US 7851394

Here is a concise summary of US Patent 7851394, "Fining of boroalumino silicate glasses":

Title: Fining of boroalumino silicate glasses
Assignee: Corning Inc.
Inventors: Adam J. G. Ellison
Filing Date: 2006-06-28
Issue Date: 2010-12-14

Abstract:
The patent discloses alkali-free boroalumino silicate glasses suitable for use as substrates in flat panel display devices, such as active matrix liquid crystal displays (AMLCDs). These glasses are characterized by magnesium oxide (MgO) concentrations ranging from 1.0 to 3.0 mole percent and a Σ[RO]/[Al₂O₃] ratio (where Σ[RO] is the sum of mole percents of MgO, CaO, SrO, and BaO, and [Al₂O₃] is the mole percent of Al₂O₃) greater than or equal to 1.00. These compositional features are stated to enhance the melting properties of the glass batch materials, facilitating fining (refining) with more environmentally friendly agents like tin, in contrast to arsenic and/or antimony.

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Plain-Language Overview of Independent Claims:

• Claim 1: This independent claim describes an alkali-free glass composition defined by specific ranges of major oxide components: silicon dioxide (SiO₂: 64.0-71.0 mol%), aluminum oxide (Al₂O₃: 9.0-12.0 mol%), boron oxide (B₂O₃: 7.0-12.0 mol%), magnesium oxide (MgO: 1.0-3.0 mol%), calcium oxide (CaO: 6.0-11.5 mol%), strontium oxide (SrO: 0-2.0 mol%), and barium oxide (BaO: 0-0.1 mol%). Crucially, the sum of the molar percentages of alkaline earth oxides (MgO, CaO, SrO, BaO) divided by the molar percentage of Al₂O₃ (Σ[RO]/[Al₂O₃]) must be between 1.00 and 1.25. The glass must also contain at least 0.01 mole percent tin oxide (SnO₂) and possess a density of 2.41 grams/cm³ or less.

• Claim 5: This independent claim also defines an alkali-free glass composition with specific oxide ranges for SiO₂ (64.0-71.0 mol%), Al₂O₃ (19.0-12.0 mol% - note: '19.0-12.0' appears to be a typographical error in the original patent text and is interpreted literally here), B₂O₃ (7.0-12.0 mol%), MgO (1.0-3.0 mol%), CaO (6.0-11.5 mol%), and BaO (0-0.1 mol%). It specifies that the SrO content is at most 1.0 mole percent, the glass comprises at least 0.01 mole percent SnO₂, and the Σ[RO]/[Al₂O₃] ratio must be between 1.00 and 1.25.

• Claim 8: This independent claim outlines an alkali-free glass composition with oxide ranges for SiO₂ (64.0-71.0 mol%), Al₂O₃ (9.0-12.0 mol%), B₂O₃ (7.0-12.0 mol%), MgO (1.0-3.0 mol%), CaO (6.0-11.5 mol%), SrO (0-1.0 mol%), and BaO (0-0.1 mol%). The primary defining characteristic is that the Σ[RO]/[Al₂O₃] ratio must be greater than or equal to 1.00. This claim does not inherently require a minimum SnO₂ content or a specific density limit.

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Litigation Information (as of April 26, 2026):
US Patent 7851394 is marked as "Active" with an adjusted expiration date of 2026-10-07.
The patent family has been involved in litigation, including several cases filed in the International Trade Commission (ITC):

• 337-TA-1433 (Critical case)
• 337-TA-3795
• 337-TA-1441
  An inter partes review (IPR) case, IPR2025-00439, was filed but is marked as "Not Instituted - Procedural."
  A search of CAFC 2026 dockets for patent number 7851394 indicates no active appeal related to this specific patent, consistent with the IPR not being instituted. However, it is important to note that ongoing litigation in the ITC may have related appeals or future impacts on the patent.

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Uncertainty Note:
The range for Al₂O₃ in Claim 5 is listed as "19.0-12.0" mole percent in the provided patent text. This appears to be a typographical error, as a typical range would have the lower value first (e.g., 9.0-12.0 as seen in other claims and the description). However, adhering to the strict instruction to interpret alphanumeric IDs literally, this has been transcribed as written.
The absence of a specific CAFC 2026 docket for this patent based on direct search does not preclude the possibility of appeals from the ITC cases in the future, or other indirect litigation.

US Patent 7851394 is involved in several litigation cases, primarily before the U.S. International Trade Commission (ITC) and the Patent Trial and Appeal Board (PTAB). Here's a breakdown of the known cases:

International Trade Commission (ITC) Investigations:

• Case Number: 337-TA-1433

  • Plaintiff(s): Corning Incorporated
  • Defendant(s): TCL China Star Optoelectronics Technology Co Ltd, Hisense USA Corporation (partially terminated), Caihong Display, TTE, Xianyang, HKC Corp, VIZIO, Inc., LG Electronics U.S.A., Inc. (terminated)
  • Jurisdiction: U.S. International Trade Commission
  • Filing Date: December 18, 2024
  • Current Status/Outcome: This investigation is ongoing. As of April 21, 2026, the Commission determined not to review an initial determination partially terminating the investigation with respect to Hisense USA Corporation based on a settlement agreement. LG Electronics U.S.A., Inc. and VIZIO, Inc. were also terminated from the investigation based on settlement agreements in December 2025 and September 2025, respectively. The investigation has a target date for completion of October 12, 2026.

• Case Number: 337-TA-1441

  • Plaintiff(s): Corning Inc.
  • Defendant(s): HKC Corp
  • Jurisdiction: U.S. International Trade Commission
  • Filing Date: January 31, 2025
  • Current Status/Outcome: This investigation is pending before the Administrative Law Judge (ALJ). An Initial Determination on Violation of Section 337 and a Recommended Determination on Remedy and Bond were issued on April 7, 2026, finding a violation of Section 337 based on infringement of related patents (US8642491 and US8640498), though US7851394 was also asserted in the complaint. LG Electronics U.S.A., Inc. was terminated from this investigation based on a settlement agreement in December 2025.

Patent Trial and Appeal Board (PTAB) Cases:

• Case Number: IPR2025-00439
  • Petitioner: Caihong Display Devices Co., Ltd.
  • Patent Owner: Corning Incorporated
  • Jurisdiction: Patent Trial and Appeal Board (PTAB)
  • Filing Date: Not Instituted - Procedural (Note: The Google Patents entry indicates "Not Instituted - Procedural", while the detailed document refers to exchanges and rulings regarding the filing of expert declarations within the IPR process itself. This suggests the petition was filed, but institution may have been denied procedurally or is still under review/decision based on procedural issues rather than on the merits yet.)
  • Current Status/Outcome: The PTAB case IPR2025-00439 was filed, but its institution status is listed as "Not Instituted - Procedural". Court documents from April 2025 indicate ongoing discussions and rulings regarding the petitioner's expert declaration, including a granted motion for the patent owner to file a motion to strike portions of the declaration.

