turns off, the voltage Vns1 across the
secondary winding 102 reverses polarity just as the time interval T2 begins.
Id. at 2:55-57. As shown in Figure 2, the voltage across the secondary
winding 102 is not a constant value but rather a variable voltage that
collapses to zero during the subsequent time interval T3, which occurs prior
to the subsequent conduction interval of the power switch 101. Id. at 2:60-
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65. As a result, this voltage is operative to drive the rectifier 105 on during
only a portion of the time interval T2, as indicated by the cross-hatched area
202, thereby substantially diminishing the performance of rectifier 105 as a
low loss rectifier device. Id. at 2:65-3:4.
Requester characterizes the prior art converter depicted in Figure 1 of
Rozman ‘571 as employing a “resonant reset” method. Request 5.
Figure 3 of Rozman ‘571 is reproduced below.

Figure 3 is a schematic of a clamped-mode forward converter including a
synchronous rectifier in accordance with the Rozman ‘571 invention. Id. at
1:63-65. In contrast to the prior art Figure 1 converter, MOSFET power
switch 101 is shunted by a series connection of a clamp capacitor 321 and a
a a MOSFET switch device 322. Id. at 3:24-27. The conducting intervals of
power switch 101 and switch device 322 are mutually exclusive, with the
duty cycle of power switch 101 being D and the duty cycle of swirch device
322 being 1-D. Id. at 3:27-30. The voltage inertia of capacitor 321 limits
the amplitude of the reset voltage appearing across the magnetizing
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inductance during the non-conducting interval of power switch 101. Id. at
3:30-33.
The Figure 3 converter further differs from the Figure 1 prior art
converter by replacing MOSFET rectifying device 106 with a diode 323 (id.
at 3:34-36), which does not have a control terminal and thus is not a
synchronous rectification device. As explained below, the Figure 5
embodiment does not include this replacement.
Figure 4 of Rozman ‘571 is reproduced below.

Figure 4 is a voltage waveform 401 of the secondary transformer winding of
the Figure 3 converter. Id. at 1:66-67; 3:38-41. The clamping action of the
clamping circuitry results in a constant voltage level 402 across the
secondary winding 102 during the time period T2, thereby driving MOSFET
rectifier 105 it into conduction for the entire T2 reset interval. Id. at 3:41-43.
Figure 5 of Rozman ‘571 is reproduced below.
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Figure 5 is a schematic of another version of a clamped-mode forward
converter with a synchronous rectifier in accordance with the Rozman ‘571
invention. Id. at 2:1-3. This Figure 5 converter is similar to the Figure 3
converter except that MOSFET rectification device 106 of prior art Figure 1
has not been replaced by a diode 323. Id. at 4:17-22. Thus, in the Figure 5
converter, as in prior art Figure 1 converter, MOSFETS 105 and 106 serve
as first and second synchronous rectifying devices.

B. The Claims on Appeal
The independent claims on appeal are claims 1, 2, 5, 11, 21, 31, 41,
and 51, of which claims 1, 2, and 21 are reproduced below.
Claim 1 recites a “rectifier” including “a synchronous rectification
device” and “a rectifying device” (that need not be synchronous):
1. In a power converter, comprising:
an input for accepting a DC voltage; a power transformer
including a primary and secondary winding;
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a power switch for periodically connecting the input to
the primary winding;
an output for accepting a load to be energized;
clamping means for limiting a voltage and extending the
voltage’s duration across the secondary winding at a
substantially constant amplitude during substantially an entire
extent of a clamping interval of a cyclic period of the power
converter;
a rectifier connecting the secondary winding to the
output; and including: a synchronous rectification device with a
control terminal connected to be responsive to signal across the
secondary winding such that the synchronous rectification
device conducts a load current during substantially the entire
extent of the clamping interval; and a rectifying device
connected for enabling conduction of the load current during a
second interval other than the clamping interval.
Claims App. (Br. 56).
Claim 2 is similar to claim 1 but more specifically recites “a first
synchronous rectification device” and “a second synchronous rectification
device”:
2. In a power converter, comprising an input for
accepting a DC voltage;
a power transformer including a primary and secondary
winding; a power switch for periodically connecting the input
to the primary winding during a second interval of a cyclic
period;
an output for accepting a load to be energized; clamping
means for limiting a voltage and extending the voltage’s
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duration across the secondary winding at a substantially
constant amplitude during substantially an entire extent of a
clamping interval of a cyclic period of the power converter;
[a] rectifier circuit connecting the secondary winding to
the output; and including:
a first synchronous rectification device with a
control terminal connected to be responsive to a signal across
the secondary winding such that the synchronous rectification
device conducts a load current during substantially the entire
extent of the clamping interval, and
a second synchronous rectification device with a
control terminal connected to be responsive to a signal across
the secondary winding such that the second synchronous
rectification device conducts the load current during
substantially an entire extent of the second interval other than
the clamping interval.
Claims App. (Br. 57).
The other independent claims recite “a synchronous rectification
device” without additionally reciting a rectifying device or a second
synchronous rectification device. Claim 21, for example, reads as follows:
21. A power converter, comprising:
a power transformer having a plurality of windings;
a synchronous rectification device coupled to at least one
of said plurality of windings and having a control terminal; and
a clamping circuit, coupled to said power transformer,
that limits a voltage applied to said control terminal such that
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said synchronous rectification device is active for substantially
all of a clamping interval.
Claims App. (Br. 60).
During reexamination, claims are given the broadest reasonable
interpretation consistent with the specification and limitations in the
specification are not read into the claims. Manual of Patent Examining
Procedure (MPEP) § 2258(I)(G) (8th ed., rev. July 2010) (citing In re
Yamamoto, 740 F.2d 1569 (Fed. Cir. 1984); In re Trans Texas Holdings
Corp., 498 F.3d 1290, 1298 (Fed. Cir. 2007).4

C. The Rejections
1. Claims 1-3, 5-7, 9, 11-13, 15-23, 25-33, 35-43, 45-53, 56-60 stand
rejected under 35 U.S.C. § 103(a) for obviousness over APA (i.e., the

4 Although MPEP § 2258(I)(F) provides that admissions of a patent owner
made during litigation regarding how to interpret or modify a patent or
printed publication may be considered during a reexamination proceeding.
Appellant’s arguments made during litigation concerning how the asserted
claims of the Rozman ‘571 patent read on an allegedly infringing device do
not constitute such admissions, as suggested in the Request. See, e.g.,
Request 33 (“Lineage, in the referenced litigation, has asserted Claims 1, 2
(through claim 3) and 5 against circuitry wherein a synchronous rectifier is
responsive to a signal across a winding other than the claimed secondary
winding. Accordingly, based on the broad Lineage claim interpretation,
Claims 1, 2 and 5 are anticipated by Fig. 6C (and the corresponding text) in
the Smith ‘875 patent . . . .”).
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admitted prior art shown in Figure 1 of Rozman ‘571) in view of Bassett.5
Final Action 8, para. III.6
2. Dependent claims 8, 14, 24, 34, 44, 54, and 55 stand rejected under
§ 103(a) for obviousness over APA in view of Bassett and Jitaru.7 Id. at 17,
para. IV.
3. Claims 1, 3-6, 8-13, 15, 17-23, 25, 27-33, 35, 37-43, 45, 47-53, 55-
60 stand rejected under § 102(e) for anticipation by Smith ‘875.8 Id. at 19,
para. V.
4. Independent claim 2 and dependent claims 14, 24, 34, 44, and 54
stand rejected under § 103(a) for obviousness over Smith ‘875. Id. at 23,
para. VI.

