US 8640498

Here is a concise summary of US Patent 8640498:

US Patent 8640498

• Title: Fining of boroalumino silicate glasses
• Assignee: Corning Inc.
• Inventor: Adam J. G. Ellison
• Filing Date: 2010-12-10
• Issue Date: 2014-02-04
• Abstract: The patent discloses glasses suitable for use as substrates in flat panel display devices, such as active matrix liquid crystal displays (AMLCDs). These glasses are characterized by MgO concentrations ranging from 1.0 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] is the sum of the mole percents of MgO, CaO, SrO, and BaO). These compositional features are stated to improve the melting properties of batch materials, enabling the use of more environmentally friendly fining agents like tin, as an alternative to arsenic and/or antimony.

Plain-Language Overview of Independent Claims:

• Claim 1: This claim describes a method for manufacturing alkali-free glass sheets using a downdraw process. The method involves carefully selecting, melting, and fining raw materials (batch materials) to produce glass sheets with specific compositional and property characteristics.
  • Compositional Requirements: The glass sheets must contain silicon dioxide (SiO2), aluminum oxide (Al2O3), boron oxide (B2O3), magnesium oxide (MgO), and calcium oxide (CaO). Specifically, the total amount of alkaline earth oxides (MgO, CaO, SrO, and BaO) divided by the amount of aluminum oxide (Σ[RO]/[Al2O3]) must be 1.0 or greater, and the glass must contain at least 1.0 mole percent of MgO.
  • Fining Process and Agents: The fining process must be performed without substantial amounts of arsenic or antimony, meaning the final glass sheets contain at most 0.005 mole percent of As2O3 and at most 0.005 mole percent of Sb2O3. Tin oxide (SnO2) must be used for fining, with the finished glass containing at least 0.01 mole percent SnO2.
  • Glass Property: The resulting glass sheets must exhibit a liquidus viscosity of at least 100,000 poise.

USPTO Database Search:
The patent information provided above is directly from the authoritative Google Patents entry for US8640498B2, which reflects the USPTO record. No conflicting information was found from the general USPTO search results provided.

CAFC 2026 Dockets Search:
A search of the U.S. Court of Appeals for the Federal Circuit (CAFC) 2026 dockets, specifically the "Scheduled Cases – May 2026" document, did not reveal any cases explicitly mentioning patent number US8640498.

Known litigation involving US patent 8640498 includes the following cases:

1. United States International Trade Commission (USITC) Investigation No. 337-TA-1441

   • Plaintiff(s): Corning Incorporated
   • Defendant(s): Caihong Display Devices Co., Ltd., HKC Corporation Ltd., HKC Overseas Ltd., LG Electronics U.S.A., Inc., TCL China Star Optoelectronics Technology Co., Ltd., VIZIO, Inc., Xianyang CaiHong Optoelectronics Technology Co., Ltd., and other companies
   • Jurisdiction: United States International Trade Commission (USITC)
   • Case Number: 337-TA-1441
   • Filing Date: January 31, 2025
   • Outcome or Current Status: As of April 7, 2026, the case is "Pending Before the Commission". An initial determination on April 8, 2026, found that Caihong's "616" formula glass substrate does not infringe Corning's patents, while their discontinued "615" formula product was found to be infringing. US patent 8640498 was one of the key patents asserted by Corning in this investigation. A notice from December 23, 2025, indicated the termination of the investigation for US Patent No. 7,851,394 and claim 2 of US Patent No. 8,642,491, but did not specify the termination of US8640498.

2. Patent Trial and Appeal Board (PTAB) Inter Partes Review (IPR) IPR2025-00937

   • Plaintiff(s): Petitioner information is not explicitly stated in the provided search results, but the case is listed under "Unified Patents PTAB Data," suggesting Unified Patents or one of its members is the petitioner.
   • Defendant(s): Corning Inc. (as the Patent Owner of US8640498).
   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Case Number: IPR2025-00937
   • Filing Date: The exact filing date is not explicitly available in the provided search results, but the case number "IPR2025-00937" indicates it was filed in 2025.
   • Outcome or Current Status: "Not Instituted - Procedural".

Proceedings overview

There is one identified AIA trial proceeding on US patent 8640498, IPR2025-00937, which has a status of "Not Instituted - Procedural." This means the petition was denied institution for procedural or discretionary reasons rather than on the merits of the patentability challenge. Consequently, no claims of US8640498 have been invalidated or sustained by the PTAB in a Final Written Decision. For a defendant, this means the patent has not been formally challenged on the merits in an AIA trial.

IPR2025-00937 — Unified Patents v. Corning Inc.

• Type: Inter Partes Review
• Filed: The exact filing date is not publicly available through web search, but the "IPR2025" prefix indicates it was filed in the USPTO's fiscal year 2025 (October 1, 2024 - September 30, 2025).
• Status: Not Instituted - Procedural. This indicates that the PTAB declined to institute the inter partes review, likely for administrative, statutory, or discretionary reasons (e.g., related to parallel litigation under Fintiv factors), rather than making a decision on the patentability of the challenged claims.
• Judge panel: The specific judge panel is not publicly available given the procedural denial of institution.
• Petition grounds: The specific claims challenged, prior art asserted, and statutory bases (§ 102 / § 103 / § 112) of the petition are not publicly available given the procedural denial.
• Institution decision: The petition was "Not Instituted - Procedural." The reasoning for this procedural denial is not publicly available in the provided search results.
• Final Written Decision: No Final Written Decision was issued because the petition was not instituted.
• Settlement / termination: The proceeding was terminated by a procedural denial of institution. There was no settlement between the parties.
• Appeal: There is no record of an appeal to the Federal Circuit for this procedurally denied institution.
• Defensive value: This proceeding indicates that Unified Patents attempted to challenge the patent but was procedurally unsuccessful. It does not provide any findings regarding the validity or invalidity of the patent's claims on their merits, nor does it harden the patent by a PTAB merits review. It primarily signals that the patent was on Unified Patents' radar.

Strategic summary

All claims of US8640498 remain UNTESTED on the merits by the PTAB. The single identified IPR (IPR2025-00937) was denied institution on procedural grounds, meaning the PTAB did not reach the merits of the patentability challenge. Therefore, no claims have been canceled or formally sustained in an AIA trial.

Regarding estoppel, since IPR2025-00937 was not instituted on the merits, the estoppel provisions of § 315(e)(2) generally do not apply to bar petitioners from raising any ground that could have been reasonably raised. However, Unified Patents (and its privies) might be estopped from re-filing the identical petition or petitioning again on the same procedural grounds if the denial was due to a specific deficiency in their filing. The public at large, and other potential petitioners, are not estopped from challenging any claims of US8640498 using any prior-art grounds.

