Here's a concise summary of US Patent 8642491:

Title: Fining of boroalumino silicate glasses

Assignee: Corning Inc. (Current Assignee is listed as Corning Incorporated as of 2024-04-17 and 2025-01-13 reassignments).

Inventors: Adam J. G. Ellison

Filing Date: 2010-12-10 (Application number US12/965,032)

Issue Date: 2014-02-04 (Publication date)

Abstract: Glasses are disclosed which can be used to produce substrates for flat panel display devices, such as active matrix liquid crystal displays (AMLCDs). The glasses have MgO concentrations in the range from 1.0 mole percent to 3.0 mole percent and Σ[RO]/[Al2O3] ratios greater than or equal to 1.00, where [Al2O3] is the mole percent of Al2O3 and Σ[RO] equals the sum of the mole percents of MgO, CaO, SrO, and BaO. These compositional characteristics have been found to improve the melting properties of batch materials used to produce the glass, which, in turn, allows the glasses to be fined (refined) with more environmentally friendly fining agents, such as tin as opposed to arsenic and/or antimony.

Plain-Language Overview of Independent Claims:

• Claim 1: This claim describes an alkali-free glass composition specifically for use in a downdraw process. The glass must contain certain mole percentages of SiO2 (64.0-71.0), Al2O3 (9.0-12.0), B2O3 (7.0-12.0), MgO (1.0-3.0), CaO (6.0-11.5), SrO (0-2.0), and BaO (0-0.1). Key to the invention, the ratio of the sum of the alkaline earth oxides (MgO, CaO, SrO, BaO, denoted as Σ[RO]) to Al2O3 must be greater than or equal to 1.00. Furthermore, the glass is characterized by being substantially free of arsenic (at most 0.05 mole percent As2O3) and antimony (at most 0.05 mole percent Sb2O3), and it must contain at least 0.01 mole percent SnO2 (tin oxide). Finally, the glass must exhibit a high liquidus viscosity, specifically greater than or equal to 100,000 poise.

• Claim 13: This claim focuses on an alkali-free glass sheet produced by a downdraw process. The glass sheet comprises a glass composition containing SiO2, Al2O3, B2O3, MgO, and CaO. Similar to Claim 1, the glass must have a Σ[RO]/[Al2O3] ratio greater than or equal to 1.0, and an MgO content greater than or equal to 1.0 mole percent. This glass sheet is further defined by being even more substantially free of arsenic (at most 0.005 mole percent As2O3) and antimony (at most 0.005 mole percent Sb2O3), while still containing at least 0.01 mole percent SnO2. It also requires a liquidus viscosity greater than or equal to 100,000 poise.

Regarding CAFC 2026 dockets for US patent 8642491, the provided patent text notes "Family has litigation" and links to external litigation datasets (Darts-ip and Unified Patents) for general litigation information related to the patent family. However, specific dockets for the year 2026 in the Court of Appeals for the Federal Circuit (CAFC) for this patent were not found within the provided information. A direct live search of CAFC 2026 dockets would be required to definitively confirm the presence or absence of such cases.

Known litigation involving US patent 8642491 as of April 26, 2026:

1. United States International Trade Commission (ITC) Investigation

   • Case Number: 337-TA-1441
   • Jurisdiction: International Trade Commission
   • Plaintiff(s): Corning Incorporated (as the current assignee of US8642491B2)
   • Defendant(s): Specific defendants are not immediately visible from the provided snippet but typically involve importers or manufacturers of infringing articles.
   • Filing Date: Not explicitly stated in the snippet, but the entry indicates it is an active US case.
   • Outcome/Current Status: Active.

2. Patent Trial and Appeal Board (PTAB) Inter Partes Review (IPR)

   • Case Number: IPR2025-01017
   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Plaintiff(s): Petitioner (not explicitly named in the snippet, but typically a challenger to the patent's validity)
   • Defendant(s): Corning Incorporated (as the patent owner)
   • Filing Date: Not explicitly stated in the snippet, but the "2025" in the case number indicates it was filed in 2025.
   • Outcome/Current Status: Not Instituted - Procedural. This means the PTAB decided not to proceed with the full IPR, likely due to a procedural reason rather than a judgment on the merits of the challenge.

The Google Patents page also mentions a general "Family has litigation" linked to Darts-ip. However, specific case details (plaintiff, defendant, jurisdiction, case number, filing date, and outcome/status) for additional cases were not directly available in the provided search results for this entry without navigating to the external Darts-ip link.

No specific litigation results from CAFC or PACER were directly returned in the provided search snippets for US patent 8642491.Known litigation involving US patent 8642491 as of April 26, 2026:

1. United States International Trade Commission (ITC) Investigation

   • Case Number: 337-TA-1441
   • Jurisdiction: International Trade Commission
   • Plaintiff(s): Corning Incorporated
   • Defendant(s): HKC Corp, Caihong Display Devices Co., Ltd., Hisense USA Corporation, TCL, TTE, and Xianyang. Hisense USA Corporation was terminated from the investigation based on settlement.
   • Filing Date: January 31, 2025
   • Outcome/Current Status: An Initial Determination (ID) was issued on April 7, 2026, finding a violation of Section 337 based on infringement of US Patent No. 8,642,491 and US Patent No. 8,640,498. The investigation is currently pending before the Commission, with a target date of August 6, 2026. The investigation as to respondent Hisense USA Corporation was terminated based on a settlement, with the Commission determining not to review the ALJ's ID granting the joint motion to terminate on April 20, 2026.

2. Patent Trial and Appeal Board (PTAB) Inter Partes Review (IPR)

   • Case Number: IPR2025-01017
   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Plaintiff(s): Not explicitly named in the provided search results, but referred to as "Petitioner".
   • Defendant(s): Corning Incorporated (as the patent owner).
   • Filing Date: The case number indicates it was filed in 2025. A precise filing date for IPR2025-01017 was not directly found in the provided search results.
   • Outcome/Current Status: Not Instituted - Procedural. This means the PTAB did not proceed with a full review of the patent's claims on procedural grounds.

Proceedings overview

There is one AIA trial proceeding on file for US Patent 8642491, IPR2025-01017. This petition resulted in a discretionary denial, meaning the PTAB did not institute a trial on the merits. This status indicates that the patent has successfully resisted a PTAB challenge at the institution phase, suggesting a hardened defensive posture for the patent owner against future IPRs on similar grounds.

IPR2025-01017 — Caihong Display Devices Co., Ltd. v. Corning, Inc.

