PTAB

IPR2025-01526

Hisense USA Corp v. Light Guide Innovations LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Light Source and Display Device
  • Brief Description: The ’778 patent discloses a light source, primarily for backlighting Liquid Crystal Display (LCD) panels. The invention describes an assembly comprising side-emitting Light Emitting Diodes (LEDs), a light guide plate, and a specific arrangement of optical and color-converting sheets to produce a target output color.

3. Grounds for Unpatentability

Ground 1: Obviousness over Asada and Kinoshita - Claims 1-7, 11-14, and 23 are obvious over Asada in view of Kinoshita.

  • Prior Art Relied Upon: Asada (Japanese Patent Pub. No. 2005-332963) and Kinoshita (Japanese Patent Pub. No. 2008-117879).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Asada disclosed nearly all elements of independent claim 1, including an edge-lit backlight with LEDs, a light guide plate, a reflector, an optical sheet (comprising a diffuser and prism sheet), and a phosphor-based conversion sheet. Asada also taught that the conversion sheet could be placed at any location in the light path, including on top of the optical sheet. The only element Petitioner contended Asada did not explicitly disclose was organizing the LEDs into a "light emitting module." Kinoshita was asserted to cure this deficiency by teaching the conventional practice of mounting multiple LEDs on a substrate (a board) to form modules for edge-lighting a light guide plate.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Kinoshita's LED modules with Asada's backlight design for predictable benefits. Using prefabricated modules, as taught by Kinoshita, would simplify the manufacturing, alignment, and wiring of the LEDs in Asada's device. This combination was presented as a simple substitution of one known element (individual LEDs) with an equivalent (LED modules) to achieve a predictable result.
    • Expectation of Success: A POSITA would have a high expectation of success, as both references describe similar edge-lit LED backlights and the combination involved applying a conventional modular design to an existing architecture to improve manufacturability.

Ground 2: Obviousness over Asada, Kinoshita, and Ashdown - Claims 8-10 and 24-26 are obvious over Asada in view of Kinoshita and Ashdown.

  • Prior Art Relied Upon: Asada, Kinoshita, and Ashdown (a 2006 conference paper on solid-state lighting).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the Asada/Kinoshita combination from Ground 1 to address claims requiring the use of at least two LEDs having different color coordinate distributions within the same color spectrum (i.e., from different manufacturing "bins" or "ranks"). Petitioner argued that Ashdown directly taught this concept. Ashdown explained that for edge-lit devices, unlike direct-lit backlights, strict color binning is unnecessary because the light is mixed in the diffuser. Ashdown explicitly disclosed a "six-color binning solution" where multiple LEDs of the same nominal color but with different chromaticities (e.g., two slightly different blue LEDs) could be used together to achieve the desired final color output.
    • Motivation to Combine: A POSITA would be motivated to apply Ashdown's teachings to the Asada/Kinoshita device to reduce costs and improve manufacturing yield. By relaxing the requirement for carefully matched LEDs from the same bin, as taught by Ashdown, a manufacturer could use a wider range of available LEDs, thereby lowering overall system cost, which is a powerful and recognized market driver.
    • Expectation of Success: Success would be expected because Ashdown's teachings were specifically directed at edge-lit devices like the one resulting from the Asada/Kinoshita combination. The principles of color mixing are well-understood, and applying Ashdown's cost-saving binning strategy would have been a straightforward optimization for a POSITA.

Ground 3: Obviousness over Asada, Kinoshita, and Cho - Claims 20-22 are obvious over Asada in view of Kinoshita and Cho.

  • Prior Art Relied Upon: Asada, Kinoshita, and Cho (Korean Patent No. 10-0664982).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground addressed claims directed to a complete "display device" that incorporated the light source from other claims. The Asada/Kinoshita combination taught the core light source. Petitioner asserted that Cho supplied the remaining elements: a cover for the light source and a display panel (e.g., an LCD panel) placed on top of the optical stack. Cho disclosed an edge-lit backlight module for an LCD that included a cover over the LED module and an LCD panel positioned to receive the backlight's light.
    • Motivation to Combine: A POSITA would combine these references to use the Asada/Kinoshita light source for its intended and primary purpose: backlighting a display. Cho simply taught the conventional and necessary components to turn a backlight unit into a functional display device. Adding a protective cover and a display panel was a routine and obvious step to complete the device for its known use.
    • Expectation of Success: A POSITA would have expected to succeed, as integrating a backlight with a cover and an LCD panel was a standard practice in the industry. The combination represented the assembly of well-known components in a conventional manner to create a finished product.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge for claim 15 based on Asada, Kinoshita, and Dejima (Application # 2006/0255711), which was relied upon for its teaching of a casing or cover for a backlight unit.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial by stipulating that, if the Patent Trial and Appeal Board (PTAB) institutes review, Petitioner will not pursue any grounds raised in the Petition, or any grounds that could have been reasonably raised, in the parallel district court litigation. This stipulation was offered to address the Fintiv factors concerning efficiency and overlap between PTAB proceedings and co-pending litigation.

5. Relief Requested

  • Petitioner requests that the Board institute an inter partes review (IPR) and cancel claims 1-15 and 20-26 of Patent 8,408,778 as unpatentable.