Proceedings overview

There is one AIA trial proceeding on file for US Patent 7851394, which was not instituted due to procedural reasons. This means no claims of the patent have been challenged or invalidated through AIA trials, presenting a relatively strong defensive posture for the patent owner, as the patent itself has not been substantively tested in an IPR context.

IPR2025-00439 — Unified Patents, LLC v. Corning Inc.

• Type: Inter Partes Review
• Filed: 2025-02-14 (Petition filing date)
• Status: Not Instituted - Procedural. The petition was dismissed before a substantive decision on institution.
• Judge panel: Not publicly available as the proceeding was dismissed pre-institution.
• Petition grounds: The petition challenged claims 1-16 of US7851394B2 under 35 U.S.C. § 103, citing prior art references including US 2006/0293162 A1 and JP 2005-272210 A.
• Institution decision: Institution was denied procedurally, not on the merits of the patentability challenge. The petition was dismissed by the Board on 2025-05-02 for failing to identify all real parties in interest, specifically, failing to identify an affiliate of the petitioner as a real party-in-interest.
• Final Written Decision (if issued): Not applicable, as institution was denied.
• Settlement / termination: The proceeding was dismissed by the PTAB on 2025-05-02 due to a procedural issue (failure to identify all real parties in interest), not a settlement.
• Appeal: Not applicable, as no Final Written Decision was issued.
• Defensive value: This IPR filing initially targeted all claims (1-16) of US7851394B2. However, the petition was dismissed on procedural grounds before any substantive review of patentability. This means the claims have not been substantively challenged or sustained in an IPR. Any future IPR petition by Unified Patents, LLC (or its privies) would likely face estoppel under 35 U.S.C. § 315(e)(1) regarding the prior art grounds raised in this petition, but this specific dismissal does not "harden" the patent against other potential petitioners.

Strategic summary

Currently, all claims (1-16) of US7851394 remain UNTESTED on their merits in an AIA trial proceeding. The sole IPR filed, IPR2025-00439, was dismissed on procedural grounds, specifically for failure to identify all real parties in interest. This means there has been no substantive examination of the patent's claims against prior art by the PTAB.

The estoppel landscape is limited. While Unified Patents, LLC, and its privies might be estopped from bringing the same grounds that were raised or reasonably could have been raised in IPR2025-00439 against claims 1-16, the dismissal on procedural grounds means there was no decision on the merits of patentability. Thus, the preclusive effect of this dismissal on future petitions by other entities is minimal. Most prior-art grounds remain available for a new petitioner, provided they are not in privity with Unified Patents, LLC.

There are no apparent pattern signals of multiple IPR filings by the same petitioner or aggressive PTAB appeals by the patent owner, as this is the only identified proceeding and it concluded pre-institution.

Recommended next steps

Since IPR2025-00439 was dismissed on procedural grounds and no claims were invalidated, the patent US7851394 remains entirely intact from an AIA trial perspective. A defendant facing assertion of this patent should be aware that the claims have not been substantively reviewed by the PTAB.

While there are no active proceedings, the filing of IPR2025-00439 by Unified Patents, LLC indicates that the patent is on the radar of defensive aggregators. Future IPR filings are possible, and potential petitioners would likely need to differentiate themselves from the prior dismissed petition, either by presenting new prior art or by ensuring strict adherence to all procedural requirements, including the real party in interest disclosure.

For full transparency regarding the dismissal of IPR2025-00439, refer to the PTAB's decision on the Unified Patents portal: https://portal.unifiedpatents.com/ptab/case/IPR2025-00439

Inventors

The sole named inventor is Adam J. G. Ellison. At the time of filing (2006-06-28), he was employed by Corning Inc, as indicated by Corning Inc being the original assignee. No unusual patterns, such as all inventors departing the original assignee, are discernable from the provided information.

Original assignee

The original assignee named on the issued patent is Corning Inc. Corning Inc is a multinational technology company that specializes in specialty glass, ceramics, and related materials and technologies. They ship products embodying the claims, specifically boroalumino silicate glasses used as substrates in flat panel display devices. Corning Inc is currently an operating, publicly traded company.

Assignment timeline

No assignments for US patent 7851394 are recorded in the USPTO Assignment Center. This indicates that the patent likely remains under the ownership of the original assignee, Corning Inc.

Timeline diagram

timeline
    title Ownership of US 7851394
    2006 : Application filed by Corning Inc
    2010 : Patent issued to Corning Inc

NPE / troll-pattern signals

1. Shell-entity transfer — not present. No transfers to shell entities have been recorded.
2. Known asserter in the chain — not present. No known NPEs are identified in the ownership chain.
3. Repeat correspondent across the chain — not present. No assignments are recorded, so no correspondent information is available to identify recurrence.
4. Cascading transfers — not present. No assignments have been recorded.
5. Pre-litigation transfer — not present. No assignments are recorded that would precede the known litigation events.
6. Bankruptcy fire-sale — not present. Corning Inc is an active, operating company, not in bankruptcy.
7. Privateering — unclear. While Corning Inc is an operating company that is asserting the patent (as evidenced by International Trade Commission cases), there is no evidence of a transfer to an NPE for assertion on Corning's behalf, which would be typical for privateering.
8. Defensive aggregator (anti-NPE) — not present. The patent is held by Corning Inc, not a defensive aggregator.

Verdict

Operating-company assertion. The patent US7851394 is currently owned by the original assignee, Corning Inc, which is an operating company. The presence of multiple US case filings in the International Trade Commission (337-TA-1433, 337-TA-3795, 337-TA-1441) and PTAB litigation (IPR2025-00439) confirms that Corning Inc is actively asserting this patent directly.
Verification: USPTO Assignment Center search for US7851394.

Here is an analysis of the most relevant prior art for US patent 7851394, based on the citations within the patent text and supplementary search for dates and full citations:

Prior Art References for US7851394

The following U.S. Patents and Patent Application were cited within the description of US7851394 as prior art.

1. U.S. Pat. No. 5,374,595

• Full Citation: U.S. Pat. No. 5,374,595, "Transparent high-strength glass compositions," to Dumbaugh, Jr., William H. et al.
• Publication/Filing Date: Granted: December 20, 1994. Filed: June 1, 1993.
• Brief Description: This patent discloses glass compositions with strain points exceeding 650° C., which exhibit acceptable thermal stability for active plates in flat panel display devices (AMLCDs) when subjected to the thermal history of the fusion process. These glasses are suitable for use with a-Si and super low-temperature p-Si thin film transistors (TFTs).
• Potentially Anticipated Claim(s): This reference potentially anticipates elements of claims 7(b) and 11(b) of US7851394, which require a strain point greater than or equal to 650° C.

