  United States Court of Appeals
      for the Federal Circuit
                 ______________________

         ATEN INTERNATIONAL CO., LTD.,
                Plaintiff-Appellant

                            v.

      UNICLASS TECHNOLOGY CO., LTD.,
ELECTRONIC TECHNOLOGY CO., LTD., AIRLINK
    101, PHOEBE MICRO, INC., BROADTECH
  INTERNATIONAL CO., LTD., DBA LINKSKEY,
    BLACK BOX CORPORATION, BLACK BOX
      CORPORATION OF PENNSYLVANIA,
              Defendants-Appellees
             ______________________

                       2018-1606
                 ______________________

   Appeal from the United States District Court for the
Central District of California in No. 2:15-cv-04424-AG-
AJW, Judge Andrew J. Guilford.
                 ______________________

                Decided: August 6, 2019
                ______________________

   LAURENCE M. SANDELL, Mei & Mark LLP, Washington,
DC, argued for plaintiff-appellant. Also represented by LEI
MEI.

   JOSEPH PIA, Pia Anderson Moss Hoyt, Salt Lake City,
UT, argued for defendants-appellees. Also represented by
ROBERT AYCOCK.
2       ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY
                                                     CO., LTD.


                   ______________________

    Before MOORE, WALLACH, and TARANTO, Circuit Judges.
MOORE, Circuit Judge.
    ATEN International Co., Ltd. (“ATEN”) appeals the
United States District Court for the Central District of Cal-
ifornia’s denial of judgment as a matter of law (“JMOL”),
which declined to overturn the jury’s findings that the as-
serted claims of U.S. Patent No. 8,589,141 are invalid as
anticipated under 35 U.S.C. § 102 and not infringed; and
that the asserted claims of U.S. Patent No. 7,640,289 are
not infringed. For the reasons discussed below, we reverse
as to invalidity and affirm as to noninfringement.
                         BACKGROUND
    Uniclass Technology Co., Ltd. (“Uniclass”) and ATEN
are involved in making and selling keyboard-video-mouse
(“KVM”) switch systems that allow a user to control multi-
ple computers from a single keyboard, video device, and
mouse. ATEN sued Uniclass as well as Electronic Technol-
ogy Co., Ltd.; Airlink 101; Phoebe Micro, Inc.; Broadtech
International Co., Ltd. d/b/a Linkskey; Black Box Corpora-
tion; and Black Box Corporation of Pennsylvania (collec-
tively, the “customer defendants”) alleging, as relevant
here, infringement of claims 3, 8, and 10 of the ’141 patent
and claims 1–20 of the ’289 patent. The ’141 patent is di-
rected to technology for switching between computers that
share a keyboard, monitor, and mouse through a KVM
switch, such as a keyboard shortcut. ’141 patent at 2:51–
61. Claim 3 depends from claims 1 and 2, and claim 8 de-
pends from claim 1. Independent claim 1 recites:
      1. A method for controlling a resource sharing ap-
      paratus coupling at least one input device to a plu-
      rality of hosts including a first host, the method
      comprising:
ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY      3
CO., LTD.


       connecting the input device to the first
       host;
       while the input device is connected to the
       first host, acquiring a first input signal
       from the input device and determining
       whether the first input signal comprises a
       standby indication of a switch command
       and wherein the standby indication is for
       indicating that connection between the in-
       put device and the first host can be
       changed; and
       in response to a determination that the
       first input signal comprises the standby in-
       dication, disconnecting the input device
       from the first host without connecting the
       input device to any other host and starting
       emulating the input device to the first host;
       and
       acquiring a second input signal from the in-
       put device, wherein the second input signal
       is not transferred to the hosts when it is in-
       putted to the resource sharing apparatus.
    The ’289 patent is directed to technology for stringing
together several KVM switches. ’289 patent at 2:1–6. It
provides that each KVM switch can detect whether it is a
master or slave by, for example, detecting whether the port
used to connect other KVM switches is occupied. Id. at 4:1–
4. Independent claim 1 recites:
   1. A computer switch comprising:
       a set of peripheral device ports for connect-
       ing to a set of peripheral devices;
       a first port;
       a second port;
4     ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY
                                                   CO., LTD.


