| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device capable of preventing an image from being thin in density in a development using particulate toner even without increasing the abutting pressure of an elastic blade and capable of being miniaturized by making a developing sleeve small in its diameter, and to provide a process cartridge. SOLUTION: The magnetic toner to be used for this developing device 3 is the negatively chargeable particulate toner whose weight mean diameter is <=6.5 μm, and strontium titanate is added to the toner as reverse-polarity positive additive. The abutting pressure of the elastic blade 10 on the developing sleeve 6 is <=20 g/cm in terms of drawing pressure. Then, duty bias is used as the developing bias applied to the sleeve 6. The first and second peak voltages V1 and V2 satisfy the relation of |V1-VL|/H>=3.7×106 V/m and |V2-VD|/H<=2.9×106 V/m (wherein, the light part potential of the surface of a photosensitive drum 1 is VL, the dark part potential thereof is VD and an SD gap is H). |
