| 摘要 |
PURPOSE:To prevent the occurrence of toner shortage and uneven concentrations by letting a toner concentration maintaining device of two component developer actuate continually at the ending of copying when the toner concentration is insufficient and let the same stand by when the toner concentration has reached a specified value. CONSTITUTION:With the toner concentration maintaining device being put in a developing tank 1, the developer is stirred by its stirring screw and the toner concentration of the developer 4 circulating along the surface of a magnetic roll 2 and scraping-off plate 3 is detected with a toner sensor 5. When the toner concentration is insufficient, the toner in a toner tank 6 is replenished into the developing tank 1 by the toner replenisher which actuates according to the output of the toner sensor 5. This toner concentration maintaining device is actuated not only at the copying operation but at the standby as well until the toner concentration reaches the specified value. Namely, if toner replenishing is accomplished at intervals of a time shorter than the specified time at the ending of copying operation, the toner sensor and toner replenishing part are actuated continually unitl the specified time is reached. |
