| 摘要 |
PURPOSE:To properly deal with a photosensitive body deterioration by controlling a charging means with an image density. CONSTITUTION:A P sensor 25 of an image density detecting means is provided to be faced to a photosensitive body 1 in a position after a development and before a transfer, and the density after the development of a reference pattern formed on a position between image areas just after is detected continuously to the latent image formation and development of the original image area. Further, an F sensor 30 of an agent concentration detecting means is provided to a developing device 4. A recovered developer is made to pass in a coil arranged in the flow of the developer recovered from the photosensitive body 1 through a developing sleeve 12 into a developing container 9, the change of the transmissivity of the developer at such a time is detected, and a developer concentration is known. In such a way, the developer concentration in the device 4 is captured with the magnetic permeability change of a sensor coil, it is detected as an inductance change, a generation frequency change and further, a voltage change, it is fed back to a toner feeding system, and the concentration is made fixed. In such a way, the toner concentration cannot be abnormally concentrated, and the photosensitive body deterioration, etc., can be dealt with by the variance of a charging potential. |
