| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass substrate having the degree of flatness which is capable of satisfactorily coping with an application that has been conventionally considered difficult or impossible by accurately selecting the direction for measuring the difference in the plate thickness from an optional point of the glass substrate and by optimizing the minimum unit of a range for measuring the plate thickness. SOLUTION: The glass substrate has a longitudinal size a not smaller than 300 mm and a transverse size b not smaller than 300 mm, and has an average plate thickness in a range of 0.3-4.0 mm, and when an optional position in the plane is defined as a reference point O and the directions which direct along the two sides 2, 3 intersecting each other at a right angle are defined as X-direction and Y-direction respectively, there are defined total 8 points, i. e. A point and B point which are separated from the reference point O on both sides of the X-direction by 20 mm respectively, and C point and D point which are separated from the reference point O on both sides of the Y-direction by 20 mm respectively, and E point, F point, G point and H point which are separated from the reference point O on both sides of the X-direction by 20 mm respectively and separated from the reference point O on both sides of the Y-direction by 20 mm respectively, wherein the absolute values of the differences between the respective plate thicknesses of the 8 points and the plate thickness of the reference point O are not larger than 3μm. COPYRIGHT: (C)2009,JPO&INPIT
|
