| 摘要 |
PURPOSE:To always and constantly maintain density and chromaticity of a transfer image by controlling a developing bias voltage value changing means by carrying out formation and measuring of a test toner image immediately before the next image forming action when a power source has been connected, when the image formation of a set number of pieces has been finished, or when more than a specified period of time has passed. CONSTITUTION:The period of time between the image forming actions are counted, formation and measuring of the test toner image on a surface of a photosensitive body 1 for measuring toner adhered quantity by a photo sensor 15 is carried out when the power source is connected or when the image forming action of the set number of pieces is finished. At the same time, the forming and the measuring of the test toner image is carried out immediately before the next image forming action after more than the specified time has passed between the image forming actions and the developing bias voltage value changing means is controlled. Thus, the image density and chromaticity can always be kept constant. |
