| 摘要 |
<p>This invention provides an optical flat plate member produced by injection molding a thermoplastic resin using a mold with a multipoint gate. The optical flat plate member is characterized in that gate marks are present within an optical effective face and the ratio between the arithmetical mean roughness Ra<SUB>1</SUB> of the gate marks and the arithmetical mean roughness Ra<SUB>2</SUB> of the part other than the gate marks within the optical effective face, i.e., Ra<SUB>1</SUB>/Ra<SUB>2</SUB>, is 0.4 to 3. The optical flat plate member has features that there is no need to treat gate marks present within the optical effective face, the gate marks used as an optical flat plate member are not noticeable, and the optical flat plate member can easily be produced by injection molding a thermoplastic resin.</p> |
