The very first optical sorter for the rice milling industry in Japan was introduced on a trial basis in the early 1960s. As far as records show, it was a European sorter of small capacity with only three channels. This optical sorter did not become widely used in the Japanese rice milling industry for two reasons - the purchase and running costs were high, and the market requirement was low. The 1960s were a period of very rapid growth in Japan. Demand for rice exceeded supply, mainly due to poor logistics, and discolored rice was not an issue at the time. In the late 1970s, the demand-and-supply balance of rice was reversed and the supply exceeded the demand. The Government restricted the use of agrichemicals and controlled rice production. As a result, areas of fallow paddy field increased. Grass invaded even areas still under cultivation, and pests increased, causing rice discoloration. In the meantime, grass seeds often contaminated harvested rice due to insufficient weeding. Japanese rice mills began to require optical sorters.
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