Dry process developing method and device employed therefore

Claim 1

A magnetic brush developing method for electrophotography which consists essentially of the steps of mixing magnetizable toner and electrically insulating non-magnetizable toner in a predetermined weight ratio to form a developing material, and applying said developing material onto an electrical potential pattern formed on a recording medium to develop said electrical potential pattern into a visible image, said magnetizable toner having a resistivity of 10 8 to 10 14 Ω·cm and particle diameter of 3 to 30 μm, said electrically insulating non-magnetizable toner having a particle diameter of 3 to 30 μm, and said predetermined mixing ratio in weight being 1 part of said magnetizable toner to less than 2.5 to 0.01 parts of electrically insulating non-magnetizable toner, and both said magnetizable and non-magnetizable toners being consumed in a similar manner by attraction to the latent image thereby forming said visible image, said non-magnetizable toner to be imparted with triboelectric charge having opposite polarity to that of said electrical potential pattern by said magnetizable toner.