PTAB

PGR2026-00028

LG Display Co Ltd

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1. Case Identification

2. Patent Overview

  • Title: DISPLAY DEVICE AND COMPUTER READABLE MEDIA
  • Brief Description: The ’691 patent is directed to a display device that includes pixels with different arrangements of subpixels to reduce color edge artifacts. The claims recite specific layouts for first and second types of pixels, each comprising three subpixels of different colors, and define the positioning of thin-film transistor (TFT) circuits and their connection parts relative to the subpixels.

3. Grounds for Unpatentability

Ground 1: Claims 1-8 are Indefinite under 35 U.S.C. §112

  • Prior Art Relied Upon: Not applicable.
  • Core Argument for this Ground: Petitioner argued that claims 1-8 fail to inform a person of ordinary skill in the art (POSITA) about the scope of the invention with reasonable certainty due to numerous inconsistencies, contradictions, and ambiguous terms.
    • Contradictory Terms of Degree: Petitioner contended that claim 1 is indefinite because it simultaneously requires a "relatively different" position for a connection part in limitation [1.12] and a "relatively same" position for that same connection part in limitation [1.13]. The specification provides no guidance or definition for these terms of degree, making it impossible to determine the boundary between compliance and non-compliance.
    • Ambiguous Antecedents: Petitioner asserted that claim 1 introduces multiple, potentially distinct instances of "one of the first pixels" (in limitations [1.1], [1.6], [1.8], [1.10]) without providing proper antecedent basis for subsequent references to "the first pixel" (e.g., in limitation [1.14]). This ambiguity left a POSITA unable to determine which of the four previously recited "first pixels" the later limitations referred to. A similar lack of clarity was argued for "the connection part."
    • Inconsistency with Specification: Petitioner argued that limitation [1.2], requiring a TFT circuit to be "disposed below each of the subpixels," directly contradicts the patent’s specification, which consistently describes the TFT circuit as a component of each subpixel, not a separate element located below it.
    • Undefined Terms: Petitioner noted that claim 1 introduces the term "an array direction" without any definition or support in the specification, which describes at least eleven other directions (e.g., row, column, upward, downward). This left the scope of the "array direction" unclear.

Ground 2: Claims 1-6 and 8 are obvious over Hwang in view of Lee

  • Prior Art Relied Upon: Hwang (Application # 2015/0207094) and Lee (Application # 2014/0292622).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Hwang taught a display device with a pixel structure nearly identical to that of the ’691 patent, including columns of green subpixels arranged alternately with columns of red and blue subpixels. Hwang also disclosed the underlying TFT circuits and connection vias. Petitioner asserted that Lee taught grouping these types of subpixels into two distinct types of "unit pixels" (corresponding to the claimed "first pixels" and "second pixels") with different internal arrangements to improve display resolution and aperture ratio. The combination of Hwang’s pixel layout with Lee’s grouping strategy was argued to disclose all limitations of the challenged claims.
    • Motivation to Combine: A POSITA would combine Hwang’s fundamental pixel layout with Lee’s teachings on grouping subpixels into different unit pixels to achieve the well-understood and stated goals of improving display resolution and quality. Lee provided an explicit implementation for grouping subpixels that was already suggested by Hwang’s layout, making the combination a predictable application of known techniques to achieve a predictable result.
    • Expectation of Success: Petitioner contended there was a high expectation of success, as both references are directed to OLED display technology, address similar problems, and disclose compatible structures. The combination merely involved applying Lee's known grouping method to Hwang's compatible pixel arrangement.

Ground 3: Claim 7 is obvious over Hwang and Lee in view of Park’531

  • Prior Art Relied Upon: Hwang (Application # 2015/0207094), Lee (’622 application), and Park’531 (Application # 2012/0056531).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon the Hwang-Lee combination to address claim 7, which adds limitations requiring "the OLED layer" to be disposed above and overlap with "the at least one connection part." Petitioner argued that while Hwang-Lee provided the base pixel structure, Park’531 supplied the missing teachings. Park’531 explicitly described a common OLED fabrication technique where the emissive material (the "OLED layer") is intentionally deposited over an area larger than the subpixel’s light-emitting opening. This overlap covers underlying structures, such as the connection part (i.e., the non-emissive portion of the anode), to prevent electrical short circuits.
    • Motivation to Combine: A POSITA seeking to manufacture the display of Hwang-Lee would have been motivated to consult a reference like Park’531 for established fabrication details. The specific motivation to extend the OLED layer to overlap the connection part was to mitigate the known risk of manufacturing defects and short circuits between the anode and cathode, a well-known problem with a known solution in the art.
    • Expectation of Success: Petitioner argued for a high expectation of success because incorporating the teachings of Park’531 was a standard, non-inventive step in the manufacturing process for improving the yield and reliability of OLED displays like those described in Hwang and Lee.

  • Additional Grounds: Petitioner also asserted that claims 1-8 lack written description support and are not enabled under 35 U.S.C. §112. These grounds relied on arguments similar to the indefiniteness challenges, contending that because the claim terms were ambiguous and internally inconsistent, the specification could not adequately describe or enable the full scope of the claimed invention.

4. Relief Requested

  • Petitioner requested institution of a Post Grant Review and cancellation of claims 1-8 of Patent 12,293,691 as unpatentable.