Patent ID: 7495248

Claim:
A position detecting apparatus comprising: at least one first illuminating unit that is located so that a rear surface of a substrate and a radiation center of an illuminating mechanism of the first illuminating unit are positioned on a substantially same plane, and radiates light onto the substrate in a direction substantially parallel to a front surface and the rear surface of the substrate from a lateral direction of the substrate; a second illuminating unit that is provided above the front surface of the substrate and radiates light onto an area including an edge portion of the substrate in a direction substantially perpendicular to the front surface of the substrate; an image pickup unit that is disposed on a rear surface side of the substrate so that an edge of the substrate is positioned within an image pickup range thereof and takes an image of the substrate from the rear surface side of the substrate while the light is being radiated from the first illuminating unit or while the light is being radiated from the second illuminating unit, respectively; and an edge-position detecting unit that detects at least one edge position of the substrate, based on a first image taken by the image pickup unit while the light is being radiated from the first illuminating unit and a second image taken by the image pickup unit while the light is being radiated from the second illuminating unit, respectively.