5 U.S. Patent 5,066,900, filed June 22, 1990, issued November 19, 1991.
6 Final Office action mailed July 22, 2011.
7 U.S. Patent 5,434,768, filed February 12, 1993, issued July 18, 1995.
Although Jitaru U.S. Patent 5,126,931 is listed in the Evidence Appendix
(App. B) to the Brief and discussed in the “Declaration of Allen Frank
Rozman in Accordance with 37 C.F.R. §1.132” (hereinafter “Rozman Rule
132 Declaration”) at 3, this Jitaru patent is not discussed in the Brief and
therefore will not be considered. See 37 C.F.R. § 41.37(c)(1)(vii) (2011),
which provides that the Argument portion of the Brief shall include “[t]he
contentions of appellant with respect to each ground of rejection presented
for review in paragraph (c)(1)(vi) of this section, and the basis therefor, with
citations of the statutes, regulations, authorities, and parts of the record
relied on.”).
8 U.S. Patent 5,304,875, filed April 28, 1992, issued April 19, 1994. As
discussed below, Appellant’s Brief (at 26, ¶ 3) relies on the discussion of
Smith U.S. Patent 5,430,633 in the Rozman Rule 132 Declaration.
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5. Dependent claims 7, 16, 26, 36, 46, 55, and 56 stand rejected under
§ 103(a) for obviousness over Smith ‘875 in view of Loftus ‘543.9 Id. at 24.

6. Dependent claim 55 stands rejected under § 103(a) for obviousness
over Smith ‘875 in view of Wolfel.10 Id.
7. Claims 1-54 and 56-60 stand rejected under § 102(b) for
anticipation by Loftus ‘212.11 Id. at 26, para. VII.
8. Dependent claim 55 stands rejected under § 103(a) for obviousness
over Loftus ‘212 in view of Loftus ‘543. Id. at 29, para. VIII.
9. Claims 1-60 stand rejected under § 102(e) for anticipation by
Loftus ‘543. Id. at 30, para. IX.
10. Claims 1-54 and 56-60 stand rejected under § 102(e) for
anticipation by Jitaru. Id. at 31, para. X.
11. Dependent claim 55 stands rejected under § 103(a) for
obviousness over Jitaru in view of either of Loftus ‘543 and Wolfel. Id. at
32, para. XI.
12. Claims 1-3, 5-7, 9, 11-13, 15-17, 20-23, 25-27, 30-33, 35-37, 40-
43, 45-47, 50-53, 55-57, and 60 stand rejected under § 102(e) for
anticipation by Wolfel. Id. at 33, para. XII.

9 U.S. Patent 5,274,543, filed September 23, 1992, issued December 28,
1993.
10 U.S. Patent 5,128,603, filed May 7, 1990, issued July 7, 1992
(misidentified at Final Action 24 as “Wolfel ‘875”).
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13. Claims 1-3, 5-7, 9, 11-13, 15-17, 20-23, 25-27, 30-33, 35-37, 40-
43, 45-47, 50-53, 56, 57, and 60 stand rejected under § 102(b) for
anticipation by Kuwabara.12 Id. at 35, para. XIII.
14. Dependent claim 55 stands rejected under § 103(a) for
obviousness over Kuwabara in view of either of Loftus ‘543 and Wolfel. Id.
at 38, para. XIV.

II. DISCUSSION
A. Whether Jitaru has been antedated under 37 C.F.R. § 1.131
Appellant’s sole response to the rejections based on Jitaru is to assert
that this reference has been antedated pursuant to 37 C.F.R. § 1.131 (i.e.,
Rule 131). Br. 41-42.13 Appellant does not assert an actual reduction to
practice of the claimed subject matter prior to Jitaru’s February 12, 1993,
filing date. Rather, Appellant (Br. 41, para. H) argues conception of the
claimed subject matter prior to Jitaru’s filing date coupled with diligence

11 U.S. Patent 5,353,212, filed April 20, 1992, issued October 4, 1994.
12 Kuwabara Koji et al. Japanese Patent Application Publication 59-044971,
published March 13, 1984. Our understanding of this reference is based on
an English-language translation of this document (hereinafter “Trans.”) and
the corresponding abstract from Patent Abstracts of Japan.
13 Inventor Allen Rozman concedes that “Jitaru ’768 recognizes the novelty
of a power converter including both a clamping circuit and a self-driven
synchronous rectification device (see Figure 23).” Rozman Rule 132
Declaration 3, para. 4.
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during the “critical period,” which runs from prior to that filing date up to
Appellant’s April 29, 1993, effective filing date.14
The only evidence submitted prior to the July 22, 2011, Final Action
for the purpose of antedating Jitaru is an “Affidavit Under 37 C.F.R.
§ 1.131” by inventor Allen Rozman, dated March 2, 2011 (hereinafter,
“Rozman Rule 131 Affidavit”), including exhibits A-D. Regarding
conception, Mr. Rozman (Rozman Rule 131 Aff. ¶ 2) relies on the converter
depicted in the second figure from page 62 of his notebook, pages 62-64 of
which constitute Exhibit A.15 This figure is reproduced below.

Mr. Rozman’s testimony regarding conception, which the Examiner found
persuasive (Final Action 3), is as follows:

