Patent ID: 8270882

Claim:
A developing device comprising: a developer container for storing a developer comprising a toner and a magnetic carrier; a developer conveying passage through which the developer is conveyed in the developer container; a developer conveying member disposed inside the developer conveying passage for agitating and conveying the developer in a predetermined direction; and, a developing roller which supports the developer in the developer conveying passage and supplies the toner contained in the developer to a photoreceptor drum; characterized in that the developer conveying member includes: a rotary shaft; and a plurality of helical blades provided on the periphery of the rotary shaft, the plural helical blades being composed of a first helical blade formed on the periphery of the rotary shaft and a second helical blade arranged along the axis of the rotary shaft and radially outside the outer periphery of the first helical blade, and the helical pitch of the second helical blade is specified to be shorter than the helical pitch of the first helical blade.