AU Optronics Corpporation

Patent Trials and Appeals Board

Apr 20, 2021

2020000747 (P.T.A.B. Apr. 20, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
15/371,672 12/07/2016 Sen-Chuan HUNG 67507-081 9463
65358 7590 04/20/2021
WPAT, PC
INTELLECTUAL PROPERTY ATTORNEYS
8230 BOONE BLVD. SUITE 405
VIENNA, VA 22182
EXAMINER
ZUBAJLO, JENNIFER L
ART UNIT PAPER NUMBER
2623
MAIL DATE DELIVERY MODE
04/20/2021 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 PATENT TRIAL AND APPEAL BOARD
Ex parte SEN-CHUAN HUNG and CHIA-YUAN YEH
Appeal 2020-000747
Application 15/371,672
Technology Center 2600
BEFORE JASON V. MORGAN, MICHAEL J. STRAUSS, and
CHRISTA P. ZADO, Administrative Patent Judges.
ZADO, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision to reject claims 1–19. We have jurisdiction under
35 U.S.C. § 6(b).
We AFFIRM.

1 We use the word Appellant to refer to “applicant” as defined in 37 C.F.R.
§ 1.42(a). Appellant identifies the real party in interest as AU Optronics
Corp. Appeal Br. 3.
Appeal 2020-000747
Application 15/371,672
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CLAIMED SUBJECT MATTER
The Specification relates to a display apparatus and control method
capable of compensating for shifts in threshold voltages of transistors
driving organic light-emitting diode (“OLED”) pixels. Spec. ¶¶ 1, 7.
Claim 1, reproduced below, is illustrative of the claimed subject matter:
1. A display apparatus, comprising:
a display panel comprising a plurality of pixel circuits, each of
the pixel circuits comprising:
a plurality of pixels, wherein each of the pixels comprises:
an organic light-emitting diode (OLED), wherein the OLED has
a first end and a second end;
a driving transistor for driving the OLED, wherein the driving
transistor has a first end for receiving a data signal;
a capacitor having a first end and a second end coupled to a
control end of the driving transistor; and
a compensation circuit for controlling electrical connections
between the second end of the capacitor and the first end of the
OLED, and between the control end of the driving transistor and
the first end of the OLED according to a second control signal;
and
a first shared circuit, coupled to the pixels, for compensating a
shift in a threshold voltage of the driving transistor of each pixel
of each pixel circuit according to a reference voltage; and
a correction circuit, coupled to the pixel circuits, for detecting a
driving current of pixels of each pixel circuit and adjusting the
reference voltage received by the first shared circuit of each pixel
circuit according to the detected driving current of the pixels of
the each pixel circuit.
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Application 15/371,672
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REFERENCES
The prior art relied upon by the Examiner is:
Name Reference Date
Chaji US 2014/0285407 A1 Sept. 25, 2014
Kim US 2015/0001504 A1 Jan. 1, 2015
Tan US 2016/0300532 A1 Oct. 13, 2016