14 37 C.F.R. § 1.131(b) (2011) provides: “The showing of facts shall be
such, in character and weight, as to establish reduction to practice prior to
the effective date of the reference, or conception of the invention prior to the
effective date of the reference coupled with due diligence from prior to said
date to a subsequent reduction to practice or to the filing of the application.”
15 As permitted by MPEP § 715.07(II), the actual dates of these notebook
pages have not been disclosed.
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C. Considering Claim 1 of the ‘571 Patent as an example,
the second figure on page 62 of the notebook illustrates a power
converter including a clamping means represented by switch S2
and capacitor C1. Additionally, the illustrated converter
includes a synchronous rectifying device represented by Q2.
D. The control terminal of Q2 is connected to be
responsive to a signal across the secondary winding of the
converter such that Q2 conducts a load current during
substantially the entire extent of a clamping interval of a cyclic
period of the converter. Figure 2 on page 63 of the notebook
illustrates operation of the switch Q2 when the power switch S1
is off and the switch S2 is on.
Rozman Rule 131 Aff. ¶ 2. The Examiner found that “conception has been
established by the Affidavit filed under Rule 1.131” (Final Action 3) but that
diligence has not been demonstrated throughout the critical period. Id. For
the following reasons, we agree that diligence has not been established by
this affidavit or by the additional declarations filed after the Final Action,
which are addressed below.
Diligence can be either or a combination of: (1) “engineering
diligence,” i.e., efforts to achieve an actual reduction to practice; and
(2) “attorney diligence,” i.e., efforts to achieve a constructive reduction to
practice. Keizer v. Bradley, 270 F.2d 396, 398 (CCPA 1959). In general,
proof of actual reduction to practice requires a showing that the apparatus
actually existed and worked for its intended purpose. MPEP § 715.07(III).
However, “there are some devices so simple that a mere construction of
them is all that is necessary to constitute reduction to practice.” Id. (citing In
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re Asahi/America Inc., 68 F.3d 442, 445 (Fed. Cir. 1995)). Attorney
diligence consists of efforts to prepare and file a patent application for the
claimed invention. See Bey v. Kollonitsch, 806 F.2d 1024, 1026 (Fed. Cir.
1986) (“Bey’s case for diligence hinged on whether his patent attorney, Ruth
Hattan (Hattan), had been reasonably diligent in preparing and filing the
patent application during the 41-day critical period.”).
Evidence of diligence, to be persuasive, must show diligence
throughout the entire critical period. Monsanto Co. v. Mycogen Plant Sci.
Inc., 261 F.3d 1356, 1369 (Fed. Cir. 2001) (citing Fitzgerald v. Arbib,
268 F.2d 763, 766 (CCPA 1959)). “However, there need not necessarily be
evidence of activity on every single day if a satisfactory explanation is
evidenced.” Id. See also Griffith v. Kanamaru, 816 F.2d 624, 626 (Fed. Cir.
1987) (“A review of caselaw on excuses for inactivity in reduction to
practice reveals a common thread that courts may consider the reasonable
everyday problems and limitations encountered by an inventor.”).
The applicant must give a clear explanation of the exhibits pointing
out exactly what facts are established and relied on by applicant. In re
Borkowski, 505 F.2d 713, 718-19 (CCPA 1974). Furthermore, it is
necessary to identify specific acts and dates. See In re Harry, 333 F.2d 920,
922 (CCPA 1964) (Rule 131 affidavit insufficient because “[i]t asserts that
facts exist but does not tell what they are or when they occurred.”)
Regarding diligence, the Rozman Rule 131 Affidavit relies on
Exhibits B-D as follows:
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3. . . . The 08/054,918 patent application was diligently
prepared and filed with the United States Patent Office on
April 29, 1993, as evidenced by Exhibits B-D.
For example, on March 28, 1993, in-house counsel
recommended to proceed with filing the patent application as
evidenced by Exhibit B. On April 6, 1993, the in-house counsel
indicated that an Invention Disclosure Submission (IDS)
number had been assigned to my invention as evidenced by
Exhibit C. On April 21, 1993, I approved filing of the
application as evidenced by Exhibit D. The patent application
was then filed on April 29, 1993.
Rozman Rule 131 Aff. ¶ 3. The Examiner concluded that
evidence indicating due diligence is required between the dates
of before 02/12/1993 to 03/28/1993 (Exhibit B date); from
before 02/12/1093 [sic] to 04/06/1993 (Exhibit C date); and
from before 02/12/1993 to 04/21/1993 (Exhibit D date). Patent
Owner has failed to provide evidence explaining activities
during the above periods, except on those particular dates. . . .
Facts showing continuous work activity until the
subsequent reduction to practice date must be provided to
explain what occurred during these time periods (especially for
the six week plus period to 03/28/1993) with respect to the
invention in order to support and satisfy the “due diligence”
requirement of [a] Rule 1.131 Affidavit. See MPEP 715.
Final Action 4-5 (bolding omitted).
On September 22, 2011, Appellant responded to the Final Action by
filing a “Request for Reconsideration Under 37 C.F.R. §1.116 for Ex Parte
Reexam,” accompanied by the following additional declarations offered to
antedate Jitaru:
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(1) a “Declaration of Allen Frank Rozman in Accordance with
37 C.F.R. § 1.131,” dated September 5, 2011 (“Rozman Rule 131
Declaration”), including Exhibits A-E, of which Exhibits A and C-E are
identical to Exhibits A-D of the Rozman Rule 131 Affidavit. Exhibit B to
this new declaration consists of pages 76-79, dated “3-16-93,” of Mr.
Rozman’s notebook. Rozman Rule 131 Declaration ¶ 3.16
(2) a “Declaration of Mark E. Jacobs in Accordance with 37 C.F.R.
§ 1.132,” dated September 16, 2011 (“Jacobs Declaration”) (no exhibits);
and
(3) a “Declaration of Richard Hock in Accordance with 37 C.F.R.
§ 1.132,” dated September 16, 2011 (“Hock Declaration”), including, as
Exhibit A, Mr. Rozman’s above-mentioned notebook pages 76-79.
In an Advisory Action mailed October 14, 2011, the Examiner (at 3-4)
responded to these additional declarations by indicating that the
“affidavit/declaration . . . has been considered but does NOT overcome the
rejection(s)” and stating only that “the ‘due diligence’ arguments are not
sufficient to overcome Jitaru ‘768.”
The merits of these additional declarations are not discussed in the
Answer. At page 23 of the Answer, the Examiner correctly notes that

16 Because all of the assertions made in the Rozman Rule 131 Affidavit are
repeated in the Rozman Rule 131 Declaration, we will henceforth refer to
only the latter.
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Appellant argues on page 41-43 of the Brief that the
anticipation rejection of Claims 1-54 and 56-60 based on Jitaru
‘768 is improper because the Rule 1.131 affidavit submitted
together with two Rule 1.132 affidavits to support the Rule
1.131 affidavit, antedate Jitaru ‘768 to show “due diligence”
[that] should have been accepted.
However, the Examiner next states, incorrectly, that “[p]ages 3-6 of the
second Final Rejection [i.e., the Final Action] address[] the Rule 1.131 and
Rule 1.132 Affidavits” and incorporates these pages by reference into the
Answer. Id. As already noted, the three additional declarations relied on in
the Brief were filed after the Final Action; the only Rule 131 evidence
addressed in the Final Action is the Rozman Rule 131 Affidavit.
Although we therefore lack the benefit of the Examiner’s specific
reasons for being unpersuaded by the additional declarations, we have
reviewed them and, for the reasons given below, agree with his conclusion
that diligence has not been shown for the first six weeks of the critical
period, i.e., for the six weeks running from prior to Jitaru’s February 12,
1993, filing date up to March 28, 1993, when “in-house counsel
recommended to proceed with filing the patent application.” Rozman Rule
131 Decl. ¶ 4. The only exhibit to this declaration that relates to the initial
six weeks of the critical period is Exhibit B, i.e., notebook pages 76-79,
dated March 16, 1993, which include Figures 1-5 and explanatory text.
Figure 1 (at page 76) is reproduced below.
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Figure 1 is described at page 76 of Exhibit B as “an extension” of the
synchronous rectifier implementation decsribed at notebook pages 62-64
(Ex. A to Rozman Rule 131 Decl.).
Figure 2 (at page 76) is reproduced below.

Page 76 explains that Figure 2 shows the circuit of Figure 1 simplified by
replacing one of the FETs with a diode.

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Figure 3 (at page 77) is reproduced below.

Page 77 describes Figure 3 as showing an improvement of the Figure 2
circuit.
Figure 4 (at page 79) is reproduced below.

