| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain an electrophotographic image forming apparatus which stably forms an image having high image density and high image quality over a long term by exactly detecting toner concentration in a developing tank of a developing device used in the image forming apparatus and always replenishing the developing tank with appropriate amount of toner in accordance with toner consuming circumstances, thereby preventing the lowering of image density and the occurrence of an image defect such as thinning of the image. <P>SOLUTION: The image forming apparatus 1 includes a toner image forming means 2 equipped with a developing device 13 having a developing tank 20 in which two-component developer is reservoired, a transfer means 3, a fixing means 4, a recording medium supply means 5 and an ejection means 6, and is provided with a toner concentration detection means for detecting the toner concentration in the developing tank 20, a print speed switching means, a toner concentration calculation means for calculating the toner concentration by correcting a result of detection by the toner concentration detection means in accordance with print speed, and a toner replenishment control means for replenishing the developing tank with toner in accordance with a result of calculation by the toner concentration calculation means. <P>COPYRIGHT: (C)2008,JPO&INPIT |
