Glass-ceramic cover glass, process for production thereof and use thereof, and digital display device comprising such a cover glass

US12269768B2 · kind B2 · utility

Assignees

• Schott AG · DE
• SCHOTT TECHNICAL GLASS SOLUTIONS GMBH · DE

Inventors

• Ruediger Dietrich · Jena, DE
• Bernd Ruedinger · Wörrstadt, DE
• Meike Schneider · Taunusstein, DE
• Jochen Alkemper · Klein-Winternheim, DE
• Lars Mueller · Cardiff, GB
• Thomas Pfeiffer · Kumhausen, DE
• Julian Koch · Zürich, CH

Key dates

• Filing date: Dec 12, 2022
• Grant date: Apr 8, 2025
• Expiry date: Jun 21, 2043

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03C2204/00
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A cover glass is provided that includes a silica based glass ceramic with a thickness between 0.4 mm and 0.85 mm. The glass ceramic has a transmittance of more than 80% from 380 nm to 780 nm and a stress attribute selected from: an overall compressive stress (CS) of at least 250 MPa and at most 1500 MPa, a compressive stress at a depth of 30 μm (CS30) from one of the two faces of at least 160 MPa and at most 525 MPa, a depth of the compression layer (DoCL) of at least 0.2 times the thickness and less than 0.5 times the thickness, and any combinations thereof. The glass ceramic has at least one silica based crystal phase having in a near-surface layer a unit cell volume of at least 1% by volume larger than that of a core where the crystal phase has minimum stresses.