Abstract: A magnetic carrier for a developer used in electrostatically forming a visual image, comprising a magnetic core material, an electrically-conductive particle-containing resin layer and electrically-conductive particles externally added to the electrically-conductive particle-containing resin layer, the magnetic carrier having a magnetization (.sigma..sub.1000) of 61-100 emu/g at 1 kOe magnetic field, a specific volume resistance of 10.sup.6 .OMEGA..multidot.cm or less, and an average particle size of 10-100 .mu.m. The magnetic carrier of low specific volume resistance has a high durability and provides high quality images. In particular, when the magnetic carrier is applied to an image forming process by rear side exposure, the residual toner on the image-bearing member can be effectively removed without using an additional cleaning means, and high quality images free from the background fogging and contamination can be produced.

Abstract: An image forming method for developing an electrostatic latent image on a moving image-bearing member with a magnetic developer and for removing the residual toner after transfer of a developed toner image onto a transfer member is described. The method includes providing a rotatable, cylindrical permanent magnet having a plurality of magnetic poles on the surface for supporting and conveying the magnetic developer directly on the magnet surface; forming an electrostatic latent image into a toner image by attracting and conveying a magnetic developer including a nonspherical magnetic toner obtained by a polymerization or a nonspherical magnetic or non-magnetic toner obtained by a polymerization and magnetic carriers; and removing the residual toner remaining on the image-bearing member after transferring this toner image by a cleaning blade. The method also includes a surface magnetic flux density ranging from 50 to 1200 G, and a value of h, defined as .pi.D.multidot.Vp/(M.multidot.

Abstract: An image forming method for operating a moving image-bearing member bearing an electrostatic latent image and a plurality of developing units disposed near the image-bearing member and being selectively operable is described.

Abstract: An image forming method for developing an electrostatic latent image on an image-bearing member that moves bearing electrostatic latent images formed of a two-component magnetic developer is described. The method includes the steps of providing a rotatable cylinder for supporting and conveying said magnetic developer, the cylinder including a permanent magnet with a plurality of magnetic poles provided on the surface. Magnetic carriers in the magnetic developer are attracted and conveyed on the surface of the permanent magnet, the magnetic carriers having an average particle size of 5 to 20 .mu.m and opposite to toner in polarity of charge. A carrier particle magnetization .sigma..sub.1000 in a magnetic field of 1000 Oe so as to amount to 50 emu/g or less is also used. The method also includes a surface magnetic flux density ranging from 50 to 1200 G, and a value of h, defined as .pi.D.multidot.Vp/(M.multidot.

Abstract: An Li--Mn type ferrite carrier for use in electrophotographic development comprising ferrite particles having a chemical composition of 3 to 15% of Li.sub.2 O, 5 to 35% of MnO and 60 to 90% of Fe.sub.2 O.sub.3, each in terms of percent by mole. The ferrite particles consisting essentially of crystal grains having an average grain size of 1 to 50 .mu.m. The surface of the crystal grains is provided with a minute roughness or unevenness during the production of the ferrite carrier. The minute roughness on the grain surface enhances the ability of the ferrite carrier to triboelectrically charge the toner and the bonding strength of the resin coating to the carrier surface.

Abstract: An Li--Mn ferrite carrier comprising 2 to 15 mol % of Li.sub.2 O, 5 to 30 mol % of MnO and 60 to 90 mol % of Fe.sub.2 O.sub.3. The carrier may contain at least one sintering aid selected from the group consisting of CaO, Na.sub.2 O, SiO.sub.2, V.sub.2 O.sub.5, Al.sub.2 O.sub.3, As.sub.2 O.sub.3, Bi.sub.2 O.sub.3, Sb.sub.2 O.sub.3 and B.sub.2 O.sub.3 to improve the surface properties thereof. The carrier may be made sensitive to the intensity of electric field by regulating the specific volume resistivities at 200 V/cm and 10 kV/cm within the specific ranges. This carrier is particularly suitable in the reversal developing method, and in the developing method where an A.C. bias voltage is superimposed to a D.C. bias voltage.