        a control device coupled to the first port and
        the second port, the control device repeat-
        edly detecting whether the first port is oc-
        cupied to repeatedly determine a master or
        slave status of the computer switch,
        wherein
        if the first port is occupied, the control de-
        vice determines the computer switch to be
        a slave and provides data to a first external
        computer switch connected to the first port,
        and
        if the first port is unoccupied, the control
        device determines the computer switch to
        be a master and controls a second external
        computer switch connected to the second
        port and obtains data from the second ex-
        ternal computer switch; and
        a plurality of computer connection ports
        coupled to the control device for connecting
        to and controlling a plurality of computers,
        wherein the plurality of computers are con-
        trolled by the set of peripheral devices if the
        computer switch is determined to be a mas-
        ter, and are controlled by the first external
        computer switch connected to the first port
        if the computer switch is determined to be
        a slave.
     At trial, the jury found that Uniclass did not infringe
the asserted claims of the ’141 or ’289 patents. It also found
the asserted claims of the ’141 patent were invalid as an-
ticipated without specifying which reference was the basis
for its finding. ATEN moved for JMOL, which the district
court denied in the aspects relevant to this appeal.
   ATEN timely appealed. We have jurisdiction under 28
U.S.C. § 1295(a)(1).
ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY         5
CO., LTD.


                        DISCUSSION
     We review denials of JMOL under the law of the re-
gional circuit. TVIIM, LLC v. McAfee, Inc., 851 F.3d 1356,
1362 (Fed. Cir. 2017). The Ninth Circuit reviews a denial
of JMOL de novo. Harper v. City of Los Angeles, 533 F.3d
1010, 1021 (9th Cir. 2008). JMOL is proper when the evi-
dence permits only one reasonable conclusion which is con-
trary to the jury’s verdict, but the jury’s verdict must be
upheld if it is supported by substantial evidence. Id. An-
ticipation and infringement are questions of fact that we
review for substantial evidence. Cordis Corp. v. Bos. Sci.
Corp., 561 F.3d 1319, 1330, 1335 (Fed. Cir. 2009). Whether
a reference is prior art is a question of law based on under-
lying factual questions. TypeRight Keyboard Corp. v. Mi-
crosoft Corp., 374 F.3d 1151, 1157 (Fed. Cir. 2004).
Whether a reference is publicly accessible is a question of
fact. In re NTP, Inc., 654 F.3d 1279, 1296 (Fed. Cir. 2011).
                              I
     At trial, Uniclass asserted anticipation of the claims of
the ’141 patent based on two references (1) CS-1762, an
earlier product by ATEN, and/or its user manual; and (2)
Great Britain Patent No. 2,352,540 (“GB ’540”). The jury
found that the asserted claims of the ’141 patent were in-
valid as anticipated, but there was no special verdict indi-
cating whether one or both references formed the basis for
the jury’s decision. J.A. 9769. The district court denied
ATEN’s JMOL motion, upholding the jury’s finding of an-
ticipation based on the first theory, that the CS-1762 refer-
ence anticipated the asserted claims. It did not address the
second theory. Because the jury’s verdict of anticipation
was not supported by substantial record evidence as to ei-
ther reference, we reverse the denial of JMOL on anticipa-
tion.
6     ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY
                                                   CO., LTD.


                              A
    To establish that an asserted reference is prior art un-
der § 102(b), the patent challenger must prove, by clear and
convincing evidence, that it predates the critical date. Ma-
hurkar v. C.R. Bard, Inc., 79 F.3d 1572, 1578 (Fed. Cir.
1996).
    The undisputed critical date for the ’141 patent is July
24, 2006—one year prior to its filing date. J.A. 4; J.A. 24;
J.A. 9302–9303 at 176:24–177:3.            Uniclass’ expert
Mr. Dezmelyk relied on his testing of a 2009 CS-1762 spec-
imen to meet certain limitations of claim 1 of the ’141 pa-
tent. Uniclass argues the 2009 specimen qualifies as prior
art because it uses firmware that was released in 2006 be-
fore the critical date of the ’141 patent. See Appellee’s Br.
20. But Mr. Dezmelyk testified merely that the firmware
dated to 2006, without specifying a day or month. J.A.
9313 at 14–17 (“I then looked on the wayback machine to
find when that firmware update came out and the last time
it was changed, and that was in 2006. So this firmware is
prior art firmware operating on this, the test hardware.”).
    To establish that the CS-1762 qualifies as prior art,
Uniclass was required to prove by clear and convincing ev-
idence that the firmware existed prior to July 24, 2006.
Merely establishing that the firmware existed in the same
year as the critical date is insufficient. This deficiency was
highlighted on cross-examination:
    Q. Yes or no, you did not testify to a particular
    month in 2006?
    A. No, I don’t believe I mentioned that in my testi-
    mony.
    Q. And you did not testify to a specific date in 2006?
    A. I don’t believe I testified to a particular day ei-
    ther.
ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY          7
CO., LTD.


