PTAB

IPR2025-01017

Caihong Display Devices Co Ltd v. Corning Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Alkali-Free Boroaluminosilicate Glasses
  • Brief Description: The ’491 patent is directed to alkali-free boroaluminosilicate glasses suitable for use as substrates in flat panel displays, such as active-matrix liquid crystal displays. The invention focuses on specific glass compositions and their properties, including the use of SnO2 as a non-toxic fining agent to achieve dimensional stability, low density, and a low level of defects.

3. Grounds for Unpatentability

Ground 1: Obviousness over Miwa ’535 in view of Peuchert ’469 and JP ’741 - Claims 1-24 are obvious over Miwa ’535 in view of Peuchert ’469 and/or JP ’741.

  • Prior Art Relied Upon: Miwa ’535 (JP Application # 2004-189535A), Peuchert ’469 (Application # 2005/0101469), and JP ’741 (JP 1998059741).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Miwa ’535, a reference directed to the same field of alkali-free glass for display substrates, discloses nearly all limitations of the challenged claims. Specifically, Embodiment 15 of Miwa ’535 teaches a glass composition with mole percentages of SiO2, Al2O3, B2O3, MgO, CaO, and SrO that fall within the ranges of independent claim 1. It also discloses the required ratio of alkaline earth oxides to alumina (Σ[RO]/[Al2O3]), the use of SnO2 as a fining agent, and physical properties like density, thermal expansion, and liquidus temperature that meet the limitations of various dependent claims. The only component falling outside the claimed range in Miwa ’535’s Embodiment 15 is BaO, which is disclosed at 0.21 mol% versus the claimed maximum of 0.1 mol%.
    • Motivation to Combine (for §103 grounds): A POSITA would combine Miwa ’535 with Peuchert ’469 to arrive at the claimed invention. Petitioner asserted that Peuchert ’469 explicitly teaches that BaO and SrO are interchangeable network modifiers and that eliminating BaO is desirable to achieve a lightweight glass. Therefore, a POSITA would have been motivated to modify the composition in Miwa ’535 by reducing its BaO content to within the claimed range—a predictable optimization to improve a known property (density). For certain claims requiring very low levels of toxic fining agents (As2O3, Sb2O3), JP ’741 provides the motivation to minimize their use in favor of SnO2, which Miwa ’535 already discloses.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because modifying the BaO content based on Peuchert ’469’s teachings involved the simple substitution of known, equivalent components to optimize a predictable property, which would not alter the fundamental characteristics of the Miwa ’535 glass.

Ground 2: Obviousness over JP ’643 in view of JP ’741 and Peuchert ’469 - Claims 1-24 are obvious over JP ’643 in view of JP ’741 and Peuchert ’469.

  • Prior Art Relied Upon: JP ’643 (JP Application # 2002308643), JP ’741 (JP 1998059741), and Peuchert ’469 (Application # 2005/0101469).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that JP ’643 serves as an alternative primary reference disclosing an alkali-free glass for display substrates. Embodiment 5 of JP ’643 discloses a glass composition meeting most of the mole percent ranges of claim 1, including SiO2, Al2O3, B2O3, MgO, and CaO. The physical properties disclosed, such as density, liquidus temperature, and viscosity, also align with limitations in the dependent claims. However, JP ’643’s Embodiment 5 uses Sb2O3 as a fining agent and contains 0.2 mol% BaO.
    • Motivation to Combine (for §103 grounds): A POSITA would combine JP ’643 with the teachings of JP ’741 and Peuchert ’469. JP ’741 provides a strong motivation to avoid toxic fining agents like Sb2O3 and instead use SnO2. Since the base glass composition of JP ’643 falls within the ranges described in JP ’741, a POSITA would find it obvious to apply JP ’741’s fining agent teachings. As in Ground 1, Peuchert ’469 provides the rationale for reducing or eliminating BaO to lower the glass density, teaching that BaO and SrO have similar functions and can be substituted.
    • Expectation of Success: The proposed combination represented a predictable path of optimization. A POSITA would expect that substituting the fining agent and adjusting the alkaline earth metal oxide content, based on the explicit teachings of the secondary references, would successfully yield a glass with the claimed properties without undue experimentation.

Ground 3: Anticipation and Obviousness over Miwa ’377 and Peuchert ’469 - Claims 13-14 and 19-21 are anticipated by Miwa ’377; Claim 16 is obvious over Miwa ’377 in view of Peuchert ’469; Claims 22-23 are obvious over Miwa ’377.

  • Prior Art Relied Upon: Miwa ’377 (JP Application # 2003192377) and Peuchert ’469 (Application # 2005/0101469).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sample 8 of Miwa ’377 anticipates claims 13-14 and 19-21. This embodiment allegedly discloses every limitation of these claims, including an alkali-free glass sheet produced by a downdraw process with the required oxide composition, a Σ[RO]/[Al2O3] ratio of 1.20, an MgO content of 3.24 mol%, an SnO2 content of 0.07 mol%, and zero As2O3 and Sb2O3. It further discloses a liquidus temperature and strain point meeting the claim limitations. For claim 16 (substantially free of BaO), Miwa ’377 discloses 0.2 mol% BaO.
    • Motivation to Combine (for §103 grounds): To render claim 16 obvious, Petitioner combined Miwa ’377 with Peuchert ’469. Peuchert ’469’s teaching to eliminate BaO to reduce glass density would have motivated a POSITA to modify the Miwa ’377 composition to be substantially free of BaO. For claims 22 and 23 (relating to low defect levels and high viscosity), Petitioner argued that obtaining these properties is an obvious outcome of manufacturing the Miwa ’377 glass using the disclosed downdraw process, as reducing defects is a known goal in the art.
    • Expectation of Success: The modification to remove BaO was a simple, predictable substitution taught by Peuchert ’469, with a high likelihood of success.

4. Key Technical Contentions (Beyond Claim Construction)

  • A central technical premise underlying multiple grounds was the established interchangeability of SrO and BaO as alkaline earth metal oxides in glass chemistry. Petitioner argued that a POSITA would have understood these components to have similar roles as network modifiers, making it an obvious and predictable design choice to substitute one for the other (e.g., replacing BaO with SrO) to optimize known glass properties like density.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-24 of the ’491 patent as unpatentable.