| 摘要 |
PURPOSE:To prevent a large amount of toner from being supplied to a developing device at a time by storing the quantity of shortage in a memory again when toner can not be supplied within the range of a set time and supplying the toner corresponding to the shortage when copying operation is performed afterward with small toner consumption. CONSTITUTION:An electrostatic latent image is formed on the surface of a photosensitive body 1 and a developing roll 10 is applied with a developing bias from a developing bias power source 15. Then, a current detecting circuit 17 is provided in the middle of the line 16 connecting the developing bias power source 15 to the developing roll 10 to detect the value of a current generated when toner is transferred from the developing roll 10 to the photosensitive body 1 during development. The current value detected during copying operation is stored in the memory temporarily and the driving motor 13a for an auger 13 for toner supply is rotated for 0.5-3.5sec according to the stored value to supply toner in a toner bottle 12 to the developing device 4. Consequently, the amount of toner to be supplied is 15-200mg in every copying cycle and a large amount of toner is prevented from being supplied to the developing device 4 at a time. |
