Magnetic brush development apparatus for an electrostatic copier

In a magnetic brush development apparatus of the type comprising a plurality of magnetic rollers, each of which comprises a non-magnetic rotary sleeve and magnetic field generating means disposed in said non-magnetic rotary sleeve, and each of which successively transfers therebetween a magnetic developer carried on the surfaces of said sleeves for developing a latent electrostatic image on a photoconductor, wherein the improvement comprises means for forming a uniform magnetic brush comprising:

• a developer regulating means for regulating the quantity of said magnetic developer on a first magnetic roller of said plurality of magnetic rollers by removing excess developer from the surface of the sleeve of said first roller, which first roller is disposed in close proximity to said photoconductor for transferring developer to and developing said latent electrostatic image;
• a second magnetic roller of said plurality of rollers;
• rotatable in the same direction as said first magnetic roller for supplying said magnetic developer to said first magnetic roller in a transfer region and disposed with a predetermined space between it and said first magnetic roller such that the excess developer removed by said developer regulating means is received on the surface of the sleeve thereof upstream of said transfer region for resupplying said developer to said region;
• and
• said magnetic field generating means disposed in said first magnetic roller and said second magnetic roller are arranged so as to overlap the respective magnetic forces thereof in said transfer region in such manner as to remove an excessive amount of said magnetic developer from said region, through said space between said first and second magnetic rollers, on said sleeve of said second magnetic roller.