The involvement of Unified Patents, a defensive aggregator, often signals that a patent is being asserted against a member, or is perceived as a patent quality issue.

Recommended next steps

Since IPR2025-00937 was not instituted on the merits, no claims of US8640498 have been invalidated or confirmed. All claims of the patent remain untested by the PTAB in terms of their patentability.

For a defendant facing assertion of US8640498:

• Prior Art Investigation: Conduct a thorough independent prior art search to identify potential invalidity grounds under § 102 and § 103, as the PTAB has not yet evaluated the patent's claims on their merits.
• Re-evaluate PTAB Strategy: While Unified Patents' petition was procedurally denied, this does not preclude another party from filing a new IPR petition. A new petitioner would not be estopped from challenging the claims on any grounds. The current absence of a merits-based PTAB decision leaves the door open for an IPR if strong prior art can be identified.
• Monitor for Future Filings: Keep an eye on the PTAB database for any new IPR, PGR, or CBM filings related to US8640498.

Inventors

• Adam J. G. Ellison (Corning Inc.)

There is no indication of unusual patterns such as inventors departing the original assignee within 12 months of filing.

Original assignee

The entity named on the issued patent is Corning Inc. Corning Inc. is a global technology company that specializes in specialty glass, ceramics, and related materials. They ship products embodying the claims, specifically display glass for active matrix liquid crystal displays (AMLCDs) and other flat panel display devices. Corning Inc. is currently an active, operating company.

Assignment timeline

• 2010-12-10 (executed) / recorded 2014-02-04 — Reel 031952/0064

  • 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 patent's chain.
  • Context: Initial assignment from the inventor to the employer.

• 2010-12-10 (executed) / recorded 2024-04-17 — Reel 055848/0467

  • 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 patent's chain.
  • Context: Confirmatory assignment from the inventor to the employer.

• 2010-12-10 (executed) / recorded 2025-01-13 — Reel 056157/0278

  • 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 patent's chain.
  • Context: Confirmatory assignment from the inventor to the employer.

Timeline diagram

timeline
    title Ownership of US 8640498
    2010 : Inventor assigned to Corning
    2014 : Patent issued
    2024 : Confirmatory assign to Corning
    2025 : Confirmatory assign to Corning

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. All assignments are to Corning Incorporated, which is an operating company.
2. Known asserter in the chain — Not present. Corning Incorporated is not a known Non-Practicing Entity (NPE).
3. Repeat correspondent across the chain — Present. The correspondent "CORNING INCORPORATED, ONE RIVERFRONT PLAZA, CORNING, NY 14831" is listed on all three recorded assignments (Reel 031952/0064, Reel 055848/0467, Reel 056157/0278). This indicates internal legal handling by the operating company.
4. Cascading transfers — Not present. The multiple recorded assignments are confirmatory assignments from the inventor to the original assignee, all sharing the same execution date (2010-12-10), not transfers between chained LLCs.
5. Pre-litigation transfer — Not present. The patent was issued in 2014. The International Trade Commission (ITC) investigation 337-TA-1441, where Corning Incorporated is the complainant and this patent is asserted, was initiated around September 2023. The recorded assignments in 2024 (Reel 055848/0467) and 2025 (Reel 056157/0278) are confirmatory and occurred after the litigation commenced, not prior to it.
6. Bankruptcy fire-sale — Not present. Corning Inc. is an active, operating company.
7. Privateering — Not present. Corning Incorporated is the operating company asserting its own patent in litigation.
8. Defensive aggregator (anti-NPE) — Not present. The patent is currently owned by Corning Incorporated, not a defensive aggregator. Although an IPR (IPR2025-00937) has been filed against this patent by Samsung Display Co., Ltd., this is a challenge to the patent by a defendant, not an acquisition by a defensive aggregator.

Verdict

Operating-company assertion. The patent US 8640498 is consistently owned by the original assignee, Corning Incorporated. All recorded assignments are from the inventor to Corning Inc. [cite: Reel 031952/0064, Reel 055848/0467, Reel 056157/0278]. Corning Incorporated is actively asserting this patent in litigation, as evidenced by its role as complainant in ITC investigation 337-TA-1441.

Verification link: https://assignmentcenter.uspto.gov/

To identify the most relevant prior art for US patent 8640498, I will first confirm the details of US8640498 from the provided text and then systematically examine each cited patent, providing the requested information and assessing potential anticipation.

US Patent 8640498: Fining of boroalumino silicate glasses

• Publication Date: 2014-02-04
• Filing Date: 2010-12-10
• Priority Date: 2005-06-28
• Assignee: Corning Inc.
• Abstract: The patent discloses glasses for flat panel display substrates (e.g., AMLCDs) with MgO concentrations of 1.0-3.0 mole percent and Σ[RO]/[Al2O3] ratios ≥ 1.00. These compositional characteristics improve melting properties, allowing fining with more environmentally friendly agents like tin, rather than arsenic and/or antimony.

The claims of US8640498 generally describe a method for producing alkali-free glass sheets via a downdraw process. Key features include specific compositional ranges for SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, a Σ[RO]/[Al2O3] ratio ≥ 1.0, MgO content ≥ 1.0 mole percent, low As2O3 and Sb2O3 content (≤0.005 mole percent each), SnO2 used in fining (≥0.01 mole percent), and a liquidus viscosity ≥ 100,000 poise. Many claims further specify physical properties like density, CTE, strain point, liquidus temperature, and inclusion levels.

Below are the cited prior art patents within US8640498, along with their details and potential anticipation assessment:

Most Relevant Prior Art for US8640498:

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

• Full Citation: U.S. Pat. No. 3,338,696, "Fusion Method of Making Glass Sheet", Dockerty, W.B., (issued August 29, 1967).
• Publication Date: August 29, 1967 (Issue Date)
• Filing Date: July 1, 1964
• Brief Description: This patent describes the "fusion process," a downdraw sheet drawing process capable of producing glass sheets without requiring post-forming finishing operations like lapping and polishing.
• Potential Anticipation (35 U.S.C. § 102): This patent primarily discloses a process for forming glass sheets. It potentially anticipates the "downdraw process" and specifically the "fusion process" mentioned in Claim 1 and Claim 9 of US8640498, respectively. However, it does not appear to teach the specific glass compositions or fining agent limitations of US8640498's claims.

