Oce-Nederland B.v.

Antoon L Hoep

Jozef A Corver

Johannes G Van Stiphout

Gerardus C Vercoulen

Ronald Berkhout

Lambertus M Van Sas

Robertus Petrus Quirijnen

Johannes F Van Gageldonk

Berend J Knapen

Arnold B Van Der Mey

A method of forming visible images in which magnetically attractable toner powder comprising resin particles containing magnetically attractable material is introduced to an image forming zone between an image registration medium and a moving conveying medium which has, within said image forming zone, a magnetic induction of at least 0.2T at its surface, thus imparting a force of attraction on the toner powder in which image forming zone the toner powder is selectively deposited on the image registration medium by electrostatic attraction in accordance with an image pattern, the toner powder used containing no more than 3% by volume of the magnetically attractable material.

Method of forming visible images

A printing device for reproducing information, comprising a movable image-forming element having a dielectric surface, an image-forming station including a magnetic roller provided with a rotatable electrically conductive sleeve and a magnetic system within the electrically conductive sleeve, electrodes to generate an electric field between the image-forming element and the magnetic roller in accordance with an information pattern, while an electrically conductive magnetically attractable toner powder is present in an image-development zone formed between the image-forming element and magnetic roller, the magnetic system generating a magnetic field in the image-forming zone and forming the toner powder into a magnetic toner brush and system for providing a well-defined space in the image-development zone between the electrically conductive sleeve and the image-forming element so that no distortion of the magnetic toner brush occurs during image development in the image-development zone.

Printing device with control of developer roller spacing

A printing device for reproducing information having movable image-forming element with a dielectric surface. An image-forming station is provided in which a magnetic roller having a rotatable electrically conductive non-magnetic sleeve is disposed near the surface of the image-forming element. An electric field between the image-forming element and the magnetic roller is generated in accordance with an information pattern. An electrically conductive magnetically attractable toner powder is placed in the zone between the magnetic roller and the image-forming element during generating of the electric field. A magnetic field formed in the zone by stationary ferromagnetic knife blade disposed inside the magnetic roller sleeve and the blade is held between like poles of two magnets at an angle of between 70.degree. and 85.degree. to the tangential plane to the sleeve.

Magnetic roller means with stationary magnetic knife blade for use in

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Molenhoek, Netherlands

Antoon L Hoep