Patent ID: 7035576

Claim:
A method of developing a latent image formed on a surface of an image carrier with toner grains, said toner grains comprising a developer together with magnetic carrier grains, said developing method comprising: depositing said developer on a developer carrier, which faces said image carrier and accommodates magnets therein, causing said developer carrier to convey said developer to a developing zone formed between said image carrier and said developer carrier; and forming, in said developing zone, a magnet brush consisting of said magnetic carrier grains, which hold said toner grains thereon and gather in a form of brush chains, and free toner grains to be released from said carrier grains, at least one position where said brush chains of said magnetic carrier grains rise exists in a portion where an electric field formed between a facing zone where said image carrier and said developer carrier face each other has a strength E(V/m) expressed as: E ≥  ( A · ρ T · d · R ) ( 3 ⁢ B 1 2 · ɛ 0 · V SL )  where B is representative of T c ·D 3 ·ρ c /(100−T c )·d 3 ·ρ T , A denotes a mean amount of charge (C/kg) deposited on the toner grains, T c denotes the content of toner grains (wt %), d denotes the mean grain size (m) of the toner grains, D denotes the mean grain size (m) of the magnetic carrier grains, ρ T denotes the specific weight (kg/m 3 ) of the toner grains, ρ c denotes the specific gravity (kg/m 3 ) of the carrier grains, ε o is 8.854×10 −12 (F/m), R denotes the diameter of the developer carrier, and V SL denotes the linear velocity of the developer carrier.