PTAB

IPR2025-01480

BOE Technology Group Co Ltd v. Samsung Display Co Ltd

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1. Case Identification

2. Patent Overview

  • Title: Display Apparatus
  • Brief Description: The ’015 patent relates to a display apparatus with thin-film transistors (TFTs) and signal lines arranged in different layers. The invention discloses using one or more shield layers positioned between a signal line and a TFT layer to prevent electrical noise from deteriorating image quality.

3. Grounds for Unpatentability

Ground 1A: Obviousness over Kim-584 - Claims 1-4, 8-10, 14, 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 OLED device with a six-transistor, one-capacitor (6T1C) pixel structure, discloses every limitation of independent claim 1. The central contention was that Kim-584’s second capacitor electrode (116-1) meets the "first shield layer" limitation. This electrode is positioned between the data signal line (DLm-1, the noise source) and the first TFT’s active layer and is connected to a constant voltage line, enabling it to function as a shield.
    • Motivation to Combine: As a single-reference ground, the argument focused on the obviousness of recognizing an inherent function. A person of ordinary skill in the art (POSITA) would find it obvious to use the existing second capacitor plate in Kim-584 as a shield layer, as shielding a TFT from a nearby data line was a known problem with a known solution, and the component was already ideally positioned and connected for this purpose.
    • Expectation of Success: A POSITA would have a high expectation of success, as using a large, conductive plate held at a constant voltage to shield against electromagnetic interference was a well-understood and predictable technique in display circuit design.

Ground 1B: Obviousness over Kim-584 and Han - 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: Petitioner asserted this combination addresses claims requiring additional circuit elements, such as the "third thin-film transistor" and a "second shield layer" of claim 5. Kim-584 was argued to provide the base pixel circuit, including its double-gated third TFT (T3). Han was argued to teach the addition of a second capacitor (C2) to a similar 6TFT circuit specifically to reduce leakage currents in multi-gated TFTs. In the proposed combination, the upper plate of Han's added capacitor would serve as the claimed "second shield layer," shielding Kim-584's third TFT.
    • Motivation to Combine: A POSITA would combine these references because both sought to improve OLED display performance by reducing leakage currents. A POSITA would be motivated to apply Han’s known technique (adding a leakage-reducing capacitor) to Kim-584's known circuit to achieve the predictable benefit of enhanced performance.
    • Expectation of Success: The proposed modification was a routine design task. Adding a capacitor to an existing OLED circuit to reduce leakage was a known technique taught by Han, leading to a high expectation of success.

Ground 2B: Obviousness over Kim-923 and Moon - 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: Petitioner argued this combination addresses claims requiring specific TFT configurations and shield layer implementations not explicitly shown in a single reference. Kim-923 provided a base 6TFT OLED pixel circuit. Moon was argued to teach modifying an initialization TFT (T4) to be multi-gated and relocating its associated voltage line (124) to overlap the TFT. This overlapping voltage line in Moon serves as a shield layer, thereby teaching the limitations of claims like claim 24, which recites a shield layer overlapping a second TFT between its channel areas.
    • Motivation to Combine: A POSITA would combine Moon's teachings into Kim-923's circuit to improve the device. Implementing a multi-gated TFT as taught by Moon would reduce leakage current, and rearranging the voltage line to overlap the TFT would free up pixel space, enabling a more compact layout and higher-resolution display.
    • Expectation of Success: A POSITA would have a high expectation of success because the combination involved applying well-known design principles (multi-gated transistors, layout optimization) from one OLED circuit (Moon) to another highly similar one (Kim-923) to achieve predictable improvements.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds based on Kim-923 alone, Kim-923 combined with Han, Moon combined with Jeon-078, and Masao alone or combined with Ohtani, relying on similar circuit modification and shielding principles.

4. Relief Requested

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