Abstract: A multi-color image formation apparatus and method of its use prevent deterioration of stability due to a recharging process in one cycle of multi-color image formation and also effectively avoid color mixing in the toner image previously formed. The multi-color image formation apparatus includes an electrostatic latent image formation member, a first electrostatic latent image formation device for forming a first electrostatic latent image on the electrostatic latent image formation member, a first developer for developing the first electrostatic latent image with a first toner, a second electrostatic latent image formation device for forming a second electrostatic latent image on the electrostatic latent image formation member, and a second developer for developing the second electrostatic latent image with a second toner.

Abstract: The development apparatus of this invention includes a developer supporting body consisting of a rotatable non-magnetic sleeve and a magnet roll fixedly installed within the rotatable non-magnetic sleeve.

Abstract: A color image recording apparatus according to the present invention comprises a light-sensitive drum, a first developing device for developing a first electrostatic latent image on the drum surface as a first toner image, a second developing device for developing a second electrostatic latent image as a second toner image on the drum surface along with the first toner image, and a developing bias voltage source for applying a developing bias voltage to the second developer device comprising a DC component and an AC component of a predetermined period, wherein the AC component has a waveform such that the time for the voltage to change from a value such that an electric field making toner move toward the electrostatic latent image is maximum to a value such that the electric field becomes minimum is set to be at least 1/2 of the predetermined period of the AC component.

Abstract: A first negative or positive latent electrostatic image is formed on a latent image bearing body with a first writing device, and developed with a monochromatic toner. A second latent image of the type different than the first latent image is formed by a second writing device after setting the background voltage of the second image to have an absolute value larger than the first image, and then developed with one or two color toners selected from three color toners of respective multi-color developing units. A plurality of multi-color toner images may be formed in respective rotation cycles of the latent image bearing body. A monochromatic toner image may be formed in the same rotation cycle as one of the multi-color toner images. Finally, a plurality of toner images thus produced are transferred onto a recording sheet at once after polarities of the plurality of toner images have been arranged into the same polarity.

Abstract: There is disclosed a dual component developing device for developing an electrostatic latent image formed on a latent image carrier. The system comprises a rotatable nonmagnetic sleeve, a magnetic roll mounted inside the sleeve, and a developer-limiting member made from a nonmagnetic material. The magnetic roll has neighboring magnetic poles which have the same polarity and repel each other. The limiting member is disposed opposite to the repelling magnetic poles and between the position at which the magnetic force produced by the repelling pole located on the upstream side as viewed in the direction of movement of developer is maximal and the position at which the magnetic forces produced between the repelling poles is minimal. Thus, the developing device is capable of forming a thin film of the developer without aging. The amount of the transferred developer depends to a lesser extent on the spacing between the sleeve and the limiting member.

Abstract: In a color recording apparatus, charges are applied to a latent electrostatic image carrier by a scorotron having a grid after development of a first latent electrostatic image on the carrier with a first color toner. Thereafter, a second electrostatic latent image is formed and developed with a second color toner. If the charges given by the scorotron have the same polarity as a charging polarity of the first color toner, a potential of the grid is set to be equal to a non-image portion potential of the first latent electrostatic image, or set to have a polarity opposite to that of an image portion potential of the first latent electrostatic image assuming that the non-image portion potential is regarded as 0 V as a reference potential.

Abstract: An image forming method of the present invention comprises: a first toner image formation process for forming a first toner image by forming, on a latent image carrier, a first latent image which corresponds to a first image and developing the first latent image by a first toner charged to one polarity through a development process selected from normal and reverse development process selected from normal and reverse development processes so as to correspond to the polarity of the first toner; a second toner image formation process for forming a second toner image by forming, on the latent image carrier, a second latent image which correspond to a second image and developing the second latent image by a second toner charged to the other polarity by the other development process while applying a developing bias; and a transfer treatment process for simultaneously transferring said first and second toner images to a transfer medium; wherein said developing bias VB2 satisfies the following equations:.vertline.

Abstract: Image recording method of the present invention comprises the steps of forming electrostatic latent image on a latent image carrier by a latent image forming means, developing the formed electrostatic latent image with toner, and transferring the visualized toner image to a transfer material after repeating at least the developing step plural times, wherein double-element developer formed from mixing toner and magnetic carrier with its density of 4.0 g/cm.sup.3 or less is used in at least the second and the succeeding developing steps among the plural times of the developing steps.

Abstract: A latent color image developing system for copying a document having a first color images and second color images develops the first color images with a first color developer and the second color images with a second color developer. The second color developer includes a toner and a magnetic carrier having a density of less than 4.0 g/cm.sup.3 and a particle size in the range of 30-50 microns. A developer roll is used having a main developing pole with a flux density of more than 500 gauss in a nip region proximate a photosensitive member having latent electrostatic images to be developed.

Abstract: In electrostatic latent image developing process capable of effecting either positive or negative reproduction a magnetic toner of a high resistivity is controlled to form a magnetic brush having a potential insufficient for development. The toner chain constituting the brush is separated under the influence of an electric field between the developing roll and the image carrier, to produce toner particles having one polarity continuing with the developing roll, and particles of the opposite polarity transferred to the carrier.

Abstract: Developer mixtures comprising finely-divided toner particles electrostatically clinging to the surface of carrier particles. The toner particles comprise a colorant and at least about 60 percent by weight, based on the weight of the toner particles, of a resin mixture comprising between about 40 and about 90 parts by weight of a styrene resin and from about 10 to about 60 parts by weight of an epoxy resin. Electrostatographic imaging processes employing said developer mixtures are also disclosed.