WO2010138451A3 - Laser scoring of glass at elevated temperatures - Google Patents

Abstract

Laser scoring of individual glass sheets (45, 112) and glass ribbons (27) at elevated temperatures is disclosed. A uniform vent can be created along an intended score line (31, 115) by heating a glass surface (114) with a laser beam (113) up to a temperature in a range whose lower limit (11) is defined by the stress required to maintain propagation of an initial flaw (111) to form the vent and whose upper limit (13) is equal to or less than the strain point of the glass. In certain embodiments, the glass temperature under the laser beam (113) stays within these limits regardless of the background temperature of the glass through the use of flexible laser power control provided by a controller (35) which causes a laser (37) to produce a laser power profile along the score line (31, 115) which varies inversely with the glass temperature gradient. The glass temperature gradient can, for example, be detected in real time using a detector (33), e.g., an infrared camera. By controlling the laser beam power in this way, process margins can be significantly increased during the scoring of individual glass sheets (45, 112) and glass ribbons (27) that exhibit significant glass temperature variations.