| 摘要 |
PURPOSE:To accurately control toner concentration and to prevent the abnormal lowering of image density caused by the shortage of toner by performing toner supplying action based on the image on the photosensitive drum which is the closest to a final image. CONSTITUTION:The image on a reference density board attached to the scanning starting side of a platen glass is previously scanned so as to carry and develop the latent image of the image on the reference density board. Then, the density of the image, what is called a patch image 20, is detected by a density sensor 9, and the detection output from the sensor is set as Vsp. Erasion is performed before and after the image on the reference density board and the output from the sensor at that time is set as Vsg. In the case that the value of Vsp/Vsg is larger than a specified reference value Vsq, the toner supply roller of the developing device is driven by the specified number of times or for a fixed time, so that the toner is supplied to a sleeve side. Thereafter, density is detected again, and when the detected value satisfies the specified reference value Vsq, toner end display is turned off, and when it does not satisfy the reference value Vsq, toner end display is continued. |
