Developer transferring device, developing device, process unit, and image forming apparatus

摘要

In an image forming apparatus capable of reducing the number of toner concentration detection errors caused by variation in the volume of a toner below that of the related art, a reverse vane for transferring K developer in an opposite direction to a screw vane as a rotary shaft member rotates protrudes from the rotary shaft member in a region of an entire rotary axis direction region of a first screw member where a gravitational direction lower side faces a bottom wall of a first transfer chamber and two lateral sides that are orthogonal to the rotary axis direction face respective side walls of the first transfer chamber, and a K toner concentration detection sensor is disposed to detect the toner concentration of the K developer as the K developer is transferred between the reverse transfer vane and a location of the screw vane adjacent to the reverse transfer vane. Thus, the K developer is pushed against the K toner concentration sensor more forcibly, enabling a reduction in the number of toner concentration detection errors.