• Type: Inter Partes Review
• Filed: 2025-05-21
• Status: Discretionary Denial — The PTAB declined to institute an IPR trial.
• Judge panel: The search results do not explicitly state the judge panel for this specific IPR. However, it is noted that as of October 20, 2025, the USPTO Director (John Squires) personally determines institution decisions in IPR and PGR cases, often issuing "summary notices" without detailed reasoning, though they consult with at least three PTAB judges. This IPR was filed before that date. Therefore, it would have been subject to the previous bifurcated process where discretionary considerations were reviewed by the Director, and merits by a PTAB panel if not discretionarily denied.
• Petition grounds: The specific claims challenged and prior art asserted are not detailed in the provided search results. However, it's known that IPRs generally challenge patent validity based on anticipation (§ 102) or obviousness (§ 103) using patents or printed publications.
• Institution decision: Denied. The institution decision for IPR2025-01017 was a discretionary denial, issued on November 7, 2025. This denial was likely based on the "settled expectations" doctrine, a recently established doctrine where institution is denied if the challenged patent issued at least six years before the discretionary denial. This doctrine was a new consideration articulated in the USPTO's "Interim Process for PTAB Workload Management" memorandum, issued March 26, 2025. US Patent 8642491 was issued on 2014-02-04, making it over 11 years old at the time of the denial, which aligns with the "settled expectations" rationale.
• Final Written Decision (if issued): Not applicable. A discretionary denial means a trial was not instituted, so no Final Written Decision on the merits was issued.
• Settlement / termination: Not applicable. The proceeding was terminated via discretionary denial of institution, not a settlement.
• Appeal: The statute for IPRs states that the institution decision cannot be appealed.
• Defensive value: The discretionary denial of this IPR means that the patent owner successfully defended against this challenge at the preliminary stage. A defendant facing assertion of this patent today should be aware that a PTAB challenge, particularly one relying on similar arguments that might trigger the "settled expectations" doctrine or other discretionary denial factors, would be harder to institute.

Strategic summary

Only one IPR, IPR2025-01017, has been filed against US Patent 8642491, and it resulted in a discretionary denial. This means no claims of 8642491 have been canceled or sustained by the PTAB on their merits; all claims of the patent remain untested by a full IPR trial. This outcome significantly strengthens the patent owner's position, as the patent has successfully withstood a challenge to its institution.

The estoppel landscape following a discretionary denial is typically less broad than after a Final Written Decision. Generally, § 315(e)(2) estoppel bars petitioners (and their privies) from raising any ground raised or reasonably could have been raised in an IPR that resulted in a Final Written Decision. However, for a discretionary denial, the scope of estoppel is often narrower, potentially limited to the specific grounds actually presented and ruled upon in the decision, not necessarily those that "could have been raised." For Caihong Display Devices Co., Ltd., depending on the specific reasoning in the denial, they might be barred from re-raising the exact arguments presented in their petition if the denial was also based on the merits (which it was not, in this case, being a discretionary denial). However, due to the discretionary nature of the denial based on "settled expectations," new prior-art grounds or different legal arguments may still be available for other potential challengers.

The single IPR against US8642491, filed by Caihong Display Devices Co., Ltd., and its subsequent discretionary denial due to "settled expectations," indicates a specific trend in PTAB practice. The patent owner, Corning Inc., appears to have benefited from the USPTO's recent policy shifts aimed at curtailing IPRs, particularly for older patents, by the then-Acting Director Coke Morgan Stewart and later by Director John Squires, who took personal control over institution decisions in October 2025. This suggests that the patent owner is actively leveraging evolving PTAB rules.

Recommended next steps

Since IPR2025-01017 resulted in a discretionary denial, there is no Final Written Decision on the merits to link to or quote for claim invalidation. The patent has not been narrowed through this proceeding.

For a defendant considering a challenge to US Patent 8642491:

• Carefully review the specifics of the institution denial for IPR2025-01017. While summary notices are now common, the decision should outline the rationale, even if brief. Understanding the exact "settled expectations" argument applied is crucial.
• Assess whether new prior art, or different theories of unpatentability, could potentially overcome the "settled expectations" or other discretionary denial factors that led to the denial of IPR2025-01017. The patent was issued in 2014, making it an older patent, which was a key factor in the discretionary denial.
• Be aware of the evolving PTAB landscape. As of October 20, 2025, Director John Squires personally makes all institution decisions, often issuing summary denials without detailed reasoning, which makes future institution decisions less predictable. This shift centralizes control and expands the bases for discretionary denial.
• No active PTAB proceedings are currently pending against US Patent 8642491. The absence of further challenges, particularly given the recent increase in discretionary denials, might signal that potential petitioners perceive significant hurdles.

Inventors

• Adam J. G. Ellison: Employed by Corning Inc. at the time of filing.

Original assignee

The original assignee named on the issued patent is Corning Inc. The patent describes glass compositions and methods for fining boroalumino silicate glasses used as substrates in flat panel display devices, specifically active matrix liquid crystal displays (AMLCDs). Corning Incorporated is a global leader in specialty glass and ceramics, and has historically manufactured and continues to manufacture glass products, including display glass (e.g., Corning Incorporated Code 7059, 1737, and EAGLE 2000 glasses mentioned in the patent text). Corning Incorporated is a publicly traded, operating company.

Assignment timeline

No assignments from Corning Incorporated to another entity are recorded on the USPTO Patent Assignment Search for US8642491. The two recorded assignments are from the inventor to the original assignee, Corning Incorporated, which is standard practice.

• 2024-03-22 (executed) / recorded 2024-04-17 — Reel 041315/0504

  • Conveyance: Assignment of Assignors Interest
  • Assignor: ELLISON, ADAM J.G.
  • Assignee: CORNING INCORPORATED
  • Correspondent: CORNING INCORPORATED, One Riverfront Plaza, Corning, NY 14831. This correspondent recurs in this chain.
  • Context: Inventor's assignment of interest to the original assignee.

• 2024-01-11 (executed) / recorded 2025-01-13 — Reel 041864/0833

  • Conveyance: Assignment of Assignors Interest
  • Assignor: ELLISON, ADAM J. G.
  • Assignee: CORNING INCORPORATED
  • Correspondent: CORNING INCORPORATED, One Riverfront Plaza, Corning, NY 14831. This correspondent recurs in this chain.
  • Context: Inventor's assignment of interest to the original assignee.

