Witness layers for glass articles
AssigneeApple Inc.
InventorsDale N. Memering, Dezheng Qu, Victor Luzzato
Life of this patent
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Abstract
Glass articles having a base layer formed of glass and having a first compressive stress, an adjacent compression layer formed in the glass and having a second compressive stress, and a witness layer formed in the glass adjacent the compression layer and having a third compressive stress. The first, second and third compressive stresses all differing from one another. The witness layer also having a higher index of refraction than an index of refraction for the base or compression layers. Methods for manufacturing and methods of quality control that include the use of the witness layer are also disclosed.
Claims20
A glass article, comprising:
- a base layer formed in a glass and having a first compressive stress;
- a compression layer formed in the glass and having a second compressive stress, the compression layer adjacent the base layer;
- a witness layer formed in the glass and adjacent the compression layer and having a third compressive stress;
- wherein
- the first, second and third compressive stresses all differ;
- and
- the witness layer defines:
- a first thickness at a first location of the glass article;
- and
- a second thickness, greater than the first thickness, at a second location of the glass article that is different than the first location.
A lithium ion strengthened glass article comprising:
- an interior portion comprising a base glass and lithium ions;
- a witness layer having different thicknesses at different locations of the lithium ion strengthened glass article;
- and
- a compression layer between the interior portion and the witness layer;
- wherein:
- the compression layer is under compression;
- the compression layer has a lower content of lithium ions and a greater content of sodium ions than the interior portion;
- the witness layer is under compression;
- and
- the witness layer has a lower content of sodium ions and a greater content of potassium ions than the compression layer.
A portable electronic device, comprising:
- a housing;
- and
- a cover glass affixed to the housing and defining:
- a central region;
- and
- a peripheral region adjacent the housing and surrounding the central region;
- wherein
- the cover glass is at least partially covered by a witness layer having a greater thickness at a first location within the central region than at a second location within the peripheral region;
- and
- the witness layer has a compressive stress differing from the cover glass.
A portable electronic device, comprising:
- a component defining a first portion of a polished exterior surface of the portable electronic device;
- and
- a glass cover having an outer surface defining a second portion of the polished exterior surface that is adjacent to and coplanar with the first portion, the glass cover comprising:
- a witness layer formed at the outer surface, comprising a first content of potassium ions, a first content of sodium ions, and a first content of lithium ions, and having a thickness at the second portion of the polished exterior surface less than a thickness at a location away from the second portion of the polished exterior surface;
- a compressive stress layer formed below the witness layer and comprising a second content of potassium ions less than the first content of potassium ions, a second content of sodium ions greater than the first content of sodium ions, and a second content of lithium ions greater than the first content of lithium ions;
- and
- an interior portion comprising a third content of lithium ions greater than the second content of lithium ions.
Dependencies are inferred from the claim text.