Konishiroku Photo Industry Co., Ltd.

Shigeru Uetake

Yoshio Yamazaki

Nin-ichi Kamogawa

Shotaro Watanabe

Yuzo Ohmuro

Katsutoshi Tozawa

Fumio Koizumi

An image-forming method using a developer comprising as the main component ferromagnetic and insulating toner particles. Said method comprises the steps of holding said developer on a delivery member by a magnetic force, causing the developer to tuft at the developing position and to fall in contact with an electrostatic latent image-supporting member, developing the electrostatic latent image and forming a toner image by the toner particles charged predominantly by mutual friction of the toner particles, and transferring the toner image onto a plain paper superposed on the electrostatic latent image-supporting member by electrostatic transfer means. Said developer has a specific resistance of at least 10.sup.14 .OMEGA.-cm and the potential decay ratio of the developed developer is lower than 50% as measured according to the method defined in the specification.

Electrostatic image developing and transfer method uses single component

An image-forming method using a developer comprising as the main component ferromagnetic and insulating toner particles. Said method comprises the steps of holding said developer on a delivery member by a magnetic force, causing the developer to tuft at the developing position and to fall in contact with an electrostatic latent image-supporting member, developing the electrostatic latent image and forming a toner image by the toner particles charged predominantly by mutual friction of the toner particles, and transferring the toner image onto a plain paper superimposed on the electrostatic latent image-supporting member by electrostatic transfer means. Said developer has a specific resistance of at least 10.sup.14 .OMEGA.-cm and the potential decay ratio of the developed developer is lower than 50% as measured according to the method defined in the specification.

Image-forming developer

A one-component developer for developing a latent electrostatic image which comprises magnetic particles, thermoplastic resins and electric charge controlling dyestuffs as main components and in which the magnetic particles are substantially coated with the electric charge controlling dyestuffs. The resulting toner forms no fringe or ghost and has good duplicativity of halftone images. The toner is made by coating the magnetic particles with the electric charge controlling dyestuffs before mixing the magnetic particles with the resin.

Magnetic toner for developing latent electrostatic images and a process

The present invention is for the improvements of a developer for a one-component latent electrostatic image and the process for the preparation thereof. The present invention is the one which has improved points at issue in the case of using a developer for the conventional conductive one-component latent electrostatic image for a copying machine using a corona discharger and in which particles are prepared by uniformly mixing a magnetic substance in resin and the magnetic substance is substantially exposed on the particle surface by heat treatment and hydrophobic silica fine powders are supported on, or interposed in, said particles; the particles are, as a whole, electrically insulating and given electric charge necessary to form an image by friction of mutual particles; thus even in a copying machine using a corona discharger, good development can be obtained with this developer; and further the present invention is the one which provides a process for the preparation of said particles.

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Sayama, Japan

Shigeru Uetake