Patent ID: 8760635

Claim:
A displacement measuring apparatus for measuring a displacement amount of a moving object, the displacement measuring apparatus comprising: a light source configured to irradiate the moving object using luminous flux emitted from a light emitting area; a light receiving element including a plurality of light receiving areas arranged in a movement direction of the moving object, the light receiving element being arranged such that luminous flux emitted from the light emitting area and reflected from one concave portion, of a plurality of concave portions in the moving object, is converged on a light receiving surface of the light receiving element by reflection from the one concave portion, the luminous flux emitted from the light source being reflected only once by the one concave portion and then entering the light receiving surface; and a measurement unit configured to measure the displacement amount of the moving object based on a movement amount of a light emitting area image that is formed on the light receiving element.