| 摘要 |
PURPOSE:To detect a remaining amount of toner accurately by providing a nonmagnetic body at one terminal of a magnet roll part for sticking the toner to a photosensitive drum, and by detecting the intensity of a reflected wave by emitting an acoustic wave to the nonmagnetic body. CONSTITUTION:An acoustic wave is emitted from transmitter 7 to nonmagnetic part 5a of magnet roll 5 and then received by receiver 8. When there is enough toner, toner 3 sticks to even nonmagnetic body 9 provided at the terminal part of magnet roll part 5 and a low output B is generated by receiver 8. As toner 3 decreases in quantity, toner 3 is attracted to magnet roll part 5 and nonmagnetic body 9 has no stuck toner, so that receiver 8 will generate high output D. For this purpose, the slice level for whether the toner is to be supplied is set between B and D, detecting the remaining amount of the toner accurately. |
