Abstract: The present invention provides toners of different colors in which coloring agents of at least four unicolors are internally added to, respectively, and hydrophobic silica particles and metallic soap particles are externally added to toner mother particles, wherein color superposition of the toners is conducted during development of latent images on a latent image carrier or during transfer to a recording medium after the development, being characterized in that the difference (absolute value) between the work functions of two of said toners is 0.02 eV or more, the color superposition is conducted with the toners sequentially from the toner having the largest work function in descending order of work function of the toners, and the difference (absolute value) between the work function of the toner mother particles and the work function of the metallic soap particles is 0.

Abstract: The invention provides an imaging system wherein toners of two or more colors are used to form toner images and the toner images are successively used to form a color image on a recording material. The imaging system can form an image with high transfer efficiency. An electrostatic latent image is formed on an image carrier. Using developing units for two or more colors, images are formed. Then, the images are successively transferred onto an intermediate transfer medium at a transfer voltage fed from a constant-voltage power supply. The developing units are located such that development occurs in descending toner work function order.

Abstract: A liquid developer contains an insulation liquid containing as its main component a glyceride of an unsaturated fatty acid, toner particles dispersed in the insulation liquid; and an oxidation polymerization accelerator for accelerating oxidation polymerization reaction of the glyceride during fixing process of the toner particles. The oxidation polymerization accelerator accelerates the oxidation polymerization reaction by supplying oxygen during the fixing process of the toner particles. The liquid developer may further contain an antioxidizing agent. Preferably, the oxidation polymerization accelerator is contained in the insulation liquid being encapsulated.

Abstract: The present invention provides a negatively chargeable spherical toner having: a toner mother particle having a binder resin and a colorant, which has: a number average particle size of from 4.5 to 9 ?m; a particle size distribution that has an integrated value of particle sizes of 3 ?m or less of 1% or less; and an average sphericity of from 0.95 to 0.99; and an alumina fine particle externally added to the toner mother particle, which has a number average particle size of from 0.1 to 1.0 ?m, wherein a work function (?t) of the toner mother particle is larger than a work function (?A) of the alumina fine particle by at least 0.4 eV.

Abstract: An electrostatic latent image is formed on an image carrier. A first roller is opposed to the image carrier with a gap in between. A second roller is in contact with the first roller such that toner of a one-component type is supplied onto the image carrier by way of the first roller to develop the electrostatic latent image as a visible toner image. A single power source supplies a bias voltage in which an AC voltage is superposed on a DC bias voltage. The bias voltage is supplied to the first roller through a first path and to the second roller through a second path. A resistor is provided on the first path between the first roller and a branching point of the first path and the second path.

Abstract: An image forming apparatus including a latent image carrier and a developing means for charging a toner into a negative polarity by triboelectric charging, wherein the work function of the toner is set to be larger than the work function of the surface of the latent image carrier. When the apparatus includes an intermediate transfer medium, the work function of the toner is set to be larger than the work function of the surface of the intermediate transfer medium. In another embodiment, the work function ?OPC of the surface of the latent image carrier, the work function ?t of the toner, and the work function ?TM of the surface of the intermediate transfer medium are set to satisfy a relationship ?t>?OPC>?TM. These relationships help to reduce fog, and improve transfer efficiency which reduces the consumption of the toner.

Abstract: The present invention provides a toner which ensures large mean charging amount and excellent transfer efficiency with no or little amount of reversely charged toner and provides an image forming apparatus using the same. The toner is produced by adding external additives to resin particles containing a coloring agent, wherein the external additives are silica particles and modified silica particles of which outer surfaces are modified with oxide or hydroxide of at least one metal selected from a group consisting of titanium, tin, zirconium, and aluminum, the amount of the modified silica particles being 1.5 times or less of the amount the silica particles. The image forming apparatus uses the toner.

