| 摘要 |
PURPOSE:To combine a means for detecting the concentration of developer with a means for discriminating between a new developing unit and an old one by causing the means for detecting the concentration of the developer to discriminate whether the developing unit is new or old. CONSTITUTION:The photosensitive drum 21 is integrally incorporated in the developing unit 56 which houses the developer and the drum 21 is wound with protective paper 73. A detection probe 45 consisting of a power supply part 70 and a detection part 71 and the toner concentration detecting means (A) constituted of a light emission diode and a photodiode are provided out of the image formed area of the drum 21. And the unit 56 is mounted in a device main body and used after taking up the paper 73 on a shaft 51. In such a case, the means A performs recognition between the new unit and the old unit from the difference of reflectance between the paper 73 and the detection part 71. The recognition between the new one and the old one is stored. At the time of acting, thereafter, the number of printed sheets is counted every unit and the life of the unit is controlled based on the counted number of sheets. When the number of sheets attains a specified one, the displacement of the unit is displayed on a panel. |