Timeline diagram

timeline
    title Ownership of US 8642491
    2010 : Application filed by Corning Inc
    2014 : Patent granted to Corning Inc
    2024 : Inventor Ellison assigns to Corning
    2025 : Inventor Ellison assigns to Corning

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The patent remains with Corning Incorporated, a large operating company.
2. Known asserter in the chain — not present. Corning Incorporated is not a known patent assertion entity (PAE) or "patent troll."
3. Repeat correspondent across the chain — not present (in the context of transfers between different entities). The correspondent, "CORNING INCORPORATED, One Riverfront Plaza, Corning, NY 14831," is the legal department of the original operating company, consistently handling inventor assignments to the company. This is not indicative of an NPE pattern.
4. Cascading transfers — not present. There are no multiple consecutive assignments between different entities.
5. Pre-litigation transfer — not present. The patent has not been transferred from Corning Incorporated to another entity. While the patent family has litigation, this patent itself has not been transferred in a manner suggesting pre-litigation maneuvering by a separate asserting entity.
6. Bankruptcy fire-sale — not present. Corning Incorporated is an active, operating company.
7. Privateering — not present. There is no indication of a transfer to an NPE for assertion on behalf of Corning.
8. Defensive aggregator (anti-NPE) — not present. The patent has not been acquired by a defensive aggregator.

Verdict

Operating-company assertion

The patent US8642491 remains assigned to the original assignee, Corning Incorporated, which is a large operating company that manufactures products embodying the claims of the patent. There are no recorded transfers to any shell entities or known patent assertion entities. The only assignments recorded are from the inventor to Corning Incorporated in 2024 and 2025 (Reel 041315/0504 and 041864/0833), which are routine internal assignments within an operating company.

USPTO Assignment Center search for US8642491

To identify the most relevant prior art for US Patent 8642491, I will examine the patent's own cited references. The patent document itself provides a list of "Prior art keywords" and explicitly mentions several U.S. patents in its background and detailed description sections as relevant to the field of boroalumino silicate glasses and their manufacturing processes.

Here are the prior art references mentioned within the text of US Patent 8642491, along with their potential relevance:

1. U.S. Pat. No. 3,338,696 (Dockerty)

• Full Citation: US3338696A - Sheet forming apparatus - Google Patents.
• Publication/Filing Date: Filed May 6, 1964; Patented Aug. 29, 1967.
• Brief Description: This patent describes a new and improved apparatus for the production of thermoplastic sheet material, particularly an accurately contoured trough or weir device for forming glass sheets by the overflow downdraw fusion process. It focuses on the apparatus and method to produce uniform sheet material with virgin surfaces.
• Potential Anticipation (35 U.S.C. § 102): This patent describes a foundational aspect of the "downdraw sheet drawing processes, and in particular, the fusion process" mentioned in US8642491. While US8642491 claims specific glass compositions and fining methods, US3338696A potentially anticipates aspects of claims 1 and 13 relating to the method of producing glass sheets by a downdraw or fusion process, specifically the mechanical aspects of forming the sheet.

2. U.S. Pat. No. 3,682,609 (Dockerty)

• Full Citation: US3682609A - Controlling thickness of newly drawn glass sheet - Google Patents.
• Publication/Filing Date: The provided text indicates it's to Stuart M. Dockerty and is related to the fusion process. The publication date of the US patent is August 8, 1972.
• Brief Description: This patent focuses on controlling the thickness of newly drawn glass sheets, specifically in the context of the overflow downdraw fusion process. It describes apparatus and methods for achieving a substantially uniform temperature profile across the width of the glass sheet, which impacts thickness.
• Potential Anticipation (35 U.S.C. § 102): Similar to US3338696A, this patent details another fundamental aspect of the fusion process. It could potentially anticipate the "downdraw process (e.g., a fusion process)" steps in claims 1 and 13, particularly regarding the control and consistency of the glass sheet production.

3. U.S. Pat. No. 5,374,595 (Dumbaugh et al.)

• Full Citation: U.S. Pat. No. 5,374,595 (Dumbaugh et al.) (as cited by US8642491, full text not retrieved in search results for brevity)
• Publication/Filing Date: The US8642491 patent text mentions this patent as disclosing glasses. The Google Patents entry for US7851394B2, from which 8642491 claims priority, also references US5374595. This patent was issued on December 20, 1994, based on an application filed on April 1, 1993.
• Brief Description: Discloses glasses with strain points exceeding 650° C., which, when subjected to the thermal history of the fusion process, demonstrate acceptable thermal stability for active plates based on a-Si and super low temperature p-Si TFTs.
• Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates elements of claims 1 and 13 related to the desired physical property of a strain point greater than or equal to 650°C for flat panel display applications. While US8642491 introduces specific compositional ranges and fining agents, the general thermal stability requirement and strain point value could be considered in light of this prior art.

4. U.S. Pat. No. 6,319,867 (Chacon et al.)

• Full Citation: US6319867B1 - Glasses for flat panel displays - Google Patents.
• Publication/Filing Date: Filed on November 30, 1998; issued on November 20, 2001.
• Brief Description: Discloses alkali-free aluminosilicate glasses with desirable physical and chemical properties for substrates in flat panel display devices, including strain points in excess of 650° C. and acceptable thermal stability for TFT applications.
• Potential Anticipation (35 U.S.C. § 102): Similar to US5374595, this patent also addresses glasses with high strain points and thermal stability for display applications. It could potentially anticipate aspects of claims 1 and 13 related to the alkali-free nature of the glass, the general application in flat panel displays, and the strain point property.

5. U.S. Pat. No. 5,785,726 (Dorfeld et al.)

• Full Citation: U.S. Pat. No. 5,785,726 (Dorfeld et al.) (as cited by US8642491, full text not retrieved in search results for brevity)
• Publication/Filing Date: This patent was issued on July 28, 1998, based on an application filed on October 25, 1996.
• Brief Description: This patent is cited in US8642491 as disclosing processes for manufacturing arsenic-free glasses.
• Potential Anticipation (35 U.S.C. § 102): This patent directly addresses the concept of "arsenic-free glasses." While US8642491 specifies particular compositional ranges and fining agents (including tin), the general concept of producing glass without substantial amounts of arsenic (as required by claims 1 and 13, at most 0.05 mole percent or 0.005 mole percent As2O3) is taught by this prior art.

6. U.S. Pat. No. 6,128,924 (Bange et al.)

• Full Citation: U.S. Pat. No. 6,128,924 (Bange et al.) (as cited by US8642491, full text not retrieved in search results for brevity)
• Publication/Filing Date: This patent was issued on October 3, 2000, based on an application filed on September 15, 1999.
• Brief Description: This patent is cited in US8642491 as disclosing processes for manufacturing arsenic-free glasses.
• Potential Anticipation (35 U.S.C. § 102): Similar to US5785726, this patent contributes to the prior art concerning arsenic-free glass manufacturing. It could potentially anticipate the arsenic-free aspects of claims 1 and 13.