Page 78 explains that Figure 4 shows a center-tapped circuit configuration.
Figure 5 (at page 79) is reproduced below.
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Page 79 explains that Figure 5 shows construction of “an inverted [illegible]
winding output, similar to a flyback.” Pages 76-79 also provide a discussion
of the operation of the converters depicted in these figures.
Regarding the issue of diligence, Mr. Rozman states:
3. After memorializing the conception of the invention
as recited in the Claims of the ‘571 Patent, I continued working
on the invention as evidenced by Exhibit B and submitted
information to in-house patent counsel about the invention for
consideration regarding filing a patent application. Exhibit B is
a true and correct copy of pages 76-79 of my notebook that I
entered on March 16, 1993, with a date redacted that antedates
February 12, 1993. The redacted date refers to the above noted
pages 62-64 of my notebook [Ex. A].
Rozman Rule 131 Decl. ¶ 3. Mr. Hock describes Mr. Rozman’s notebook
pages 76-79, which constitute Exhibit A to the Hock Declaration, as follows:
6. On March 16, 1993, I witnessed and understood a
notebook entry of Allen Frank Rozman that provided a
synchronous rectifier circuit as evidenced by Exhibit A. As
stated in Exhibit A, the notebook entry was an extension of a
synchronous rectifier implementation previously entered by
Allen Frank Rozman in his notebook. Exhibit A is a true and
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correct copy of pages 76-79 of Allen Frank Rozman’s notebook
with a redacted date that antedates February 12, 1993.
Hock Decl. ¶ 6.
Appellant argues that “Exhibit B [to the Rozman Rule 131
Declaration] provides evidence that the inventor, Allen Frank Rozman,
continued to work on the invention after conception and during the critical
period.” Br. 43. However, merely continuing to work on the invention is
not enough, in and of itself, to establish conception. As explained in Moore
v. Harris, 92 USPQ 187, 189 (Bd. Pat. Int. 1951):
[M]ere work is not necessarily diligence; it must be work
toward constructing the invention. . . . “It takes something more
than merely keeping a complete patentable idea under
consideration to constitute proof of diligence in reduction to
practice.” Cottrell v. Shafer, 496 O.G. 864, 1938 C.D. 585, 25
C.C.P.A. 1171, 37 USPQ 726, 728.
Notebook pages 76-79 do not describe any efforts to make a physical
embodiment of the claimed invention (i.e., engineering diligence) or to
prepare and file a patent application for the claimed invention (i.e., attorney
diligence).
Nor has Appellant established an excuse for the absence of such
activity. Where, as here, the critical period begins with an excuse, it is
necessary to prove an intention to reduce the invention to practice but for the
circumstances cited as the excuse. See Moore, 92 USPQ at 189 (“[B]efore
work can begin towards constructing an invention in a corporation someone
in authority must reach the conclusion that it is desirable to produce the
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invention; and, after reaching this conclusion, approve the project. All work
done before the conclusion is reached is aimless with respect to the
construction of the invention . . . .”); Smith v. Crivello, 215 USPQ 446, 453
(Bd. Pat. Int. 1982) (“an essential requirement of every acceptable excuse for
lack of diligence is a reasonable showing that except for the excuse the
inventor would have been working on the invention during the period he
seeks excused.”). Cf. Keizer v. Bradley, 270 F.2d 396, 399 (CCPA 1959)
(holding that the evidence shows a continuing intent to reduce automatic
chroma control circuit to practice as soon as television receiver reached a
suitable stage of development). The evidence of record does not establish
that a decision to reduce to practice, either actually or constructively, was
made prior to Jitaru’s February 12, 1993, filing date. Instead, the decision to
constructively reduce to practice (i.e., to prepare and file a patent application
for the invention) was allegedly made on March 28, 1993, six weeks after
Jitaru’s filing date. Rozman Rule 131 Decl. ¶ 4. Furthermore, Appellant
does not assert, and the evidence does not establish, that a decision was
made prior to the April 29, 1993, effective filing date of the Rozman ‘571
patent to achieve an actual reduction to practice of the claimed invention.
For the above reasons and also because it fails to identify specific acts
and dates, Mr. Hock’s following testimony fails to establish an acceptable
excuse for the inactivity during any part of the first six weeks of the critical
period:
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In addition to working on the synchronous rectifier
implementation, Allen Frank Rozman also had other
responsibilities in 1993 for products in manufacture and in
development. These responsibilities included responding to
production problems in the factory. Responding to production
problems often took precedence over other responsibilities to
prevent production slow downs.
Hock Decl. ¶ 7. The Jacobs Declaration, which provides a general
description of the operation of the AT&T Patent review Committee, does not
describe any efforts to achieve a reduction to practice or any excuse for
inactivity during the initial six weeks of the critical period.
Because the evidence fails to establish efforts to reduce to practice or
an excuse for the absence of such efforts during the first six weeks of the
critical period, we agree with the Examiner that Jitaru has not been removed
as a reference pursuant to 37 C.F.R. § 1.131. See Fitzgerald, 268 F.2d at
766 (“It has been held that a party has not exercised reasonable diligence in
reducing the invention to practice where there is unexplained inactivity prior
to the opponent’s entry into the field, for periods as abbreviated as one to
two months in duration.”); Moller v. Harding, 214 USPQ 724, 729 (Bd. Pat.
Int. 1982) (unexplained inactivity for one and one-half months, i.e., from
June 1 to mid-July, defeated claim of diligence); Morway v. Bondi, 203 F.2d
742, 749 (CCPA 1953) (party not diligent where, following June 7 activity,
which was just prior to opponent’s June 14 entry into the field, party did not
perform other acts until August 1). See also Fleming v. Bosch, 181 USPQ
761, 764 (Bd. Pat. Int. 1973) (“[p]eriods of six weeks or less of [unexcused]
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inactivity have been held as showing a lack of reasonable diligence”) (citing
Hull v. Davenport, 90 F.2d 103 (CCPA 1937); Ireland v. Smith, 97 F.2d 95
(CCPA 1938)).
Furthermore, assuming for the sake of argument that notebook pages
76-79, dated March 16, 1003, can been credited toward diligence, that still
leaves the first month of the critical period unaccounted for, which is long
enough to defeat the claim of diligence. Fitzgerald, 268 F.2d at 766.
We accordingly sustain (1) the rejection of claims 1-54 and 56-60
under § 102(e) for anticipation by Jitaru and (2) the rejection of claim 55
under § 103(a) for obviousness over Jitaru in view of either of Loftus ‘543
and Wolfel. Although our decision on these rejections disposes of all the
claims on appeal, we also address some additional rejections.

B. The Rejections Based on the APA (Admitted Prior Art Depicted Figure 1
of Rozman ’571) in View of Bassett
The Examiner, in rejecting claims 1-3, 5-7, 9, 11-13, 15-23, 25-33,
35-43, 45-53, 56-60 for obviousness over the admitted prior art shown in
Figure 1 of the Rozman ‘571 patent in view of Bassett, adopts (i.e.,
incorporates by reference) the reasoning set forth at page 18-27 of the
Request and in the associated claim chart, Appendix A.1. Final Action 8,
para. III.
Figure 1 of Rozman ‘571, reproduced above, is reproduced again
below for convenience.
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As noted earlier, Figure 1 is a schematic of a prior art forward converter
having a synchronous rectifier that includes two synchronous rectification
devices in the form of MOSFETs 105 and 106. This prior art converter
lacks a clamp on the primary side of the transformer, as required by each of
the independent claims. Requester relies on Figures 2, 2A, and 5 of Bassett
to remedy this deficiency. Request 20-22. As explained below, the
Examiner’s reliance on Figures 2A and 5 of Bassett is based on different
rationales under KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398 (2007). We will
first address the Examiner’s reliance on Bassett’s Figures 2 and 2A.