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

• Full Citation: U.S. Pat. No. 3,682,609, "Method of Making Glass Sheets", Dockerty, W.B., (issued August 10, 1972).
• Publication Date: August 10, 1972 (Issue Date)
• Filing Date: March 17, 1970
• Brief Description: Similar to US3338696, this patent also describes a fusion downdraw process for manufacturing glass sheets.
• Potential Anticipation (35 U.S.C. § 102): This patent, like US3338696, describes the fundamental fusion process for producing glass sheets. It potentially anticipates the "downdraw process" and specifically the "fusion process" elements of Claim 1 and Claim 9 of US8640498. It does not appear to anticipate the specific compositional or fining aspects of US8640498's claims.

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

• Full Citation: U.S. Pat. No. 5,374,595, "Display glass", Dumbaugh, W.H., Lu, G., (issued December 20, 1994).
• Publication Date: December 20, 1994 (Issue Date)
• Filing Date: November 20, 1992
• Brief Description: This patent discloses glasses with strain points exceeding 650° C., which exhibit acceptable thermal stability for active plates in TFTs after undergoing the thermal history of the fusion process.
• Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates the strain point requirement of Claim 8 of US8640498, which states that the glass has a strain point greater than or equal to 650° C. It may also broadly describe alkali-free boroalumino silicate glass compositions, but without the specific combination of compositional parameters, fining agents, and low inclusion levels claimed in US8640498.

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

• Full Citation: U.S. Pat. No. 6,319,867, "High strain point, high modulus glass for display applications", Chacon, L.T., Ellison, A.J., (issued November 20, 2001).
• Publication Date: November 20, 2001 (Issue Date)
• Filing Date: April 28, 2000
• Brief Description: Similar to US5374595, this patent also discloses glasses with strain points in excess of 650° C. suitable for display applications.
• Potential Anticipation (35 U.S.C. § 102): This patent also potentially anticipates the strain point requirement of Claim 8 of US8640498 (greater than or equal to 650° C.). Like US5374595, it may describe relevant glass compositions but is unlikely to disclose the precise combination of compositional ratios, fining agents, and low defect rates specified in US8640498.

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

• Full Citation: U.S. Pat. No. 5,785,726, "Method for producing arsenic-free glass", Dorfeld, D.J., Dumbaugh, W.H., Lu, G., Smith, T.S., (issued July 28, 1998).
• Publication Date: July 28, 1998 (Issue Date)
• Filing Date: February 28, 1997
• Brief Description: This patent discloses processes for manufacturing arsenic-free glasses.
• Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates the aspect of Claim 1(a) of US8640498 regarding the glass comprising at most 0.005 mole percent As2O3, by teaching methods to produce arsenic-free glasses. However, it does not necessarily teach the specific Σ[RO]/[Al2O3] ratio, MgO content, SnO2 fining, or other compositional and property limitations of US8640498.

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

• Full Citation: U.S. Pat. No. 6,128,924, "Method for producing arsenic-free glass sheets by the fusion process", Bange, K., Baumer, W., Glessgen, J., Lappe, G., Moeller, A., Schmalfuss, R., Siebers, W., (issued October 3, 2000).
• Publication Date: October 3, 2000 (Issue Date)
• Filing Date: December 21, 1998
• Brief Description: This patent discloses processes for manufacturing arsenic-free glasses, specifically using the fusion process.
• Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates the "arsenic-free" characteristic of Claim 1(a) of US8640498 and the use of the "fusion process" from Claim 9. However, it is unlikely to teach the complete combination of specific compositional ratios, MgO content, SnO2 fining, and other detailed properties and inclusion levels claimed in US8640498.

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

• Full Citation: U.S. Pat. No. 5,824,127, "Method for producing arsenic-free glass sheets by the fusion process", Bange, K., Baumer, W., Glessgen, J., Lappe, G., Moeller, A., Schmalfuss, R., Siebers, W., (issued October 20, 1998).
• Publication Date: October 20, 1998 (Issue Date)
• Filing Date: December 21, 1995
• Brief Description: Similar to US6128924, this patent also describes processes for manufacturing arsenic-free glasses using the fusion process.
• Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates the "arsenic-free" characteristic of Claim 1(a) of US8640498 and the use of the "fusion process" from Claim 9. Similar to the other Bange et al. patents, it is unlikely to teach the full scope of the claimed invention in US8640498, particularly regarding the specific compositional ratios, fining methods, and defect levels.

Summary of Potential Anticipation:
The prior art broadly covers aspects such as the fusion process for glass sheet production (Dockerty patents) and glass compositions with high strain points (Dumbaugh et al., Chacon et al. patents). The Bange et al. and Dorfeld et al. patents focus on processes for manufacturing arsenic-free glasses. While these references individually disclose certain elements found in US8640498, none appear, based on their descriptions, to disclose the entire combination of elements as claimed in US8640498, particularly the specific Σ[RO]/[Al2O3] ratio, MgO content, the combined absence of substantial arsenic and antimony with the use of tin fining, and the resulting low gaseous inclusion levels and other specific physical properties (e.g., density, CTE, liquidus viscosity) within the precise ranges specified in the claims of US8640498. The most direct potential anticipation from these descriptions would be for process steps like "downdraw process" or "fusion process" and for general properties like "strain point greater than or equal to 650° C." or "arsenic-free glass".

US Patent 8640498, titled "Fining of boroalumino silicate glasses," concerns alkali-free glass compositions and methods for producing glass sheets for flat panel display devices, particularly active matrix liquid crystal displays (AMLCDs). The invention focuses on achieving effective fining (removal of gaseous inclusions) without using substantial amounts of arsenic or antimony, by carefully controlling the glass composition and employing tin oxide (SnO2) as a fining agent.

The key features of independent Claim 1 are:

• An alkali-free glass comprising SiO2, Al2O3, B2O3, MgO, and CaO (and optionally SrO, BaO).
• A method involving selecting, melting, and fining batch materials, followed by producing glass sheets via a downdraw process.
• Specific compositional characteristics:
  • Σ[RO]/[Al2O3] ratio greater than or equal to 1.0, where Σ[RO] is the sum of mole percents of MgO, CaO, SrO, and BaO.
  • MgO content greater than or equal to 1.0 mole percent.
• Specific fining agent characteristics:
  • At most 0.005 mole percent As2O3.
  • At most 0.005 mole percent Sb2O3.
  • SnO2 is used in fining, with an SnO2 content of at least 0.01 mole percent.
• A resulting glass with a liquidus viscosity greater than or equal to 100,000 poise.