7. U.S. Pat. No. 5,824,127 (Bange et al.)

• Full Citation: U.S. Pat. No. 5,824,127 (Bange et al.) (as cited by US8642491, full text not retrieved in search results for brevity). Note: A search for "US5824127" directly returned results for "Kennametal 5824127 Square End Mill", which is clearly unrelated to glass compositions. The citation within US8642491 to "U.S. Pat. No. 5,824,127 (Bange et al.)" is therefore interpreted as a patent related to glass, and the search results for the tool were disregarded as a false positive.
• Publication/Filing Date: This patent was issued on October 20, 1998, based on an application filed on May 19, 1997.
• Brief Description: This patent is cited in US8642491 as disclosing processes for manufacturing arsenic-free glasses.
• Potential Anticipation (35 U.S.C. § 102): Similar to US5785726 and US6128924, this patent contributes to the prior art concerning arsenic-free glass manufacturing. It could potentially anticipate the arsenic-free aspects of claims 1 and 13.

8. Co-pending patent application Ser. No. 11/116,669

• Full Citation: Co-pending patent application Ser. No. 11/116,669. (as cited by US8642491, not a granted patent at the time of US8642491's filing, but referenced as prior art). This application matured into US 7,260,960.
• Publication/Filing Date: The US8642491 patent text states "co-pending patent application Ser. No. 11/116,669". This application was filed on April 28, 2005.
• Brief Description: This application is cited in US8642491 as disclosing processes for manufacturing arsenic-free glasses.
• Potential Anticipation (35 U.S.C. § 102): This application further demonstrates the prior art's efforts in producing arsenic-free glasses, which is a key characteristic claimed in US8642491 (claims 1 and 13).

9. U.S. Pat. No. 7,851,394 (Ellison)

• Full Citation: US7851394B2 - Fining of boroalumino silicate glasses - Google Patents.
• Publication/Filing Date: Filed June 28, 2006; issued December 14, 2010. This patent is a parent application to US8642491, as US8642491 is a continuation of U.S. application Ser. No. 11/478,493, filed Jun. 28, 2006, now U.S. Pat. No. 7,851,394.
• Brief Description: This patent, also titled "Fining of boroalumino silicate glasses," relates to alkali-free, boroalumino silicate glasses for flat panel display devices and methods for their fining. It discusses the importance of the Σ[RO]/[Al2O3] ratio and MgO content for meltability and fining, similar to US8642491.
• Potential Anticipation (35 U.S.C. § 102): As a direct parent of US8642491, US7851394B2 contains substantially the same disclosure. It would likely anticipate virtually all aspects of claims 1 and 13 of US8642491, particularly the compositional ranges, the Σ[RO]/[Al2O3] ratio, the MgO content, the absence of arsenic and antimony, the presence of tin oxide, and the liquidus viscosity requirements. This is a continuation patent, so the content of the parent application is prior art for the continuation, but the claims in the continuation might be narrower or different to overcome any rejections during prosecution.

Most Relevant Prior Art:

U.S. Pat. No. 7,851,394 (Ellison) is the most relevant prior art as it is a parent application with the same title and inventor, sharing substantial disclosure with US8642491. It directly addresses the core inventive concepts of US8642491, including the specific glass compositions, the Σ[RO]/[Al2O3] ratio, MgO content, and the use of environmentally friendly fining agents like tin while minimizing arsenic and antimony. Therefore, it would likely anticipate or render obvious most, if not all, of the claims in US8642491.

The Dockerty patents (US3338696A and US3682609A) are highly relevant for establishing the prior art of the fusion downdraw process itself, which is a key manufacturing method mentioned in US8642491. They provide the context for the "downdraw process" limitations in claims 1 and 13.

The patents by Dumbaugh et al. (US5374595) and Chacon et al. (US6319867) are significant for establishing prior art regarding desirable glass properties for flat panel displays, particularly high strain points and thermal stability, which are also claimed in US8642491.

Finally, the patents and application by Dorfeld et al. (US5785726) and Bange et al. (US6128924, US5824127, and Ser. No. 11/116,669) are crucial for demonstrating prior efforts in developing arsenic-free glasses, directly impacting the fining agent limitations in claims 1 and 13 of US8642491.

Obviousness Analysis of US Patent 8642491 Under 35 U.S.C. § 103

This analysis identifies combinations of prior art references, as disclosed within US Patent 8642491, that would render the independent claims 1 and 13 obvious to a person having ordinary skill in the art (PHOSITA). The primary motivation for combining these references stems from well-known industry challenges and scientific principles detailed within the patent itself.

Independent Claims Overview

• Claim 1 (Glass Composition): Describes an alkali-free boroalumino silicate glass with specific oxide ranges (SiO2: 64.0-71.0; Al2O3: 9.0-12.0; B2O3: 7.0-12.0; MgO: 1.0-3.0; CaO: 6.0-11.5; SrO: 0-2.0; BaO: 0-0.1). Critical features include a Σ[RO]/[Al2O3] ratio ≥ 1.00 (where Σ[RO] is the sum of MgO, CaO, SrO, and BaO), low concentrations of As2O3 (≤ 0.05 mol %) and Sb2O3 (≤ 0.05 mol %), at least 0.01 mol % SnO2, and a liquidus viscosity ≥ 100,000 poise for downdraw processing.
• Claim 13 (Glass Sheet): Describes an alkali-free glass sheet produced by a downdraw process, comprising a glass with SiO2, Al2O3, B2O3, MgO, and CaO. Similar to Claim 1, it requires a Σ[RO]/[Al2O3] ratio ≥ 1.00 and MgO content ≥ 1.0 mol %. It specifies even lower As2O3 (≤ 0.005 mol %) and Sb2O3 (≤ 0.005 mol %), with at least 0.01 mol % SnO2, and a liquidus viscosity ≥ 100,000 poise.

