PTAB

IPR2025-00439

Caihong Display Devices Co Ltd v. Corning Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Alkali-Free Boroaluminosilicate Glass
  • Brief Description: The ’394 patent discloses alkali-free boroaluminosilicate glass compositions suitable for use as substrates in flat panel displays. The invention is directed at achieving specific physical and chemical properties, including low thermal expansion, high liquidus viscosity, high strain point, and low density, through a refined glass composition and fining process.

3. Grounds for Unpatentability

Ground 1: Obviousness over Miwa and Bange - Claims 1-16 are obvious over Miwa in view of Bange under 35 U.S.C. §103.

  • Prior Art Relied Upon: Miwa (JP Publication # 2004-189535A) and Bange (Patent 5,824,127).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Miwa, which discloses alkali-free glass for display substrates, teaches nearly all limitations of the challenged claims. Specifically, embodiment 15 of Miwa discloses a glass composition that, when converted to mole percent, meets the claimed ranges for SiO₂, Al₂O₃, B₂O₃, MgO, CaO, and SrO in independent claim 1. It also meets the limitations for the ∑[RO]/[Al₂O₃] ratio (1.21 in Miwa vs. 1.00-1.25 claimed), the SnO₂ content (0.04 mole % vs. ≥0.01 claimed), and density (2.39 g/cm³ vs. ≤2.41 claimed). The only element outside the claimed range is BaO (0.21 mole % in Miwa vs. 0-0.1 claimed). Petitioner contended it would be obvious to reduce the BaO to zero and replace it with SrO, a known network modifier, to achieve a low-density glass. Bange was cited to teach that a liquidus viscosity greater than 100,000 poise, as required by dependent claim 7, is a well-known and preferred property for glasses used in downdraw manufacturing processes.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Miwa and Bange because both relate to the same technical field of alkali-free glass for flat panel displays and are thus analogous art. A POSITA would be motivated to optimize the properties of Miwa’s glass, such as density, by adjusting the concentrations of known network modifiers like BaO and SrO. Bange confirmed that the physical properties sought by the ’394 patent, such as high liquidus viscosity, were desirable and achievable goals in the art.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in modifying Miwa’s composition as suggested, as the roles of BaO and SrO as interchangeable network modifiers were well-understood, and achieving the desired physical properties was a matter of routine optimization.

Ground 2: Anticipation by Miwa - Claims 1 and 3 are anticipated by Miwa under 35 U.S.C. §102.

  • Prior Art Relied Upon: Miwa (JP Publication # 2004-189535A).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that embodiment 20 of Miwa explicitly discloses a glass composition that falls within every limitation of independent claim 1. After converting the weight percentages of embodiment 20 to mole percentages, the composition meets all claimed oxide ranges, including SiO₂ (69.80%), Al₂O₃ (9.96%), MgO (1.14%), CaO (7.60%), SrO (1.26%), and BaO (0.0%). Furthermore, embodiment 20 discloses a ∑[RO]/[Al₂O₃] ratio of 1.00, SnO₂ content of 0.04 mole percent, and a density of 2.41 g/cm³, all of which fall within the ranges required by claim 1. Petitioner also argued that Miwa’s embodiment 20 anticipates claim 3, as it discloses zero As₂O₃, which satisfies the claim’s requirement of "at most 0.05 mole percent As₂O₃."

Ground 3: Obviousness over Miwa - Claims 2 and 4-16 are obvious over Miwa under 35 U.S.C. §103.

  • Prior Art Relied Upon: Miwa (JP Publication # 2004-189535A).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that even without Bange, Miwa alone renders the remaining claims obvious. This ground primarily relied on combining the teachings of Miwa’s embodiment 15 and embodiment 20 with other disclosures in the reference. For example, claim 2 requires at most 0.05 mole percent Sb₂O₃; Miwa's embodiment 15 discloses 0.02 mole percent, meeting this limitation. For the physical properties recited in claims 7 and 11 (e.g., strain point >650°C and specific CTE range), Miwa’s examples (embodiments 15 and 20) disclose values meeting these requirements (strain points of 673°C and 685°C, respectively). Petitioner argued that a POSITA would have found it obvious to modify the composition of Miwa’s anticipating embodiment 20 to include the features of other embodiments, like the Sb₂O₃ levels of embodiment 15, as a predictable variation.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under §325(d) is unwarranted because the prior art references (Miwa and Bange), while cited in an Information Disclosure Statement during prosecution, were never substantively considered or discussed by the Examiner. The petition presented new arguments and expert analysis not previously before the Office.
  • Petitioner further argued against discretionary denial under §314(a) based on the Fintiv factors. It asserted that the parallel district court litigation is in its earliest stages, with no scheduling order entered and no trial date set. Given the minimal investment by the court and parties, and the likelihood that an inter partes review (IPR) would conclude before a district court trial, Petitioner contended that instituting the IPR would be an efficient use of resources and would narrow the issues for litigation.

5. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 1-16 of the ’394 patent as unpatentable.