| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To avoid such a trouble that a defect due to an external injury on the outer surface of a bulb is developed to a crack by thermal stress by forming a proper physically strengthened compressive stress layer in the lower layer of a chemically strengthened compressive stress layer. <P>SOLUTION: A chemically strengthened compressive stress layer A formed by ion exchange. and a physically strengthened compressive layer B formed by cooling, which extends in the lower layer of the chemically strengthened layer A, are formed on the outer surface 2a of a glass panel part. The thickness of the physically strengthened compressive stress layer B is not less than 2.0 mm and less than 3.5 mm, and its compressive stress value is not less than 3.0 MPa and less than 8.5 MPa. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