Motivation for a Person Having Ordinary Skill in the Art (PHOSITA)

The patent explicitly outlines several driving forces in the art at the time of the invention:

1. Environmental and Health Concerns: There was a "continuing effort in the art to produce glasses with lower arsenic levels and, preferably, glasses which are substantially arsenic free." Similar concerns existed for antimony, which also presents "environmental and health issues." This provides a clear and strong motivation to eliminate or substantially reduce arsenic and antimony as fining agents.
2. Known Alternative Fining Agent: Tin oxide (SnO2) was already a "ubiquitous material which has no known hazardous properties." Furthermore, SnO2 "has been a component of AMLCD glasses through the use of tin oxide electrodes in the Joule melting of the batch materials for such glasses (e.g., the melting of Corning Incorporated Code 7059, 1737, and EAGLE 2000 glasses)." This indicates that a PHOSITA would readily consider SnO2 as a replacement fining agent, despite its acknowledged lower effectiveness compared to arsenic or antimony.
3. Need for High-Performance AMLCD Glass: The background details the stringent requirements for AMLCD glass substrates, including tight dimensional control, suitability for downdraw processes (requiring high liquidus viscosities, preferably >100,000 poises), desirable coefficient of thermal expansion (CTE) (28-34 × 10−7 /° C.), high strain point (> 650° C.), chemical durability, and low density (≤ 2.45 grams/cm3). These are all known objectives for a PHOSITA.
4. Achieving Low Gaseous Inclusions: The patent stresses the need for extremely low gaseous inclusion levels (≤ 0.10 inclusions/cm3, preferably ≤ 0.05 inclusions/cm3 for sheets ≥ 500 cm3 volume) consistently over sequential sheets.

Obviousness Argument: Combination of Prior Art References

A PHOSITA, aiming to develop an improved alkali-free boroalumino silicate glass for AMLCDs, particularly one that uses environmentally friendly fining agents while maintaining properties suitable for downdraw processing, would have been motivated to combine the following teachings:

1. Primary Reference: A Known Alkali-Free Boroalumino Silicate Glass Composition for AMLCDs.
A PHOSITA would start with a base glass composition for AMLCDs known in the art (e.g., Corning's own commercial glasses like Code 7059, 1737, or EAGLE 2000), which would provide a general framework for the required components (SiO2, Al2O3, B2O3, alkaline earth oxides) and target properties (e.g., high strain point from Dumbaugh et al. or Chacon et al., and liquidus viscosity for downdraw processes from Dockerty patents). These existing glasses were also known to contain SnO2 as a component.

2. Secondary Reference: Arsenic/Antimony-Free Fining Processes (Dorfeld et al., Bange et al., and general knowledge of SnO2).
Motivated by the well-established desire to eliminate toxic fining agents, as taught by Dorfeld et al., Bange et al. (for arsenic-free processes) and the general industry trend, the PHOSITA would deliberately remove As2O3 and Sb2O3 from the batch. Given that SnO2 was already a known component in some AMLCD glasses and had no known hazardous properties, the PHOSITA would naturally elect to use SnO2 as the primary fining agent.

3. Secondary Reference: Principles of Glass Chemistry and Phase Diagrams (Taylor et al., McMillan et al., Navrotsky et al., Geisinger et al., and Levin et al.).
To compensate for SnO2's acknowledged lower effectiveness as a fining agent, the PHOSITA would seek to optimize the glass composition to improve fining efficiency or reduce initial gas solubility. The patent itself extensively details the principles of glass chemistry related to gas solubility: "The solubility of gases is comparatively high in aluminum-rich glasses and falls steeply as the Σ[RO]/[Al2O3] ratio increases beyond 1.00." This explicit teaching would motivate a PHOSITA to adjust the glass composition to ensure the Σ[RO]/[Al2O3] ratio is greater than or equal to 1.00, thereby predictably reducing initial gas solubility and making the fining process "easier to perform and more effective" with SnO2.

Furthermore, regarding MgO, while the patent notes a "prior belief" that MgO concentrations ≥ 1.0 mole percent "raised liquidus temperatures (lowered liquidus viscosities), thereby compromising high viscosity forming processes, such as, downdraw processes", the patent also provides counter-instruction rooted in fundamental glass chemistry. It references the MgO—Al2O3—SiO2 phase diagram from Levin et al., highlighting its uniqueness in having an Σ[RO]/[Al2O3] ratio slightly greater than 1 at a eutectic composition. More importantly, the patent explains that "the addition of MgO not only forces all initial melting to the RO-rich side of the phase diagram, but also produces local minima in liquidus temperatures below those that might be expected from either the MgO— or CaO-based systems alone." This is attributed to "freezing point depression," where "a suitably small amount of any oxide will initially reduce liquidus temperatures."

This detailed explanation, drawing on established phase diagrams and glass chemistry principles, would provide a PHOSITA with a clear motivation to explore MgO concentrations within the 1.0-3.0 mole percent range. Despite the general "prior belief," the scientific understanding presented in the patent (and implicitly available in the cited phase diagrams) would teach that, under careful control of the overall composition (including the SiO2 concentration and Σ[RO]/[Al2O3] ratio), MgO could reduce liquidus temperatures (and thus increase liquidus viscosity) while also contributing desirable properties like lower density and CTE, and higher strain point and modulus.

Conclusion of Obviousness:

Given the strong motivation to use environmentally friendly fining agents and achieve optimal properties for AMLCDs via downdraw processes, a PHOSITA would have been motivated to:

1. Eliminate arsenic and antimony as fining agents.
2. Utilize SnO2 as the primary fining agent, a known component in commercial AMLCD glasses.
3. Adjust the base glass composition to achieve a Σ[RO]/[Al2O3] ratio ≥ 1.00 to predictably improve fining by reducing gas solubility, a known effect in glass chemistry.
4. Incorporate MgO within the disclosed range (1.0-3.0 mol %) to achieve desired physical properties. Despite a general "prior belief" about MgO's negative impact on liquidus viscosity, the fundamental principles of glass chemistry, particularly concerning phase equilibria (Levin et al.) and freezing point depression as detailed within the patent itself, would have provided a PHOSITA with a reasonable expectation that optimizing MgO within a carefully controlled overall composition could indeed lead to the desired high liquidus viscosity necessary for downdraw processes.

The specific compositional ranges for other oxides (SiO2, Al2O3, B2O3, CaO, SrO, BaO) are well-known parameters to adjust for achieving the full suite of desired AMLCD glass properties (CTE, density, strain point) within boroalumino silicate systems. The combination of these steps, guided by the explicit motivations and scientific principles discussed within the patent itself, would have rendered the claimed alkali-free glass compositions and methods of producing glass sheets obvious to a PHOSITA.

To determine the most accurate and up-to-date information on US patent 8642491 regarding patent term adjustments, extensions, continuation/divisional applications, related family members, and projected expiration date, a direct search of the USPTO's Patent Center database would be ideal. However, based on the provided search results and the authoritative patent text, here's a detailed breakdown:

US Patent 8642491: Fining of boroalumino silicate glasses

• Filing Date: 2010-12-10 (Application number US12/965,032)
• Issue Date: 2014-02-04
• Original Expiration Date (20 years from filing): 2030-12-10

1. Patent Term Adjustments (PTA):
Patent Term Adjustment (PTA) is granted to compensate for delays caused by the USPTO during the prosecution of a patent application. These delays can include failing to issue an office action within 14 months of filing, failing to respond to an applicant's reply within 4 months, or failing to issue a patent within 4 months of the issue fee payment, or failing to issue the patent within 36 months from the filing date. The USPTO calculates the PTA and it is indicated in the issue notification letter and on the patent itself.

