| 摘要 |
PROBLEM TO BE SOLVED: To directly restore the electrificication amount itself of the toner of two-component type developer to an appropriate value and to obtain a toner image having appropriate image density by actuating an electrification amount regulating means so that the electrification amount of the toner may be increased at the time of detecting that the image density of a reference toner image is lowered to be under a specified level. SOLUTION: When a transmissivity sensor 18 detects that toner concentration in the two-component type developer D in a developer container 10 is equal to or above the specified value and an image density sensor 25 detects that the image density of the reference toner image formed on the surface of a photoreceptor is lowered to be under the specified level, a developer path W between a developer path regulating member 26 and a developing roller 12 is made narrow. Therefore, a chance on which the developer D comes in contact with a doctor blade 13 is increased and frictional action strongly acts on the toner and carrier, so that the electrification amount of the toner is increased. The toner and the carrier whose electrification amount is increased in such a way pass through a doctor gap G and are carried to a developing area S. |
