Caihong Display Devices, Co., Ltd v. Corning Incorporated

Petition

Petition summary

Invalidity analysis

Prosecution analysis

Examiner search

## 1. Case Identification
- Case Number: [IPR2025-01040](https://ai-lab.exparte.com/case/ptab/IPR2025-01040)
- Patent #: [9,512,025](https://ai-lab.exparte.com/patent/9512025)
- Filed: May 22, 2025
- Petitioner(s): [Caihong Display Devices Co., Ltd.](https://ai-lab.exparte.com/party/caihong-display-devices-co-ltd)
- Patent Owner(s): [Corning Incorporated](https://ai-lab.exparte.com/party/corning-optical-communications-llc)
- Challenged Claims: 1-20

## 2. Patent Overview
- Title: Apparatus and Method for Manufacturing Glass Ribbons
- Brief Description: The [’025](https://ai-lab.exparte.com/patent/9512025) patent is directed to an apparatus and process for manufacturing glass ribbons, such as those used for liquid crystal displays (LCDs). The technology employs a fusion down-draw process and incorporates a replaceable heating cartridge with a specific inclined geometry to reduce devitrification (crystal formation) on the glass surface, particularly at the edges.

## 3. Grounds for Unpatentability

#### Ground 1: Obviousness over El Kahlout, Tsuda, and CN '869 - Claims 1-20 are obvious over El Kahlout in view of Tsuda and CN ’869.
  - **Prior Art Relied Upon:** U.S. Application # 2011/0209502 ("[El Kahlout](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1004)"), U.S. Application # 2012/0111060 ("[Tsuda](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1006)"), and Chinese Application # CN102765869 ("[CN ’869](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1005)").
  - **Core Argument for this Ground:**
    - **Prior Art Mapping:** Petitioner argued that the challenged claims simply combined known elements from three analogous prior art references to achieve a predictable result.
        - **[El Kahlout](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1004)** was asserted to disclose the foundational apparatus and method for forming a glass sheet using a fusion down-draw process. This included the key components recited in independent claims 1 and 15, such as a forming wedge with downwardly inclined surfaces that converge to form a root, an edge director for guiding the glass edges, and a plurality of edge rollers positioned downstream to engage the glass ribbon. [El Kahlout](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1004) thus provided the basic framework for the claimed invention.
        - **[Tsuda](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1006)** was introduced to teach the concept of a *replaceable* heating element for use in such a glass manufacturing system. Petitioner argued [Tsuda](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1006) explicitly disclosed using an external heater whose "replacement and repair are facilitated." This heater is part of a support mechanism located in the vicinity of an opening in the furnace wall, which corresponds to the claimed "replaceable heating cartridge located in a port in the housing." [Tsuda](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1006) was argued to provide the missing element of a removable heater, which was not explicitly taught in [El Kahlout](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1004).
        - **[CN ’869](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1005)** was relied upon to teach the specific geometry of the heating cartridge claimed in the [’025](https://ai-lab.exparte.com/patent/9512025) patent. Petitioner contended [CN ’869](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1005) disclosed a platinum heating apparatus with inclined heating surfaces (surfaces 4 and 5) designed to compensate for temperature variations at the ends of an isopipe. This directly taught a heat-directing surface inclined at an angle less than 90° relative to its bottom surface. Petitioner argued this structure inherently achieves the claimed orientation where the heat-directing surface faces the edge director with a greater view factor than at the edge rollers, a necessary consequence of its function to direct heat to the glass edge.
        - For the dependent claims, Petitioner argued that the recited features—such as specific angular ranges for the heating surfaces (e.g., 45° to 75°), the use of multiple facets, curved surfaces, and specific materials (e.g., platinum)—were all either explicitly disclosed in the prior art (primarily [CN ’869](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1005)) or would have been obvious design choices and optimizations for a person of ordinary skill in the art (POSITA) seeking to improve thermal efficiency and temperature control.
    - **Motivation to Combine (for §103 grounds):** Petitioner asserted that a POSITA would combine these references to solve a known problem in the field: managing temperature at the edges of the glass ribbon to prevent defects. A POSITA would start with a standard fusion-draw process like that in [El Kahlout](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1004) and seek to improve it. To simplify maintenance, they would incorporate the replaceable heater taught by [Tsuda](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1006). To improve temperature control, they would adopt the inclined, multi-faceted heater design from [CN ’869](https://ai-lab.exparte.com/case/ptab/IPR2025-01040/doc/1005), which was explicitly designed for temperature compensation in a similar glass manufacturing process. All three references are in the same technical field and address interrelated problems.
    - **Expectation of Success (for §103 grounds):** Petitioner argued that a POSITA would have had a high expectation of success because the combination involved integrating well-understood components (heaters, rollers, forming wedges) using conventional and predictable engineering principles to achieve the desired, foreseeable result of improved temperature control and easier maintenance.

## 4. Relief Requested
- Petitioner requests institution of an inter partes review and cancellation of claims 1-20 of the [’025](https://ai-lab.exparte.com/patent/9512025) patent as unpatentable under 35 U.S.C. §103.

Corning's LCD glass patent challenged: El Kahlout, Tsuda & CN '869 cited for obviousness of all 20 claims over replaceable heater geometry.