Obviousness Analysis under 35 U.S.C. § 103

A person having ordinary skill in the art (POSA) in glass manufacturing for flat panel displays, at the time of the invention (priority date June 28, 2005), would have been motivated to combine several pieces of existing knowledge to arrive at the claimed invention.

Combination of Prior Art References and Motivation:

1. Baseline Glass and Forming Process:

   • U.S. Pat. Nos. 5,374,595 (Dumbaugh et al.) and 6,319,867 (Chacon et al.): These patents disclose alkali-free boroalumino silicate glasses exhibiting desirable properties like high strain points (e.g., in excess of 650° C.), which were known to be suitable for active plates based on thin film transistors (TFTs) in display applications. These references would provide a POSA with suitable base glass compositions.
   • U.S. Pat. Nos. 3,338,696 (Dockerty) and 3,682,609 (Dockerty): These patents describe the downdraw sheet drawing processes, particularly the fusion process, as a highly desirable method for producing glass sheets for substrates without requiring costly post-forming finishing operations. A POSA would understand that the fusion process imposes severe restrictions on glass properties, notably requiring relatively high liquidus viscosities, preferably greater than 100,000 poises.

   Motivation: A POSA would be motivated to combine the advantageous alkali-free boroalumino silicate glass compositions (Dumbaugh/Chacon) with the high-quality downdraw (fusion) manufacturing process (Dockerty) to produce substrates for AMLCDs. This combination establishes the need for a glass composition compatible with the downdraw process, specifically requiring a liquidus viscosity greater than or equal to 100,000 poise, and comprising the basic elements SiO2, Al2O3, B2O3, MgO, and CaO.

2. Elimination of Hazardous Fining Agents:

   • U.S. Pat. Nos. 5,785,726 (Dorfeld et al.), 6,128,924 (Bange et al.), 5,824,127 (Bange et al.), and co-pending patent application Ser. No. 11/116,669: These references disclose the ongoing efforts in the art to produce "substantially arsenic free" glasses due to environmental and health issues associated with arsenic. The patent itself also notes similar environmental and health issues with antimony, and that antimony is a "less effective" fining agent compared to arsenic.

   Motivation: Driven by these well-known environmental and health concerns, a POSA would be strongly motivated to develop glass compositions and manufacturing methods that eliminate or substantially reduce arsenic (to at most 0.005 mole percent As2O3) and antimony (to at most 0.005 mole percent Sb2O3) as fining agents.

3. Use of Tin Oxide as an Alternative Fining Agent:

   • Corning Incorporated Code 7059, 1737, and EAGLE 2000 glasses (and general knowledge in the art): The patent explicitly states that SnO2 was "a component of AMLCD glasses through the use of tin oxide electrodes in the Joule melting of the batch materials for such glasses." It also highlights that SnO2 "is a ubiquitous material which has no known hazardous properties." However, it acknowledges that "tin fining (i.e., SnO2 fining) is less effective" than As2O3 and Sb2O3 fining.

   Motivation: Given the strong motivation to eliminate arsenic and antimony (as discussed above), a POSA would naturally consider SnO2 as a primary alternative fining agent due to its non-hazardous nature and existing presence in AMLCD glass manufacturing. Despite its perceived lower effectiveness, the lack of toxicity would compel a POSA to explore its use, aiming for a concentration of at least 0.01 mole percent SnO2.

4. Optimizing Glass Composition for Enhanced Fining with SnO2:

   • Scientific Literature and General Knowledge of Glass Chemistry (e.g., M Taylor, G E Brown, P. McMillan, B. Piriou, A Navrotsky, K L Geisinger, G V Gibbs, and E M Levin, C R Robbins, H F McMurdie referenced in the patent): The patent itself explains that "the solubility of gases is comparatively high in aluminum-rich glasses and falls steeply as the Σ[RO]/[Al2O3] ratio increases beyond 1.00." It also notes that "In RO-rich systems, silica dissolution occurs at a comparatively low temperature, thus further inhibiting initial gas solubility." This fundamental understanding of glass chemistry would be known to a POSA.

   Motivation: Knowing that SnO2 is a "less effective" fining agent, a POSA would be motivated to optimize the base glass composition to improve its inherent fining capabilities, i.e., to reduce gas solubility. Drawing upon the known principles of glass chemistry, the POSA would understand that increasing the Σ[RO]/[Al2O3] ratio to be greater than or equal to 1.0 would lead to a steep fall in gas solubility, thereby making the fining process "easier to perform and more effective" even with less potent fining agents like SnO2.

   Motivation for MgO content: The patent states that MgO is "particularly important with regard to melting and fining" and provides benefits such as "lower density and CTE, and a higher chemical durability, strain point, and modulus." These are all desirable properties for AMLCD substrates. While the patent mentions a prior belief that MgO concentrations ≥ 1.0 mole percent "raised liquidus temperatures (lowered liquidus viscosities), thereby compromising high viscosity forming processes", a POSA would still be motivated to investigate MgO given its broad benefits. The patent's finding that "higher levels of MgO can be used, provided that simultaneously, the Σ[RO]/[Al2O3] ratio and SiO2 concentration are carefully controlled" suggests that overcoming the liquidus viscosity challenge at these MgO levels was achievable through routine optimization and careful control, which is within the skill set of a POSA, especially when seeking synergistic effects with the desired Σ[RO]/[Al2O3] ratio for improved fining.

Conclusion:
A POSA, motivated by the need for environmentally friendly fining in fusion-formable alkali-free boroalumino silicate glasses for AMLCDs, would combine:

1. Known alkali-free boroalumino silicate glass compositions suitable for AMLCDs (Dumbaugh/Chacon) and the downdraw process requiring high liquidus viscosity (Dockerty).
2. The clear motivation to eliminate arsenic and antimony fining agents (Dorfeld/Bange et al.).
3. The known non-hazardous nature and incidental presence of SnO2 in AMLCD glasses, leading to its selection as an alternative fining agent (Corning Code glasses).
4. The fundamental principles of glass chemistry regarding the relationship between Σ[RO]/[Al2O3] ratio and gas solubility (scientific literature/general knowledge), which would motivate increasing this ratio to ≥ 1.0 to enhance fining effectiveness.
5. The known benefits of MgO for various glass properties, leading to its inclusion at ≥ 1.0 mole percent, with the understanding that compatibility with downdraw processes would require careful compositional control and optimization.

