| 摘要 |
PURPOSE: To enable the replenishment of an adequate amount in accordance with the consumption of a developer, without delaying, during recording by simultaneously detecting parts where the maximum and minimum values of the concn. of toner are obtained with the pitch of a stirring screw, so as to output an average value. CONSTITUTION: The developer of a mixture of the toner and carriers is stirred by the stirring screw, to detect the toner concn. of the developer. The distribution of the toner carried in the axial direction of the stirring screw 24 has a concentrated region and a thin region. On the other hand, a toner concentration detecting sensor 28 is constituted in such a manner that a plane coil 28b is composed of a conductor on a flexible board 28a and the plane coil 28b detects a change in permeability caused by the concentration of the mixture of the carried toner and the carrier. At this time, the plane coil 28b is set in the length of an integral multiple of the pitch interval of the stirring screw 24 and regions becoming the maximum and minimum values in accordance with the concentrated and thin parts of the mixture are simultaneously detected. Therefore, an actual concn. can be recognized in a short time, without requiring the circulation of the average value. |
