| 摘要 |
PURPOSE:To restrain the early deterioration of developer caused by excessive stirring and to prevent image density from lowering by providing a means for judging the state of the developer. CONSTITUTION:This developing device is provided with a memory storing toner concentration at the time of finishing developing operation, a timer measuring elapsed time from finishing the pre-stage developing operation to starting next developing, and a counter counting all the number of developing times(number of copies) from starting use by the same developer. A CPU controls the actuation time of a stirring member before starting the actuation of a developing member based on values obtained from the respective means. Namely, at the time of developing, 1st and 2nd stirring rollers 21 and 22 in a stirring part 20 are actuated for a specified time before starting the actuation of a developing part 20 and stir the developer. When the developing part 20 is actuated, the developer is supplied to a developing sleeve 11 by the rotation of the 1st stirring roller 21, and carried to a developing area facing to a photosensitive drum PC while it is held on the sleeve 11 by the magnetic force of a fixed magnetic body 12 in the sleeve 11. |