REJECTIONS
Claims 1, 2, and 14 are rejected under 35 U.S.C. § 103 as
unpatentable over the combination of Kim and Tan. Final Act. 2–7; Ans. 3.
Claims 3–13 and 15–19 are rejected under 35 U.S.C. § 103 as
unpatentable over the combination of Kim, Tan, and Chaji. Final Act. 7–16;
Ans. 3.
OPINION
Specification
According to the Specification, a problem exists with OLED displays
in which each OLED is driven by a separate transistor. Specifically,
variances in the threshold voltage (i.e., voltage at which the transistor turns
on) of each transistor can lead to non-uniform brightness of frames due to
different characteristics of each transistor, and image quality can deteriorate
over time. Spec. ¶ 4.
In order to address this alleged problem, the Specification proposes, in
one embodiment, that each pixel include a compensation circuit configured
to control electrical connection between the gate and drain of the transistor
driving the OLED. Spec. ¶¶ 9, 29–30; id. Fig. 3. The Specification’s
Figure 3, an excerpt of which is reproduced below, is illustrative.
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Application 15/371,672
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Figure 3 is a schematic diagram of a pixel of Figure 2. Spec. ¶ 13.
The Specification’s Figure 3 is a schematic diagram of pixel 200 in a
preferred embodiment. Spec. ¶¶ 13, 28, Fig. 2. Driving transistor T2B
drives OLED 210, and includes gate G, source S, and drain D. Spec. ¶ 29,
Fig. 3. The data signal Sdata for determining the current, and therefore
brightness, of OLED 210, passes through switch T2A to source S of driving
transistor T2B. Id. Drain D of driving transistor T2B connects to the anode
of OLED 210. Gate G and drain D of driving transistor T2B are connected
to compensation circuit 230. Id.
In another embodiment, the Specification proposes a correction circuit
to compensate for a shift in threshold voltage of driving transistor T2B
according to a received reference voltage. Spec. ¶ 9, Fig. 3. Figure 2,
reproduced below, is illustrative.
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Application 15/371,672
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Figure 2 is a functional block diagram of a display apparatus. Spec. ¶ 12.
Figure 2 is a functional block diagram of a display apparatus. Spec. ¶ 12.
Figure 2 shows display panel 160 comprising correction circuit 170 and a
plurality of pixel circuits 180, wherein each pixel circuit 180 comprises a
plurality of pixels 200. Id. Fig. 2, ¶ 28.
In another embodiment, the Specification proposes shared circuitry
coupled to a plurality of OLED driving transistors, wherein the circuitry
compensates for shifts in the threshold voltages of the driving transistors
according to a received reference voltage. Spec. ¶ 7. The Specification’s
description of Figure 2 is illustrative. With reference to Figure 2, the
Specification discloses that each pixel circuit 180 comprises a shared circuit
(not shown in Figure 2, but described in the Specification with reference to
Figure 2), in addition to comprising a plurality of pixels 200. Id. ¶ 28.
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Discussion
Appellant contends the Examiner has not shown unpatentability of
independent claims 1 and 14 because Kim does not disclose: 1) “a
compensation circuit for controlling electrical connections between the
second end of the capacitor and the first end of the OLED, and between the
control end of the driving transistor and the first end of the OLED according
to a second control signal,” 2) a driving transistor having “a first end for
receiving a data signal,” or 3) a capacitor having a “second end coupled to a
control end of the driving transistor,” wherein the second end of the
capacitor also is connected to the OLED. Appeal Br. 11–16. Appellant
further contends the Examiner has not shown unpatentability of claims 2–13
and 15–19, which depend either from claim 1 or 14, because the Examiner’s
rejections of claims 2–13 and 15–19 do not cure the deficiencies regarding
the rejection of claims 1 and 14. For the reasons that follow, we affirm the
Examiner’s rejections.
Kim generally relates to an OLED display device. Kim ¶ 3. The
OLED display device in Kim includes individual OLED display elements
each driven by a driving transistor. Id. ¶ 8. Current flowing through a
driving transistor is adjusted by adjusting a potential difference between the
gate and source of the driving transistor, wherein the current flowing
through the transistor determines the quantity of light emitted by, and
therefore the brightness, of the OLED. Id. ¶¶ 8–9.
Kim explains that a problem occurs in the prior art in that it is difficult
to obtain optimized OLED brightness due to deviations in the threshold
voltages of the driving transistors in the display device. Id. Kim addresses
this problem by, inter alia, providing a compensation circuit, e.g., voltage
reference unit 110, to compensate for a threshold voltage of the driving
Appeal 2020-000747
Application 15/371,672
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transistor included in each pixel of the display device. Id. ¶ 56. Figures 5
and 8 of Kim, reproduced below, are illustrative.

