ABSTRACT -- A new design of a low-cost high-efficiency rice-sorting machine is reported. The sorting mechanism is based on the assumption that the unwanted rice with dark or brown color has different optical characteristics. This difference can be realized using a simple transmission technique. The optical module consists of a light source and an array of photodetectors positioned above and under the rice trays, respectively. After passing through the optical module, the unwanted rice will be ejected by mechanical or pneumatic ejectors. The machine has an on-board signal-processing unit for an accurate control. Results from a working prototype are promising. Details of the optical module, electronics and mechanical structures of the machine will be discussed.

KEYWORDS -- rice-sorting machine, sorting apparatus, optical module, transmission technique