| 摘要 |
PURPOSE:To preciously detect residual developers in each developing unit in a color image forming device on which plural developing units are disposed on the circumference of an image carrier. CONSTITUTION:A transparent window 61 is provided on the sidewall of a container main body 41, and a light emitting element 54 and a light receiving element 55 are disposed in the vicinity of the outside of the window 61. Then, the part of the above-mentioned window 61 is irradiated with the light L1 projected from the light emitting element 54, and the reflecting light L2 is received by the above-mentioned light receiving element 55, to detect the residual toner. On the other hand, the revolving speed of a developing sleeve 42 is detected through a reduction gear part 42, and a switch 58 by a gear 62 coupled to the developing sleeve 42. Both detection results are compared by a comparing means 59, and when a second comparator 68 judges the presence of toner even if a first comparator 65 judges the absence of the toner, an AND circuit 69 judges that the judgement of the first comparator 65 is wrong, and a display for the absence of the toner is not executed. |
