| 摘要 |
PURPOSE:To obtain a lens of high precision in a plastic lens mold by a method wherein a projection or a groove to be undercut when the lens is taken out are provided in the inner diametrical part of a circular gasket to limit the outer periphery of the lens and a rigid outer frame fitting to the outer periphery of said gasket is provided. CONSTITUTION:In the plastic lens mold provided with a circular gasket 6 to form the cavity 5 between the top force 3 and the bottom force 4 of the plastic lens mold, a projection 9 or a groove to be undercut when the lens is taken out are provided in the inner diametral part 6b of the above-mentioned circular gasket 6 of elastic material to insert the outer peripheral part 6a of said gasket 6 into the outer frame 10 of rigid material. When plastic material is injected into the cavity 5 of such mold to be cured, the projection 9 combines firmly with plastic material and early separation from the gasket wall 8 is hindered to obtain a lens of high precision corresponding well to the curing and shrinkage of the material. |