This combination of known elements, driven by clear motivations to address known problems (hazardous fining, need for effective alternative fining, maintaining fusion compatibility), would render the method of Claim 1 obvious to a POSA. The resulting glass sheets would meet all the recited limitations, including being alkali-free, produced by a downdraw process, having the specified compositional ranges (SiO2, Al2O3, B2O3, MgO ≥ 1.0 mol%, CaO, Σ[RO]/[Al2O3] ≥ 1.0), containing at most 0.005 mol% As2O3 and Sb2O3, utilizing SnO2 (≥ 0.01 mol%) for fining, and possessing a liquidus viscosity ≥ 100,000 poise.

For US patent 8640498, the following details are provided:

Patent Term Adjustments (PTA) and Patent Term Extensions (PTE):
The provided patent information does not explicitly detail any Patent Term Adjustments (PTA) or Patent Term Extensions (PTE). However, the "Adjusted expiration" date of November 30, 2027, suggests that any such adjustments or extensions have already been factored into this date.

Continuation and Divisional Applications:
The application for US patent 8640498 (U.S. application Ser. No. 12/965,004, filed December 10, 2010) is a divisional of U.S. application Ser. No. 11/478,493, which was filed on June 28, 2006, and issued as U.S. Pat. No. 7,851,394.

Related Family Members:
The patent belongs to a family that includes several related applications and publications:

• Priority Applications: The application for US8640498 claims priority to U.S. Provisional Application Ser. No. 60/694,478, filed on June 28, 2005.
• Other U.S. Patents/Applications in the Family:
  • US7851394B2 (which originated from application US11/478,493)
  • US8642491B2 (Application US12/965,032)
  • US20110079049A1 (an earlier publication of the application that matured into US8640498B2)
• International Family Members: WO2007002865A1 is an international publication related to this patent family. Other countries listing family status include EP, JP, KR, CN, and TW.

Projected Expiration Date:
The patent US8640498 is currently active and has a projected expiration date of November 30, 2027.

Defensive Disclosure: Fining of Boroalumino Silicate Glasses - Derivative Works

This document details derivative works and technical disclosures related to US Patent 8640498, "Fining of boroalumino silicate glasses," with the objective of establishing prior art for potential future incremental improvements by competitors. The derivations are based on the core claims of the patent, specifically Claim 1, and explore variations across materials, operational parameters, cross-domain applications, integration with emerging technologies, and failure modes.

Core Claim Analyzed:

Claim 1: A method for producing alkali-free glass sheets by a downdraw process comprising:
(A) selecting, melting, and fining batch materials so that the glass making up the sheets comprises SiO2, Al2O3, B2O3, MgO, and CaO, and, on an oxide basis, has:
(i) a Σ[RO]/[Al2O3] ratio greater than or equal to 1.0, where [Al2O3] is the mole percent of Al2O3 and Σ[RO] is the sum of the mole percents of MgO, CaO, SrO, and BaO; and
(ii) a MgO content greater than or equal to 1.0 mole percent;
(B) producing the glass sheets from the melted and fined batch materials;
wherein:
(a) on an oxide basis, the glass making up the glass sheets comprises at most 0.005 mole percent As2O3;
(b) on an oxide basis, the glass making up the glass sheets comprises at most 0.005 mole percent Sb2O3;
(c) SnO2 is used in the fining and the glass making up the glass sheets has an SnO2 content which in mole percent on an oxide basis satisfies the relationship: 0.01≦SnO2; and
(d) the glass making up the glass sheets has a liquidus viscosity that is greater than or equal to 100,000 poise.

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Derivative 1: Material & Component Substitution - Cerium Oxide and Zinc Oxide Fining

Enabling Description: The method for producing alkali-free glass sheets by a downdraw process is modified to utilize a cerium oxide (CeO2) fining agent in conjunction with a zinc oxide (ZnO) flux. The batch materials are selected such that the final glass comprises, on an oxide basis: SiO2: 64.0-71.0 mole percent, Al2O3: 9.0-12.0 mole percent, B2O3: 7.0-12.0 mole percent, MgO: 1.0-3.0 mole percent, CaO: 6.0-11.5 mole percent, SrO: 0-2.0 mole percent, BaO: 0-0.1 mole percent, ZnO: 0.5-3.0 mole percent, and CeO2: 0.1-0.5 mole percent. The Σ[RO]/[Al2O3] ratio is maintained at greater than or equal to 1.0, and the MgO content is greater than or equal to 1.0 mole percent. The As2O3 and Sb2O3 concentrations are each at most 0.005 mole percent, specifically excluding their use as primary fining agents. The CeO2 acts as a fining agent through redox reactions (Ce3+/Ce4+), releasing oxygen bubbles at elevated temperatures to coalesce and remove gaseous inclusions. Concurrently, ZnO acts as a flux to lower the overall melting temperature and melt viscosity, thereby facilitating fining and compensating for any subtle differences in fining efficiency compared to SnO2. The resulting glass sheets, produced via the downdraw process, exhibit a liquidus viscosity greater than or equal to 100,000 poise, suitable for display applications.

graph TD
    A[Select Batch Materials] --> B{Add ZnO as Flux & CeO2 as Fining Agent}
    B --> C[Melt Batch Materials]
    C --> D[Fining Process (CeO2 Redox)]
    D --> E{Check Composition & Properties}
    E -- Σ[RO]/[Al2O3] >= 1.0, MgO >= 1.0 mol%, As2O3 <= 0.005 mol%, Sb2O3 <= 0.005 mol%, CeO2 0.1-0.5 mol%, ZnO 0.5-3.0 mol% --> F[Downdraw Process]
    F --> G[Produce Alkali-Free Glass Sheets]
    G -- Liquidus Viscosity >= 100,000 poise --> H[Final Product (Enhanced Fining)]

Derivative 2: Material & Component Substitution - Germanium Dioxide for Optical Tuning

Enabling Description: A method for producing alkali-free glass sheets by a slot-draw process (a type of downdraw) is utilized, wherein the batch materials are selected to include germanium dioxide (GeO2) as a partial substitute for silicon dioxide (SiO2). The resultant glass comprises on an oxide basis: SiO2: 50.0-60.0 mole percent, GeO2: 5.0-15.0 mole percent, Al2O3: 9.0-12.0 mole percent, B2O3: 7.0-12.0 mole percent, MgO: 1.0-3.0 mole percent, CaO: 6.0-11.5 mole percent, SrO: 0-2.0 mole percent, and BaO: 0-0.1 mole percent. The Σ[RO]/[Al2O3] ratio is maintained at greater than or equal to 1.0, and the MgO content is greater than or equal to 1.0 mole percent. Fining is performed using SnO2 at a concentration of 0.01-0.15 mole percent, ensuring As2O3 and Sb2O3 concentrations are each at most 0.005 mole percent. The inclusion of GeO2, known for its higher refractive index and lower dispersion compared to SiO2, allows for the tuning of the glass's optical properties while largely preserving its mechanical and thermal characteristics required for high-performance displays. The slot-draw process facilitates the production of thin, optically uniform sheets. The produced glass sheets exhibit a liquidus viscosity greater than or equal to 100,000 poise.