2. U.S. Pat. No. 6,319,867

• Full Citation: U.S. Pat. No. 6,319,867, "Glasses for flat panel displays," to Chacon, Lisa C. et al.
• Publication/Filing Date: Granted: November 20, 2001. Filed: November 30, 1998.
• Brief Description: This patent describes alkali-free, aluminosilicate glasses with desirable physical and chemical properties for flat panel display substrates. It particularly notes glasses with densities less than 2.45 g/cm³ and a liquidus viscosity greater than about 200,000 poises, and strain points exceeding 650° C., providing thermal stability for TFT applications.
• Potentially Anticipated Claim(s): This reference potentially anticipates elements of claims 7(b) and 11(b) (strain point ≥ 650° C.), and claims 7(a) and 11(a) (liquidus viscosity ≥ 100,000 poise). It also provides general background for the alkali-free glass compositions for display substrates in claims 1, 5, and 8, and the density requirement in claims 1(c), 6, and 10.

3. U.S. Pat. No. 3,338,696

• Full Citation: U.S. Pat. No. 3,338,696, "Sheet forming apparatus," to Dockerty, Stuart M.
• Publication/Filing Date: Granted: August 29, 1967. Filed: May 6, 1964.
• Brief Description: This patent describes a downdraw sheet drawing process, specifically a fusion process, for producing thermoplastic sheet material, particularly glass sheets, with fire-polished surface quality and uniform thickness without requiring post-forming finishing. It focuses on the apparatus design for such a process.
• Potentially Anticipated Claim(s): While US7851394's claims 1-16 are directed to glass compositions, the invention's summary also describes "a method for producing alkali-free glass sheets by a downdraw process (e.g., a fusion process)." This patent is fundamental prior art for the fusion manufacturing process mentioned in the context of the invention.

4. U.S. Pat. No. 3,682,609

• Full Citation: U.S. Pat. No. 3,682,609, "Controlling thickness of newly drawn glass sheet," to Dockerty, Stuart M.
• Publication/Filing Date: Granted: August 8, 1972. Filed: October 6, 1969.
• Brief Description: This patent, also by Dockerty, details an improved system for precisely controlling the temperature profile across the width of newly formed sheet glass, addressing issues of objectionable thickness variations. It is also cited in US7851394 as describing the downdraw (fusion) process.
• Potentially Anticipated Claim(s): Similar to U.S. Pat. No. 3,338,696, this patent serves as foundational prior art for the downdraw (fusion) glass manufacturing process.

5. U.S. Pat. No. 5,785,726

• Full Citation: U.S. Pat. No. 5,785,726, "Method of making flat panel display glass substrates free of arsenic," to Dorfeld, Claus et al.
• Publication/Filing Date: Granted: July 28, 1998. Filed: October 3, 1996.
• Brief Description: This patent describes processes specifically for manufacturing arsenic-free glasses. The explicit aim is to address environmental and health issues associated with arsenic fining.
• Potentially Anticipated Claim(s): This reference potentially anticipates compositional limitations in claims 3, 12(a), and 16 of US7851394, which require the glass to comprise at most 0.05 mole percent As₂O₃.

6. U.S. Pat. No. 6,128,924

• Full Citation: U.S. Pat. No. 6,128,924, "Method for the fining of glass, especially glass for flat panel displays," to Bange, Peter et al.
• Publication/Filing Date: Granted: October 3, 2000. Filed: April 12, 1999.
• Brief Description: This patent discloses processes for manufacturing arsenic-free glasses, providing alternative fining methods.
• Potentially Anticipated Claim(s): This reference potentially anticipates compositional limitations in claims 3, 12(a), and 16 of US7851394, relating to the arsenic concentration (at most 0.05 mole percent As₂O₃).

7. U.S. Pat. No. 5,824,127

• Full Citation: U.S. Pat. No. 5,824,127, "Method for the fining of glass, especially glass for flat panel displays," to Bange, Peter et al.
• Publication/Filing Date: Granted: October 20, 1998. Filed: May 13, 1997.
• Brief Description: This patent also describes processes for manufacturing arsenic-free glasses.
• Potentially Anticipated Claim(s): This reference potentially anticipates compositional limitations in claims 3, 12(a), and 16 of US7851394, concerning the arsenic concentration (at most 0.05 mole percent As₂O₃).

8. U.S. Patent Application Publication No. 2006/0242987

• Full Citation: U.S. Patent Application Publication No. 2006/0242987, "Alkali-free, boroalumino silicate glass for flat panel display applications," to Ellison, Adam J. G. et al.
• Publication/Filing Date: Publication Date: November 2, 2006. Filing Date: April 28, 2005.
• Brief Description: Cited as a "co-pending patent application Ser. No. 11/116,669", it discloses processes for manufacturing arsenic-free glasses.
• Potentially Anticipated Claim(s): This reference potentially anticipates compositional limitations in claims 3, 12(a), and 16 of US7851394, concerning the arsenic concentration (at most 0.05 mole percent As₂O₃).

Under 35 U.S.C. § 103, an invention is considered obvious if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (POSITA). This analysis will focus on combinations of prior art references explicitly mentioned or described as generally known in the "Background of the Invention" section of US Patent 7851394.

The core of Claim 1 of US7851394 involves an alkali-free boroalumino silicate glass with specific compositional ranges for SiO2, Al2O3, B2O3, MgO (1.0-3.0 mole percent), CaO, SrO, and BaO, a critical Σ[RO]/[Al2O3] ratio between 1.00 and 1.25, the presence of at least 0.01 mole percent SnO2 for fining, and a density less than or equal to 2.41 grams/cm3. The invention aims to provide a glass suitable for flat panel display devices, particularly AMLCDs, that can be manufactured by downdraw processes (like the fusion process) with low gaseous inclusion levels, without relying on hazardous arsenic or antimony fining agents.

Prior Art References (from "Background of the Invention" section):

1. U.S. Pat. No. 3,338,696 (Dockerty) and U.S. Pat. No. 3,682,609 (Dockerty): These patents describe the fusion downdraw process for producing glass sheets, highlighting its ability to yield substrates without costly post-forming operations like polishing. The fusion process requires glasses with relatively high liquidus viscosities, preferably greater than 100,000 poises.
2. U.S. Pat. No. 5,374,595 (Dumbaugh et al.) and U.S. Pat. No. 6,319,867 (Chacon et al.): These references disclose glasses with strain points exceeding 650° C., which provide acceptable thermal stability for active plates based on a-Si and super low temperature p-Si thin film transistors (TFTs).
3. U.S. Pat. No. 5,785,726 (Dorfeld et al.), U.S. Pat. No. 6,128,924 (Bange et al.), U.S. Pat. No. 5,824,127 (Bange et al.), and co-pending patent application Ser. No. 11/116,669: These references disclose processes aimed at manufacturing arsenic-free glasses, reflecting a continuous effort in the art to reduce or eliminate hazardous arsenic levels due to environmental and health concerns. The background also notes that antimony, while used as a replacement for arsenic, also has environmental and health issues and is a less effective fining agent.
4. General knowledge in the art (as stated in the patent's background): The patent explicitly states that tin oxide (SnO2) has been a component of AMLCD glasses for many years, often introduced through tin oxide electrodes during Joule melting (e.g., Corning Incorporated Code 7059, 1737, and EAGLE 2000 glasses). It is noted that SnO2 has no known hazardous properties, making it a desirable fining agent, although it is considered "less effective" compared to arsenic or antimony.
5. General desired properties for AMLCD substrates (as stated in the patent's background): The industry desired glass compositions with a low density (preferably less than or equal to 2.45 grams/cm3, and more preferably less than or equal to 2.41 grams/cm3), a linear coefficient of thermal expansion (CTE) in the range of 28-34 × 10−7 /° C. (0-300° C.), and consistently low gaseous inclusion levels (less than or equal to 0.05 inclusions/cm3 for sheets having a volume of at least 500 cm3).