1. The Examiner’s Reliance on Bassett’s Figures 2 and 2A
Figures 2 and 2A of Bassett are reproduced below.
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Bassett describes the converters depicted in Figures 2 and 2A as follows:
FIGS. 1-2 illustrate examples of DC/DC converters. . . .
FIG. 2 illustrates an isolated, single switch forward converter
having transistor Q3, capacitors C4 and C5, diodes D2 and D3,
inductor L4 and transformer T1. FIG. 2A illustrates a forward
converter with a second flux reset switch Q4 and capacitor C4.
Bassett 1:26-38 (emphasis added). Requester correctly characterizes
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Bassett’s Figure 2 converter and the APA converter (Figure 1 of Rozman
‘571) as each employing a “resonant reset” scheme (i.e., no active
clamping), Request 20, and Basset’s Figure 2A converter as employing
active clamping. Id. at 21.
While it is fair to describe Bassett’s Figures 2 and 2A as showing
known converter alternatives, Requester is incorrect to more particularly
characterize Bassett as “disclos[ing] that an active clamp (Fig. 2A) as a
means for resetting the transformer in a forward converter was known as a
preferred alternative to the resonant reset scheme (Fig. 2).” Id. (emphasis
added.) To the contrary, Bassett describes the Figure 2 and Figure 2A
converters (and also the converters depicted in Figures 1A and 1B) as having
the following disadvantage:
The performance of any circuit is related to the
characteristics of the components used in the design, and many
recent advances in technology have improved the
characteristics of components. Unfortunately, the realization of
ideal or lossless switching cannot be achieved with the simple
circuits identified above, since in all cases, the switch is turned
on while voltage is impressed across it. Any real device will
exhibit capacitance between its terminals, and the energy
stored in this capacitance (½CV2) will be dissipated when the
device turns on.
Bassett 1:39-49 (emphasis added). Nevertheless, because Bassett’s Figures
2 and 2A show two known alternatives for the primary-side circuitry of a
forward converter, and because Basset’s Figure 2 converter resembles the
APA converter (Fig. 1 of Rozman ‘571) in not including an active clamp, we
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agree with the Examiner that it would have been obvious in view of
Bassett’s Figures 2 and 2A to replace the primary-side circuitry of the APA
converter, which does not include an active clamp, with the primary-side
circuitry depicted in Bassett’s Figure 2A, which includes an active clamp.
Final Action 15-16. As correctly stated by the Examiner, this position is
consistent with the KSR rationale (discussed in MPEP § 2143(B)) that a
conclusion of obviousness can be based on simple substitution of one known
element for another to obtain predictable results. KSR, 550 U.S. at 416. As
explained in MPEP § 2143(B):
To reject a claim based on this rationale, Office personnel
must resolve the Graham [v. John Deere Co., 381 U.S. 1
(1966)] factual inquiries. Then, Office personnel must
articulate the following:
(1) a finding that the prior art contained a device
(method, product, etc.) which differed from the claimed device
by the substitution of some components (step, element, etc.)
with other components;
(2) a finding that the substituted components and their
functions were known in the art;
(3) a finding that one of ordinary skill in the art could
have substituted one known element for another, and the results
of the substitution would have been predictable; and
(4) whatever additional findings based on the Graham
factual inquiries may be necessary, in view of the facts of the
case under consideration, to explain a conclusion of
obviousness.
(Emphasis added.) The Examiner correctly found, in our view, that factors
(1)-(3) are present and that prima facie obviousness has accordingly been
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demonstrated. Final Action 15-16. Appellant’s Rule 132 evidence
regarding factor (4) is addressed infra. Appellant’s arguments against the
prima facie case for obviousness are unpersuasive. The principal argument
is that reliance on a “substitution” rationale is improper because
no substitution has been made. An active clamp (which is one
example of a clamping means or a clamping circuit as the ‘571
Patent specification provides) is not a substitute for a resonant
reset. An active clamp is always used to limit a reset voltage. If
an active clamp is used, a resonant reset is still used; the active
clamp just limits the reset voltage. (See, for example, column 3,
lines 19-22 and 30-33, of the ‘571 Patent.) Therefore, while an
active clamp may enhance a resonant reset, it is not a substitute.
Br. 16. As pointed out by the Examiner, this argument misconstrues the
rationale of the rejection, which does not involve substituting an active
clamp for resonant reset. As explained by the Examiner: “[O]f course it is
obvious that a resonant reset action is still taking place in Fig. 2A (and Fig.
5) of Bassett ‘900. Otherwise, the active clamp would not perform the
desired function.” Final Action 15. Rather, the rejection involves
substituting the “active clamp scheme” (i.e., primary-side circuitry including
an active clamp) of Bassett’s Figure 2 for the “resonant reset scheme” (i.e.,
primary-side circuitry without an active clamp) of the APA converter. Id.
Appellant’s next argument is that “[e]ven were an active clamp reset
to be substituted for a resonant reset, the resulting active clamp reset would
not be equivalent to a resonant reset.” Br. 16 (emphasis added). As pointed
out by the Examiner, “it is the schemes (with their attend[ant] structure) that
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are deemed equivalent and being substituted” (Final Action 15), which we
understand to mean that the two schemes are equivalent in the sense that
they both perform the function of driving the primary winding in a forward
converter.
Appellant further argues that
[t]his KSR-based rejection appears to rely on advantages in lieu
of predictable results for the purported substitution of an active
clamp reset for a resonant reset. Assuming advantages were the
same as predictable results, the rejection erroneously states that
the advantages of an active clamp reset scheme for forward
converters were known at least as of Bassett’s filing date based
on the mere fact that Bassett combines an active clamp and a
diode rectifier. (See page 5 of the Second Final Office Action.)
Br. 17. This argument is unpersuasive because reliance on KSR’s
substitution rationale does not require a finding that the substitution would
have been considered advantageous. In contrast, such a finding is required
when obviousness is based, for example, on the different KSR rationale,
discussed below, of applying a known technique to a known device (method,
or product) ready for improvement to yield predictable results. MPEP
§ 2143(D).
Appellant also argues that the proposed combination of reference
teachings is non-enabling because
[a]dding a clamping circuit to a converter with a synchronous
rectification device is not a trivial matter. For example, if an
active clamping circuit is used, control of the various switches
has to be coordinated to obtain the desired results. As noted in
MPEP 2121.01, “[t]he disclosure in an assertedly anticipating
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reference must provide an enabling disclosure of the desired
subject matter; mere naming or description of the subject matter
is insufficient, if it cannot be produced without undue
experimentation.” Elan Pharmaceuticals, Inc. v. Mayo
Foundation for Medical Education & Research, 346 F.3d 1051,
1054, 68 USPQ2d 1373, 1376 (Fed. Cir. 2003).
Br. 18-19. This argument is unpersuasive because Appellant has not met the
burden of providing sufficient facts to establish inoperability. See MPEP
§ 2121(I):
When the reference relied on expressly anticipates or
makes obvious all of the elements of the claimed invention, the
reference is presumed to be operable. Once such a reference is
found, the burden is on applicant to provide facts rebutting the
presumption of operability. In re Sasse, 629 F.2d 675, 207
USPQ 107 (CCPA 1980).
The factors to be considered in determining whether a disclosure would have
required “undue experimentation” are identified in In re Wands, 858 F.2d
731, 737 (Fed. Cir. 1988) as follows: (1) the quantity of experimentation
necessary; (2) the amount of direction or guidance presented; (3) the
presence or absence of working examples; (4) the nature of the invention;
(5) the state of the prior art; (6) the relative skill of those in the art; (7) the
predictability or unpredictability of the art; and (8) the breadth of the claims.
However, the Wands factors “are illustrative, not mandatory. What is
relevant depends on the facts.” Amgen, Inc. v. Chugai Pharm. Co., Ltd., 927
F.2d 1200, 1213 (Fed. Cir. 1991). None of these factors has been addressed
by Appellant.
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For the foregoing reasons, we are not persuaded of error in the
Examiner’s conclusion that claims 1-3, 5-7, 9, 11-13, 15-23, 25-33, 35-43,
45-53, 56-60 would have been prima facie obvious over the admitted prior
art converter shown in Figure 1 of Rozman ‘571 in view of Figures 2 and 2A
of Basset.

