Reflective optical sensor

Abstract

A reflective optical sensor includes a substrate; a light-emitting element and a light-receiving element both of which are provided on the substrate; and a light-shielding wall provided between the light-emitting element and the light-receiving element. A distance de between the light-emitting element and the light-shielding wall, a distance dr between the light-receiving element and the light-shielding wall, and a thickness t of the light-shielding wall satisfy the following relationship: de+dr<t. A shortest distance between a region that does not belong to any of a region, in which light emitted from the light-emitting element does not reach a measurement target, and a region, in which light reflected or scattered by the measurement target does not enter the light-receiving element, and a sensor surface in which the reflective optical sensor and the measurement target are in contact is 0.2 mm or greater and 0.3 mm or less.

Dependencies are inferred from the claim text.