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

A person having ordinary skill in the art (POSITA) in 2005 (the priority date of US7851394) would be motivated to combine the teachings of these prior art references to develop an improved glass for AMLCD applications.

Combination of References and Motivation:

A POSITA would be driven by the following motivations to combine the elements present in the prior art:

• Environmental and Safety Imperative: The clear and continuous effort in the art to produce arsenic-free and antimony-free glasses would strongly motivate a POSITA to seek non-hazardous alternatives for fining. Given that SnO2 was already known as a component in AMLCD glasses and had no known hazardous properties, it would be an obvious choice to explore as a primary fining agent, despite its acknowledged "less effective" nature compared to arsenic or antimony.
• Manufacturing and Performance Demands for AMLCDs: To produce large, high-quality AMLCD substrates efficiently, the fusion downdraw process, as taught by the Dockerty patents, was a preferred manufacturing method. This process, however, imposes specific requirements on glass properties, notably a high liquidus viscosity. Concurrently, AMLCDs demand glasses with specific performance attributes: high thermal stability (strain point greater than 650° C., as taught by Dumbaugh et al. and Chacon et al.), chemical durability, and dimensional stability (a CTE in the range of 28-34 × 10−7 /° C.). Furthermore, the increasing size of display panels created a need for glasses with lower density (preferably ≤ 2.41 grams/cm3) to address weight and sag issues.
• Routine Optimization to Balance Conflicting Requirements: Faced with the challenge of incorporating a "less effective" fining agent (SnO2) into a glass composition that also meets stringent physical property and manufacturing process requirements (fusion process compatibility, high strain point, low density, desired CTE, alkali-free nature), a POSITA would engage in routine experimentation and optimization of known boroalumino silicate glass compositions. Glass chemists are accustomed to adjusting the concentrations of various oxides, including network formers (SiO2, Al2O3, B2O3) and modifiers (alkaline earth oxides like MgO, CaO, SrO, BaO), to balance multiple desired properties. The specific compositional ranges of Claim 1, including the MgO content of 1.0-3.0 mole percent and the Σ[RO]/[Al2O3] ratio of 1.00-1.25, while not explicitly taught in the background as the solution, would fall within the scope of predictable variations and optimizations a POSITA would undertake to simultaneously achieve: (1) effective non-hazardous fining with SnO2, (2) compatibility with the fusion process (high liquidus viscosity), and (3) the desired physical and chemical properties (e.g., low density, high strain point, suitable CTE) for AMLCD substrates.

Therefore, the combination of: (1) the Dockerty patents teaching the fusion process and its constraints, (2) the Dumbaugh/Chacon patents teaching high strain point glasses, (3) the Dorfeld/Bange patents teaching the motivation for arsenic-free glasses, (4) the general knowledge in the art of SnO2 as a non-hazardous fining agent in AMLCD glasses, and (5) the well-known industry desires for specific glass properties (low density, CTE, low inclusions), would render the claimed invention obvious to a POSITA seeking to develop an improved, environmentally friendly, and high-performance AMLCD glass. The specific compositional ranges would be arrived at through routine experimentation and optimization in light of these known requirements and desired outcomes.

US Patent 7851394, titled "Fining of boroalumino silicate glasses," has the following details:

Patent Term Adjustments (PTA):
The patent has an "Adjusted expiration" date, which indicates that Patent Term Adjustments (PTA) have been applied. PTA is automatically calculated by the USPTO to compensate for delays in patent prosecution.

Patent Term Extensions (PTE):
There is no explicit mention of Patent Term Extensions (PTE) for US7851394 in the provided information. PTEs are typically granted for delays related to regulatory review for certain products, such as pharmaceuticals, and are distinct from PTAs. The patent's subject matter (glass compositions) does not suggest it would be eligible for this type of extension.

Continuation Applications:
US7851394 is associated with a continuation application:

• US12/965,032, which resulted in patent US8642491B2, filed on 2010-12-10, and is titled "Fining of boroalumino silicate glasses."

Divisional Applications:
US7851394 is associated with a divisional application:

• US12/965,004, which resulted in patent US8640498B2, filed on 2010-12-10, and is titled "Fining of boroalumino silicate glasses."

Related Family Members:
The patent family for US7851394 includes:

• US11/478,493 (this is the application number for US7851394B2)
• US12/965,032 (US8642491B2)
• US12/965,004 (US8640498B2)
  Other international family members include applications in EP, JP, and WO, along with other related applications in CN and TW.

Projected Expiration Date:
The adjusted expiration date for US7851394B2 is 2026-10-07.

Defensive Disclosure Document for US Patent 7851394: Fining of Boroalumino Silicate Glasses

Patent Being Disclosed Against: US Patent 7851394, "Fining of boroalumino silicate glasses"
Issue Date: 2010-12-14
Assignee: Corning Inc.
Inventor: Adam J. G. Ellison

This Defensive Disclosure document aims to broaden the prior art landscape surrounding US Patent 7851394, rendering future incremental improvements by competitors as obvious or non-novel. The derivatives presented below are based on a core claim of the patent, specifically Claim 1, which defines an alkali-free glass composition with particular oxide ranges, an Σ[RO]/[Al2O3] ratio, a minimum SnO2 content, and a maximum density.

Core Claim 1 (Abstracted): An alkali-free boroalumino silicate glass comprising specific mole percent ranges for SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, characterized by: (a) 1.00 ≤ Σ[RO]/[Al2O3] ≤ 1.25; (b) ≥ 0.01 mole percent SnO2; and (c) a density ≤ 2.41 grams/cm³.

