Prior art

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".