PTAB

IPR2025-01480

BOE Technology Group Co Ltd v. Samsung Display Co Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Display Apparatus
  • Brief Description: The ’015 patent relates to a display apparatus with thin-film transistors (TFTs) that incorporates one or more shield layers positioned between signal lines and the TFTs. This structure is intended to reduce electrical noise from the signal lines, thereby preventing image quality deterioration.

3. Grounds for Unpatentability

Ground 1A: Claims 1-4, 8-10, 20-23, and 33 are obvious over Kim-584

  • Prior Art Relied Upon: Kim-584 (Application # 2014/0132584).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kim-584, which describes an active-matrix organic light-emitting diode (OLED) display with a six-transistor, one-capacitor (6T1C) structure, discloses every limitation of the challenged claims. For independent claim 1, Petitioner mapped Kim-584’s driving TFT T1 to the "first thin-film transistor" and its associated semiconductor layers. The "first electrode layer" was mapped to Kim-584's first capacitor electrode (114-1), which also serves as the gate of T1. The "second electrode layer" and the "first shield layer" were both mapped to Kim-584's second capacitor electrode (116-1). Petitioner asserted that a person of ordinary skill in the art (POSITA) would have found it obvious that this second capacitor electrode, being connected to a constant voltage line and positioned between the data line (the "first signal line") and the TFT's active layer, inherently functions as a shield layer. Dependent claims were mapped to corresponding structures within Kim-584’s detailed pixel layout, such as other TFTs and voltage lines.

Ground 1B: Claims 5, 11-14, and 28-32 are obvious over Kim-584 in view of Han

  • Prior Art Relied Upon: Kim-584 (Application # 2014/0132584) and Han (Application # 2012/0019504).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claims requiring a "third" TFT and a "second shield layer" overlapping it. Petitioner asserted that while Kim-584 provided the base circuit, including the "third" TFT (mapped to T3), it did not explicitly disclose a second shield layer for that specific TFT. Han, however, teaches adding a second capacitor (C2) to a similar 6TFT OLED circuit specifically to reduce leakage currents associated with a multi-gated compensation TFT. Petitioner argued for modifying Kim-584 by adding Han's second capacitor (C2) to the circuit. The upper plate of this new capacitor, connected to a constant voltage source, would then function as the claimed "second shield layer" and would be positioned to overlap the semiconductor region of Kim-584’s third TFT (T3) between its dual gates.
    • Motivation to Combine: A POSITA would combine Han with Kim-584 because both references address improving 6TFT OLED display operations by reducing leakage currents. A POSITA would have been motivated to apply Han’s known technique of adding a second capacitor to Kim-584’s device to achieve the predictable result of further leakage current reduction.
    • Expectation of Success: Petitioner argued a POSITA would have a reasonable expectation of success because adding a capacitor was a routine design task for improving OLED circuits, as taught by Han, and the necessary modifications were well within a POSITA’s skillset.

Ground 2B: Claims 6-7, 15-19, and 24-27 are obvious over Kim-923 in view of Moon

  • Prior Art Relied Upon: Kim-923 (Application # 2014/0034923) and Moon (Application # 2014/0042405).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground primarily addressed independent claim 24 and other claims requiring a multi-gated "second" or "fourth" TFT and an associated shield layer. Petitioner argued that Kim-923 provides a base OLED pixel structure, including an initialization TFT (T4). Moon, however, explicitly teaches using a multi-gated initialization TFT and arranging the initialization voltage line to overlap the entire TFT, thereby serving as a shield. The proposed combination involved modifying Kim-923's single-gate initialization TFT (T4) to be a multi-gated TFT as taught by Moon. Concurrently, Kim-923's initialization voltage line (124) would be relocated to overlap the modified multi-gated TFT T4. This relocated voltage line, carrying a constant voltage, would then constitute the claimed "shield layer."
    • Motivation to Combine: A POSITA would combine the references to improve the operation of Kim-923's display. Implementing Moon’s multi-gated TFT structure would reduce leakage current, a well-known benefit. Furthermore, rearranging the initialization voltage line as shown in Moon would free up space, allowing for a more compact pixel layout and a higher-resolution display, which was an advantageous and known design goal.
    • Expectation of Success: The use of multi-gated TFTs and the strategic routing of voltage lines were well-known techniques in 2014. Since the modifications were already described in Moon and involved routine layout changes, a POSITA would have had a high expectation of success.
  • Additional Grounds: Petitioner asserted additional obviousness challenges based on Kim-923 alone, Kim-923 plus Han, Moon plus Jeon-078, Masao alone, and Masao plus Ohtani, relying on similar component mapping and design modification theories.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-33 of Patent 10,439,015 as unpatentable.