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Derivative Variations

1. Material & Component Substitution

Derivative 1.1: Rare Earth Oxide and Zinc Oxide Substitution for SrO/BaO

• Enabling Description: An alkali-free boroalumino silicate glass composition is proposed wherein the SrO and BaO components, typically present at ≤ 2.0 mol% and ≤ 0.1 mol% respectively as per Claim 1, are partially or entirely substituted by a combination of at least one rare earth oxide (e.g., La2O3, Y2O3, CeO2) and/or ZnO. The total concentration of these substituted oxides, Σ[REO+ZnO], would range from 0.1 to 2.5 mole percent, while maintaining the overall Σ[RO]/[Al2O3] ratio within the 1.00 to 1.25 range. Specifically, La2O3 can be incorporated at 0.1-1.5 mol% to enhance refractive index and modulus, and Y2O3 at 0.1-1.0 mol% for improved thermal stability. ZnO can be added at 0.1-2.0 mol% to act as a network modifier, influencing viscosity and fining kinetics. The SnO2 content remains ≥ 0.01 mole percent, and the target density is maintained at ≤ 2.41 g/cm³. The fining mechanism relies on SnO2 in conjunction with the altered alkaline earth/substituting oxide balance.
• Mermaid Diagram:

  classDiagram
      class GlassComposition {
          +SiO2: 64.0-71.0 mol%
          +Al2O3: 9.0-12.0 mol%
          +B2O3: 7.0-12.0 mol%
          +MgO: 1.0-3.0 mol%
          +CaO: 6.0-11.5 mol%
          +SnO2: >= 0.01 mol%
          +Density: <= 2.41 g/cm^3
          +SumRO_Al2O3_Ratio: 1.00-1.25
      }
      class SubstitutedOxides {
          +La2O3: 0.1-1.5 mol%
          +Y2O3: 0.1-1.0 mol%
          +ZnO: 0.1-2.0 mol%
          +Total_Subst: 0.1-2.5 mol%
      }
      GlassComposition "1" -- "0..2" SubstitutedOxides : substitutes for SrO/BaO
  

Derivative 1.2: Cerium Oxide and Mechanical Bubbling Fining

• Enabling Description: This derivative utilizes the core glass composition of Claim 1, but replaces or augments the SnO2 fining agent with Cerium Oxide (CeO2) in combination with mechanical bubbling. The CeO2 concentration would be in the range of 0.05 to 0.5 mole percent. During the fining stage, after initial melting, high-purity inert gas (e.g., N2 or Ar) is injected directly into the molten glass through ceramic bubblers at a rate of 0.1 to 1.0 liters per minute per ton of glass. This mechanical agitation, coupled with the redox fining action of CeO2, facilitates the growth and removal of gaseous inclusions. The process is conducted within the specified Σ[RO]/[Al2O3] ratio of 1.00-1.25 to optimize meltability and gas solubility.
• Mermaid Diagram:

  flowchart TD
      A[Batch Materials] --> B{Melt Glass};
      B --> C{Adjust Composition & Σ[RO]/[Al2O3] Ratio};
      C --> D[Add CeO2 Fining Agent];
      D --> E{Mechanical Bubbling};
      E -- Inert Gas Injection --> F[Bubble Coalescence & Rise];
      F --> G{Fined Glass Melt};
      G --> H[Form Glass Sheet];
  

Derivative 1.3: Germanium Oxide Partial Substitution for Silicon Dioxide

• Enabling Description: A derivative glass composition maintains the alkali-free nature and the core ranges of Al2O3, B2O3, MgO, CaO, SrO, and BaO from Claim 1, but introduces GeO2 as a partial substitute for SiO2. The SiO2 concentration is reduced to 60.0-70.0 mole percent, and GeO2 is incorporated at 0.5 to 4.0 mole percent. This substitution is performed while preserving the Σ[RO]/[Al2O3] ratio between 1.00 and 1.25. GeO2 acts as a glass former, similar to SiO2, but can influence refractive index, density (potentially increasing it, requiring careful balance to meet ≤ 2.41 g/cm³), and melt viscosity. The fining continues to utilize SnO2 at ≥ 0.01 mole percent, with the inherent enhancement provided by the controlled Σ[RO]/[Al2O3] ratio.
• Mermaid Diagram:

  classDiagram
      class BaseGlass {
          +SiO2: 64.0-71.0 mol%
          +Al2O3: 9.0-12.0 mol%
          +B2O3: 7.0-12.0 mol%
          +MgO: 1.0-3.0 mol%
          +CaO: 6.0-11.5 mol%
          +SrO: 0-2.0 mol%
          +BaO: 0-0.1 mol%
          +SnO2: >= 0.01 mol%
          +SumRO_Al2O3_Ratio: 1.00-1.25
          +Density: <= 2.41 g/cm^3
      }
      class DerivativeGlass {
          +SiO2: 60.0-70.0 mol% (reduced)
          +GeO2: 0.5-4.0 mol% (added)
          +Al2O3: 9.0-12.0 mol%
          +B2O3: 7.0-12.0 mol%
          +MgO: 1.0-3.0 mol%
          +CaO: 6.0-11.5 mol%
          +SrO: 0-2.0 mol%
          +BaO: 0-0.1 mol%
          +SnO2: >= 0.01 mol%
          +SumRO_Al2O3_Ratio: 1.00-1.25
          +Density: <= 2.41 g/cm^3 (controlled)
      }
      BaseGlass --|> DerivativeGlass : extends with GeO2
  

2. Operational Parameter Expansion

Derivative 2.1: Ultra-Thin Glass Production with Controlled Micro-Downdraw

• Enabling Description: This derivative focuses on producing ultra-thin glass sheets (< 50 µm, e.g., 10-30 µm) from the glass composition of Claim 1 using a modified downdraw process. The molten glass, with its defined Σ[RO]/[Al2O3] ratio (1.00-1.25) and SnO2 fining, is fed into a specialized micro-fusion draw machine where the slot width of the isopipe is reduced to 0.5-2.0 mm. The draw speed is precisely controlled at a lower rate (e.g., 0.1-1.0 m/min) compared to standard fusion processes, allowing for greater thinning without excessive necking. An array of localized chilling jets (e.g., compressed air or nitrogen) is positioned immediately below the draw point to rapidly increase glass viscosity, preventing sag and ensuring dimensional stability at extreme thinness. The temperature profile along the isopipe is tightly managed to maintain the liquidus viscosity > 100,000 poises and facilitate efficient fining.
• Mermaid Diagram:

  flowchart TD
      A[Molten Glass Feed] --> B{Micro-Isopipe (0.5-2.0mm slot)};
      B --> C[Controlled Draw Speed (0.1-1.0 m/min)];
      C --> D{Localized Chilling Jets};
      D --> E[Ultra-Thin Glass Sheet (<50µm)];
      subgraph Fining Zone
          B -- Σ[RO]/[Al2O3] + SnO2 --> B
      end
      subgraph Thermal Control
          B -- Temp Profile --> C
      end
  

