St Case1tech, LLC v. John A. Squires, Under Secretary of Commerce for Intellectual Property

NOTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
ST CASE1TECH, LLC,
Appellant
v.
JOHN A. SQUIRES, UNDER SECRETARY OF
COMMERCE FOR INTELLECTUAL PROPERTY
AND DIRECTOR OF THE UNITED STATES
PATENT AND TRADEMARK OFFICE,
Intervenor
______________________
2023-2387
______________________
Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. IPR2022-
00253.
______________________
Decided: February 18, 2026
______________________
TIMOTHY DEVLIN, Devlin Law Firm LLC, Wilmington,
DE, for appellant. Also represented by ANDREW PETER
DEMARCO, ROBERT J. GAJARSA, JASON MITCHELL SHAPIRO.
OMAR FAROOQ AMIN, Office of the Solicitor, United
States Patent and Trademark Office, Alexandria, VA, for
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ST CASE1TECH, LLC v. SQUIRES 2
intervenor. Also represented by PETER J. AYERS, MAI-
TRANG DUC DANG.
______________________
Before REYNA, TARANTO, and STARK, Circuit Judges.
STARK, Circuit judge.
Appellant ST Case1Tech, LLC (“ST1”) appeals from a
final written decision (“FWD”) of the Patent Trial and Ap-
peal Board (“Board”) in an inter partes review (“IPR”) of its
U.S. Patent No. 9,491,542 (the “’542 patent”), which found
claims 1-9 and 11-18 unpatentable as obvious. As to ST1’s
request that we vacate the Board’s decision with respect to
claims 11 and 12, which the petitioners, Samsung Electron-
ics America, Inc. and Samsung Electronics Co., Ltd. (to-
gether, “Samsung”),1 did not petition to invalidate, relief is
unopposed, and we grant it. In all other respects we affirm
the Board.
I
ST1 is the owner of the ’542 patent, entitled “Automatic
Sound Pass-Through Method and System for Earphones.”
J.A. 93. The ’542 patent aims to address a problem associ-
ated with the use of sound isolating earphones: that
“user[s] may be acoustically detached from their local
sound environment[s],” which may negatively impact their
ability to “communicat[e] with people in [their] immediate
environment.” J.A. 101 at 1:33-36. To solve this problem,
the patent discloses an earphone device with: (1) an ambi-
ent sound microphone that captures environmental sound;
(2) a signal processing system that receives an audio
1 Although Samsung filed a response brief and cross
appealed, ECF Nos. 1, 23, it later withdrew its participa-
tion, ECF No. 37. The Director of the United States Patent
and Trademark Office intervened, adopting Samsung’s
brief. ECF No. 40.
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ST CASE1TECH, LLC v. SQUIRES 3
content signal from a remote device; and (3) the ability to
detect voice activity by analyzing microphone signals to de-
termine when the user is speaking. Id. at 1:53-67.
When the system detects that the user is speaking, it
turns up the volume (or “gain”) of the ambient sound signal
(i.e., sound from the user’s surroundings picked up by the
earphone’s microphone), turns down the volume (“gain”) of
the audio content signal (i.e., audio content, such as music,
from a remote device), and then combines the two signals
into one signal that plays through a small speaker in the
user’s ear. Id. at 1:60-67. Claims 1-6 and 13-21 further
require that when the system subsequently detects that
the user has stopped speaking, it retains the same settings
for a set time. See id. at 11:56-58, 13:22-25.
Claim 1 is reproduced below (with emphasis added to
the disputed claim term):
A method for passing ambient sound to an ear-
phone device configured to be inserted in an ear ca-
nal of a user, the method comprising the steps of:
[1a] capturing the ambient sound from an
ambient sound microphone (ASM) proxi-
mate to the earphone device to form an
ASM signal;
[1b] receiving an audio content (AC) signal
from a remote device;
[1c] detecting voice activity of the user of
the earphone device;
[1d] mixing the ASM signal and the AC sig-
nal to form a mixed signal, such that, in the
mixed signal, an ASM gain of the ASM sig-
nal is increased and an AC gain of the AC
signal is decreased when the voice activity
is detected;
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ST CASE1TECH, LLC v. SQUIRES 4
[1e] detecting a cessation of the voice activ-
ity;
[1f] delaying modification of the ASM gain
and the AC gain for a predetermined time
period responsive to the detected cessation
of the voice activity; and
[1g] directing the mixed signal to an ear ca-
nal receiver (ECR) of the earphone device.
