CUTTING METHOD FOR STRENGTHENED GLASS PLATE

摘要

A cutting method for a strengthened glass plate, having a step that irradiates a laser light (20) on the surface (12) of the strengthened glass plate (10) and moves the irradiation area (22) for the laser light (20) on top of the surface (12) of the strengthened glass plate (10), and which cuts the strengthened glass plate (10) by causing a crack penetrating the strengthened glass plate (10) in the plate thickness direction to follow behind the irradiation area (22). By irradiating the laser light (20) on the surface (12) of the strengthened glass plate (10), an intermediate layer (17) in the irradiation area (22) is heated at an annealing point temperature max., a tensile stress or a compression stress smaller than the value for the internal residual tensile stress is formed in the intermediate layer (17) in the center of the irradiation area (22), and the extension of the crack is restrained.