| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect color toner concentration even when the toner concentration is high. SOLUTION: A toner concentration sensor 46 is equipped with a short- wavelength visible light LED 91 composed of a blue LED, a long-wavelength LED 92 composed of a red LED, and a photodiode 93 for generating a photoelectric current in proportion to an amount of received light. The short-wavelength visible LED 91 emits light toward a cyan toner image, and the long-wavelength LED 92 emits light toward magenta and yellow toner images. Toner concentration is judged by a control part 80 by receiving diffuse reflection light, which is a reflection of light of each of LEDs 91 and 92 from a reference concentration pattern. |
