| 摘要 |
PURPOSE:To remove practical delay between a toner feed stopping period and a detecting period obtained by a detecting means by arranging plural detecting means in a circulation course and arranging at least one of them close to an agitating means. CONSTITUTION:The toner concentration detecting means 29a-29c arranged along the londitudunal direction of a screw roller 14, e.g. the center and both the sides. Respective detecting means 29a,-20b output detecting signals every prescribed period and these signals are stored in a RAM 35 through an I/O interface 31. The average value of these values is calculated by an operation part 36, and when the average value reaches the lower limit value of the toner concentration, toner feeding is started. Then the mean value is compared with a value correspond-into to the upper limit value of toner concentration. If the states that the average value exceeds a specific value found out experimentally is continued for a prescribed period, the toner concentration is substituted by the average value and the arrival of the toner concentration at the upper limit value is decided by a deciding part 37. Then, the toner feeding is stopped. |
