摘要 |
PROBLEM TO BE SOLVED: To accurately control supply of toner to a developing unit.SOLUTION: A supply controller 110 comprises a band stop filter 113 and a first determination part 114. The band stop filter 113 reduces a long-period ripples that are generated according to a period of circulation of developer caused by screws 58 and 59 in the density of toner detected by a density sensor 20. The first determination part 114 determines a first supply amount R1n on the basis of the density of toner with a long-period ripples reduced by the band stop filter 113. The frequency of the long-term ripples changes according to the speed of process, and the stop band of the band stop filter 113 is adjusted according to the speed of process.SELECTED DRAWING: Figure 3 |