DEVELOPING DEVICE AND IMAGE FORMING APPARATUS USING THE SAME

A developing device includes a developing vessel for storing a developer, a first conveying passage, a second conveying passage, a first conveying member and a second conveying member to supply toner to a photoreceptor drum. The first conveying member includes a first rotary shaft and a first multi-helically structured blade. The first multi-helically structured blade includes a first inner helical blade and ring-shaped first outer helical blade. The first inner helical blade is formed so that the radius of the helical blade varies cyclically. The second helical pitch of the first outer helical blade is smaller than the first helical pitch of the first inner helical blade. The first outer helical blade inscribes the outer periphery of the first inner helical blade at its minimum radius portions.