| 摘要 |
PROBLEM TO BE SOLVED: To execute a density control processing at an appropriate timing in accordance with a density change by measuring the relative density of a toner image for density measurement as a base part whose surface density is removed, and then, controlling an image forming condition based on the measurement results. SOLUTION: After ending a normal printing sequence, the number of printed sheets in a nonvolatile memory 50 loaded in each color developing unit 4a to 4d is individually made incremental. A density control execution counter B is compared with a threshold, and in the case B<200 is established, a density control execution counter A is compared with a threshold. In the case A=50 is established, the density control processing is executed only by the developing unit standing in an initial state, or in a deteriorated state. In the case A<50 is established, the density control processing is finished as it is. In this case, it is judged by a CPU 60 based on the read number of printed sheets at every developing unit 4a to 4d whether each developing unit 4a to 4d is in an initial state, or a stable state, or a function deteriorated state, then, the density control processing system is set in accordance with each state. |
