| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming a core for a mold for molding a light guide sheet of such a type that no streaky irregularities are generated at a borderline between blast bands, in the formation of a gradation pattern by an embossing process. SOLUTION: This method purports the formation of the gradation pattern on the molding surface (1a) of the core (1) for the mold for molding the light guide sheet by projecting a shot blast material (3) parallel in the form of a band under a controlled pressure. Between the adjacent blast bands (a), (b), etc., with the varying diameters (s1), (s2), etc., and depth (h1), (h2), etc., of the embossment (2), the difference in the change level of an embossing pressure is 0.02 MPa or less. |
