Patent ID: 7603046

Claim:
An image forming apparatus, comprising: a developer container that holds a two-component developer containing a toner and a carrier; a toner concentration detector that detects toner concentration in the developer in a developing unit; a toner supplying unit configured to supply new toner to the developing unit; a process-linear-velocity setting unit that sets a process linear velocity from among a reference velocity, a first linear velocity lower than the reference velocity, and a second linear velocity lower than the first linear velocity; and a toner supply controlling unit, wherein Vt 0 is a toner concentration detected by the toner concentration detector for the reference linear velocity, Vt 1 is a toner concentration detected by the toner concentration detector for the first linear velocity, Vt 2 is a toner concentration detected by the toner concentration detector for the second linear velocity, and the toner supply controlling unit controls the toner supplying unit to supply the new toner to the developing unit to compensate for a deficit ΔVt 1= Vt 1− Vt 0 ΔVt 2= Vt 2 −Vt 0 in toner concentration in the developer in the developing unit.