PTAB

IPR2023-00941

MianYang BOE OptoelecTronics Technology Co Ltd v. SamSung DisPlay Co Ltd

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1. Case Identification

2. Patent Overview

  • Title: Organic Light Emitting Device Pixel Circuit and Driving Method Therefor
  • Brief Description: The ’599 patent discloses a pixel driver circuit for an Organic Light-Emitting Diode (OLED) display. The invention aims to counteract "display nonuniformity" caused by variations in the threshold voltage of the driving transistor over time by employing a specific circuit architecture that self-compensates for such deviations.

3. Grounds for Unpatentability

Ground 1: Claims 1-18 are obvious over Kimura in view of the knowledge of a Person of Ordinary Skill in the Art (POSITA).

  • Prior Art Relied Upon: Kimura (Application # 2003/0132931).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kimura discloses a pixel driver circuit with a five-transistor topology that is fundamentally the same as that claimed in the ’599 patent. Kimura addresses the identical problem of brightness irregularities in OLED displays resulting from threshold voltage (Vth) dispersion. It employs the same core solution: a diode-connected transistor configuration that self-compensates for Vth variations in the driving transistor. The primary distinction is that the challenged claims of the ’599 patent require all-PMOS transistors, whereas Kimura’s corresponding circuit primarily uses NMOS transistors for its switching elements. Petitioner contended this difference does not confer patentability.
    • For dependent claims requiring a sixth transistor (e.g., claim 8, which adds an initialization transistor), Petitioner argued that Kimura separately teaches adding a dedicated initialization transistor to its baseline circuit to solve a known issue of undesired light emission during the reset phase. Kimura's figures (e.g., Figs. 16-17) explicitly disclose this sixth transistor and its function to discharge the capacitor without activating the OLED, rendering the addition obvious.
    • Motivation to Combine: Petitioner asserted that a POSITA would be motivated to modify Kimura’s circuit to use all PMOS transistors for several reasons. First, Kimura itself expressly teaches that its switching transistors "function as simple switching devices, and therefore any polarity may be used." Second, it was a well-known and advantageous manufacturing practice to fabricate all transistors on a substrate with the same polarity (e.g., all-PMOS). This motivation is not just based on general knowledge but is explicitly suggested within the primary reference. For the sixth transistor, Kimura expressly teaches it can be placed in any location that prevents spurious light emission, motivating its combination with the base circuit.
    • Expectation of Success: A POSITA would have possessed a high degree of confidence in successfully modifying Kimura’s circuit to an all-PMOS implementation. The interchangeability of NMOS and PMOS transistors in switching applications was a fundamental concept in circuit design. The necessary adjustments, such as using active-low signaling, were well within the ordinary skill in the art and considered trivial to implement.

4. Arguments Regarding Discretionary Denial

  • §325(d) - Same or Substantially Same Art or Arguments: Petitioner argued that discretionary denial under §325(d) is unwarranted because Kimura is neither the same nor cumulative to the art considered during prosecution. The sole reference applied by the examiner, Dawson (Patent 6,229,506), disclosed a four-transistor circuit, whereas the challenged claims and Kimura both recite circuits with five or more transistors. Petitioner contended this difference is material. Furthermore, although a Japanese-language version of Kimura was submitted in an Information Disclosure Statement (IDS), it was submitted after the examiner had already indicated the claims were allowable and without an English translation, making it highly unlikely the examiner gave it any substantive consideration.
  • §314(a) - Fintiv Factors: Petitioner argued that denial under the Fintiv framework is inappropriate. There is no co-pending district court litigation. While there is a parallel investigation at the International Trade Commission (ITC), Petitioner noted that current USPTO policy, as stated in a Director’s memorandum, is not to discretionarily deny IPR institution based on a parallel ITC proceeding.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-18 of the ’599 patent as unpatentable.