| 摘要 |
PROBLEM TO BE SOLVED: To improve environmental resistance by enlarging the degree of freedom for material selection of a resin code disc of an optical encoder. SOLUTION: A material having a spectral transmittance of 70% or higher to detection light and having a spectral transmittance of 50% or lower to part of light having a visible wavelength (for example, blue light) is adopted in a translucent part relative to at least a code pattern of the code disc in the optical encoder. When using infrared light having the wavelength of 800-1,000 nm as the detection light, polyether imido, polyether sulfone or polyphenyl sulfone is preferably adopted as a colored resin material. These materials are excellent in heat resistance, oil resistance or the like compared with conventional transparent and colorless materials (PMMA, PC, glass or the like), and hardly generate dissolution, deformation, clouding or the like even in a severe environment. COPYRIGHT: (C)2005,JPO&NCIPI
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