| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of a defective image caused by damage on a developing sleeve and a developing blade by providing a contact part between a developer carrier and a developer regulating member with specified polymer particles as lubricant in a state where developer does not exist at the contact part before the expected use of a developing device. SOLUTION: In the state where the developer does not exist at the contact part between the developer carrier and the developer regulating member before the expected use of the developing device, polymer particles whose weight average particle size is 5-45 μm and which are selected from following (1) or (2) are provided at the contact part as the lubricant. When the charge amount of only the developer is set as T, and that per unit lubricant on the developer carrier at the time of imparting an electric charge to the lubricant is set as J, the polymer particles (1) have the relation of -0.5×T<=J<=2.0×T when the charge amount T is positive, and also have the relation of 2.0×T<=J<=-0.5×T when the charge amount T is negative. The polymer particles (2) are particles of indefinite shape having an average roundness of the polymer particle as the lubricant of >=0.7<=0.9. |