Figure 5 is a circuit diagram showing a reference voltage unit and sub-
pixels of an OLED display device.
Kim’s Figure 5 is a circuit diagram showing voltage reference
supplier 330 and red, white, green, and blue sub-pixels of an OLED display.
Kim ¶¶ 33, 73.
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Figure 8 is a circuit diagram illustrating operation of a red sub-pixel
Kim’s Figure 8 is a circuit diagram illustrating operation of a red sub-pixel.
Id. ¶¶ 34, 96.
In Figure 5 of Kim, transistor T1 drives OLED D1 of the red OLED
sub-pixel. Id. ¶ 76. Kim explains that sensing transistor T3, shown in
Figure 5, of the red sub-pixel is controlled by a sensing control signal of
sensing unit 111. Id. ¶ 80. Sensing unit 111 senses the voltage threshold of
driving transistor T1, and reference voltage unit 110 adjusts and outputs a
reference voltage based on the sensed data. Id. ¶¶ 57, 70. As explained in
Kim, sensing unit 111 allows a compensation circuit—e.g., reference voltage
unit 110—to compensate for a threshold voltage of a driving transistor. Id.
¶ 56.
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Figure 8 of Kim shows a circuit for a sub-pixel, i.e., red-sub-pixel of
Figure 5. The sub-pixel includes OLED D1, driving transistor T1,
capacitor C1, sensing transistor T3, and scan transistor T2. Kim Fig. 5.
Sensing transistor T3 is controlled by a sensing control signal of sensing
unit 111 as shown in Figure 5, wherein the sensing control signal is received
at the gate electrode of T3. Id. ¶ 80.
1. Compensation Circuit
There is no dispute that, as found by the Examiner, Kim discloses a
compensation circuit. Final Act. 3 (citing Kim ¶ 56 (e.g., “sensing unit 111
can enable a compensation circuit such as the reference voltage unit 110”),
Figs. 5–8). However, as pointed out by Appellant, claim 1 recites that the
compensation circuit is “for controlling electrical connections between the
second end of the capacitor and the first end of the OLED, and between the
control end of the driving transistor and the first end of the OLED according
to a second control signal.” Appeal Br. 11–13. Appellant argues the
Examiner has not shown that Kim discloses the recited compensation circuit
along with the recited connections. Id. at 12. Specifically, Appellant
submits that Kim “merely discloses whether to supply the compensation
signals; it does not provide or suggest that the Kim’s compensation circuit
controls the connection between the OLED and the capacitor, and the
connection between the OLED and driving transistor.” Id. According to
Appellant, in Figure 5 of Kim the only circuit element between Kim’s
OLED and capacitor, and between the OLED and driving transistor, is node
N1, but node N1 is only a connecting point and not a compensation circuit to
control electrical connections between these points. Id. at 12–13. Appellant
argues, therefore, that node N1 of Kim fails to disclose compensation
circuitry for controlling the electrical connections to the OLED. Id. at 13.
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We are not persuaded by Appellant’s arguments. The Examiner
neither finds nor asserts that node N1 of Kim is compensation circuitry.
Rather, the Examiner identifies Kim’s sensing unit 111 which enables a
compensation circuit such as reference voltage unit 110 for disclosure of
compensation circuitry. Final Act. 3; Ans. 3–5. To the extent Appellant’s
argument is that Kim’s sensing unit 111 and reference voltage unit 110 do
not satisfy the claimed compensation circuitry because this circuitry is not
physically located at node N1, claim 1 and the similar recitation of claim 14
neither recite nor require that compensation circuitry be connected directly
to the recited nodes—i.e., second end of the capacitor (i.e., N2) and first end
of the OLED (i.e., N1), and the control end of the driving transistor (i.e., N2)
and first end of the OLED (i.e., N1). Rather, the claims recite that the
compensation circuitry is for controlling electrical connection between the
recited nodes (e.g., N2 and N1), without reciting any requirement of a direct
connection to the recited nodes.
The Examiner explains that Kim’s compensation circuit (e.g.,
reference voltage unit 110) is for controlling all the electrical connections of
the OLED panel. Ans. 4. We agree with the Examiner that Kim teaches or
suggests a compensation circuit for controlling the electrical connection
between nodes N2 and N1, and therefore teaches or suggests the recited
claim limitation at issue.
Specifically, Kim’s sensing unit 111 and compensation circuit (e.g.,
reference voltage unit 110) control the voltage between N2 and N1, and
therefore are for controlling electrical connections between node N2 (i.e., the
gate of Kim’s driving transistor T1 and the second end of Kim’s
capacitor C1) and node N1 (i.e., the anode of OLED D1). Kim ¶¶ 8–9
(disclosing that current flowing through the driving transistor is adjusted by
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Application 15/371,672
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adjusting a potential difference between the gate (i.e., N2) and source (i.e.,
N1) of the driving transistor). Kim adjusts the potential difference by setting
the voltage at node N2 (which controls driving transistor T1, Kim ¶ 82),
which is set through the compensation of the threshold voltage, i.e., through
