Ex Parte Qi et al

Patent Trial and Appeal Board

Jul 30, 2018

13656559 (P.T.A.B. Jul. 30, 2018)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
13/656,559 10/19/2012
122912 7590
Patent Law Group LLP
PO Box 61839
Sunnyvale, CA 94088
08/01/2018
FIRST NAMED INVENTOR
XinQi
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
ATTORNEY DOCKET NO. CONFIRMATION NO.
LTC-P-00546 5985
EXAMINER
KING, MONICA C
ART UNIT PAPER NUMBER
2844
NOTIFICATION DATE DELIVERY MODE
08/01/2018 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):
sandy@patentlawgroup.com
eofficeaction@appcoll.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte XIN QI, ERIC S. YOUNG, and KEITH D. SZOLUSHA
Appeal2016-005885
Application 13/656,559
Technology Center 2800
Before LINDA M. GAUDETTE, BRIAND. RANGE, and MICHAEL G.
MCMANUS, Administrative Patent Judges.
GAUDETTE, Administrative Patent Judge.
DECISION ON APPEAL 1
Appellant2 appeals under 35 U.S.C. § 134(a) from the Examiner's
decision twice rejecting claims 1-10 under 35 U.S.C. § 103(a) as
unpatentable over Desimone (US 2012/0250367 Al, published Oct. 4, 2012)
in view ofMarosek (US 7,321,203 B2, issued Jan. 22, 2008). We have
jurisdiction under 35 U.S.C. § 6(b).
1 This Decision includes citations to the following documents: Specification
filed Oct. 19, 2012 ("Spec."); Non-Final Office Action dated May 12, 2015
("Non-Final Act."); Appeal Brief filed Sept. 30, 2015 ("Appeal Br.");
Examiner's Answer dated Mar. 11, 2016 ("Ans."); and Reply Brief filed
May 4, 2016 ("Reply Br.").
2 Appellant is the Applicant and real party in interest, Linear Technology
Corporation. See Appeal Br. 1.
Appeal 2016-005885
Application 13/656,559
We REVERSE.
"Th[ e] invention relates to controlling the dimming of light emitting
diodes (LEDs) using pulse width modulation (PWM) and, in particular, to a
technique for reducing flicker of the LEDs when controlling switching of a
switch mode regulator using spread spectrum frequencies." Spec. 1: 8-11.
Claim 1, the sole independent claim on appeal, is reproduced below:
1. A light emitting diode (LED) driver-comprising:
a PWM dimming circuit for receiving a dimming control
signal, wherein the dimming circuit outputs a string of PWM
pulses having pulse widths corresponding to the perceived
brightness of at least one LED, where the PWM pulses control
a first switch in series with the at least one LED using pulse
width modulation;
a switching converter for supplying a regulated current or
regulated voltage, the converter controlling at least a second
switch at a switching frequency to supply the regulated current
or regulated voltage to the at least one LED, the converter
comprising a first oscillator for generating a first signal that
controls the switching frequency;
a spread spectrum control (SSC) circuit configured to
generate a varying second signal level, the varying second
signal level being coupled to the first oscillator to control the
first oscillator to vary the switching frequency during operation
of the converter; and
a synchronizing circuit coupled to the SSC circuit for
controlling the SSC circuit to generate substantially the same
second signal level at a start of each PWM pulse in the string of
PWM pulses while the pulse widths are constant, such that the
switching frequency of the converter is forced to be
substantially the same at the start of each PWM pulse while the
pulse widths are constant.
Appeal Br. 7, Claims Appendix ( emphasis added).
2
Appeal 2016-005885
Application 13/656,559
The Examiner finds Desimone discloses the invention as claimed in
claim 1 with the exception of two features associated with the PWM
dimming circuit, shown in italics in claim 1, above. Non-Final Act. 3; Ans.
5-6. The Examiner finds Marosek discloses a PWM dimming circuit having
the features recited in claim 1. Non-Final Act. 4. The Examiner further
finds one of ordinary skill in the art would have
incorporate[d] the PWM dimming circuit [including the LEDs]
in Marosek with the control methodology of utilizing spread
spectrum control circuit disclosed in Desimone since it is
desirable to drive a[ n] LED using a switching circuit controlled
by an oscillator's ramping signal while synchronized with the
PWM dimming circuit to effectively prevent LED flickering.
Id.; see Ans. 6 (citing Marosek 2: 1-54, 6:47-54).
Appellant contends the Examiner's motivation to combine the
references is not supported by the evidence of record. See Appeal Br. 5---6;
Reply Br. 2-3. Appellant explains that the invention is directed to reducing
the problem of flicker by LED drivers which occurs with spread spectrum
control. Reply Br. 3; see also Appeal Br. 4--5. Appellant argues Marosek
does not utilize spread spectrum control and Desimone is unrelated to
synchronizing a PWM dimming signal with a spread spectrum control
signal. Appeal Br. 5-6. Appellant argues Desimone' s PWM is within the
converter itself and is used "for switching the converter's power switch QI,
which is unrelated to any PWM dimming signal that controls a brightness of
LEDs." Id. at 5. In this regard, Appellant points out that the claims require
the switching converter control a second switch and argues the Examiner has
identified only a single switch, Q 1, in Desimone. Reply Br. 3. Appellant
further contends Desimone discloses "synchronizing the switching of the
power switch to the demagnetization of the converter's transformer to create
3
Appeal 2016-005885
Application 13/656,559
a quasi-resonant flyback converter[, which] ... has nothing to do with any
synchronizing of the power switch frequency to any PWM dimming control
of LEDs." Appeal Br. 6.
Having considered the respective positions of Appellant and the
Examiner, we find Appellant's arguments persuasively demonstrate that the
Examiner's motivation for combining Desimone and Marosek is based on
improper hindsight reasoning. In particular, as argued by Appellant, the
Examiner has not clearly explained how the cited disclosure in Marosek
(i.e., column 2, lines 1-54 and column 6, lines 47-54) supports a finding that
one of ordinary skill in the art would have utilized Desimone's control
methodology, which is unrelated to PWM dimming to control the brightness
of LEDs, with Marosek' s PWM dimming circuit. See Reply Br. 2-3.
REVERSED
4