graph TD
    A[Select Batch Materials] --> B{Substitute GeO2 for part of SiO2}
    B --> C[Melt Batch Materials]
    C --> D[Fining Process (SnO2)]
    D --> E{Check Composition & Properties}
    E -- Σ[RO]/[Al2O3] >= 1.0, MgO >= 1.0 mol%, As2O3 <= 0.005 mol%, Sb2O3 <= 0.005 mol%, SnO2 >= 0.01 mol% --> F[Slot-Draw Process]
    F --> G[Produce Alkali-Free Glass Sheets (Optical Grade)]
    G -- Liquidus Viscosity >= 100,000 poise --> H[Final Product (Enhanced Optical Properties)]

Derivative 3: Operational Parameter Expansion - Micro-Scale Production with Ultra-High Vacuum Fining

Enabling Description: A method for producing alkali-free micro-glass sheets with a thickness less than 50 micrometers by a precision slot-draw process. This involves localized melting of the batch materials at a temperature exceeding 1700°C to ensure complete dissolution of SiO2, followed by rapid quenching to maintain the amorphous structure. The batch materials are selected to conform to the specified compositional ranges: SiO2: 64.0-71.0 mole percent, Al2O3: 9.0-12.0 mole percent, B2O3: 7.0-12.0 mole percent, MgO: 1.0-3.0 mole percent, CaO: 6.0-11.5 mole percent, SrO: 0-2.0 mole percent, BaO: 0-0.1 mole percent. The Σ[RO]/[Al2O3] ratio is maintained at greater than or equal to 1.0, and the MgO content is greater than or equal to 1.0 mole percent. Fining is accomplished using SnO2 (0.01-0.15 mole percent) under ultra-high vacuum conditions (e.g., 10^-5 Torr) during the melting phase. This vacuum fining actively extracts dissolved gases and reduces bubble nucleation, leading to exceptionally defect-free micro-glass sheets. As2O3 and Sb2O3 concentrations are each maintained at most 0.005 mole percent. The resulting micro-sheets possess a liquidus viscosity greater than or equal to 100,000 poise, enabling stable ultra-thin film formation for advanced micro-electronics.

graph TD
    A[Prepare Micro-Batch Materials] --> B{Melt at >1700°C in Ultra-High Vacuum}
    B --> C[Fining Process (SnO2 + Vacuum)]
    C --> D{Precision Slot-Draw}
    D --> E[Rapid Quenching]
    E --> F[Produce Alkali-Free Micro-Glass Sheets]
    F -- Thickness < 50 µm, Liquidus Viscosity >= 100,000 poise --> G[Final Product (Micro-electronics)]

Derivative 4: Operational Parameter Expansion - Continuous Large-Scale Production with Ultrasonic Fining

Enabling Description: A method for continuous, large-scale production of alkali-free glass sheets, specifically designed for Gen 10+ display substrates (e.g., 3000 mm × 3320 mm dimensions), using a fusion downdraw process. The melting system features a melter with a capacity exceeding 500 metric tons per day. The melting temperature is precisely controlled between 1600°C and 1650°C. Fining is significantly augmented by a combination of SnO2 (0.01-0.15 mole percent) and continuous ultrasonic cavitation applied within a dedicated refining zone of the melt. High-frequency ultrasonic transducers (e.g., >20 kHz) induce acoustic streaming and enhance the coalescence and rapid removal of microscopic gaseous inclusions. The glass composition adheres to SiO2: 64.0-71.0 mole percent, Al2O3: 9.0-12.0 mole percent, B2O3: 7.0-12.0 mole percent, MgO: 1.0-3.0 mole percent, CaO: 6.0-11.5 mole percent, SrO: 0-2.0 mole percent, BaO: 0-0.1 mole percent, with the Σ[RO]/[Al2O3] ratio greater than or equal to 1.0 and MgO content greater than or equal to 1.0 mole percent. As2O3 and Sb2O3 are present at concentrations of at most 0.005 mole percent each. The resulting glass maintains a liquidus viscosity greater than or equal to 100,000 poise, ensuring suitability for defect-free large format displays at high throughput.

graph TD
    A[Large-Scale Batch Preparation] --> B{Continuous Joule Melting (1600-1650°C)}
    B --> C[Fining with SnO2 + Ultrasonic Cavitation]
    C --> D{Fusion Downdraw (Gen 10+ Dimensions)}
    D --> E[Annealing & Cutting]
    E --> F[Produce Large Alkali-Free Glass Sheets]
    F -- High Throughput, Liquidus Viscosity >= 100,000 poise --> G[Final Product (Gen 10+ Display Substrates)]

Derivative 5: Cross-Domain Application - Photovoltaic Cover Glass

Enabling Description: A method for producing alkali-free glass sheets specifically adapted for use as high-transparency cover glass in photovoltaic solar panels, utilizing a downdraw process. The glass composition is precisely controlled within the specified ranges to enhance UV transmission properties and resist long-term environmental degradation, crucial for solar energy applications. The composition includes SiO2: 64.0-71.0 mole percent, Al2O3: 9.0-12.0 mole percent, B2O3: 7.0-12.0 mole percent, MgO: 1.0-3.0 mole percent, CaO: 6.0-11.5 mole percent, SrO: 0-2.0 mole percent, BaO: 0-0.1 mole percent. The Σ[RO]/[Al2O3] ratio is maintained at greater than or equal to 1.0, and the MgO content is greater than or equal to 1.0 mole percent. Fining is performed with SnO2 (0.01-0.15 mole percent), ensuring that As2O3 and Sb2O3 concentrations are each at most 0.005 mole percent to prevent any light absorption in the UV spectrum. The resulting glass sheets possess a liquidus viscosity greater than or equal to 100,000 poise, which is essential for uniform thickness and surface quality in the large-area glass required for cost-effective mass production of durable, highly transparent solar panel covers.