Kim’s reference voltage unit 110 (Kim Fig. 8, ¶¶ 82, 111–12).
For the foregoing reasons, the Examiner did not err in finding that
Kim teaches or suggests “a compensation circuit for controlling electrical
connections between the second end of the capacitor and the first end of the
OLED, and between the control end of the driving transistor and the first end
of the OLED according to a second control signal,” as recited in claim 1, and
the similar recited limitation in claim 14.
2. Data Signal
Appellant argues Kim does not disclose receiving a data signal at a
“first end” of the transistor driving the OLED. Appeal Br. 13–15. Claims 1
and 14 recite, in pertinent part, “a driving transistor for driving the OLED,
wherein the driving transistor has a first end for receiving a data signal.” For
this claim recitation, the Examiner identifies the signal Vdata in Kim. Final
Act. 3 (citing Kim ¶¶ 57, 100, 105, Figs. 5–8); Ans. 6–8. As is shown in,
e.g., Fig. 8, data line DL, which supplies Vdata, is connected to the gate end
(see node N2) of driving transistor D1. Kim Fig. 8; Ans. 6.
Appellant argues, however, that the gate end of driving transistor T1
is not a “first end” of the transistor. Appeal Br. 13 (“data line DL can only
electrically connect to T1’s control end . . . Kim’s data line does not connect
to either ends of transistor T1 as recited in the claim 1”). Appellant does not
provide any evidence or argument in support of its interpretation of the
claims as precluding the gate end of the driving transistor from being a “first
end.” The Examiner determines, and we agree, that the claim language and
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Application 15/371,672
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Specification neither limits the “first end” of the driving transistor to being a
source or drain, nor precludes the “first end” from being the gate end of the
driving transistor. Ans. 6. Appellant has not identified any claim language
or disclosure in the Specification showing otherwise.
For the foregoing reasons, the Examiner did not err in finding that
Kim teaches or suggests “a driving transistor for driving the OLED, wherein
the driving transistor has a first end for receiving a data signal,” as recited in
claims 1 and 14.
3. Capacitor’s Second End
According to Appellant, the claims require that the “second end” of
the capacitor must be connected to both the control end of the driving
transistor and to the OLED. Appeal Br. 15–16. However, as explained by
the Examiner, at most the claims require a second end of the capacitor to be
coupled to a control end of the driving transistor. Ans. 8–9. Specifically,
claims 1 and 14 recite “a capacitor having a first end and a second end
coupled to a control end of the driving transistor.” However, contrary to
Appellant’s arguments, the claims do not require that end of the capacitor to
also be connected to the OLED. Id.
Specifically, there is no claim language that requires the second end of
capacitor C1 to be connected to OLED D1. Appellant does not identify any
claim language in support of such requirement. Appeal Br. 15–16. Rather,
Appellant merely: 1) states that “[a]s discussed above, the capacitor’s second
end is connecting to the OLED via the compensating circuit,” 2) identifies
the claim recitation requiring that the second end of the capacitor is coupled
to a control end of the driving transistor, and 3) concludes that “[i]n essence,
the claim 1 provides that both OLED and the control end of the driving
transistor are connecting to the same end of the capacitor.” Id. at 15.
Appeal 2020-000747
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Presumably, Appellant’s statement “[a]s discussed above” refers to
Appellant’s argument that Kim does not disclose a compensation circuit
controlling the first end of the OLED to connect with both the second end of
the capacitor and the control end of the driving transistor. Appeal Br. 11–
13. For reasons discussed above, we do not find Appellant’s arguments
regarding compensation circuitry to be persuasive. Moreover, even
considering Appellant’s arguments regarding compensation circuitry,
Appellant simply has not identified any claim language that supports its
argument that the second end of the capacitor must be connected to the
OLED. Nor has Appellant explained sufficiently why any such requirement
should be read into the claims.
For the foregoing reasons, Appellant’s argument that Kim does not
disclose the capacitor’s second end connecting to both the OLED and the
control end of the driving transistor does not persuade us of Examiner error.
CONCLUSION
The Examiner’s rejections are affirmed.
More specifically, we affirm the Examiner’s rejection of
claims 1, 2, and 14 under 35 U.S.C. § 103 as unpatentable over the
combination of Kim and Tan; and
claims 3–13 and 15–19 under 35 U.S.C. § 103 as unpatentable over
the combination of Kim, Tan, and Chaji.
DECISION SUMMARY
In summary:
Claims
Rejected
35 U.S.C.
§
Reference(s)/Basis Affirmed Reversed
1, 2, 14 103 Kim, Tan 1, 2, 14
Appeal 2020-000747
Application 15/371,672
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3–13, 15–19 103 Kim, Tan, Chaji 3–13, 15–19
Overall
Outcome
1–19

TIME PERIOD FOR RESPONSE
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R.
§ 1.136(a)(1)(iv).
AFFIRMED