Hitachi Metals, Ltd.

Takafumi Aoyama

Kazunori Tabaru

Toshio Kumakura

Keitarou Yamashita

The invention involves a method for making one component or single component toner compositions for developing electrophotographic images. A binding component is mixed with magnetic particles, pulverized, then carbon black is mixed with the powder and fixed to the surface of the particles. Compositions having a measured resistivity of 4.3.times.10.sup.3 to 4.3.times.10.sup.6 ohm-cm at a D.C. field of below 20 volts/cm under substantially no-load conditions are selected for use.

Preparation method of magnetic toner

An electrostatic developing apparatus for developing an electrostatic latent image formed on an electrostatic copy paper according to a magnetic brush developing process is disclosed. In this electrostatic developing apparatus, there is formed a magnetic brush of developer on a non-magnetic cylinder between the non-magnetic cylinder and an electrostatic copy paper, the aforesaid non-magnetic cylinder being rotated around the outer periphery of a stationary permanent magnet having a plurality of developing magnetic poles so that the electrostatic copy paper is slidingly rubbed with the magnetic brush to provide a visible image for the electrostatic latent image.

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Kumagaya, Japan

Takafumi Aoyama