Patent ID: 7812897

Claim:
A method for making a prism sheet, comprising: providing a cutting device, the cutting device comprising a cutter, a table plate, and a control unit, wherein the table plate is controlled to move up and down by the control unit, and the cutter has a blade rotatable along its center axis; providing a mold insert preform on the table plate, the mold insert preform having a flat surface; moving the cutter with the rotating blade to etch the flat surface of the mold insert preform along a first direction, and simultaneously driving the table plate to move up and down by the control unit in a first predetermined manner, thereby forming a first elongated depression in the flat surface, wherein widths and sizes of the first elongated depression vary according to the first predetermined manner; repeating the step of forming the first elongated depression to form a plurality of first elongated depressions in the flat surface; moving the cutter with the rotating blade to etch the flat surface of the mold insert preform along a second direction, and simultaneously driving the table plate to move up and down by the control unit according to a second predetermined manner, thereby forming a second elongated depression being formed in the flat surface, wherein widths and sizes of the second elongated depression vary according to the second predetermined manner, and the second elongated depression intersect the first elongated depressions; repeating the step of forming the second elongated depression to form a plurality of second elongated depressions in the flat surface, thereby forming a mold insert; using the mold insert to form the prism sheet by injection molding method.