| 摘要 |
PROBLEM TO BE SOLVED: To obtain a dome cover making mold distortion, etc., difficult to occur by making a center part thicker than an opening edge. SOLUTION: This dome cover 5 is molded out of a mold (injection molded part of acrylic resin) having optical transparency. And, for instance, the inner spherical surface 5a of the cover 5 has a radius R1=47.1 mm, the outer spherical surface 5b has a radius R2=49.0 mm, and the center O11 of the surface 5a is offset, e.g. about 0.5 mm offset quantity OS toward the outside of an opening edge 5c against the center O12 of the surface 5b. Then, the cover 5 is formed while the thickness of an opening edge 5c is defined as T11 = about 1.9 mm and while the thickness of a center part (summit part) 5d part is defined as T12 = about 2.4 mm. And, a variable thickness part 5e is formed on the opening edge 5c along the entire circumference with height H12 = about 8.8 mm width.
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