| 摘要 |
PURPOSE:To always inform correct toner replenishing timing by detecting a current flowing between a developer carrier and an image carrier at a developing position and judging whether or not a toner concentration drops to a tolerance or below, based on the detected current position. CONSTITUTION:A developing device is provided with a developer carrying means 2 carrying toner (d) along a prescribed route including a developing region, a developing bias source 8 applying a bias voltage to the developer carrying member 2, a current detecting means 7 detecting the value of a current flowing into the developer carrying member 2 from the developing bias source 8, a concentration deciding means 9 deciding whether the toner concentration in the toner (d) is high or low based on the detected current value of the current detecting means 7, and a means informing a result decided by the concentration deciding means 9. A signal generating circuit 10 serving as the informing means generates a signal indicating the decided result to an optical writer/printer control part 11. Thus, the lack of the toner (d) can be always and correctly detected and informed regardless of the presence of absence of the toner (d). |