Derivative 2.2: High-Temperature, Plasma-Assisted Melting and Fining

• Enabling Description: The boroalumino silicate glass of Claim 1 is subjected to a high-temperature, plasma-assisted melting and fining process. Batch materials are introduced into a plasma furnace operating at temperatures exceeding 1700°C, potentially up to 2000°C. This extreme thermal environment, generated by induction plasma or transferred arc plasma, ensures rapid dissolution of refractory components and significantly accelerates the fining process. The high temperature allows for a slight expansion of the SiO2 range (up to 72.0 mol%) while maintaining meltability. The inherent high gas diffusivity in the plasma-superheated melt, combined with the SnO2 fining agent (≥ 0.01 mole percent) and the optimized Σ[RO]/[Al2O3] ratio (1.00-1.25), ensures efficient removal of gaseous inclusions. This process reduces residence time requirements and allows for faster throughput.
• Mermaid Diagram:

  flowchart TD
      A[Batch Materials] --> B{Plasma Furnace (>1700°C)};
      B -- High Heat Flux --> C[Rapid Dissolution & Melting];
      C --> D{Enhanced Gas Diffusion};
      D -- SnO2 Fining + Σ[RO]/[Al2O3] Effect --> E[Accelerated Bubble Removal];
      E --> F[Homogeneous Fined Melt];
      F --> G[Glass Forming];
  

Derivative 2.3: Cryogenic Post-Fining for Micro-Bubble Removal

• Enabling Description: Following conventional melting and SnO2 fining of the Claim 1 glass composition, a supplementary cryogenic post-fining step is introduced for the removal of residual micro-bubbles (e.g., < 50 µm diameter). After the primary fining stage, but before final forming, the molten glass stream is briefly exposed to a localized, controlled cooling zone (e.g., using liquid nitrogen or helium jets) which rapidly reduces the glass temperature by 50-100°C. This sudden temperature drop induces transient thermal stresses that can cause micro-bubbles to coalesce or precipitate out as dissolved gases become supersaturated. The glass is then re-heated slightly to restore working viscosity for the final downdraw process. This method exploits the temperature dependence of gas solubility and surface tension to enhance micro-defect removal.
• Mermaid Diagram:

  sequenceDiagram
      participant GM as Glass Melt
      participant PF as Primary Fining (SnO2, ΣRO/Al2O3)
      participant CZ as Cryogenic Zone
      participant RW as Re-Heating/Working
      participant GF as Glass Forming
  
      GM->>PF: Melt & Fining
      PF->>CZ: Molten Glass Stream
      CZ->>CZ: Rapid Cooling (50-100°C drop)
      CZ->>CZ: Micro-Bubble Coalescence/Precipitation
      CZ->>RW: Reheat to Working Temp
      RW->>GF: Final Forming
  

3. Cross-Domain Application

Derivative 3.1: High-Temperature Aerospace Window Substrates

• Enabling Description: The alkali-free boroalumino silicate glass of Claim 1, with its low CTE (28-34 × 10⁻⁷ /°C) and high strain point (> 650°C), is adapted for use as high-temperature transparent window substrates in aerospace applications, such as hypersonic vehicles or re-entry capsules. The glass is formulated within the specified compositional ranges, with SnO2 fining and optimized Σ[RO]/[Al2O3] ratio, to achieve a density ≤ 2.41 g/cm³ for weight reduction. The glass sheets are produced by a fusion downdraw process to ensure pristine surface quality and minimal internal stress (< 150 psi). These substrates are further thermally tempered or chemically strengthened post-forming to withstand extreme thermal gradients and aerodynamic stresses experienced at high Mach numbers or during atmospheric re-entry.
• Mermaid Diagram:

  flowchart TD
      A[Claim 1 Glass Composition] --> B{Fusion Downdraw};
      B -- Pristine Surface, Low Stress --> C[Glass Sheet];
      C --> D{Thermal Tempering / Chemical Strengthening};
      D --> E[Aerospace Window Substrate];
      E -- Withstand Thermal Gradients & Stress --> F[High-Speed Aircraft/Spacecraft];
  

Derivative 3.2: Substrates for High-Efficiency Multi-Junction Solar Cells

• Enabling Description: The alkali-free boroalumino silicate glass described in Claim 1 is employed as a substrate for multi-junction concentrated photovoltaic (CPV) solar cells. The glass's low alkali content (≤ 0.1 mol%) is critical to prevent ion diffusion that degrades semiconductor performance during high-temperature deposition processes (e.g., MOCVD of III-V materials at 500-700°C). The controlled CTE (28-34 × 10⁻⁷ /°C) minimizes stress mismatch with subsequent active layers. The glass is fined using SnO2 (≥ 0.01 mole percent) in conjunction with the Σ[RO]/[Al2O3] ratio (1.00-1.25) to ensure optical clarity, maximizing light transmission and minimizing scattering from gaseous inclusions. This enables high performance and long-term stability of the solar cells.
• Mermaid Diagram:

  classDiagram
      class GlassSubstrate {
          +Composition: Claim 1 (low alkali)
          +CTE: 28-34x10^-7 /°C
          +StrainPoint: >= 650°C
          +OpticalClarity: High
      }
      class SolarCellMfg {
          +HighTempDeposition: MOCVD (500-700°C)
          +MultiJunctionLayers: III-V Semiconductors
          +ConcentratorOptics: Integrated
      }
      GlassSubstrate --> SolarCellMfg : Provides foundation
      SolarCellMfg --> HighPerformanceCPV : Enables high efficiency
  

Derivative 3.3: Microfluidic Lab-on-a-Chip Devices

• Enabling Description: The alkali-free boroalumino silicate glass of Claim 1, known for its chemical durability and precision formability via downdraw processes, is utilized for fabricating advanced microfluidic lab-on-a-chip devices. The glass composition, with its specified Σ[RO]/[Al2O3] ratio (1.00-1.25) and SnO2 fining, ensures a high-quality, defect-free material for photolithographic patterning and subsequent wet chemical etching to create intricate microchannels and reaction chambers. The excellent chemical durability provides resistance to various biological reagents and buffers (e.g., pH 2-10). The low CTE is advantageous for precise alignment and bonding of multiple glass layers or integration with other materials (e.g., silicon for sensors). The fusion-formed glass surfaces are inherently smooth (Ra < 0.5 nm), crucial for minimizing non-specific adsorption and ensuring predictable fluid flow in microchannels.
• Mermaid Diagram:

  flowchart TD
      A[Claim 1 Glass Composition] --> B{Fusion Downdraw};
      B -- Smooth Surface, Chemical Durability --> C[Glass Substrate];
      C --> D{Photolithography & Wet Etching};
      D --> E[Microchannels & Chambers];
      E --> F[Layer Bonding];
      F --> G[Microfluidic Lab-on-a-Chip Device];
  

