| 摘要 |
PURPOSE:To appropriately administer developer and to surely control image density by providing a photosensor for detecting a visible image obtained by developing a reference latent image and a sensor for detecting the toner concentration in the developer. CONSTITUTION:The photosensor (P sensor) 20 for detecting the light reflectance of the visible image obtained by developing the reference latent image formed on a photosensitive body and the flow sensor (F sensor) 21 for detecting the toner concentration in the developer are provided as an image density control means. Then, a 1st reference level which is fixed every machine and a 2nd reference level which can be switched in accordance with the detection signal of the P sensor 20 are prepared in order to decide the control level (reference value) of the F sensor 21 for controlling the toner concentration in the developer. Thus, the variation of the developer over a long term is decided based on the compared result of the 1st reference level with the 2nd reference level. Based on the 2nd reference level, the variation of the concentration of the developer in a short term is also detected. The developer is appropriately administered and the image density is held in an appropriate state. |