2. The Examiner’s Reliance on Bassett’s Figures 2 and 5
Bassett, following the above-quoted description of the converters
depicted in Figures 2 and 2A, explains that although known “resonant
converters” of the type depicted in Figure 3 (not reproduced below) can be
operated to exhibit either zero current or zero voltage switching in order to
significantly reduce the switching loss, the reactive components must handle
considerable power, resulting in losses greater than the decrease in switching
loss. Id. 1:52-66. Also, the operating voltage and/or RMS current stress on
the semiconductor devices is often increased. Id. at 1:66-68.
Bassett’s invention is a DC/DC converter that allows zero-voltage
switching while maintaining the beneficial features of the basic topologies
and avoiding the disadvantages relating to resonant converter schemes. Id.
at 2:3-7.
Figure 4 of Bassett is reproduced below.
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Figure 4 shows a zero voltage switching converter (id. at 3:4-5) that does not
include a transformer and thus is non-isolated. As shown in this figure, a
capacitor 20 and a transistor 21 (FET) are connected in series across
inductor 15.
Bassett’s Figure 4A is reproduced below.
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Figure 4A shows the current and voltage waveforms in the Figure 4
embodiment. Id. at 2:52-53. Minimal switching loss occurs because, as
shown in waveform VX, the voltage across transistor 21 is approximately
zero when, during period II, that transistor is turned on. Id. at 4:17-20.
Furthermore, the voltage across transistor 12 is small when, during period
IV, that transistor is turned on. Id. at 4:44-49.
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Figure 5 of Bassett is reproduced below.

Figure 5 shows an isolated embodiment that allows zero voltage switching in
a manner similar to the non-isolated circuit of Figure 4. Id. at 5:27-29.
More particularly, Bassett explains that
[i]ntrinsic capacitance 33 shunting transistor 32 is discharged
by energy stored in the primary of transformer 30. Diode 34
[sic; unnumbered] prevents charge build-up in capacitance 33
before transistor 32 turns on.
Similarly, intrinsic capacitance 34 shunting transistor 35
is discharged by energy stored in the primary of transformer 30
and in inductor 31 before the control turns on transistor 35.
Hence, zero voltage switching is achieved and switching loss is
minimized.
Id. at 5:29-37.
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Because the clamping circuitry shown in Bassett’s Figure 2A is not
described as providing the zero voltage switching attributed to the clamping
circuitry in Bassett’s Figures 4 and 5, Appellant is correct to argue that the
clamping circuitry that is common to Bassett’s Figures 2A and 5 (i.e.,
transistor Q4 and capacitor C4 in Figure 2A; transistor 32 and intrinsic
capacitor 33 in Figure 5) does not, in and of itself, provide zero voltage
switching. See Br. 15 (“[S]ince both Figure 5 and Figure 2A include
purported active clamps, the improvement of zero voltage switching in
Figure 5 would not result from these common active clamps.”).
Nevertheless, we agree with the Examiner that the zero voltage
switching feature attributed by Bassett to the Figure 5 converter provides
sufficient motivation to substitute its primary-side circuitry, including an
active clamp, for the primary-side circuitry in the APA converter shown in
Figure 1 of Rozman ‘571, which like the Bassett Figure 2 converter lacks an
active clamp. See Final Action 14 (“Bassett ‘900, Fig. 5, which shows the
active clamp with transistor 32 (which is similar to transistor Q4 of Fig. 2A),
allows for the benefit of ‘zero voltage switching’. Such a benefit (along
with other described benefits) clearly points out a motivation to employ the
active clamp scheme over the resonant reset scheme.”). Although not
pointed out by the Examiner, this obviousness reasoning is consistent with
the KSR rationale of using a known technique to improve similar devices
(methods, or products) in the same way (MPEP § 2143(C)) and/or the KSR
rationale of applying a known technique to a known device (method, or
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product) ready for improvement to yield predictable results. Id. at §
2143(D). Therefore, the claimed invention would have been prima facie
obvious over the admitted prior art converter in Figure 1 of Rozman ‘571 in
view of Figures 2 and 5 of Bassett.

3. Appellant’s Evidence of Nonobviousness
As evidence of nonobviousness of claims 1-60, Appellant relies on the
Rozman Rule 132 Declaration (referred to by Appellant as the “June 132
Declaration”). Br. 14-15 and 26. Mr. Rozman begins his testimony by
acknowledging that power converters having a synchronous rectification
device were known before his invention and stating that “to the best of my
knowledge, I was the first to conceive of adding a clamping circuit that
limits a reset voltage of the transformer of a power converter having a self-
driven synchronous rectification device to improve the efficiency of the self-
driven synchronous rectification device.” Rozman Rule 132 Decl. ¶ 4.
As evidence of the nonobviousness of the claimed combination of
elements as of Appellant’s April 29, 1993, effective filing date, Mr. Rozman
asserts that “[a]fter the filing of the ‘571 Patent, some of my peers began to
recognize the benefit of adding a clamping circuit to a power converter to
improve the efficiency of a power converter having a self-driven
synchronous rectification device,” as evidenced by the following U.S.
patents, each of which he describes as “disclos[ing] a power converter
having a clamping circuit and a self-driven synchronous rectification device”
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(Rozman Rule 132 Decl. at 3, ¶ 4), and each of which has an effective date
that is subsequent to either Appellant’s April 29, 1993, effective filing date
or, in the case of Jitaru, Appellant’s conception date:
(a) Vazquez Lopez et al. U.S. Patent 5,535,112, filed March 30, 1994;
(b) Jitaru U.S. Patent 5,434,768 (“Jitaru”), filed February 12, 1993, and
relied on in the rejection discussed above;
(c) Lu et al. U.S. Patent 5,636,107, filed November 15, 1995;
(d) Smith et al. U.S. Patent 5,430,633, filed September 14, 1993;
(e) Shinada U.S. Patent 5,734,563, filed May 31, 1996;
(f) Shinada U.S. Patent 5,708,571, filed September 12, 1996;
(g) Xia U.S. Patent 5,781,420, filed October 11, 1996; and
(h) Takegami U.S. Patent 6,061,254, filed April 7, 1999.
Id. Appellant argues that the Rozman Rule 132 Declaration and the above
patents
reveal that, while a clamping circuit or clamping means
(properly defined) and a synchronous rectification device might
have been known as isolated concepts before the priority date of
the ‘571 Patent in 1993, their combination in a power converter
as Claims 1-60 of the ‘571 Patent recite was neither known nor
obvious.
Br. 14. We agree with the Examiner that these patents do not tend to
demonstrate that this combination of elements in a power converter would
have been nonobvious over the references relied on in the Examiner’s
§103(a) rejections. Final Action 6; Answer 26-27.

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4. Conclusion Regarding Rejections Based on APA in View of Bassett
For the above reasons, we sustain the rejection of claim 1 under 35
U.S.C. § 103(a) for obviousness over the APA converter in view of Bassett.
For the same reasons, we also sustain the § 103(a) rejection on this ground
of claims 2, 3, 5-7, 9, 11-13, 15-23, 25-33, 35-43, 45-53, 56-60, as to which
Appellant merely repeats the claim 1 arguments. Br. 19-23. We likewise
sustain the obviousness rejection, based on APA in view of Bassett and
Jitaru, of claims 8, 14, 24, 34, 44, 54, and 55, as to which Appellant merely
repeats the claim 1 arguments. Br. 23.

