| 摘要 |
PROBLEM TO BE SOLVED: To detect a translucent sheet stably with high accuracy. SOLUTION: A light emitting element 12 and a light receiving element 13 are integrally provided in a light shielding case 11 with the optical axis of the light receiving element 13 inclined to the optical axis of the light emitting element 12. A translucent sheet 20 is perpendicularly irradiated with light emitted from the light emitting element 13, and the diffuse-reflected light by the translucent sheet 20 is received by the light receiving element 13.
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