| 摘要 |
PURPOSE:To attain highly accurate position detection by forming a light collection means to a slit of a rotary slit board. CONSTITUTION:A convex lens 8 or a flat lens 9 is provided as the light collection means to the slit of the rotary slit board 1 being the major part of the rotary encoder. The light collecting means is provided to the slit in such a way, then the luminous flux 10 from a light emitting element 5 is collected by the light collecting means when it passes through the slit of the rotary slit board 1 and supplied to a light receiving element 6 through a stationary slit plate 7. Even with the presence of deflected rotation of the rotary slit plate, the dispersion due to refraction is corrected by the light collecting means and the incident luminous quantity to the light receiving element is always constant, then a stable output is obtained.
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