Patent ID: 7227640
Filing Date: 2007-06-05
Classification: G01J,G06K

Abstract:
1. A photoelectric sensor which includes a light-emitting device for emitting a plurality of different colors of light onto a detection field, and a light-receiving device for receiving light reflected from an object in the detection field due to the emitted colors of light, wherein a mark is located on the object and is detected on the basis of changes in a level of a quantity of light received by the light-receiving device, the photoelectric sensor comprising: a reference received light quantity sampling device for measuring a reference received light quantity level reflected from the object for each color of light emitted from the light-emitting device; a mark received light quantity sampling device for measuring a mark received light quantity level reflected from the mark for each color of light emitted from the light-emitting device; a first calculation device for obtaining a ratio of, a difference between the reference received light quantity level and the mark received light quantity level, to one of the reference received light quantity level or the mark received light quantity level, for each color of light emitted from the emitting device; and a selecting device for selecting the color of light which has a largest ratio from among all of the ratios obtained by the first calculation device;