| 摘要 |
PURPOSE:To eliminate an erroneous operation in detection and to prevent lowering of printing quality from occurring, by detecting a toner quantity by a reflected light of the light irradiated on a magnetic roller in a developing device. CONSTITUTION:A light is irradiated by a light emitting element 51 on a magnetic roller 12 incorporated in a developing device 1, and a reflected light is received at a photodetector 52 through an optical system 52 to detect the quantity of a toner 13 in the device 1. When the toner in the device 1 decreases to the degree not to stick to the roller 12, as the light is reflected and is received by the photodetector 52 through the optical system 52, it is recognized to be necessary to replenish the toner 13. |
