Abstract:
PROBLEM TO BE SOLVED: To respond to birefringence induced on a glass sheet by stress in a method of producing the glass sheet using a downdraw process.SOLUTION: A glass sheet quality metric level Q1 is selected, where Q1 is a measure of allowable retardation in the glass sheet. A glass ribbon temperature Tis identified at which a potential glass ribbon thermal artifact could occur in a glass ribbon while the glass ribbon is being drawn through a drawing machine enclosure. A thermal artifact envelope E1 is determined, where E1 contains various glass ribbon thermal artifacts allowable at Tand Q. A glass melt is overflowed from an isopipe to form a glass ribbon at the root of the isopipe. The glass ribbon is drawn below the root of the isopipe through the drawing machine enclosure to form the glass sheet. The drawing machine enclosure is altered at a location where the glass ribbon would be at Tsuch that during the formation of the sheet the thermal artifact is not formed in the glass ribbon at T.
Abstract:
PROBLEM TO BE SOLVED: To reduce the dimensional changes of a glass substrate during a display manufacturing process.SOLUTION: The method for reducing the dimensional changes of the glass substrate in a display manufacturing process includes a step of altering the composition of glass so as to increase the peak expansion of the glass during the process. The altering step may include a step of increasing the concentration of alkali metal oxide in the glass. The concentration of alkali metal oxide in the glass is preferably increased only 0.25 mol%, and only 1.0 mol%, more preferably. The altering step may include a step of increasing the water content of the glass. The glass substrate is also provided for use as a substrate in the process for producing a display device.
Abstract:
A method for ion exchanging glass articles is provided. The method includes ion exchanging a plurality of lots in steps within an ion exchange salt bath, wherein each of the plurality of lots comprises at least one glass article, and wherein the ion exchange salt bath comprises molten salt and, after removing the last lot from the ion exchange salt bath, removing substantially the entire volume of molten salt from the ion exchange salt bath. The method further includes maintaining steady state conditions in the ion exchange salt bath prior to removing substantially the entire volume of salt from the ion exchange salt bath such that at least one of the compressive stress and the central tension of substantially all of the glass articles varies from at least one of the compressive stress and the central tension of any other of the glass articles by less than about 20%.
Abstract:
A method of making glass through a glass ribbon forming process in which a glass ribbon is drawn from a root point to an exit point is provided. The method comprises the steps of: (I) cooling the glass ribbon at a first cooling rate from an initial temperature to a process start temperature the initial temperature corresponding to a temperature at the root point; (II) cooling the glass ribbon at a second cooling rate from the process start temperature to a process end temperature; and (III) cooling the glass ribbon at a third cooling rate from the process end temperature to an exit temperature the exit temperature corresponding to a temperature at the exit point wherein an average of the second cooling rate is lower than an average of the first cooling rate and an average of the third cooling rate.
Abstract:
A method for optimizing ion exchange of glass. The glass is ion exchanged in a series of two ion exchange baths. The first ion exchange bath contains an amount of a poisoning ion or salt and the second ion exchange bath contains an amount of the poisoning ion or salt that is less than that in the first bath. When the concentration of the poisoning ion/salt in the first bath reaches a maximum value, the first bath is discarded and replaced by the second bath and a third bath that initially does not contain the poisoning cation/salt replaces the second ion exchange bath. This cycling of baths may be repeated to produce a plurality of glass articles, each having a surface layer under a compressive stress and depth of layer that are within predetermined limits.
Abstract:
A method of making a strengthened glass article. The method includes altering the glass structure and subsequently creating a compressive layer extending from the surface of the glass to a depth of layer. In some embodiments, the structure is altered by heat treating the glass at a temperature that is less than the annealing point of the glass, and the compressive layer is formed by ion exchange. A strengthened glass article made by the method is also provided.