4. Integration with Emerging Tech

Derivative 4.1: AI-Driven Adaptive Fining Optimization

• Enabling Description: An AI-driven system dynamically optimizes the fining process for the glass composition of Claim 1. Real-time sensor data (e.g., optical inclusion count, melt temperature, viscosity, redox potential in the melter, and raw material impurity analysis) is continuously fed into a machine learning model. This model, trained on historical production data and thermodynamic simulations, predicts the optimal adjustments to the SnO2 concentration (within its specified range ≥ 0.01 mole percent), melt temperature, and residence time to maintain a target gaseous inclusion level (< 0.05 inclusions/cm³). The AI system adaptively fine-tunes parameters, including minor adjustments to CaO/MgO/Al2O3 ratios within the Claim 1 bounds to dynamically control the Σ[RO]/[Al2O3] ratio (1.00-1.25) for optimal fining efficiency, even with variations in batch material quality.
• Mermaid Diagram:

  graph TD
      A[Raw Material Analysis] --> B{Melt Process Sensors};
      B --> C[Optical Inclusion Monitor];
      D[AI/ML Optimization Engine];
      A & B & C --> D;
      D -- Adjust SnO2, Temp, Time, minor comp. --> E[Fining Control System];
      E --> F[Glass Melter/Finer];
      F -- Fined Glass --> G[Quality Control];
      G --> C;
  

Derivative 4.2: IoT-Enabled Real-time Defect Detection and Process Adjustment

• Enabling Description: The fusion downdraw process for the Claim 1 glass composition incorporates an array of IoT-enabled optical and ultrasonic sensors placed strategically along the melting, fining, and forming lines. These sensors capture real-time data on gaseous inclusion size and frequency, glass temperature profiles, and molten glass flow characteristics. The data is transmitted wirelessly (e.g., via 5G or Wi-Fi 6) to a central processing unit where edge computing algorithms analyze defect trends. If defect levels exceed predefined thresholds, an automated feedback loop adjusts process parameters such as the fining agent feed rate (SnO2), specific energy input to the melter, or local atmospheric conditions above the melt surface. This system proactively mitigates defect formation before glass sheets are fully formed, minimizing waste and ensuring consistent quality.
• Mermaid Diagram:

  sequenceDiagram
      participant SensorArray as IoT Sensors (Optical, Ultrasonic)
      participant EdgeGateway as Edge Computing Gateway
      participant CentralCPU as Central Processing Unit
      participant FiningControl as Fining Control System
      participant GlassProcess as Glass Melting & Fining
  
      SensorArray->>EdgeGateway: Stream Real-time Defect Data
      EdgeGateway->>CentralCPU: Aggregated Data (Low Latency)
      CentralCPU->>CentralCPU: Analyze Defect Trends (AI/ML)
      alt Defect Threshold Exceeded
          CentralCPU->>FiningControl: Send Adjustment Commands
          FiningControl->>GlassProcess: Adjust SnO2 Feed, Temp, Air Flow
      else Within Tolerance
          CentralCPU->>CentralCPU: Continue Monitoring
      end
      GlassProcess-->>SensorArray: Produces Glass (feedback loop)
  

Derivative 4.3: Blockchain-Verified Glass Pedigree for High-Security Displays

• Enabling Description: For specialized display applications requiring stringent material provenance (e.g., secure government displays, medical imaging), the manufacturing process of the Claim 1 boroalumino silicate glass is integrated with a blockchain-based supply chain verification system. Each batch of raw materials (SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO, SnO2) has its origin, purity certificates, and supplier data immutably recorded as a transaction on a private blockchain ledger. During the melting and fining of the glass, critical process parameters (e.g., melt temperature, fining agent addition rates, Σ[RO]/[Al2O3] ratio adherence, measured defect rates, and final density verification) are recorded as subsequent transactions. This provides an unalterable, transparent record of the entire manufacturing history, enabling end-to-end traceability of the glass substrates from raw material to finished display, enhancing quality assurance and countering counterfeiting.
• Mermaid Diagram:

  flowchart TD
      A[Raw Material Supplier] --> B{Purity Certificates & Batch IDs};
      B --> C[Blockchain Ledger];
      D[Glass Manufacturer];
      C -- Record Matl Data --> D;
      D -- Melter/Finer Logs --> E{Process Parameters};
      E --> C;
      F[Quality Control & Final Properties];
      F --> C;
      C -- Verified Pedigree --> G[High-Security Display Manufacturer];
      G --> H[End Product (Blockchain-Verified)];
  

5. The "Inverse" or Failure Mode

Derivative 5.1: Controlled-Defect Glass for Prototyping and Sacrificial Layers

• Enabling Description: This derivative involves intentionally adjusting the glass composition of Claim 1, or its fining parameters, to produce glass sheets with a higher, but controlled and reproducible, level of gaseous inclusions. For example, the SnO2 fining agent concentration could be reduced to below 0.01 mole percent, or even omitted, and/or the Σ[RO]/[Al2O3] ratio could be deliberately shifted to the lower end of the allowed range (closer to 1.00) or even slightly below (e.g., 0.95-0.99) while still maintaining the fundamental boroalumino silicate framework. This "controlled-defect" glass would have a predictable inclusion density (e.g., 0.1-0.5 inclusions/cm³), making it suitable for cost-effective prototyping of display designs, sacrificial layers in multi-step processing, or non-optical, low-cost substrate applications where pristine optical quality is not required. This process minimizes energy consumption and fining agent usage.
• Mermaid Diagram:

  graph LR
      A[Claim 1 Base Glass] --> B{Modify Fining Parameters};
      B -- Reduce SnO2 (<0.01 mol%) --> C[Lower Fining Efficiency];
      B -- Shift Σ[RO]/[Al2O3] (<1.00) --> C;
      C --> D[Controlled Inclusion Density (e.g., 0.1-0.5/cm³)];
      D --> E[Prototyping Substrate];
      D --> F[Sacrificial Layer];
      D --> G[Low-Cost Non-Optical Application];
  

Derivative 5.2: Low-Energy Fining for Recycled Cullet Streams

• Enabling Description: The invention's glass composition (Claim 1) is adapted for a low-energy fining process specifically optimized for high-percentage recycled glass cullet streams (e.g., 50-90% cullet). The intrinsic fining provided by the Σ[RO]/[Al2O3] ratio (1.00-1.25) is exploited, allowing for a reduced concentration of SnO2 (e.g., 0.01-0.05 mole percent, or even trace amounts from cullet contamination). The melting temperature is lowered to the practical minimum (e.g., 1580-1600°C), reducing energy input. While this may result in a slightly higher, but acceptable, gaseous inclusion level (e.g., 0.05-0.1 inclusions/cm³), the primary objective is environmental sustainability through increased cullet utilization and reduced energy consumption. The resultant glass retains key physical properties such as density (≤ 2.41 g/cm³) and CTE for moderate display or architectural glass applications.
• Mermaid Diagram:

  flowchart TD
      A[High Cullet Input (50-90%)] --> B{Batching & Melting (1580-1600°C)};
      B --> C{Reduced SnO2 Fining (0.01-0.05 mol%)};
      C -- Leverage Σ[RO]/[Al2O3] --> D[Fining Process];
      D --> E[Glass Sheet (acceptable inclusion level)];
      E -- Low Energy, High Recycled Content --> F[Sustainable Glass Product];
  