J.A. 106 at 11:42-60 (internal bracketed numbering
added).
Claims 7-9 recite a similar method but add that the
system must first smooth (i.e., average) the ambient sound
signal over time, compare that smoothed level to a set
threshold, and treat sound levels above that threshold as
voice activity. When voice activity is detected, the signal
adjustment behavior described above is triggered; that is,
the ambient sound signal is increased and the audio con-
tent signal is decreased.
ST1 sued Samsung for infringement of the ’542 patent.
Samsung then petitioned for IPR and the Board instituted.
In its petition, Samsung alleged that claims 1-10 and 13-
20 of the ’542 patent are invalid due to obviousness based
on (as relevant to this appeal) three prior art references:
U.S. Patent App. Pub. No. 2007/0189544 (“Rosenberg”),
U.S. Patent App. Pub. No. 2011/0096939 (“Ichimura”), and
U.S. Patent App. Pub. No. 2011/0264447 (“Visser”).
Rosenberg, “Ambient Sound Responsive Media
Player,” discloses “adjusting an output of a media player”
through “processing the ambient audio signal to determine
whether one or more characteristic forms are present
within the ambient audio signal.” J.A. 605. If such char-
acteristic forms are present, the disclosed system “re-
duc[es] an output of [the] media player from a first volume
to a second volume.” Id. Some characteristic forms Rosen-
berg detects are the voice of the user of the media player,
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ST CASE1TECH, LLC v. SQUIRES 5
an alarm, or a siren. Rosenberg further discloses maintain-
ing the reduced output of the media player so “long as the
first user’s voice continues to be identified without a time
gap of more than some threshold amount of time.” J.A. 612
at ¶ 51. Rosenberg notes that “[t]he threshold is generally
set such that if the first user speaks at a typical speaking
pace, the volume reduction will be maintained until the
first user finishes talking.” Id.
Ichimura, “Reproducing Device, Headphone and Re-
producing Method,” discloses a headphone system “config-
ured to detect that the headphone [wearer] has started or
finished talking with [a] person depending on whether the
headphone [wearer] speaks to the person.” J.A. 617; J.A.
630 at ¶ 93. Once the system has identified that the person
wearing the headphone is speaking, the system shifts into
a talking mode. When the person has stopped speaking for
a fixed period, the system switches back into listening
mode.
Visser, “Systems, Methods, and Apparatus for Speech
Feature Detection,” discloses “detect[ion of] a transition in
a voice activity state” of an audio signal, based on changes
in the signal. J.A. 686; J.A. 694 at ¶ 124. Its techniques
involve the analysis of “segments of an audio signal that
carry speech information.” J.A. 688 at ¶ 75. In one embod-
iment, Visser’s system performs “a temporal smoothing op-
eration.” J.A. 698 at ¶ 163.
The Board found that Samsung had shown by a pre-
ponderance of the evidence that claims 1-6 of the ’542 pa-
tent are obvious in view of Rosenberg in combination with
Ichimura. It further found claims 7-9 obvious based on
Rosenberg in combination with Visser. It ruled claims 13-
20 were obvious based on Rosenberg in combination with
Ichimura, Visser, and another reference not pertinent to
this appeal. The FWD also declared claims 11 and 12 un-
patentable, though it identified no reason for this conclu-
sion.
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ST CASE1TECH, LLC v. SQUIRES 6
ST1 timely appealed. We have jurisdiction under
35 U.S.C. § 141(c) and 28 U.S.C. § 1295(a)(4)(A).
II
We review the Board’s legal determinations de novo.
See In re Elsner, 381 F.3d 1125, 1127 (Fed. Cir. 2004). We
review the Board’s factual findings for substantial evi-
dence. See Acceleration Bay, LLC v. Activision Bliz-
zard, Inc., 908 F.3d 765, 769 (Fed. Cir. 2018). Substantial
evidence “means such relevant evidence as a reasonable
mind might accept as adequate to support a conclusion.”
Universal Camera Corp. v. NLRB, 340 U.S. 474, 477 (1951)
(internal quotation marks and citation omitted).
“Claim construction is a question of law with underly-
ing questions of fact.” Wasica Fin. GmbH v.
Cont’l Auto. Sys., Inc., 853 F.3d 1272, 1278 (Fed. Cir. 2017).
Where “the intrinsic record fully governs the proper con-
struction of a term,” our review is de novo. Id. Obviousness
is a legal question based on underlying factual findings.