C. The Rejections Based on Smith ‘875
The Examiner, in rejecting claims 1, 3-6, 8-13, 15, 17-23, 25, 27-33,
35, 37-43, 45, 47-53, 55-60 for anticipation by Smith ‘875, adopts the
reasoning set forth at pages 27-37 of the Request and in the corresponding
claim chart, Appendix A.2. Final Action 19, para. V. The Request (at 28-
31) specifically relies on Figures 1, 3, and 6C of Smith ‘875.
The invention of Smith ‘875 relates to drive circuits for transistor
switching devices in electrical power converters, such as switching power
supplies and the like. Smith ‘875 at 1:8-10. Specifically, the invention
employs a novel drive circuit for driving first and second switching
transistors in an anti-phase relationship. Id. at 2:45-47.
Figure 1 of Smith ‘875 is reproduced below.
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Figure 1 shows a conventional approach for driving two power transistors Q1
and Q2 of an electrical power converter unit 50 in an anti-phase relationship.
Id. at 4:48-51. A control unit 60 generates two control signals at outputs 61
and 62 to operate transistors Q1 and Q2, respectively. Id. at 4:52-54. The
signals at ports 61 and 62 are usually of limited drive capability (low current
drive and low slew-rate) and thus require power amplification by buffer
amplifiers U1 and U2 in a drive circuit 10. Id. at 4:54-57; 5:5-7, 20-22.
Drive circuit 10 also includes: (a) an isolation transformer TISO for providing
isolation and voltage-level shifting between the operating voltages used by
buffer U2 and the voltage levels applied to transistor Q2; and (b) blocking
capacitors C1 and C2 to prevent transformer TISO from saturating. Id. at 5:22-
27.
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The Smith ‘875 invention eliminates the need for the large core size of
transformer TISO, the large capacitor C1, and the large buffer amplifier U2 by
recognizing that the magnetic storage elements of electrical power transfer
circuits, such as switching-type power converters, are potential sources of
switching signals for driving switching power transistors and have sufficient
energy and power to switch a selected switching power transistor, such as
Q2. Id. at 6:18-27.
Figure 3 of Smith ‘875 is reproduced below.

Figure 3 is a detailed schematic diagram of a second embodiment of a
transistor drive circuit according to the Smith ‘875 invention. Id. at 4:19-
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21.17 This figure shows an active clamp forward converter 250 (id. at 12:6-
8) having output rectifiers 292 and 293 (id. at 12:44), depicted as diodes,
connected to the secondary winding 272 of a magnetic storage element 270
in the form of a power transformer. Id. at 12:40-41.
Transistors 260 and 265 function as first and second switching
transistors (id. at 12:57-58) that are switched by control unit 281 and drive
circuit 200, respectively. Id. at 14:47-48. Drive means 240 in drive circuit
200 couples the first control signal (VA) from control unit 281 to the gate of
first switching transistor 260. Id. at 15:14-26. As shown in Figure 3, the
gate of second switching transistor 265 receives a second control signal from
second control signal generation means 210 (including powering means 220)
and shunting means 230. Powering means 220 is responsive to auxiliary
winding 215, which generates the second control signal at its terminals 216
and 217 such that the second control signal is in its first state when the
magnitude of the magnetic flux of the magnetic storage element is increasing
and in its second state when the magnitude of the magnetic flux is
decreasing. Id. at 16:41-46.
Smith ‘875 does not disclose that either of output rectifiers 293 and
294 in Figure 3 can take the form of a synchronous rectification device.18

17 The first embodiment, depicted in Figure 2 (id. at 4:15-18), is not relied
on in the Request.
18 As noted above, each independent claim on appeal recites at least one
synchronous rectification device.
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For such a teaching, the Request relies on Figure 6C of Smith ‘875,
reproduced below.