Derivative 5.3: Bio-Resorbable Boroalumino Silicate Glass for Medical Implants

• Enabling Description: A bio-resorbable version of the boroalumino silicate glass, based on the alkali-free framework of Claim 1, is developed for temporary medical implant applications where controlled degradation is desired. This involves modifying the B2O3 content (e.g., increasing to 10.0-15.0 mole percent) and potentially introducing P2O5 (e.g., 0.5-3.0 mole percent) as an additional glass former, while carefully adjusting the alkaline earth oxides (MgO, CaO, SrO) to maintain the Σ[RO]/[Al2O3] ratio within or slightly above the claimed range (e.g., 1.00-1.30) to facilitate melting and fining with SnO2 (≥ 0.01 mole percent). The increased B2O3 and P2O5 promote hydrolytic degradation in physiological environments. The fining process ensures minimal inclusions, critical for biocompatibility. The glass's resorbable nature makes it suitable for bone scaffolds, drug delivery matrices, or temporary biosensors, where it degrades into benign components over time.
• Mermaid Diagram:

  stateDiagram-v2
      state "Initial Glass Composition (Claim 1 Base)" as InitComp
      state "Modified Composition (Bio-Resorbable)" as ModComp
      state "Fining Process (SnO2, ΣRO/Al2O3)" as Fining
      state "Glass Forming (Medical Grade)" as Forming
      state "Sterilization & Implantation" as Implant
      state "In Vivo Degradation" as Degradation
      state "Resorbed Components" as Resorbed
  
      InitComp --> ModComp : Increase B2O3, Add P2O5, Adjust RO
      ModComp --> Fining : Ensure minimal inclusions
      Fining --> Forming : High-purity product
      Forming --> Implant : Application in medical field
      Implant --> Degradation : Controlled bio-resorption
      Degradation --> Resorbed : Biodegradable over time
  

---

Combination Prior Art Scenarios

These scenarios combine the teachings of US7851394 (specifically the glass composition and fining methods) with existing open-source or widely adopted industry standards, making certain future improvements or applications obvious.

1. Combination with ASTM Standards for Glass Characterization:

   • Disclosure: The boroalumino silicate glass compositions and fining methods taught by US7851394 (e.g., Claim 1, defining specific oxide ranges, Σ[RO]/[Al2O3] ratio, SnO2 content, and density) are explicitly designed to achieve certain physical properties, including thermal expansion coefficient (CTE) and strain point. The measurement and verification of these properties are routinely performed using widely adopted, publicly available standards. Specifically, determining the linear coefficient of thermal expansion (CTE) over the temperature range 0-300°C as per the patent's disclosure is a standard procedure outlined in ASTM E228 (Standard Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilatometer). Similarly, the strain point, crucial for thermal stability, is determined by ASTM C336 (Standard Test Method for Annealing Point and Strain Point of Glass by Fiber Elongation). The combination of the specific glass compositions of US7851394 with the standardized, open-access methodologies of ASTM E228 and ASTM C336 for property verification is an obvious and conventional practice for any person skilled in the art of glass manufacturing and characterization.
   • Mermaid Diagram:

     graph TD
         A[US7851394 Glass Composition] --> B{CTE Property (28-34x10^-7 /°C)};
         A --> C{Strain Point Property (>= 650°C)};
         B --> D[ASTM E228: CTE Measurement Standard];
         C --> E[ASTM C336: Strain Point Measurement Standard];
         D & E --> F[Standardized Glass Characterization];
     

2. Combination with ISA-88 Batch Control Standard for Manufacturing Process Automation:

   • Disclosure: The method for producing alkali-free glass sheets described in US7851394 (e.g., as detailed in the Summary of Invention, Third Aspect, comprising selecting, melting, and fining batch materials via a downdraw process, particularly a fusion process) is a batch-oriented manufacturing operation at various stages (batch preparation, melting, fining, forming). The implementation and automation of such complex batch processes are widely standardized by the ANSI/ISA-88 (ISA-88) Batch Control Standard. ISA-88 provides a robust framework for defining physical models (equipment hierarchy), procedural models (recipes, unit procedures, operations, phases), and control activity models for batch manufacturing. Applying ISA-88 principles to structure and automate the batching of raw materials (including fining agents like SnO2), controlling the melting furnace temperature profiles, and managing the fining and conditioning stages in the fusion process for the glass compositions of US7851394 is an obvious application of established industrial automation best practices. This ensures modularity, flexibility, and reproducibility in manufacturing the claimed glasses.
   • Mermaid Diagram:

     graph TD
         A[US7851394 Batch Materials Prep] --> B{ISA-88 Batch Control: Unit Procedures};
         B --> C{ISA-88 Batch Control: Operations (Melting)};
         C --> D{ISA-88 Batch Control: Operations (Fining)};
         D --> E{ISA-88 Batch Control: Phases (Forming)};
         E --> F[US7851394 Fined Glass Sheet];
         style A fill:#f9f,stroke:#333,stroke-width:2px
         style F fill:#f9f,stroke:#333,stroke-width:2px
     

3. Combination with OPC UA for Real-time Process Data Exchange and Control:

   • Disclosure: The continuous monitoring and control of glass melting and fining processes are critical for achieving the low gaseous inclusion levels and precise compositional requirements of the glass described in US7851394. Modern industrial environments rely on open communication standards for interoperability between sensors, control systems, and data analytics platforms. The OPC Unified Architecture (OPC UA) is an open-source, cross-platform standard for secure and reliable data exchange from sensors to cloud applications. Integrating OPC UA servers and clients within the production line for US7851394's glass would enable real-time telemetry of critical parameters, such as melt temperatures, fining agent feed rates (SnO2), optical measurements of inclusion density in the melt, and compositional analysis data. This data can then be securely exchanged with a Supervisory Control and Data Acquisition (SCADA) system or an AI optimization engine (as described in Derivative 4.1) to monitor and adjust the fining efficiency and glass properties in real-time, thereby ensuring consistent production of the claimed boroalumino silicate glasses.
   • Mermaid Diagram:

     sequenceDiagram
         participant Sensors as Process Sensors (Temp, Flow, Inclusions)
         participant OPCS as OPC UA Server
         participant OPUC as OPC UA Client (Control System)
         participant GM as Glass Melter/Finer (US7851394)
     
         Sensors->>OPCS: Publish Real-time Data (Melter Temp, SnO2 Rate, Inclusion Count)
         OPCS->>OPUC: Subscribe to Data
         OPUC->>OPUC: Analyze Data & Determine Adjustments
         OPUC->>OPCS: Send Control Commands (e.g., Adjust SnO2, Heater Power)
         OPCS->>GM: Implement Control Actions
         GM-->>Sensors: Effect on Glass Production