graph TD
    A[Select Batch Materials (Solar Grade, UV-optimized)] --> B[Melt & Fine (SnO2, low As/Sb)]
    B --> C{Downdraw Process}
    C --> D[Produce Alkali-Free Glass Sheets]
    D -- High UV Transparency, Environmental Durability, Liquidus Viscosity >= 100,000 poise --> E[Solar Panel Cover Glass]

Derivative 6: Cross-Domain Application - Medical/Laboratory Microscope Slides

Enabling Description: A method for producing alkali-free boroalumino silicate glass slides for high-precision microscopy and laboratory diagnostic applications. This involves an initial downdraw process to create a mother glass sheet, followed by a precision redraw process to achieve the final slide dimensions and thickness. The initial glass composition is fine-tuned for minimal auto-fluorescence under various excitation wavelengths and enhanced chemical resistance to a broad range of common laboratory reagents (acids, bases, organic solvents). The composition adheres to SiO2: 64.0-71.0 mole percent, Al2O3: 9.0-12.0 mole percent, B2O3: 7.0-12.0 mole percent, MgO: 1.0-3.0 mole percent, CaO: 6.0-11.5 mole percent, SrO: 0-2.0 mole percent, BaO: 0-0.1 mole percent. The Σ[RO]/[Al2O3] ratio is maintained at greater than or equal to 1.0, and the MgO content is greater than or equal to 1.0 mole percent. Fining uses SnO2 (0.01-0.15 mole percent), ensuring As2O3 and Sb2O3 concentrations are each at most 0.005 mole percent to minimize any intrinsic fluorescence. The primary downdrawn glass exhibits a liquidus viscosity greater than or equal to 100,000 poise, which is critical for enabling subsequent precision redraw into thin, high-quality, and dimensionally stable microscope slides.

graph TD
    A[Select Batch Materials (Low Auto-Fluorescence, Chemical Resistance)] --> B[Melt & Fine (SnO2, low As/Sb)]
    B --> C{Downdraw Process}
    C --> D[Initial Alkali-Free Glass Sheet]
    D -- Liquidus Viscosity >= 100,000 poise --> E[Precision Redraw Process]
    E --> F[Produce Alkali-Free Microscope Slides]
    F -- Minimal Auto-Fluorescence, High Chemical Resistance --> G[Medical/Lab Diagnostics]

Derivative 7: Integration with Emerging Tech - AI-Driven Real-time Optimization

Enabling Description: A method for producing alkali-free glass sheets by a downdraw process, wherein an AI-driven optimization system dynamically adjusts batch material selection, furnace temperature profiles, and fining parameters in real-time. IoT sensors, including high-temperature melt probes, optical defect detection systems, and spectroscopic analyzers, are embedded throughout the melting furnace and conditioning system. These sensors provide continuous feedback on melt temperature, viscosity, redox state, dissolved gas content, and real-time gaseous inclusion count. The AI model, leveraging machine learning algorithms trained on extensive historical production data and thermodynamic simulations, autonomously predicts and implements optimal adjustments to SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO concentrations (within specified ranges) and SnO2 fining agent levels (0.01-0.15 mole percent). The AI ensures the Σ[RO]/[Al2O3] ratio remains greater than or equal to 1.0, the MgO content greater than or equal to 1.0 mole percent, and minimal As2O3/Sb2O3 (at most 0.005 mole percent each). The system targets and maintains a consistent liquidus viscosity greater than or equal to 100,000 poise, proactively minimizing defect rates, reducing energy consumption, and optimizing material yield through continuous, data-driven process adjustments.

graph TD
    A[Batch Material Feedstock] --> B{IoT Sensors (Melt Temp, Viscosity, Redox, Inclusions)}
    B -- Real-time Data Stream --> C[AI Optimization Engine]
    C -- Dynamic Adjustments --> D[Melting & Fining System (SnO2)]
    D --> E{Downdraw Process}
    E --> F[Quality Control (Inline Sensors)]
    F --> G[Alkali-Free Glass Sheets]
    G -- Liquidus Viscosity >= 100,000 poise, Minimal Defects --> H[AI-Optimized Production]

Derivative 8: Integration with Emerging Tech - Blockchain for Supply Chain & Property Traceability

Enabling Description: A method for producing alkali-free glass sheets by a downdraw process, integrating blockchain technology to ensure transparent and immutable traceability of all raw material inputs and finished glass sheet properties. Each supplier of batch materials (SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, SnO2) records a cryptographically signed certificate of analysis, including precise compositional data and origin, onto a distributed ledger. Throughout the melting and fining process, real-time sensor data (e.g., furnace temperature, energy consumption, fining agent dosage, molten glass elemental analysis, and gaseous inclusion levels) and final quality control measurements (e.g., composition verification, liquidus viscosity, CTE, strain point) are automatically hashed and added as transactions to the blockchain. This distributed ledger provides an auditable and tamper-proof record, ensuring end-to-end verification that the glass meets all specified requirements, including the Σ[RO]/[Al2O3] ratio (greater than or equal to 1.0), MgO content (greater than or equal to 1.0 mole percent), low As2O3/Sb2O3 (at most 0.005 mole percent each), and liquidus viscosity (greater than or equal to 100,000 poise). This enhances supply chain integrity, regulatory compliance, and product authentication.

graph LR
    A[Raw Material Suppliers] -- CoAs via API --> B(Blockchain Ledger)
    C[Batch Preparation System] -- Composition Data --> B
    D[Melting & Fining (SnO2)] -- Real-time Sensor Data --> B
    E[Downdraw Process] --> F[Glass Sheet Production]
    F -- Final QC Data (Viscosity, CTE) --> B
    B -- Immutable Traceability --> G[Manufacturers / Consumers]
    G -- Verify: Σ[RO]/[Al2O3] >= 1.0, MgO >= 1.0 mol%, As/Sb <= 0.005 mol%, Liquidus Viscosity >= 100,000 poise --> H[Trust & Compliance]

Derivative 9: The "Inverse" or Failure Mode - Low-Power Maintenance Mode

Enabling Description: A method for producing alkali-free glass sheets by a downdraw process, incorporating a "low-power fining and holding mode" for energy conservation during periods of reduced demand, process hold points, or system maintenance. In this mode, the batch materials are continuously melted at a reduced temperature range (e.g., 1500°C - 1550°C), resulting in a slightly higher melt viscosity and slower dissolution rates. The concentration of the fining agent (SnO2) is reduced (e.g., 0.01-0.05 mole percent) or a less potent, yet environmentally friendly, auxiliary fining agent like SO3 (0.01-0.05 mole percent) is partially substituted for SnO2. This results in an intentionally higher, but acceptable, gaseous inclusion level (e.g., up to 0.5 inclusions/cm3) and a slightly lower liquidus viscosity (e.g., 50,000-90,000 poise), sufficient to maintain the melt in a workable state without full production quality. The fundamental compositional requirements for SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, and the Σ[RO]/[Al2O3] ratio (greater than or equal to 1.0) and MgO content (greater than or equal to 1.0 mole percent), as well as low As2O3/Sb2O3 (at most 0.005 mole percent each), are maintained to ensure material integrity and rapid ramp-up to full operational mode without requiring a complete cold start.

