| 摘要 |
PROBLEM TO BE SOLVED: To permit the highly accurate detection of the degree of ripeness without damaging fruits by using a plurality of LEDs as a light source, using a plurality of different wavelengths, and determining the degree of ripeness by the presence or absence of chlorophylls. SOLUTION: A sensor part formed of LEDs 1 and 2 covered with a hood F at the back surface of the main body of a meter for the degree of ripeness and a photodiode 3 is brought into contact with the surface of a fruit to be the object of ripeness degree measurement. By pressing a measurement switch D, the LEDs 1 and 2 continuously alternately irradiate red light (in the vicinity of 660 nm) and near infrared rays (in the vicinity of 880 nm), respectively, at the timing determined by a microcomputer 4, and the photodiode 3 receives part of the reflected light of the light diffused in the fruit. The infrared light of the LED 1 with the absorption wavelength of chlorophylls is diffused at the skin of the fruit, and its part is absorbed by chlorophylls. The majority of the infrared rays of the LED 2 is reflected. The photodiode 3 measures the amount of the infrared rays of the LED 1 absorbed by chlorophylls on the basis of the amount of the reflected light of the LED 2, and its relative value is taken as the degree of ripeness and displayed on a liquid crystal display.
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