Abstract: A developer for electrostatic development, which is a mechanical mixture of a magnetic toner containing a binder resin and a magnetic powder as the essential component and a magnetic carrier having a specific volume resistance of 10.sup.9 .OMEGA..cndot. cm or more. The properties of the magnetic toner and the magnetic carrier are correlated to each other so that an average particle size of the magnetic carrier is 0.5 to 6 times an average particle size of the magnetic toner, a magnetization of the magnetic carrier is 0.5 to 4 times a magnetization of the magnetic toner, and a triboelectric charge w of the magnetic carrier (Qc) and a triboelectric charge of the magnetic toner (Qt) satisfy an equation: .vertline.Qt-Qc.vertline.=5 to 50 .mu.C/g.

Abstract: A two-component magnetic developer of the invention for printing characters on documents for magnetic ink character recognition comprises the mixture of 20 to 80 percent by weight of a magnetic toner containing binder resin and magnetic powder and the balance being a magnetic carrier, wherein the magnetic toner has magnetic powder of 30 to 60 percent by weight, residual magnetization .sigma.r of 4 to 16 emu/g and average particle diameter of 5 to 15 um. The developer rarely causes background fogging and carrier adhesion on the developed images which is suitable for MICR.

Abstract: An electrophotographic image-forming method in which a thin layer of a developer is formed on a developing roll by an elastic doctor blade tangentially contacting with the surface of the developing roll, and an image-bearing member and the developing roll are brought into contact with each other in a developing zone because either of which is made flexible. In the method of the present invention, the toner remaining on the surface of the image-bearing member is effectively removed and recovered in the developing zone. This prevents the background fogging. The flexible structure of either of the image-bearing member and the developing roll prevents the surface of the image-bearing member from being damaged to ensure a printed image of high quality.

Abstract: A two-component magnetic developer containing a magnetic iron carrier and a non-magnetic or magnetic toner. The magnetic iron carrier is non-spherical in its shape and has an average particle size of 5-100 .mu.m. The non-magnetic or magnetic toner has an average particle size of 2-9 .mu.m and is produced by polymerizing a monomer for a binder resin. The toner concentration in the developer is 2-70 weight % in case of containing the non-magnetic toner and 10-90 weight % for the developer containing the magnetic toner.

Abstract: A developer for developing an electrostatic latent image is disclosed. It is obtained by mixing a chargeable magnetic toner mainly composed of a binder resin and magnetic powder, which toner has a volume resistivity of 10.sup.13 .OMEGA..multidot.cm or greater, with a magnetic carrier having a volume resistivity of 10 .OMEGA..multidot.cm or greater and less than 10.sup.6 .OMEGA..multidot.cm at a weight ratio of between 10:90-90:10. A method of forming an image is also disclosed. An electrostatic latent image is formed on an image carrier. A magnetic brush formed of the developer slides against the surface of the image carrier. The visualized toner image is transferred to a recording medium. The previously-applied toner remaining on the surface of the image carrier is removed after transferring is completed and an electrostatic latent image is visualized when the magnetic brush slides against the surface of the image carrier.

Abstract: A developer for developing an electrostatic latent image by a developing method of a type in which residual toner particles on an image-bearing member are recovered therefrom and reused for developing the electrostatic latent image, which comprises a magnetic toner and a magnetic carrier. The magnetic toner comprises a binder resin having a number average molecular weight of 2,000-100,000, a weight average molecular weight of 5,000-500,000, and a melt viscosity of 10.sup.5 P or less at 120.degree. C., a release agent having a softening point of 160.degree. C. or lower; and a magnetic powder. The magnetic toner particle is externally added on a surface thereof or internally added thereto with a surface treating agent comprising a fine powder of at least one metal salt of stearic acid, a fine powder of at least one inorganic oxide and an optional resin powder.

Abstract: In an image forming method for developing an electrostatic latent image on an image bearing member by using a two-component magnetic developer includes the steps of supporting and conveying a magnetic developer directly on the surface of a permanent magnet with a plurality of magnetic poles provided on the surface and performing both the removal of the residual toner remaining on the surface of the image-bearing member and the development of the electrostatic latent image while rubbing said surface with said magnetic brush. The magnetic carriers in the magnetic developer have average particle sizes of 5 to 20 .mu.m and opposite to toner in polarity of charge, the magnetization .sigma..sub.1000 in a magnetic field of 1000 Oe is 50 emu/g or less. Nonspherical magnetic toner or non-magnetic toner made by a polymerization process and magnetic carriers may be used.

