Abstract
There are many types of orange fruit grading machines with machine vision systems, but it is still difficult to detect rotten parts, because their colors are similar with normal parts. Objectives of this research are to investigate the excitation wavelengths of the substances for determination of lighting device specification, and to construct an inspection system for fruit grading by color image and for the rotten part detection by UV lighting device. From an analysis of orange fruit skins, it was found one of major fluorescent substances was flavonoid methyl whose exciting wavelength was 365nm and fluorescence wavelength was about 530nm. A machine vision system consisting of a pair of white and UV LED lighting devices and a color CCD camera was proposed for orange fruit grading. Since the time between color and fluorescence image inputs was short enough (14ms), it was considered that UV LEDs addition to white LEDs-color TV camera system installed in fruit grading lines made rotten fruit detection possible.
