| 摘要 |
PURPOSE:To prevent the abnormal recording density by executing protective operation such as the stop or alarm of density control or the stop of devices when a detected value exceeds a prescribed range. CONSTITUTION:The picture of an original on a contact glass plate 1 is projected on the surface of a photosensitive drum 4 by the 1st mirror 21, the 2nd mirror 22, an in-mirror lens 3, and the 3rd mirror 23. A white pattern MRg and a black pattern MRp are added to the picture projecting visual field of the 1st mirror 21 and the left side respectively, and when the 1st mirror 21 is driven because of exposure scanning, the electrostatic latent images of the white pattern MRg and the black pattern MRp are continuously formed on the surface of the photosensitive drum. A detecting signal from a photosensor 11 detecting the toner density of the surface of the drum 4 is amplified and shaped at its waveform by an amplifier 12, A/D converted and applied to a microprocessor (MPU)14. The MPU14 calculates the density ratio of the corresponding toner images of the white pattern MRg and the black pattern MRp, fixes toner feeding variable, applies a solenoid exciting instruction to a solenoid driver 15 and supplie current to a clatch solenoid 16. The current supply makes it possible to supply toner from a toner tank to a developing roller 7. |