Abstract: The present invention provides a non-magnetic monocomponent negatively chargeable spherical toner including: a toner mother particle having a binder resin and a colorant; and an external additive including a hydrophobic inorganic fine particle having a number average primary particle size of 7 to 50 nm and a hydrophobic monodisperse spherical silica particle having a number average primary particle size of 70 to 130 nm, wherein the non-magnetic monocomponent negatively chargeable spherical toner has a mechanical strength of from 7 to 19 MPa, provided that the mechanical strength is determined from a 10% displacement load of a compression-displacement curve obtained in a microcompression test, wherein the hydrophobic monodisperse spherical silica particle has a work function (?S) smaller than a work function (?TB) of the toner mother particle, and a image forming apparatus using the toner.

Abstract: A non-magnetic single-component toner 8 of the present invention has toner mother particles 8a, and external additives 12 comprising: two hydrophobic silicas 13, 14 of which particle diameters are different from each other, i.e. a mean primary particle diameter of 7 nm to 12 nm and a mean primary particle diameter of 40 nm to 50 nm, and a hydrophobic rutile/anatase type titanium oxide 15 having a spindle shape of which major axial diameter is in a range from 0.02 nm to 0.10 nm and the ratio of the major axial diameter to the minor axial diameter is set to be 2 to 8, wherein the external additives 12 adhere to the toner mother particles 8a. By the hydrophobic silicas 13, 14 having work function smaller than the work function of the toner mother particles 8a, the negative charging property is imparted to the toner mother particles 8a and the fluidity is also insured.

Abstract: The present invention provides An image forming apparatus having: a negatively chargeable spherical toner; an latent image carrier; a charging member for charging a surface of the latent image carrier uniformly without contacting the latent image carrier; an electrostatic latent image forming member for forming an electrostatic latent image on the surface of the latent image carrier; a developing member for developing the electrostatic latent image, without contacting the latent image carrier, by using the negatively chargeable spherical toner so as to form a toner image on the latent image carrier; and an intermediate transfer medium to which the toner image is transferred, wherein the negatively chargeable spherical toner haves: a toner mother particle having a binder resin and a colorant; and a hydrophobic alumina particle as an external additive, wherein the hydrophobic alumina particle has a work function (?A1) larger than a work function (?TM) of a surface of the intermediate transfer medium.

Abstract: The present invention provides a toner including: a toner mother particle; an amorphous fine particle; a monodisperse spherical silica; and a metal soap, wherein the amorphous particle has the same polarity as the toner mother particle, a volume mean particle size of 0.1 times or less that of the toner mother particle, and a work function larger than that of a cleaning blade of a developing device, wherein an average sphericity of the toner L0/L1 is from 0.970 to 0.985, provided that L1 represents a circumferential length (?m) of a projected image of the toner particle, and L0 represents a circumferential length (?m) of a true circle having an area equal to that of the projected image of the toner particle.

Abstract: The present invention provides a toner having: a toner mother particle; a first external additive including a first inorganic fine particle having a primary particle size distribution of 200 to 750 nm and a work function approximately equivalent to that of the toner mother particle; a second external additive including a second inorganic fine particle having an mean particle size smaller than that of the first inorganic fine particle and a work function smaller than that of the toner particle, a stirring member of a developing device and/or an inner wall of the developing device; and 0.01% to 0.3% by weight of a metal soap having a work function approximately equivalent to that of the toner mother particle.

Abstract: An electrostatic latent image is formed on an image carrier. A first roller is opposed to the image carrier with a gap in between. A second roller is in contact with the first roller such that toner of a one-component type is supplied onto the image carrier by way of the first roller to develop the electrostatic latent image as a visible toner image. A single power source supplies a bias voltage in which an AC voltage is superposed on a DC bias voltage. The bias voltage is supplied to the first roller through a first path and to the second roller through a second path. A resistor is provided on the first path between the first roller and a branching point of the first path and the second path.

Abstract: An image forming apparatus of the present invention comprises: a latent image carrier; and a developing means for charging a toner into a negative polarity by triboelectric charging, for converting an electrostatic latent image on said latent image carrier to a visible image with said toner and is characterized in that (1) the work function (?t) of said toner is set to be larger than the work function (?OPC) of the surface of said latent image carrier, or (2) in case that the apparatus is of a type transferring the visible image to an intermediate transfer medium, the apparatus is characterized in that the work function (?t) of said toner is set to be larger than the work function (?TM) of the surface of said intermediate transfer medium or (3) the work function (?OPC) of the surface of said latent image carrier, the work function (?t) of said toner, and the work function (?TM) of the surface of said intermediate transfer medium are set to satisfy a relation ?t>?OPC>?TM.