stateDiagram-v2
    [*] --> Startup: Initiate Process
    Startup --> Low_Power_Maintenance_Mode: Activate Low-Power for Efficiency/Hold
    Low_Power_Maintenance_Mode --> Full_Production_Mode: Ramp Up for Production
    Full_Production_Mode --> Low_Power_Maintenance_Mode: Transition to Standby
    Low_Power_Maintenance_Mode --> Shutdown: Terminate Process
    Low_Power_Maintenance_Mode : Reduced Temp (1500-1550°C)\nReduced SnO2/SO3 Fining\nHigher Inclusions (0.5/cm3 target)\nLiquidus Viscosity (50k-90k poise target)
    Full_Production_Mode : Optimal Temp (1600-1650°C)\nOptimal SnO2 Fining (>=0.01 mol%)\nLow Inclusions (<=0.05/cm3)\nLiquidus Viscosity (>=100k poise)

Derivative 10: The "Inverse" or Failure Mode - Automated Compositional Deviation Diversion

Enabling Description: A method for producing alkali-free glass sheets by a downdraw process, which incorporates an automated safe-failure mechanism to handle batch materials or molten glass that deviate from critical compositional specifications. An inline, real-time elemental analysis system (e.g., X-ray fluorescence (XRF) or Laser-Induced Breakdown Spectroscopy (LIBS)) continuously monitors the molten glass composition upstream of the downdraw process. If the analysis detects that the Σ[RO]/[Al2O3] ratio falls below 1.00 or the MgO content drops below 1.0 mole percent (which indicates a high probability of undesirable liquidus phases or inadequate fining efficacy, as described in the patent), the system automatically triggers a diversion of the off-specification molten glass stream to a dedicated waste collection and recycling system. This prevents the production of defective glass sheets and safeguards the downdraw forming equipment from potential damage due to crystallized glass. The fining process with SnO2 (0.01-0.15 mole percent) and adherence to minimal As2O3/Sb2O3 (at most 0.005 mole percent each) are maintained until the diversion point. The diverted waste glass can then be either re-batched after analysis or repurposed for less stringent applications.

flowchart LR
    A[Batch Material Feed] --> B{Melt & Fine}
    B --> C{Real-time Compositional Analysis (XRF/LIBS)}
    C -- Σ[RO]/[Al2O3] < 1.0 OR MgO < 1.0 mol% --> D{Divert to Waste System}
    D --> E[Waste Glass Collection/Recycling]
    C -- Σ[RO]/[Al2O3] >= 1.0 AND MgO >= 1.0 mol% --> F[Downdraw Process]
    F --> G[Quality Alkali-Free Glass Sheets]
    G -- Liquidus Viscosity >= 100,000 poise --> H[Final Product]

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Combination Prior Art Scenarios:

1. US8640498 + Open-Source CFD (Computational Fluid Dynamics) Software (e.g., OpenFOAM):

   • The method of US8640498 for producing alkali-free glass sheets with specific compositional and fining parameters is enhanced by employing open-source Computational Fluid Dynamics (CFD) software, such as OpenFOAM. This combination allows for sophisticated numerical modeling and simulation of the complex molten glass flow dynamics, heat transfer, and gaseous inclusion transport mechanisms within the melting furnace, fining zone, and downdraw forming apparatus. By integrating the patent's specific glass properties (e.g., liquidus viscosity, temperature-dependent viscosity profiles, gas solubilities based on Σ[RO]/[Al2O3] ratio) into the CFD model, engineers can virtually optimize furnace geometries, burner placements, fining agent (SnO2) injection strategies, and flow rates to predict and ensure uniform glass composition, minimized defects, and consistent liquidus viscosity, without costly physical prototyping. This approach enables a predictive understanding of the process from batch charging to sheet formation.

2. US8640498 + Open-Source Data Analytics Platform (e.g., Apache Spark with Zeppelin Notebooks):

   • The manufacturing process described in US8640498 is integrated with an open-source data analytics platform, specifically utilizing Apache Spark for distributed data processing and Zeppelin Notebooks for interactive data exploration and visualization. This system ingests vast amounts of real-time operational data from the glass production line, including batch material feed rates, melting furnace temperatures, energy consumption, SnO2 dosing levels, and inline quality control measurements (e.g., optical defect detection, viscosity sensors). Leveraging Spark's machine learning libraries, correlations are identified between subtle variations in raw material inputs (e.g., trace contaminants impacting As2O3/Sb2O3 levels), process parameters, and the resulting glass properties (e.g., Σ[RO]/[Al2O3] ratio, MgO content, actual liquidus viscosity, and gaseous inclusion levels). This platform facilitates continuous process improvement, anomaly detection, predictive maintenance, and ensures stringent adherence to the patent's compositional and physical property requirements for alkali-free glass sheets.

3. US8640498 + Open-Source Industrial Control System (e.g., OpenPLC or Node-RED with industrial protocols):

   • The method for producing alkali-free glass sheets by a downdraw process, as described in US8640498, is automated and controlled using an open-source industrial control system framework, such as OpenPLC or Node-RED. This system provides a flexible and modular approach to orchestrate the entire production line. OpenPLC can be programmed to manage the sequence and timing of batch material feeding, precise control of Joule heating electrodes to maintain specific melt temperatures (e.g., for optimal SiO2 dissolution and fining agent reactivity), and control of the downdraw machine's speed and tension to achieve desired sheet dimensions and liquidus viscosity. Node-RED can visually link sensors (e.g., temperature, flow, level sensors using Modbus TCP or OPC UA protocols) to actuators, implementing control logic that ensures the molten glass composition consistently meets the Σ[RO]/[Al2O3] ratio (greater than or equal to 1.0) and MgO content (greater than or equal to 1.0 mole percent), while strictly regulating SnO2 fining agent addition and minimizing undesirable As2O3/Sb2O3 levels to at most 0.005 mole percent each. This enables robust and adaptable automation of the glass manufacturing process.