DISPLAY COVER GLASS AND DISPLAY COVER GLASS FABRICATION METHOD

• US 20140370264A1
• Filed: 06/11/2014
• Published: 12/18/2014
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: AGC, Inc.
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: OHARA, Seiki, Ono, Kazutaka, Nakashima, Tetsuya, Ohkawa, Hiroyuki
• Granted Patent: US 9,840,435 B2
• Time in Patent Office: Days
• US Class Current: 428/220
• CPC Class Codes: C03C 21/002 to perform ion-exchange between alkali ions C03C21/005 takes precedence
• CPC Class Codes: C03C 2204/00 Glasses, glazes or enamels with special properties
• CPC Class Codes: C03C 23/007 by thermal treatment
• CPC Class Codes: C03C 3/083 containing aluminium oxide or an iron compound
• CPC Class Codes: C03C 3/085 containing an oxide of a divalent metal
• CPC Class Codes: C03C 3/087 containing calcium oxide, e.g. common sheet or container glass
• CPC Class Codes: C03C 3/093 containing zinc or zirconium
• CPC Class Codes: C03C 4/18 for ion-sensitive glass
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

The present invention provides a cover glass for a display, having high durability to slow cracking and strong abraded strength even though a compressive stress is large and a depth of a compressive stress layer is deep. The present invention relates to a cover glass for a display, in which a depth of a compressive stress layer (DOL) is 30 μm or more, a surface compressive stress is 300 MPa or more, a position (HW) at which a compressive stress is half of a value of the surface compressive stress is a position of 8 μm or more from a glass surface, and the depth of the compressive stress layer (DOL) and the position (HW) at which the compressive stress is half of the value of the surface compressive stress satisfy the following formula:

0.05≦HW/DOL≦0.23  (1).

Claims

1. A cover glass for a display, wherein a depth of a compressive stress layer (DOL) is 30 μ

m or more, a surface compressive stress is 300 MPa or more, a position (HW) at which a compressive stress is half of a value of the surface compressive stress is a position of 8 μ

m or more from a glass surface, and the depth of the compressive stress layer (DOL) and the position (HW) at which the compressive stress is half of the value of the surface compressive stress satisfy the following formula;

0.05≦

HW/DOL≦

0.23 

 

(1).

2. A cover glass for a tablet PC with a touch sensor function, having a compressive stress layer in which a surface compressive stress is 300 MPa or more and a depth of the compressive stress layer (DOL) is 15 μ

m or more, and having a thickness of less than 0.8 mm, a size of 150 to 350 mm×

100 to 250 mm and a mass of 150 to 1,000 g,

wherein the surface compressive stress (CS)×

the depth of the compressive stress layer (DOL) is 35 MPa·

mm or less.

3. A method for manufacturing a cover glass for a display, the cover glass having a depth of a compressive stress layer of 30 μ

m or more and a surface compressive stress of 300 MPa or more, the method sequentially including the following steps (1) to (3);

(1) a first chemical strengthening step of forming a compressive stress layer on a glass surface by subjecting a glass to an ion-exchange treatment;

(2) a heating step of heat-treating the glass at a temperature 50°

C. or more lower than a glass transition temperature; and

(3) a second chemical strengthening step of further forming a compressive stress layer on the glass surface by subjecting the glass to an ion-exchange treatment.

4. The method for manufacturing a cover glass for a display according to claim 3, wherein the ion-exchange treatments in steps (1) and (3) are a treatment at a temperature 50°

C. or more lower than the glass transition temperature.

5. The method for manufacturing a cover glass for a display according to claim 3, wherein the depth of the compressive stress layer (DOL) and a position (HW) at which a compressive stress is half of a value of the surface compressive stress, of the cover glass for a display obtained satisfy the following formula (1), and the position (HW) at which the compressive stress is half of the value of the surface compressive stress is a position of 8 μ

m or more from the glass surface;

0.05≦

HW/DOL≦

0.23 

 

(1)

6. The method for manufacturing a cover glass for a display according to claim 4, wherein the depth of the compressive stress layer (DOL) and a position (HW) at which a compressive stress is half of a value of the surface compressive stress, of the cover glass for a display obtained satisfy the following formula (1), and the position (HW) at which the compressive stress is half of the value of the surface compressive stress is a position of 8 μ

m or more from the glass surface;

0.05≦

HW/DOL≦

0.23 

 

(1)