Method of mechanically breaking a scribed workpiece of brittle fracturing material

A method of mechanically breaking a double-bonded flat glass plate, said double-bonded flat glass plate comprising two flat glass plates bonded to each other by an array of bonding frames, said bonding frames being arranged in rows and columns between the two flat glass plates, said method comprising the steps of:

• a) scribing a first group of at least five parallel scribed lines in the double-bonded flat glass plate by means of a laser in a first cutting direction, wherein respective parallel scribed lines of said first group are arranged between corresponding adjacent columns of the bonding frames;
• b) scribing a second group of parallel scribed lines in the double-bonded flat glass plate by means of said laser in a second cutting direction that is perpendicular to the first cutting direction, wherein two parallel scribed lines of said second group are arranged between adjacent rows of the bonding frames, so that each of said two parallel lines is asymmetrically placed with respect to the bonding frames of the adjacent rows;
• c) mechanically breaking the double-bonded flat glass plate along the parallel scribed lines of the first group with at least one breaking roller;
• and
• d) mechanically breaking the double-bonded flat glass plate along the parallel scribed lines of the second group with a breaking bar in successive overlapping steps along each of the parallel scribed lines of the second group that is oriented in the second cutting direction;
• wherein the breaking bar comprises a metallic blade extending longitudinally in the second cutting direction with a length that is slightly more than twice a distance between adjacent scribed lines of the first group;
• and
• wherein from 36 to 200 of said bonding frames are present between said two flat glass plates and each of said bonding frames corresponds in size to a display format of a mobile phone.