Abstract: A non-magnetic single-component toner 8 of the present invention has toner mother particles 8a, and external additives 12 comprising: two hydrophobic silicas 13, 14 of which particle diameters are different from each other, i.e. a mean primary particle diameter of 7 nm to 12 nm and a mean primary particle diameter of 40 nm to 50 nm, and a hydrophobic rutile/anatase type titanium oxide 15 having a spindle shape of which major axial diameter is in a range from 0.02 nm to 0.10 nm and the ratio of the major axial diameter to the minor axial diameter is set to be 2 to 8, wherein the external additives 12 adhere to the toner mother particles 8a. By the hydrophobic silicas 13, 14 having work function smaller than the work function of the toner mother particles 8a, the negative charging property is imparted to the toner mother particles 8a and the fluidity is also insured.

Abstract: A negatively chargeable toner containing: resin particles containing a colorant; and an external additive which coats the surface of the resin particles, wherein the external additive contains; first silica particles having a number mean primary particle size of 5 to 20 nm and second silica particles having a number mean primary particle size of 30 to 50 nm; surface-modified silica particles which are surface modified by wet treatment using an oxide or hydroxide of at least one metal selected from the group consisting of titanium, tin, zirconium and aluminum, and are further subjected to hydrophobic treatment; and aluminum oxide-silicon dioxide composite oxide particles obtained by flame hydrolysis and hydrophobic treatment.

Abstract: Toner is for use in an image forming apparatus of the TonerJet method, which satisfies any one of the following conditions: a) toner in which the content of reverse-polarity large-diameter toner is 10% by count or smaller; b) toner in which the content of reverse-polarity fine-powder toner is 2% by count or smaller; c) toner comprising a silica additive and a titanium oxide additive such that the content x of the titanium oxide additive is in the range of 0<x?1.5 wt %. For instance, when an image is formed using toner satisfying the condition a) above, that is, toner in which the content of reverse-polarity large-diameter toner is 10% by count or smaller, filming does not occur and an image having an excellent quality is formed (denoted with “?”). On the other hand, when an image is formed using toner in which reverse-polarity large-diameter toner exceeds 10% by count, filming occurs and the quality of an image deteriorates (denoted with “X”).

Abstract: The invention provides an imaging system wherein toners of two or more colors are used to form toner images and the toner images are successively used to form a color image on a recording material. The imaging system can form an image with high transfer efficiency. An electrostatic latent image is formed on an image carrier. Using developing units for two or more colors, images are formed. Then, the images are successively transferred onto an intermediate transfer medium at a transfer voltage fed from a constant-voltage power supply. The developing units are located such that development occurs in descending toner work function order.

Abstract: The present invention provides toners of different colors in which coloring agents of at least four unicolors are internally added to, respectively, and hydrophobic silica particles and metallic soap particles are externally added to toner mother particles, wherein color superposition of the toners is conducted during development of latent images on a latent image carrier or during transfer to a recording medium after the development, being characterized in that the difference (absolute value) between the work functions of two of said toners is 0.02 eV or more, the color superposition is conducted with the toners sequentially from the toner having the largest work function in descending order of work function of the toners, and the difference (absolute value) between the work function of the toner mother particles and the work function of the metallic soap particles is 0.

Abstract: By causing the movement of charge from a toner to a latent image carrier, the amount of charge of the toner is lowered to an amount of charge suitable for facilitating the transfer of toner so as to improve the transfer efficiency. For this, an image forming apparatus includes a latent image carrier and a developing means for forming a negatively chargeable toner layer compose of two stories or less on a toner carrier by a toner layer thickness regulating member. An electrostatic latent image on the latent image carrier is developed with the toner to form a visible image and the visible image is transferred to a transfer medium. Further, the work functions (&PHgr;opc) of the surface of the latent image carrier is set to be larger than the work function (&PHgr;t) of the toner.