Method and apparatus for forming toner image

Abstract

In an image forming method wherein a toner image formed on a photoreceptor by the sequence of a charging step, an imagewise exposure step and a development step is transferred and fixed on a recording sheet by a transfer and a fixing step, the improvement wherein the developer used in the development step comprises at least 30 wt % of a toner having a particle size of no more than 8 .mu.m and a magnetic carrier of low saturation magnetization, the toner being capable of carrying electric charges in a quantity greater than the value at which a maximum amount of the toner is deposited for development, the toner being electrified to have a charge quantity greater than a predetermined level by mixing the toner and the carrier under agitation before the effective development region is reached, a magnetic brush being formed after the toner electrification, the carrier and the toner being then given a localized movement and vibrational force in the effective development region, the toner being deposited on the latent electrostatic image under the action of an electrical or mechanical disturbance that promotes the supply and separation of the toner particles, whereby a toner image is formed on the photoreceptor, the toner image being then transferred onto the recording sheet by a transfer device holding a constant electric field and, following this transfer step, the residual toner on the photoreceptor being charged again and subsequently removed from the photoreceptor under the action of an electric field.