Abstract: A tempered glass having a compressive stress layer formed at the surface and a tensile stress layer formed inside, wherein the glass thickness (t) is from 1.5 to 3.5 mm, and the minimum thickness (a) of the compressive stress layer in the direction of glass thickness is from 0.15 to 0.7 mm.

Abstract: A quenching method and apparatus for tempering a glass sheet. The method includes a step of transferring a heated glass sheet between quenching boxes which are provided with nozzles opposingly arranged near upper and lower surfaces of the glass sheet to blow air streams of cooling air supplied from the quenching boxes to the glass sheet. The method also includes the step of arranging the nozzles extending from the quenching boxes so as to face at least one of the upper and lower surfaces of the glass sheet so that openings on the end of the nozzles blow the air streams of the cooling air in different directions simultaneously so as to intersect and thus be substantially uniformly arranged with respect to the glass sheet. The number of intersections is approximately 30 or more in any 10 cm square area of the glass sheet. The end portions of the nozzles have a semi-spherical shape.

Abstract: A tempered stepped glass sheet wherein the averaged value of surface compressive stresses in an intermediate region B is 100-500 kg/cm2 larger than the averaged value of surface compressive stresses in a central region C.

Abstract: A tempered glass includes a glass sheet having a thickness of 2.3-3.5 mm, an average surface compressive stress of 1000-1300 kg/cm2, and a plurality of first and second belt-like regions. Each of the second belt-like regions is interposed between adjacent ones of the first belt-like regions. Each of the first belt-like regions has a width of 10-30 mm and a plurality of first reference points, each having a principal stress difference of 120 kg/cm2 or less, which is larger than principal stress differences at areas of each of the first belt-like regions which are peripheral to each of the first reference points. The first principal stress difference at each of the first reference points is located in a direction perpendicular to the length of the first belt-like regions. Lines connecting adjacent ones of the first reference points form a center line, as a reference line, of each of the first belt-like regions.