See In re Gartside, 203 F.3d 1305, 1316 (Fed. Cir. 2000).
“The presence or absence of a motivation to combine refer-
ences in an obviousness determination is a pure question
of fact.” Id.
III
A
ST1 first alleges error in the Board’s construction of the
claim term “detecting a cessation of the voice activity” (the
“cessation limitation”), step [1e], as used in independent
claims 1 and 13. ST1 proposes that the cessation limitation
should be construed to mean “detecting an end of speech,”
which “does not encompass momentary pauses within
speech,” i.e, “word gaps.” J.A. 6-7 (discussing exemplary
word gaps). The Board rejected ST1’s proposal and instead
sided with Samsung, concluding that the cessation limita-
tion “is broad enough to also encompass detecting the end
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ST CASE1TECH, LLC v. SQUIRES 7
of a word within a sentence or conversation.” J.A. 13-14.
We agree with the Board.
The claim language supports the Board’s construction.
As the Board observed, claim 1 recites “detecting voice ac-
tivity of the user of the earphone device” and then “detect-
ing a cessation of the voice activity.” J.A. 14 (quoting J.A.
106 at 11:50, 11:55) (emphasis added). The patent de-
scribes “voice activity” as occurring when a microphone sig-
nal, such as the ASM microphone signal, is greater than a
threshold value. Thus, as the Board concluded, “‘detecting
a cessation of the voice activity’ refers to detecting that the
ASM . . . microphone signal level has fallen below the
threshold value.” J.A. 14. Because an ASM microphone
signal level may fall below a threshold in between words
when a speaker is speaking, it follows that such “word
gaps” are included within “cessation of voice activity.”
The specification provides further support. In Figure
7, for example, once voice activity is detected, a “VAD
[Voice Activity Detection] timer” begins counting up to a
value referred to as Tinitial, and when the system later de-
tects that voice activity has ceased, the timer counts back
down; only when it reaches zero do the modified signals re-
vert to their original levels. The specification explains that
in “exemplary embodiments,” such as the one depicted in
Figure 7, the “time period of the . . . delay” (i.e., Tinitial) may
be proportional to a period of continuous user voice activity
before cessation and may be bounded above by a set period
of time. J.A. 102 at 3:63-67; see also J.A. 105 at 10:51-57.
As the Board explained:
the switching of the VAD status to an “off” state
when the user stops speaking corresponds to the
claimed “detecting a cessation of the voice activity”
(limitation 1[e]) and the decrementing of the VAD
timer before reverting the AC and ASM gains to
their original values corresponds to the claimed
“delaying modification of the ASM gain and the AC
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ST CASE1TECH, LLC v. SQUIRES 8
gain for a predetermined time period responsive to
the detected cessation of the voice activity” (limita-
tion 1[f]).
J.A. 20. The specification teaches that, in exemplary em-
bodiments, when the ASM signal level is greater than a
given threshold (i.e., when “voice activity” is detected), the
VAD “may be set to an on state. Otherwise[,] the VAD may
be set to an off state.” J.A. 102 at 4:14-21. This further
supports that, when the ASM signal drops below a thresh-
old such that voice activity is no longer detected, the VAD
timer is started. This understanding of the claims supports
the Board’s construction, as the VAD timer itself would al-
leviate ST1’s concern that allowing word gaps to constitute
“cessations” would lead to “too frequent and too abrupt” ad-
justments, as the timer itself delays any modification and
can be set for extended periods. J.A. 105 at 10:51-57, 1173
(Patent Owner Response).
Neither side claims to find support for its position in
the prosecution history. And there is no need here to con-
sult the extrinsic evidence, which cannot change the con-
struction compelled by the intrinsic evidence. See Kara
Tech. Inc. v. Stamps.com Inc., 582 F.3d 1341, 1348 (Fed.
Cir. 2009) (“[E]xtrinsic [evidence] like expert testimony
cannot overcome more persuasive intrinsic evidence.”).
In opposition to our conclusions, ST1 argues that the
Board’s construction is so broad that it undermines the
very purpose of the invention. See generally Se-
quoia Tech., LLC v. Dell, Inc, 66 F.4th 1317 (Fed. Cir.
