| 摘要 |
PURPOSE:To display toner residual accurately and to make it possible to observe the display easily from the external by comparing the rotational frequency of a toner feeding roller with plural fixed data and turning on plural display lamps successively in accordance with the compared results. CONSTITUTION:Toner concentration in a developing device is detected as the change of transmissivity by a magnetic sensor 23 formed on the side wall of the developing device. When the toner concentration is reduced, an output voltage is increased, a microcomputer 46 is turned to an auto-toner set mode and a toner feeding solenoid 49 is driven to rotate the toner feeding roller, so that toner is fed from a hopper. The rotational frequency of the roller is compared with plural fixed data stored in a ROM 50 and plural lamps on a toner residual display part 34 are successively turned on in accordance with the compared results. When the roller reaches the rotational frequency emptying the hopper finally, a red lamp lights up to demand toner feeding. Thereby, the toner residual can be easily observed from the external. |
