APPARATUS FOR DETECTING FOREIGN SUBSTANCE

PROBLEM TO BE SOLVED: To provide an apparatus for detecting a foreign substance, capable of acquiring a clear image, regardless of distances from an imaging device and amounts of the depth variation or the height difference, and precisely detecting the foreign substance by using the image. SOLUTION: An imaging means is disposed on the upper or lower side of a liquid level so that its focal position can be controlled by the outside, and at least a focused focal point of the liquid level formed by the imaging means is irradiated with a light, such as an LED illumination or the like, from above or from the side of the liquid level, thereby causing specular reflection to occur at the foreign substance on the liquid level. The focused focal point of the imaging means is varied in a range from the top section to the bottom section of a vessel which contains the liquid, and input images obtained at the focused focal point are sent from the imaging means to an image inputting means in an image processing section; and an image obtained when the liquid level is focused or an image representing the clearest liquid level is selected among them by an image selecting means in the image processing section, and then a foreign substance detecting means in the image processing section uses the image obtained, when the liquid level is focused or the image representing the clearest liquid level, checks the occurrence position of the above specular reflection and carries out detecting the foreign substance. COPYRIGHT: (C)2006,JPO&NCIPI