2023) (“[A] patent’s express purpose of the invention in-
forms the proper construction of claim terms.”) (internal
quotation marks and citation omitted). The patent de-
scribes the invention as a hands-free way to let the ear-
phone user maintain situational awareness by
automatically increasing the level of ambient sound and
decreasing the level of audio content a user is listening to
when speaking, and then restoring those levels after the
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ST CASE1TECH, LLC v. SQUIRES 9
conversation ends, without the user having to manually al-
ter the volume. ST1 asserts that if “cessation of the voice
activity” is broad enough to cover ordinary pauses between
words, the system would repeatedly and rapidly change the
relative loudness of ambient sound and audio content dur-
ing the user’s utterances, a result at odds with the patent’s
express goal of supporting natural, continuous communica-
tion while preserving awareness of the local sound environ-
ment.
This argument is unpersuasive because, as the Board
correctly found, and as we have discussed, another claim
limitation, 1[f], addresses this concern. We agree with the
Board’s analysis on this point: “The concept of determining
whether gains should be reverted to their original values is
addressed not by step 1[e] [“detecting a cessation of the
voice activity”], but rather by step 1[f], which recites ‘delay-
ing modification of the ASM gain and the AC gain for a pre-
determined period responsive to the detected cessation of
the voice activity.” J.A. 16. “By using a timer to delay mod-
ification of the AC and ASM gains, the system can prevent
the gains from reverting to their original values too
quickly, because the gains will not revert until the timer
expires.” J.A. 17.
ST1 also points us to the construction entered in paral-
lel district court litigation, where the parties stipulated to
the essentially same construction proposed here by ST1.
As the Board rightly noted, it was not obligated to adopt
the same construction as the district court, only to give it
consideration, which the Board plainly did here. Nor is the
Board bound by any disclaimer ST1 may have made in this
very IPR proceeding. See CUPP Computing AS v. Trend
Micro Inc., 53 F.4th 1376, 1383 (Fed. Cir. 2022) (“To be
clear, a disclaimer in an IPR proceeding is binding in later
proceedings, whether before the PTO or in court. We hold
only that a disclaimer is not binding on the PTO in the very
IPR proceedings in which it is made . . . .”) (internal cita-
tions omitted).
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As the claim construction issue is the only challenge
ST1 raises to the Board’s finding that claims 1-6 and 13-18
are unpatentable, we affirm these determinations of un-
patentability.
B
As to claims 7-9, ST1 argues that the Board’s finding
of a motivation to combine Rosenberg and Visser lacks sub-
stantial evidence support because incorporating Visser
would disadvantageously impact Rosenberg. We disagree.2
The Board, relying on Samsung’s expert, found that
Rosenberg expressly tells one of ordinary skill in the art
that its ambient microphone signal can be subjected to
“noise reduction, filtering, and/or other commonly known
signal processing steps” before any voice or identity recog-
nition occurs. J.A. at 68-69 (citing J.A. 611 at ¶¶ 44, 45).
Visser, in turn, teaches that applying a simple temporal
smoothing to a microphone-based gain measure “may help
to increase reliability of the onset and/or offset detection”
by deemphasizing brief, noisy spikes like a door slam. J.A.
690 at ¶ 90. The Board found that a skilled artisan would
treat Visser’s smoothing as just one kind of filtering that
fits comfortably within Rosenberg’s stated framework. The
disclosures of Rosenberg and Visser themselves, along with
the expert opinion credited by the Board, constitute sub-
stantial evidence supporting this motivation to combine.
We therefore affirm the Board’s obviousness determi-
nation as to claims 7-9.
2 The Director argues that ST1 waived this argument
by focusing on the purported inoperability of a Rosenberg-
Vissar combination below. We do not agree. See J.A. 2011-
12 (ST1 arguing that disadvantages of combination would
“frustrate the purpose of Rosenberg”).
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ST CASE1TECH, LLC v. SQUIRES 11
C
The Board additionally determined that claims 11 and
12 “have been proven by a preponderance of the evidence
to be unpatentable.” J.A. 91. The parties agree that claims
11 and 12 were not challenged in Samsung’s petition.
“[T]he Board may not invalidate patent claims on grounds
it identifies sua sponte that are not actually raised by the
petitioner.” Corephotonics, Ltd. v. Apple Inc., 84 F.4th 990,
1011 (Fed. Cir. 2023). Thus, we vacate the Board’s invalid-
ity finding as to claims 11 and 12.
IV
We have considered ST1’s remaining arguments and
find they lack merit. Accordingly, we affirm the Board’s
finding of invalidity of claims 1-9 and 13-18. We vacate its
invalidity finding as to claims 11 and 12.
AFFIRMED-IN-PART AND VACATED-IN-PART
COSTS
Each party to bear its own costs.
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