J.A. 9338 at 18–22. Mr. Dezmelyk did not provide any ad-
ditional date-related information, and Uniclass did not con-
duct re-direct examination on this issue.
    With a critical date of July 24, 2006, testimony that the
firmware running on the CS-1762 device existed in 2006
alone is not enough to support the jury’s finding that the
firmware pre-dated the critical date and thus qualifies as
prior art. We hold that the district court erred in denying
JMOL because substantial evidence does not support the
jury’s finding of anticipation based on the CS-1762 device.
                              B
    A finding of anticipation requires clear and convincing
evidence that “each and every element is found within a
single prior art reference, arranged as claimed.” Summit 6,
LLC v. Samsung Elecs. Co., 802 F.3d 1283, 1294 (Fed. Cir.
2015). Testimony concerning anticipation must typically
“explain in detail how each claim element is disclosed in
the prior art reference. The testimony is insufficient if it is
merely conclusory.” Schumer v. Lab. Comput. Sys., Inc.,
308 F.3d 1304, 1315–16 (Fed. Cir. 2002).
    The jury verdict of anticipation cannot be upheld with
regard to the GB ’540 reference. The asserted claims of the
’141 patent require “emulating the input device to the first
host.” Uniclass’ expert Mr. Dezmelyk testified about the
emulation described in GB ’540 in the context of other as-
serted patents and claim limitations. J.A. 9296 at 170:10–
20 (regarding “emulating the console devices according to the
industry standard”); J.A. 9301–9302 at 175:20–176:6 (de-
scribing that the reference “has USB device emulators in it”);
J.A. 9285–9286 at 159:16–160:18 (describing the “USB host
emulator”). But Uniclass offered no testimony explaining
how this emulation described in GB ’540 meets claim 1’s
requirement of “emulating . . . to the first host.” We also
cannot identify any place in the three pages of GB ’540 pro-
vided in the joint appendix that would support Uniclass’
theory that GB ’540 discloses this limitation. J.A. 9789;
8     ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY
                                                   CO., LTD.


J.A. 9790; J.A. 9793. We see no record evidence that GB
’540 discloses “emulating the input device to the first host.”
To the extent that the jury finding of anticipation was
based on the GB ’540 reference, that finding lacks substan-
tial evidence in this record.
    The district court erred in its denial of JMOL because
the jury’s finding of anticipation was not supported by sub-
stantial evidence as to either reference.
                              II
    On appeal, ATEN challenges the district court’s denial
of JMOL as to infringement of the ’141 and ’289 patents.
ATEN argued in its motion for JMOL that the evidence
compels a finding of infringement, but the jury was con-
fused due to Uniclass’ expert Mr. Dezmelyk’s testimony on
the scope of the claim terms. E.g., J.A. 8–12; J.A. 7937–
7938. The district court denied the motion, holding ATEN
waived any right to contest Mr. Dezmelyk’s claim construc-
tion testimony because it failed “to raise concerns regard-
ing the proper construction of claim terms at trial itself.”
J.A. 10.
    The record below indicates that Mr. Dezmelyk offered
trial testimony regarding the construction of the terms
“disconnecting” and “connecting” in the ’141 patent. At the
claim construction stage, the district court gave the term
“disconnecting the input device from the first host without
connecting the input device to any other host and starting
emulating the input device to the first host” its plain and
ordinary meaning. ATEN did not object, nor did it proffer
a different construction. In fact, it was ATEN who urged
the court to adopt the plain and ordinary meaning. At trial,
Mr. Dezmelyk opined that the accused devices “never con-
nect the input device to the host computer” based on his
interpretation of the plain and ordinary meaning of the
term “connected” as requiring a direct communication
pathway. J.A. 9237 at 15–16; see also J.A. 9240 at 16–18;
J.A. 9241 at 15–21. To inform his interpretation, Mr.
ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY             9
CO., LTD.