The provided patent text states the "Adjusted expiration" date as 2027-11-21. This indicates that the patent has received a Patent Term Adjustment, and its term has been adjusted from the original 20-year term from its filing date (2010-12-10) to this new date. The details of the calculation are not explicitly provided in the patent document or search snippets, but it is clear an adjustment was made.

2. Patent Term Extensions (PTE):
Patent Term Extensions (PTE) are available for patents on certain products (like human drugs, medical devices, food additives) to restore time lost due to premarket regulatory review by agencies such as the FDA.

Since US patent 8642491 relates to "Fining of boroalumino silicate glasses" for flat panel display devices, it does not fall into the categories of products eligible for PTE (e.g., human drugs, medical devices). Therefore, it is highly unlikely that this patent would have received any Patent Term Extensions under 35 U.S.C. § 156. The provided information does not indicate any PTE for this patent.

3. Continuation Applications:
A continuation application is filed before the patenting, abandonment, or termination of proceedings on an earlier application to introduce new claims and seek further examination. Filing a continuation application from a parent patent is often seen as an implicit admission of obviousness-type double patenting, requiring a Terminal Disclaimer to avoid ODP. New fees for continuation applications filed six or nine years after their earliest benefit date have been implemented by the USPTO, effective January 19, 2025.

The provided patent information states that US8642491B2 is a "continuation of U.S. application Ser. No. 11/478,493, filed Jun. 28, 2006, now U.S. Pat. No. 7,851,394" (under Section I. CROSS-REFERENCE TO RELATED APPLICATIONS). This confirms that US8642491B2 is a continuation application of US Pat. No. 7,851,394.

The "Family Applications" section also lists:

• US11/478,493 (US7851394B2), filed 2006-06-28, which is the parent application.
• US12/965,004 (US8640498B2), filed 2010-12-10, titled "Fining of boroalumino silicate glasses." This appears to be a co-pending or related continuation, given the identical title and filing date to US8642491B2's application number (US12/965,032).

4. Divisional Applications:
A divisional application is typically filed when an examiner makes a restriction requirement, separating claims to independent and distinct inventions within a single patent application. Divisional applications must be filed before the patenting or abandonment of the prior application.

The provided text for US8642491B2 explicitly states it is a "continuation" (of US7851394B2), not a "divisional" application. There is no information in the provided text or search results to indicate that US8642491B2 is a divisional application or that any divisional applications were explicitly filed from it.

5. Related Family Members:
The patent text lists the following related family members:

• Parent Application: US7851394B2 (application number US11/478,493, filed 2006-06-28).
• Other continuation of the same parent: US8640498B2 (application number US12/965,004, filed 2010-12-10).
• Priority Applications: US60/694,478, filed 2005-06-28.
• Publication: US20110082022A1 (published 2011-04-07).
• International/Foreign Equivalents: The "Country Status" section lists family members in EP, JP, KR, CN, TW, and WO jurisdictions. Specific patent numbers include EP3296274B1, JP5142996B2, KR101346446B1, CN101208276B, TWI387571B, and WO2007002865A1.

6. Projected Expiration Date:
Based on the "Legal status" information from the Google Patents page, the patent is "Active, expires 2027-11-21". This "Adjusted expiration" date reflects any Patent Term Adjustments. Therefore, the projected expiration date for US Patent 8642491 is November 21, 2027.

Defensive Disclosure: Advanced Fining and Application Derivatives of US Patent 8642491

This document outlines derivative variations and extensions of the alkali-free boroalumino silicate glass compositions and fining methods described in US Patent 8642491, with the strategic intent of generating prior art to render future incremental improvements by competitors as obvious or non-novel. The derivations focus on expanding the technical scope of the invention across various axes, providing sufficiently enabling descriptions for reproduction by a person skilled in the art.

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Derivative Variations

1. Material & Component Substitution: Advanced Redox Fining with Inert Gas Injection

• Enabling Description: This derivative discloses an alkali-free boroalumino silicate glass composition for downdraw processes, as broadly described in US8642491, but incorporating an advanced fining system. The glass comprises SiO2 (66.0-70.0 mol%), Al2O3 (10.0-11.5 mol%), B2O3 (8.5-11.0 mol%), MgO (1.5-2.5 mol%), CaO (7.0-10.0 mol%), and SrO (0.2-1.0 mol%). BaO is maintained at a minimal concentration (<0.05 mol%). The critical Σ[RO]/[Al2O3] ratio is precisely controlled within 1.03-1.12. The fining system explicitly excludes the use of substantial amounts of As2O3 and Sb2O3 (each <0.005 mol%). Instead, it integrates a multi-component approach: SnO2 (0.05-0.15 mol%) is combined with CeO2 (0.01-0.10 mol%) to leverage the Ce3+/Ce4+ redox couple, which promotes efficient oxygen release and subsequent bubble dissolution within the melt. This combination facilitates fining at melting temperatures ranging from 1580-1620 °C, reducing overall energy consumption. Furthermore, a fine stream of an inert gas, such as argon (Ar) or nitrogen (N2), is injected into the molten glass via a specifically designed porous refractory element positioned within the glass melter's refining zone, below the melt surface. This mechanical bubbling provides additional stirring and helps coalesce and transport smaller gaseous inclusions to the surface for removal, leading to a gaseous inclusion level of <0.03 inclusions/cm³ for glass sheets exceeding 500 cm³ in volume. The combined chemical and mechanical fining enables the achievement of liquidus viscosities greater than 250,000 poise.
• Mermaid Diagram:

  flowchart TD
      A[Batch Materials Input] --> B{Melting Furnace}
      B -- Molten Glass --> C{Fining Zone: CeO2/SnO2 Redox}
      C -- O2 Release & Bubble Dissolution --> D{Fining Zone: Inert Gas Injection}
      D -- Mechanical Coalescence & Transport --> E{Conditioning Zone}
      E -- Homogenization --> F[Downdraw Process]
      F --> G[Final Glass Sheet (<0.03 incl/cm³)]
  

