| 摘要 |
PURPOSE:To eliminate problem points of machining technology and to improve performance as a rotary plate by providing a metallic disk which is formed by a photoelectroforming method, etc., and has a rotary shaft fitting hole in the center part. CONSTITUTION:The rotary disk R of a reflection type rotary encoder is composed of the metallic disk 2. Then a nonreflective material 6 is spread or applied over the top surface of the metallic disk 2 to form a nonreflection part 8. In this case, the nonreflective material is spread or applied on the metallic disk 2 except a thin beltlike body groups 10 without being spread nor applied on the top surfaces of the thin beltlike body group 10 present radially around the fitting hole 4 along the inside of the outer periphery of the metallic disk 2. Then, films are formed of a material with high reflecting ability, e.g. rhodium on the top surfaces of the thin beltlike body group 10, which serves as reflection parts 12. Consequently, the faults of the machining technology as to a conventional rotary disk which uses glass, etc., are eliminated.
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