Abstract: A method in which a photoconductive surface is charged to a uniform potential by a charging brush and a two-component magnetic developer is directly attracted on the surfaced of a sleeve-less developing roll formed from a permanent magnet member and transported by the rotation of the permanent magnet member. An electrostatic latent image is developed with the transported magnetic developer in a developing zone to form a visual toner image on the photoconductive drum. The toner image is transferred to a recording sheet by a transfer roll and permanently fixed thereon by a suitable fixing means. The specific volume resistance of the magnetic carrier is restricted to a particular range to prevent the magnetic carrier from adhering to the photoconductive surface.

Abstract: A method for developing electrostatic latent image on a rotating photoconductive drum by a magnetic developer transported by a rotating developing roll disposed opposite to the photoconductive drum, the developing roll being made of a cylindrical permanent magnet having on circumferential surface thereof equispaced magnetic poles extending along the axial direction. In the method the magnetic poles are equispaced by an inter-pole pitch of 0.5-10 mm, the photoconductive drum and the developing roll are rotated so as to move in opposite directions in an developing zone, and the ratio of peripheral speeds of the developing roll and photoconductive drum are regulated within 1 to 5. By the above method, an electrophotographic imaging apparatus can be reduced in the size thereof while reproducing high-quality images.

Abstract: A method of developing an electrostatic latent image on a rotating image-bearing member with a magnetic developer in which a developing roll consist of only a permanent magnet member and the peripheral speed of the developing roll is regulated to be nearly equal to the moving speed of an image-bearing member. With such a construction, an electrophotographic recording apparatus can be miniaturized while producing an image of high quality.

Abstract: An image forming method includes the steps of charging a surface of a movable image-bearing member uniformly by using a roller charging means, forming an electrostatic latent image on the image-bearing member by carrying out an image exposure, delivering a magnetic developer which is attracted onto a surface of a sleeveless permanent magnetic member to a developing region located opposite to the electrostatic latent image formed on the image-bearing member, the sleeveless permanent magnetic member being formed with a plurality of magnetic poles provided on its surface and having a cylinder shape, developing the electrostatic latent image using the magnetic developer comprising a toner and magnetic carriers, the magnetic carriers having a volume resistivity of 10.sup.10 .OMEGA..cm or more, and transferring a toner image onto a transfer sheet by using a roller transfer means.

Abstract: A sleeveless magnet roller is formed of at least magnetic powder and resin. It is so arranged that, letting a developing gap Ds be the gap between an image-bearing member for holding an electrostatic latent image and a developer conveying member and a doctor gap Dg be the gap between the developer conveying member and a developer's thickness regulating member, one obtains Ds-Dg=0.1 to 0.3 (mm) and Dg=0 to 0.4 (mm). For image formation, one- or two-component magnetic developer is used and a bias voltage, formed by superimposing AC bias voltage to DC bias voltage, is applied to the developing region.

Abstract: In a direct recording method, toner supplied on a toner carrier contains at least fixing resin and magnetic grain, and has an apparent density of 0.5 g/cc or more and an angle of repose of 45.degree. or less. The magnetic flux density on the toner carring member is 600 gauss or more. A doctor blade located in opposition to the toner carring member is used to restrain the thickness of toner layer formed on the toner carring member to 5 to 100 .mu.m. When performing recording on a recording body with this invention, the image density is improved and fogging is eliminated.

Abstract: An image forming method for conveying a magnetic developer 70 held on the surface of a developer conveying member 40 opposed to a image-bearing member 30 to a developing region to develops electrostatic latent images, comprises implementing as the developer conveying member 40 a semiconductive or an insulating cylindrical magnet with a plurality of heteropolar magnet poles arranged alternatively on its surface, the overall magnet being integrally formed, rotating the developer conveying member 40 to convey the magnetic developer 70 to the developing region, and using the magnetic developer 70 conveyed to the developing region to develop electrostatic bearing member latent images formed on the image-bearing member 30.This constitution allows an inexpensive sleeveless roll magnet to be used to obtain high-quality images.