PTAB

IPR2025-00335

Samsung Electronics Co Ltd v. Sinotechnix LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Backlight Panel
  • Brief Description: The ’952 patent discloses a backlight panel for liquid crystal displays (LCDs) that purportedly reduces panel thickness. The invention centers on using a plurality of white light emitting diodes (LEDs), where each LED comprises a blue LED chip with red and green phosphors arranged on the chip to generate white light directly.

3. Grounds for Unpatentability

Ground 1: Obviousness over Hong and Lee - Claims 1, 2, 4, and 5 are obvious over Hong in view of Lee.

  • Prior Art Relied Upon: Hong (Application # 2005/0007516) and Lee (WO 2004/097949).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Hong discloses the fundamental structure of a backlight panel as claimed, including a diffusion plate, a reflective sheet below an LED array, and the use of white LEDs to reduce panel thickness. However, Hong does not specify the internal construction of its white LEDs. Lee was argued to supply this missing detail by disclosing the exact LED structure required by claim 1: a blue LED chip with an overlying resin layer containing green and red phosphors. Petitioner contended that combining Hong's overall backlight architecture with Lee's specific white LED design renders claim 1 obvious. For dependent claims, Hong's disclosure of "optical sheets" to "improve light efficiency" was argued to teach the brightness enhancement film of claim 2, and Hong’s teaching of a "gap between the diffusion plate... and the LED array" was argued to teach the air gap of claim 4.
    • Motivation to Combine: A POSITA, seeking to implement the generic "white light" LEDs in Hong's backlight panel, would have consulted known LED technologies like those in Lee. Lee explicitly taught that its white LED design—using a single blue chip with red and green phosphors—was "more appropriate for the backlight of a LCD" because it provided "high quality color purity" and reduced manufacturing costs compared to alternative designs. This provided a clear reason to select Lee's specific LED to fill the design gap left by Hong.
    • Expectation of Success: Petitioner asserted a high expectation of success because both references are in the same field of LCD backlights and address the same goal of creating thinner, more efficient displays. Lee's surface-mountable LEDs were described as being directly compatible with the printed circuit board (PCB) based LED array taught by Hong, making the combination a straightforward substitution of a known component for a generic one to achieve the predictable result of a functional backlight.

Ground 2: Obviousness over Hong, Lee, and AAPA - Claims 2, 4, and 5 are obvious over Hong and Lee in view of Applicant Admitted Prior Art (AAPA).

  • Prior Art Relied Upon: Hong (Application # 2005/0007516), Lee (WO 2004/097949), and AAPA (from the background section of the ’952 patent).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground was presented as an alternative, arguing that if the Hong/Lee combination were found insufficient to teach certain dependent claim limitations, the AAPA would remedy the deficiency. Specifically, the ’952 patent’s own "Background Art" section describes a "conventional backlight panel" that includes a brightness enhancement film (BEF) "positioned on a top surface of the diffusion plate" and defines gaps for light mixing as an "air layer." This AAPA directly teaches the precise arrangement of the brightness enhancement film recited in claim 2 and clarifies that the gap in claim 4 is an air gap, a common practice in the art.
    • Motivation to Combine: A POSITA would combine the AAPA with Hong/Lee to implement well-known, conventional features into the primary combination. If Hong's "gap" was considered ambiguous, the AAPA demonstrated that using an air gap was a common and beneficial technique for light mixing. Likewise, the AAPA showed it was standard practice to place brightness enhancement films directly on the diffusion plate to improve luminance. Applying these conventional techniques to the Hong/Lee backlight would have been an obvious design choice to optimize performance using established methods.
    • Expectation of Success: Success was expected because this combination merely involved applying features that the patentee admitted were conventional (the AAPA) to the otherwise established Hong/Lee backlight structure. No technical hurdles would be anticipated in using a standard air gap for light mixing or placing a BEF on a diffusion plate, as these were routine configurations in the art.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under either §314(a) or §325(d) would be inappropriate. For §325(d) (Advanced Bionics factors), Petitioner contended that the primary prior art references, Hong and Lee, were not considered during the original prosecution, meaning the same art and arguments were not previously before the Office. For §314(a) (Fintiv factors), Petitioner argued that the co-pending district court litigation is in its very early stages with minimal investment, the May 2026 trial date is uncertain and proximate to the Final Written Decision deadline, and the merits of the petition are strong. Petitioner also stipulated that it would not pursue the same invalidity grounds in the district court if the IPR is instituted.

5. Relief Requested

  • Petitioner requests institution of inter partes review and cancellation of claims 1, 2, 4, and 5 of the ’952 patent as unpatentable.