Dezmelyk testified about the import of the prosecution his-
tory. J.A. 9242 at 13–23 (“I look at the prosecution history
to understand what ATEN . . . was telling the patent office
. . . . In this case one of the statements they made to the
examiner was the applicant’s invention . . . has a funda-
mental difference in comparison to the teaching of [a refer-
ence] with regard to the concepts of connected and
disconnected between the input device and the host de-
vices.”). According to ATEN, this expert was testifying as
to the proper claim construction to be given to these terms.
    The record also indicates that Mr. Dezmelyk offered
trial testimony regarding the meaning of “detecting
whether the first port is occupied” in the ’289 patent.
Mr. Dezmelyk opined that he believed “the ordinary mean-
ing of the phrase, that is what an engineer would think
when they read this patent, what was meant by that
phrase when he says detecting the first port is occupied, is
detecting if a cable was plugged into the port.” J.A. 9223
at 1–5; see also J.A. 9223 at 17–18; J.A. 9221 at 20–24. To
inform his interpretation, Mr. Dezmelyk again referred to
the prosecution history. J.A. 9228 at 7–12 (“[T]he con-
nector is occupied in the [reference], but notice there is no
discussion of messages . . . . In fact, . . . the [reference] does
meet the messages test. So it has to be a determination
based on the connector itself actually having a plug in it.”);
see also J.A. 9226 at 13–14.
    Mr. Dezmelyk’s testimony on both patents amounts to
claim construction testimony before the jury. ATEN did
not object to any of this testimony during the trial, nor did
ATEN move for the district court to resolve these claim con-
struction disputes. The only objection to the expert’s testi-
mony came after the close of evidence when ATEN orally
moved for a “post-testifying Daubert on Mr. Dezmelyk’s
testimony on invalidity with respect to anything that
10       ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY
                                                      CO., LTD.


required an ATEN claim construction.” 1 J.A. 9357–9358 at
231:23–232:1 (italics added). ATEN now argues its objec-
tion regarding invalidity should be broadened to apply to
claim construction for infringement purposes. We do not
agree. Even if ATEN’s oral motion was timely, we agree
with the district court that ATEN did not object to
Mr. Dezmelyk’s claim construction testimony with respect
to infringement. J.A. 9–10. By failing to object, ATEN has
waived any challenge to the jury’s finding of infringement
based on this testimony.
     It is beyond dispute that claim construction issues are
to be decided by the court. It is thus improper for an expert
witness to testify before the jury regarding claim construc-
tion. CytoLogix Corp. v. Ventana Med. Sys., Inc., 424 F.3d
1168, 1172 (Fed. Cir. 2005). In CytoLogix, the parties
agreed to present expert witness testimony regarding
claim construction to the jury and counsel argued conflict-
ing claim constructions to the jury. Id. We noted the dis-
trict court should have refused to allow such testimony,
despite the agreement of the parties, because the risk of
confusing the jury was high. Id. But here, as in CytoLogix,
“there is no ground for reversal since there was no objection
to the expert testimony as to claim construction.” Id. at
1173. We do not fault the district court here for allowing
claim construction to go to the jury. It is the parties’ obli-
gation to raise a dispute regarding the proper scope of
claims to the court. O2 Micro Int’l Ltd. v. Beyond Innova-
tion Tech. Co., 521 F.3d 1351, 1362 (Fed. Cir. 2008) (“When
the parties present a fundamental dispute regarding the



     1    ATEN also filed a motion for JMOL on the final day
of trial that briefly discussed the term “occupied” of the ’289
patent. J.A. 7937. ATEN did not raise this issue at the
hearing. J.A. 10–11. We agree with the district court that
ATEN failed to preserve its claim construction challenge
via this motion. J.A. 11.
ATEN INTERNATIONAL CO., LTD. v. UNICLASS TECHNOLOGY         11
CO., LTD.


scope of a claim term, it is the court’s duty to resolve it.”).
We therefore affirm the district court’s denial of JMOL as
to noninfringement.
                        CONCLUSION
     For the reasons discussed above, we reverse as to inva-
lidity and affirm as to noninfringement. Because we affirm
as to noninfringement, we need not reach lost profits.
    AFFIRMED-IN-PART, REVERSED-IN-PART
                            COSTS
    No costs.
