PTAB

IPR2025-01538

Hisense USA Corp v. Light Guide Innovations LLC

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1. Case Identification

2. Patent Overview

  • Title: Backlight Unit
  • Brief Description: The ’537 patent discloses a backlight unit for a display device, such as an LCD. The invention focuses on a structure that allows a light emitting diode (LED) module to be easily separated from and replaced within its supporting case by using a combination of a "bending part" that guides and elastically fixes an end of the LED module and a "fixing part" that secures the module to the case.

3. Grounds for Unpatentability

Ground 1: Obviousness over Liu - Claims 1, 3-5, 8-9, 11-14, 16-17, 19, and 20 are obvious over Liu in view of the knowledge of a POSITA.

  • Prior Art Relied Upon: Liu (Taiwan Patent No. TWI248538).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Liu teaches all limitations of the independent claims. Liu discloses a backlight module structure comprising an LED light source on a board (the claimed "LED module") detachably installed on a backboard (the claimed "case"). Petitioner asserted that Liu's elastic "stamped protrusion part," which is integrally formed with the backboard, performs the function of the claimed "bending part" by applying a clamping force to guide and fix the LED module. Furthermore, Liu’s use of a bolt and nut assembly to fasten the board to the backboard was identified as the claimed "fixing part." Dependent claims were allegedly met by Liu's disclosure of using stainless steel for the backboard (claim 5), forming the bending part integrally with the case (claim 9), and configuring multiple LED modules (claims 11-12).
    • Motivation to Combine (for §103 grounds): This ground asserted that a person of ordinary skill in the art (POSITA), possessing common knowledge, would have found it obvious to implement the features as claimed based on Liu's express teachings. Liu's stated goal of simplifying assembly and replacing LED modules provided the motivation for the claimed configuration. For instance, a POSITA would have understood that "stainless steel," as disclosed in Liu, is a type of "Steel Use Stainless (SUS) material" recited in claim 5.
    • Expectation of Success (for §103 grounds): Success was expected because the arguments relied on applying the express teachings and inherent properties of the components disclosed in Liu to achieve the predictable functions recited in the claims.

Ground 2: Obviousness over Liu and Roberts - Claims 2, 6, 7, 15, and 18 are obvious over Liu in view of Roberts and the knowledge of a POSITA.

  • Prior Art Relied Upon: Liu (Taiwan Patent No. TWI248538) and Roberts (Application # 2007/0247414).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon Liu by adding features disclosed in Roberts. Petitioner argued Roberts taught the specific LED module structures recited in the dependent claims, which were absent in Liu. Specifically, Roberts disclosed an LED module comprising a printed circuit board (PCB) with LEDs mounted thereon (claims 2 and 15), an encapsulant or "mold part" covering the LEDs (claims 2 and 15), and a reflective sheet with apertures placed over the LED module to expose the LEDs and reflect light upward (claims 6, 7, and 18).
    • Motivation to Combine (for §103 grounds): A POSITA would combine Roberts's teachings with Liu’s backlight structure to improve Liu's design. Roberts explicitly taught the benefits of using PCBs for better electrical connections, encapsulants for improved LED emissions, and reflective sheets for enhanced light recycling and uniformity in LCD backlight units. Petitioner contended this combination was a mere application of known, conventional techniques taught by Roberts to the known backlight system of Liu to achieve predictable results.
    • Expectation of Success (for §103 grounds): A POSITA would have had a reasonable expectation of success because incorporating PCBs, encapsulants, and reflective sheets were common and well-understood methods for improving the performance of LED backlight systems at the time of the invention.

Ground 3: Obviousness over Liu and Liu-660 - Claim 10 is obvious over Liu in view of Liu-660 and the knowledge of a POSITA.

  • Prior Art Relied Upon: Liu (Taiwan Patent No. TWI248538) and Liu-660 (Application # 2006/0187660).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claim 10, which requires the "bending part" to be formed from a member separated from the case. While Liu's primary embodiment disclosed an integrated bending part (as argued in Ground 1 for claim 9), Liu-660, from the same inventor, disclosed an alternative structure. Liu-660 taught using a separate, rigid metal board that is placed over adjacent LED modules and bolted to the backboard. Petitioner argued this separate rigid board in Liu-660 performed the same clamping function as Liu’s integrated protrusion and thus constituted a "bending part" that is "formed with a member separated from the case."
    • Motivation to Combine (for §103 grounds): A POSITA would have been motivated to modify Liu's design by substituting the integrated bending part with the separate member taught in Liu-660. This was presented as a simple substitution of one known clamping mechanism for another to achieve the same function of securing the LED modules. The shared inventor and subject matter between Liu and Liu-660 suggested these were known, interchangeable design choices.
    • Expectation of Success (for §103 grounds): Success would have been reasonably expected, as both the integrated and separate clamping members were established techniques for fastening components within a backlight assembly, and the function of the separate member in Liu-660 was clear and predictable.

4. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-20 of Patent 8,267,537 as unpatentable.