2. Operational Parameter Expansion: Ultra-High Viscosity Micro-Forming via Vacuum Downdraw

• Enabling Description: This derivative details a method for producing ultra-thin glass substrates (<100 µm thickness) or micro-fibers from alkali-free boroalumino silicate glass for specialized microelectronic and optical applications. This process utilizes a modified downdraw technique optimized for significantly higher liquidus viscosities and vacuum conditions. The glass composition includes SiO2 (68.0-71.0 mol%), Al2O3 (9.5-11.0 mol%), B2O3 (7.0-9.0 mol%), MgO (1.0-2.0 mol%), CaO (6.0-9.0 mol%), and SrO (0.0-0.5 mol%), with BaO maintained at <0.05 mol%. The Σ[RO]/[Al2O3] ratio is precisely controlled between 1.00-1.05. Fining is achieved through a minimized SnO2 concentration (0.01-0.05 mol%, with As2O3/Sb2O3 <0.005 mol%) coupled with a vacuum fining step. The glass melt, after initial melting, enters a dedicated conditioning zone that is maintained under a high vacuum (operating chamber pressure of 10⁻⁴ to 10⁻⁵ Torr). This high vacuum environment actively extracts residual microbubbles and dissolved gases from the highly viscous melt. The downdraw process is then performed from this vacuum-conditioned melt, forming continuous micro-ribbons or filaments. The drawing speed and temperature gradients (e.g., maintaining a linear temperature drop of 50-70°C over 100 cm in the drawing zone) are critically controlled to leverage the exceptionally high liquidus viscosities, intentionally maintained above 500,000 poise. This results in superior surface quality (average surface roughness Ra <0.2 nm) and minimal internal stress within the ultra-thin glass articles.
• Mermaid Diagram:

  stateDiagram-v2
      [*] --> BatchPreparation
      BatchPreparation --> HighSilicaMelting: SiO2: 68-71 mol%, B2O3: 7-9 mol%
      HighSilicaMelting --> InitialFining: Minimized SnO2 (0.01-0.05 mol%)
      InitialFining --> VacuumConditioningChamber: Pressure 10^-4 - 10^-5 Torr
      VacuumConditioningChamber --> UltraHighViscosityDowndraw: Liquidus Viscosity > 500,000 poise
      UltraHighViscosityDowndraw --> MicroForming: Ultra-thin sheets/fibers < 100 µm
      MicroForming --> QualityControl: Ra < 0.2 nm, Minimized Stress
      QualityControl --> [*]
  

3. Cross-Domain Application: AgTech - Durable, Chemically Resistant Substrates for Agricultural Sensors

• Enabling Description: This derivative applies the alkali-free boroalumino silicate glass composition to the agricultural technology (AgTech) sector, specifically for the fabrication of highly durable and chemically resistant substrates used in outdoor agricultural sensors and ruggedized field displays. The glass composition is formulated for enhanced resistance to various acidic and alkaline agrochemicals (e.g., fertilizers, pesticides, herbicides). This is achieved by increasing the Al2O3 content (10.5-12.0 mol%) and maintaining a higher CaO content (8.0-11.5 mol%) to maximize the charge-balancing interactions that strengthen the glass network. SiO2 concentration is typically 64.0-68.0 mol% and B2O3 7.0-9.0 mol%. SrO and BaO concentrations are kept extremely low (<0.1 mol% each). The Σ[RO]/[Al2O3] ratio is maintained within 1.05-1.20. Fining is performed exclusively with SnO2 (0.05-0.10 mol%), ensuring As2O3 and Sb2O3 concentrations remain below 0.005 mol% for environmental safety and non-contamination of agricultural environments. The resulting glass exhibits superior chemical durability, demonstrated by a 5% HCl weight loss of less than 0.5 mg/cm² (24 hours at 95°C) and a 110 BHF weight loss of less than 1.0 mg/cm² (5 minutes at 30°C). It maintains a liquidus viscosity greater than 100,000 poise for downdraw manufacturability and a coefficient of thermal expansion (CTE) (0-300°C) in the range of 28-34 x 10⁻⁷ /°C, compatible with hermetic sealing and reliable integration into sensor arrays exposed to broad outdoor temperature fluctuations.
• Mermaid Diagram:

  classDiagram
      class AgTechGlassSubstrate {
          +Composition: Alkali-Free Boroalumino Silicate
          +Al2O3: 10.5-12.0 mol%
          +CaO: 8.0-11.5 mol%
          +SnO2: 0.05-0.10 mol%
          +As2O3, Sb2O3: <0.005 mol%
          +Σ[RO]/[Al2O3]: 1.05-1.20
          +LiquidViscosity: >= 100,000 poise
          +CTE: 28-34x10^-7 /°C
          +HCl_Durability: <0.5 mg/cm²
          +BHF_Durability: <1.0 mg/cm²
      }
      class AgriculturalSensor {
          +GlassSubstrate: AgTechGlassSubstrate
          +Encapsulation: Hermetic
          +OperatingEnvironment: Outdoor, Chemical Exposure, Temp Variation
      }
      class FieldDisplayPanel {
          +GlassSubstrate: AgTechGlassSubstrate
          +Ruggedization: Yes
          +Visibility: High Brightness
      }
      AgTechGlassSubstrate <|-- AgriculturalSensor
      AgTechGlassSubstrate <|-- FieldDisplayPanel
  

4. Integration with Emerging Tech: AI-Driven Real-time Process Optimization for Defect Fining

• Enabling Description: This derivative integrates artificial intelligence and machine learning into the real-time optimization of alkali-free boroalumino silicate glass production via downdraw. An AI system, leveraging reinforcement learning and predictive modeling, continuously processes data from a comprehensive network of sensors deployed throughout the melting furnace, fining section, and conditioning zone. These sensors capture high-resolution data on melt temperature distribution (spatial and temporal, with ±0.5°C accuracy), instantaneous liquidus viscosity via in-situ viscometry, redox potential of the glass melt (monitored by zirconia-based electrochemical probes), and real-time gaseous inclusion count and size distribution through advanced optical imaging and AI-powered image analysis. This data is processed by an on-site edge computing platform running trained machine learning algorithms. The AI identifies subtle process deviations, predicts potential increases in gaseous inclusions, or shifts in key glass properties (e.g., Σ[RO]/[Al2O3] ratio, liquidus viscosity) due to raw material variability or thermal fluctuations. Based on these predictions, the AI autonomously triggers micro-adjustments to operational parameters such as heating element power settings, precise batch material feed rates (including SiO2, Al2O3, B2O3, MgO, CaO, and SnO2), and downdraw speeds. The AI's objective function is to minimize gaseous inclusion levels below 0.05 inclusions/cm³ while adhering to the specified compositional limits (As2O3/Sb2O3 <0.05 mol%, SnO2 >0.01 mol%) and maintaining liquidus viscosity >100,000 poise, thereby maximizing yield and consistency.
• Mermaid Diagram:

  sequenceDiagram
      participant S as IoT Sensors (Melter, Finer, Isopipe)
      participant E as Edge Computing Platform
      participant M as ML Algorithms (Reinforcement Learning)
      participant C as Process Control System
      participant D as Downdraw Process
  
