| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized optical encoder high in S/N ratio. SOLUTION: In this linear optical encoder 10, light from an LED is reflected by reflection grid 41 of a refection grid plate 4 after passing through a light- transmission type moving grid 31 formed in a semiconductor moving plate 3. A reflected grid image is detected by a grid-like photodiode 32 formed in the semiconductor moving plate 3. Since the moving grid 31 and the photodiode 32 are built in a common semiconductor substrate, and since a lens effect is provided by the grid-like photodiode 32, a lens optical system is eliminated and the small compact encoder can be realized, thereby. A pair of reflection plates 7, 8 as light guide elements for changing an optical path for outgoing light are arranged between an LED luminescent point 2a and the moving plate 3 to widen a photoreceiving area for reflected light in the pohotoreceiving element 32 even when a gapΔis small between the photoreceiving element 32 and the reflection grid 41.
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