Figure 6C shows a forward converter with synchronous secondary
rectification. Id. at 24:11-12. Smith ‘875 explains that
[i]n each of FIGS. 6C and 6D, the first switching transistor is
designated as QS1 and the second switching transistor is
designated as QS2. Additionally, each magnetic storage element
is designated with corresponding language. The second control
signal is derived from the magnetic storage element and the first
control signal may be provided by a control unit such as unit
281.
Id. at 24:15-22.
Requester argues that the primary-side circuitry in the Figure 6C
converter inherently includes an active clamp even though no such clamp is
shown in that figure. Specifically, Requester argues that “[b]eing a single-
ended forward converter, the topology of Fig. 6C requires some means to
reset its magnetizing inductance” and that “Smith ‘875 clearly teaches the
use of the active clamp scheme for the circuit of Fig. 6C.” Request 31. As
support, the Request argues that (1) “[t]he active clamp was the scheme
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presented in the first 5 figures of the [Smith ‘875] patent” and (2) offers an
explanation of why an active clamp is necessary to the operation of the
Figure 6C circuit. Id. at 31-32.
In response to Appellant’s counter-argument that “Figure 6C neither
shows nor requires a primary side active clamp simply because other Figures
in Smith '875 may show or even require such a clamp” (Br. 25, para. 2), the
Examiner quoted with approval the following explanation, from pages 8-9 of
the Requester’s claim chart (App. A.2), of why the Figure 6C converter, in
order to be operable, inherently includes such a clamp:
Smith ‘875 discloses that the main switch and the synchronous
rectifier (Qs1 and Qs2, respectively) are driven such that one is
on when the other is off, and vice-versa. (The two switches
“must be driven in anti-phase . . . .” Smith ‘875, Col. 23:59-63.)
Since Qs2 is driven from the transformer, they can only be
driven in anti-phase if (1) an active clamp is used or (2) a diode
clamp is used and the converter is operated only at its maximum
duty cycle where a zero voltage state would not exist. But
Smith ‘875 states that the on and off times of the control signal
are modulated to control the output voltage. (“The first control
signal is generated by this means of sub-unit 180 such that it
alternates between its first state (ON state) and second state
(OFF state), with the duration of the first state (ON state) being
modulated to control the voltage at output port 158.” Smith
‘875, Col. 8:28-33.). If this is true, the converter cannot be
operated at a fixed maximum duty cycle and be a diode clamp
with a transformer voltage having only have [sic] two states.
Therefore, an active clamp circuit, such as the one Smith ‘875
discloses in exemplary Figure 3 and its corresponding text is
necessary in the exemplary converter of Figure 6(c).
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Final Action 22-23, para. C; Answer 16-17. Appellant has not addressed
this reasoning, let alone demonstrated that it is erroneous, as required to
satisfy Appellants’ burden on appeal with respect to this position of the
Examiner. Cf. Ex parte Frye, 94 USPQ2d 1072, 1075 (BPAI 2010)
(precedential) (an appellant may attempt to overcome an examiner’s
obviousness rejection on appeal to the Board by: (1) submitting arguments
and/or evidence to show that the examiner made an error in either (a) an
underlying finding of fact upon which the final conclusion of obviousness
was based or (b) the reasoning used to reach the legal conclusion of
obviousness; or (2) showing that the prima facie case has been rebutted by
evidence of secondary considerations of nonobviousness).
Appellant also questions the Examiner’s finding that Figure 6C
discloses a synchronous rectification device connected as claimed. Br. 24,
para. 1. Specifically, independent claims 1, 2, 5, and 51 recite that the
control terminal or gate of the synchronous rectification device or
synchronous rectifier is “connected to be responsive” to the signal across:
(1) “[a] secondary winding” (claim 1); (2) “the secondary winding” (claims
2 and 5); or (3) “at least one secondary winding” (claim 51). The remaining
independent claims (i.e., claims 11, 21, 31, and 4) more broadly recite that
the control terminal of the synchronous rectification device is coupled to “at
least one of a plurality of transformer windings.” Regarding claim 11, for
example, Requester argues (App. A.2 at 20) that the claimed connection is
present in Figure 6C because the “second control signal,” which controls
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transistor QS2, is described by Smith ‘875 as being “derived from the
magnetic storage element.” Smith ‘875 at 24:20-21. Appellant responded
by arguing that
the switch Qs2 in Figure 6C of Smith ‘875 fails to teach such a
synchronous rectification device that has a control terminal
connected to be responsive to a signal across the secondary
winding or a least one of a plurality of windings as claimed in
the ‘571 Patent. Instead, the switch Qs2 of Smith ‘875 has a
control signal derived from the magnetic flux of a magnetic
storage element. (See column 24, lines 20-22; column 8, lines
2-6; column 9, lines 21-29; Figure 2 and Figure 6C.)
Br. 24, para. 1. This argument is unpersuasive because Appellant has not
explained why the Smith ‘875 disclosure of deriving the second control
signal from the magnetic storage element would not have been understood to
be describing a connection to a winding of the transformer depicted in
Figure 6C. Nor has Appellant explained why such a transformer winding
would not have been understood to be a secondary winding, as required, for
example, by claim 1.
Appellant’s argument that “Smith ‘875 demonstrates the non-
obviousness of the ‘571 Patent’s claims” (Br. 25, para. 3; bolding omitted) is
not relevant to the rejection of claim 1 for anticipation by Smith ‘875.
For the above reasons, the rejection of claim 1 for anticipation by
Smith ‘875 is sustained. The rejection on this ground of claims 3-6, 8-13,
15, 17-23, 25, 27-33, 35, 37-43, 45, 47-53, 55-60 is sustained because
Appellant merely repeats the claim 1 arguments. Br. 26-29.
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The Examiner, in rejecting independent claim 2 and dependent claims
14, 24, 34, 44, and 54 for obviousness over Smith ‘875, adopts the reasoning
set forth at pages 27-37 of the Request and in the corresponding claim chart,
Appendix A.2. Final Action 24.
Independent claim 2 is similar to claim 1 but more particularly
specifies that the recited “rectifier circuit” includes first and second
synchronous rectification devices, whereas the rectifier circuit in Figure 6C
includes one synchronous rectifying device (QS2) and a diode rectifier
(unnumbered).
Regarding the claimed clamping circuit, which is also recited in
claim 1, Appellant has not shown error in the Examiner’s above-discussed
finding that the primary-side circuitry in the Figure 6C converter of Smith
‘875 inherently includes an active clamp. As a result, it is not necessary to
address the merits of Appellant’s arguments (Br. 30, para. D) against the
obviousness of adding an active claim to the Figure 6C converter.
Regarding the claim 2 requirement for two synchronous rectification
devices, the Request argues:
Smith ‘875 discloses, in Fig. 6C, replacing the free-wheeling
diode rectifier with a synchronous rectifier [QS2] driven from a
transformer winding. Similarly, it would be obvious to employ
a self-driven synchronous rectifier as a series rectifying device
appropriately driven from a transformer winding, as it would
yield predictable results according to the method disclosed in
Smith ‘875.
Request 35. Appellant does not dispute the obviousness of this modification
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of the Figure 6C converter.
The obviousness rejection of claim 2 is therefore sustained, as is the
rejection on that ground of dependent claims 14, 24, 34, 44, and 54, as to
which Appellant essentially repeats the arguments made against the
anticipation rejection of the corresponding independent claims 11, 21, 31,
41, and 51. Br. 30, para. 2. For the same reasons, we also sustain (a) the
rejection of dependent claims 7, 16, 26, 36, 46, 55, and 56 for obviousness
over Smith ‘875 in view of Loftus ‘543 and (b) the rejection of dependent
claim 55 for obviousness over Smith ‘875 in view of Wolfel ‘603, as to
which claims Appellant relies on only the arguments discussed above. Id.

D. The Remaining Rejections
In view of our decision sustaining the above-discussed rejections,
which disposes of each appealed claim on three alternative grounds, it is not
necessary to address the remaining rejections.

III. SUMMARY OF DISPOSITION OF REJECTIONS
A. Sustained Rejections
For the above reasons, the following rejections are sustained:
(1) The rejection of claims 1-3, 5-7, 9, 11-13, 15-23, 25-33, 35-43,
45-53, and 56-60 under 35 U.S.C. § 103(a) for obviousness over APA (i.e.,
the admitted prior art shown in Figure 1 of Rozman ‘571) in view of Bassett.
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(2) The rejection of dependent claims 8, 14, 24, 34, 44, 54, and 55
under § 103(a) for obviousness over APA in view of Bassett and Jitaru.
(3) The rejection of claims 1, 3-6, 8-13, 15, 17-23, 25, 27-33, 35, 37-
43, 45, 47-53, and 55-60 under § 102(e) for anticipation by Smith ‘875.
(4) The rejection of independent claim 2 and dependent claims 14,
24, 34, 44, and 54 under § 103(a) for obviousness over Smith ‘875.
(5) The rejection of dependent claims 7, 16, 26, 36, 46, 55, and 56
under § 103(a) for obviousness over Smith ‘875 in view of Loftus ‘543.
(6) The rejection of dependent claim 55 under § 103(a) for
obviousness over Smith ‘875 in view of Wolfel.

B. Rejections not addressed
In view of the decision sustaining the above rejections, the following
rejections have not been addressed:
(a) The rejection of claims 1-54 and 56-60 under § 102(b) for
anticipation by Loftus ‘212.
(b) The rejection of dependent claim 55 under § 103(a) for
obviousness over Loftus ‘212 in view of Loftus ‘543.
(c) The rejection of claims 1-60 under § 102(e) for anticipation by
Loftus ‘543.
(d) The rejection of claims 1-54 and 56-60 under § 102(e) for
anticipation by Jitaru ‘768.
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(e) The rejection of dependent claim 55 under § 103(a) for
obviousness over Jitaru in view of either of Loftus ‘543 and Wolfel.
(f) The rejection of claims 1-3, 5-7, 9, 11-13, 15-17, 20-23, 25-27,
30-33, 35-37, 40-43, 45-47, 50-53, 55-57, and 60 under § 102(e) for
anticipation by Wolfel.
(g) The rejection of claims 1-3, 5-7, 9, 11-13, 15-17, 20-23, 25-27,
30-33, 35-37, 40-43, 45-47, 50-53, 56, 57, and 60 under § 102(b) for
anticipation by Kuwabara.
(h) The rejection of dependent claim 55 under § 103(a) for
obviousness over Kuwabara in view of either of Loftus ‘543 and Wolfel.

IV. DECISION
The Examiner’s decision that claims 1-60 are unpatentable over the
prior art is affirmed.
Extensions of time for taking any subsequent action in connection
with this appeal are governed by 37 C.F.R. § 1.550(c). See 37 C.F.R.
§ 41.50(f).

AFFIRMED

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cc:

For Patent Owner:
HITT GAINES P.C.
P.O. BOX 832570
RICHARDSON, TX 75083

For Third Party Requester:

JAMES M. SMITH, ESQ.
HAMILTON, BROOK, SMITH & REYNOLDS, P.C.
530 VIRGINIA ROAD, P.O. BOX 9133
CONCORD, MA 01742-9133

KMF