PTAB

IPR2015-00506

LG Display Co Ltd v. Delaware Display Group LLC

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Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: Light Emitting Panel Assembly
  • Brief Description: The ’973 patent discloses light emitting panel assemblies, typically used as backlights for liquid crystal displays (LCDs). The technology involves using a light-emitting panel member with an input edge for one or more light sources and a surface featuring a pattern of "deformities" to control the extraction and distribution of light for uniform illumination.

3. Grounds for Unpatentability

Ground 1: Obviousness over the ’389 Patent in view of Pelka

  • Prior Art Relied Upon: The ’389 patent (Patent 7,195,389) and Pelka (Patent 6,473,554).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the ’389 patent, which is from the same patent family as the challenged ’973 patent, disclosed nearly all elements of the challenged claims. This included a light emitting panel assembly with multiple light sources coupled to an input edge and a pattern of light-extracting deformities that increase in density or size with distance from the light source. However, Petitioner contended the ’389 patent did not explicitly teach the specific limitation that the density of deformities is greatest at the approximate midpoints between adjacent light sources. Petitioner asserted that Pelka supplied this missing element, as it explicitly taught arranging elongate structures (deformities) with maximum density at the midpoint between light sources to achieve uniform illumination.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the teachings because both references are in the same field of backlight technology and share the common goal of improving light output uniformity. Petitioner argued it would have been obvious to apply Pelka’s specific technique for optimizing deformity density to the general backlight system of the ’389 patent to enhance its performance, a known problem with a known solution.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because combining known methods for improving light uniformity in backlight systems was a predictable design choice.

Ground 2: Anticipation by Shinohara

  • Prior Art Relied Upon: Shinohara (Patent 6,167,182).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner contended that Shinohara disclosed every limitation of claims 1-5, rendering them anticipated under 35 U.S.C. §102. Shinohara allegedly taught a surface light source device comprising an optical light guide plate (panel member) with a light incidence surface (input edge) and a plurality of point light sources. Further, Petitioner argued Shinohara disclosed a pattern of small diffuse elements (deformities) arranged concentrically around the light sources. Crucially, Petitioner asserted that Shinohara taught that the density and/or size of these elements increases as the distance from the sources increases, such that the density is greatest at the midpoint between the light sources, directly mapping onto the key limitation of claim 1. Dependent claims related to the deformities being depressions, having specific shapes, and the light sources being LEDs were also allegedly disclosed.

  • Additional Grounds: Petitioner asserted additional obviousness challenges against claims 1-5. These included combinations of Shinohara in view of Yoshikawa (Patent 5,775,791), Pelka in view of Funamoto (EP 0 878 720), and (for claims 1-2) Hooker (Patent 5,477,422) in view of Mizobe (Patent 5,057,974). These grounds relied on similar theories of combining known elements from the field of display backlighting to achieve predictable improvements in light uniformity.

4. Key Claim Construction Positions

  • "deformities" (claims 1, 3, 4): Petitioner argued this term should be construed to mean "any change in the shape or geometry of a surface and/or coating or surface treatment that causes a portion of the light to be emitted."
    • This construction was based on an explicit definition provided in the ’973 patent’s specification. Adopting this broad definition was central to Petitioner’s argument, as it ensured that the various light-extracting features described in the prior art—such as projections, depressions, diffuse patterns, recesses, and dots—would be encompassed by the claim language.

5. Key Technical Contentions (Beyond Claim Construction)

  • Priority Date Entitlement: A central contention of the petition was that the ’973 patent was not entitled to claim priority to any application filed before November 28, 2007.
    • Petitioner argued that the critical limitation of claim 1—reciting that "the density, size, depth and/or height of the deformities... is greatest at approximate midpoints between adjacent pairs of light sources"—was introduced as new matter during prosecution via an amendment filed on that date.
    • According to the Petitioner, the originally filed application and its parent applications lacked sufficient written description to support this specific arrangement of deformities. This argument was foundational, as establishing this later priority date was necessary for certain references, including the ’389 patent from the same family, to qualify as prior art against the challenged claims.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-5 of Patent 7,434,973 as unpatentable.