      S->>E: Real-time Melt Data (Temp, Viscosity, Redox, Bubbles)
      E->>M: Ingest & Pre-process Data
      M->>M: Learn & Predict Process Deviations
      M->>E: Optimal Parameter Adjustments
      E->>C: Transmit Control Commands
      C->>D: Adjust Heaters, Feeds, Speeds
      D->>S: Feedback Loop: Glass Properties & Defects
      Note right of M: Optimize Σ[RO]/[Al2O3] & Fining Efficacy
  

5. The "Inverse" or Failure Mode: Eco-Fining for Controlled-Defect Glass with Reduced Energy Footprint

• Enabling Description: This derivative describes an optimized mode of operation for the production of alkali-free boroalumino silicate glass via downdraw, where the fining process is intentionally scaled down to reduce energy consumption, resulting in a predetermined, controlled level of gaseous inclusions higher than typically acceptable for premium displays, but suitable for less critical applications. The glass composition adheres to the broad ranges of Claim 1, maintaining SnO2 at the lower end of the fining range (0.01-0.03 mol%) with As2O3 and Sb2O3 strictly kept below 0.05 mol%. Instead of targeting <0.05 inclusions/cm³, the 'eco-fining' mode aims for a gaseous inclusion level in the range of 0.10-0.25 inclusions/cm³ for sheets of at least 500 cm³ volume. This is achieved by either operating the fining section of the melting furnace at a reduced peak temperature profile (e.g., 20-50°C lower than the standard fining temperature, such as 1570°C instead of 1600°C) or by shortening the residence time of the glass in the high-temperature fining zone (e.g., 12 hours instead of 16 hours). This approach yields a significant reduction in energy consumption for the fining stage (estimated 5-15% power savings) and can extend the operational life of refractory materials due to lower thermal stress. The fundamental glass properties, including the Σ[RO]/[Al2O3] ratio (e.g., 1.00-1.05), MgO content (>1.0 mol%), and liquidus viscosity (>100,000 poise), are maintained to ensure meltability and downdraw process compatibility. The resulting "controlled-defect" glass is ideal for applications where stringent optical perfection is not required, such as architectural glazing, low-cost industrial monitoring displays, or material handling components, offering an environmentally conscious manufacturing alternative.
• Mermaid Diagram:

  graph TD
      A[Start Glass Batch] --> B{Standard Melting Furnace}
      B -- Molten Glass --> C{Decision: Fining Efficacy Required?}
      C -- High-Performance (Low Defects) --> D[Standard Fining Mode: High Temp/Duration]
      C -- Cost/Energy Optimized (Controlled Defects) --> E[Eco-Fining Mode: Reduced Temp/Duration]
      D -- High Energy, Low Defects --> F[Downdraw Process]
      E -- Lower Energy, Controlled Defects --> F
      F --> G{Quality Control}
      G -- <0.05 incl/cm³ --> H[High-End Display Applications (e.g., AMLCD)]
      G -- 0.10-0.25 incl/cm³ --> I[Industrial/Architectural Applications]
  

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Combination Prior Art Scenarios

These scenarios combine the teachings of US8642491 with existing open-source standards, demonstrating how the core inventive concepts can be rendered obvious when integrated with widely available technological frameworks.

1. US8642491 Combined with an Open-Source Data Logging and Telemetry Standard (e.g., MQTT):

   • Scenario: The manufacturing process for alkali-free boroalumino silicate glasses via downdraw (as described in US8642491) is augmented by implementing an open-source data logging and telemetry system based on the Message Queuing Telemetry Transport (MQTT) protocol (e.g., using an Eclipse Mosquitto broker). Critical process parameters such as furnace zone temperatures, glass flow rates, batch ingredient feed rates, real-time measurements of liquidus viscosity, and optical analysis of gaseous inclusion counts are continuously captured by sensors and published as MQTT messages. These messages are then subscribed to by various clients, including a central data historian (e.g., InfluxDB), a dashboard for operator visualization (e.g., Grafana), and an anomaly detection engine. This integration makes the remote monitoring, standardized data exchange, and historical analysis of glass melting and fining parameters, for the purpose of process optimization and defect reduction in US8642491, an obvious application of existing open-source Industrial IoT principles.

2. US8642491 Combined with an Open-Source Chemical Process Modeling Library (e.g., Cantera):

   • Scenario: The fining of boroalumino silicate glasses utilizing tin oxide (SnO2) as a primary agent, potentially augmented with other redox couples like CeO2 (as described in US8642491 and Derivative 1), is scientifically optimized using an open-source chemical kinetics and thermodynamics software library such as Cantera (www.cantera.org). Detailed thermodynamic and kinetic models for the SnO2/SnO and CeO2/CeO redox reactions, including the evolution and dissolution of gaseous species (e.g., O2, CO2, N2) within the molten glass, are developed within the Cantera framework. These models are used to predict the optimal temperature profiles, residence times, and atmospheric conditions required in the fining zone to achieve specified gaseous inclusion levels and liquidus viscosities. The insights gained from these simulations are then directly used to program and control the actual melting and fining equipment for the alkali-free boroalumino silicate glass. This makes the computational simulation and optimization of the fining chemistry for the glass described in US8642491, leveraging known chemical principles and open-source tools, an obvious and anticipated engineering practice.

3. US8642491 Combined with an Open-Source Robotic Control Framework (e.g., Robot Operating System - ROS):

   • Scenario: The downdraw manufacturing of alkali-free boroalumino silicate glass sheets (US8642491) is fully automated using an industrial robotic system controlled by an open-source Robot Operating System (ROS, www.ros.org). ROS-enabled robotic manipulators are deployed for precision tasks such as automated loading of pre-weighed batch materials into the melter, systematic feeding of cullet or additives, precise positioning and manipulation of the drawing apparatus (e.g., isopipe adjustments), and automated inspection, cutting, and stacking of the finished glass sheets as they emerge from the downdraw process. The ROS framework handles sensor integration (e.g., machine vision for defect detection, laser micrometers for dimension control), motion planning for robotic arms, and overall coordination of the automated workflow. This makes the robotic automation of material handling, process adjustments, and post-forming operations around the downdraw process for the glass of US8642491 an obvious implementation using widely adopted open-source robotics solutions.