| 摘要 |
PURPOSE:To perform toner density control by using only accurate detection data by digitizing the output signal of a density detecting means into toner density data, and judging an abnormal state unless the toner density detection data is within a specific range and reporting the state. CONSTITUTION:The toner density data obtained by A/D conversion is compared with upper-limit data U stored in a ROM 40 and when B<U, a normal state is judged; and the density data is compared with lower-limit data L stored in the ROM 40 and when B>L, a normal state is judged. When B>=U or when B<=L, on the other hand, it is judged that a magnetic sensor 23 as a density detecting means is abnormal, and then while copying operation is stopped, an abnormality display device 43 is turned on to indicate that the magnetic sensor 23 becomes abnormal. Consequently, when the magnetic sensor 23 becomes abnormal, that is detected securely and reported to stop the copying operation, thereby performing toner density control by using only accurate toner density without maintaining the abnormality detection. |
