US Patent 7269363 Developing apparatus, developing method, and developing agent therefor

A developing apparatus is provided in which a replenishment developer when replenished has been electrified to a sufficient extent and can immediately produce an effect of replenishment, with a small consumption of a carrier. In an developing apparatus 100 of the present invention, by means of a first and a second agitation and conveyance screw 21, 22 arranged in an upper space 13 and a lower space 14, respectively, a first two-component developer LT stored in the spaces is agitated and conveyed, so that it is supplied to a developing roller 20 so as to perform development processing of an electrostatic latent image on a photosensitive member. This developing apparatus replenishes a second two-component developer HT stored in a cartridge 30 into a first two-component developer LT in the spaces in an appropriate manner in accordance with the progress of the development process, so that a component composition of the first two-component developer can be kept within a prescribed range. In this case, amounts of electrification Q1, Q2 of the first and second two-component developers are set to be Q2=Q1×A (A=0.6−1.5) when the second two-component developer is readjusted to the same state of its toner concentration as that of the first two-component developer.