Abstract: In an image forming apparatus, a developer agitation member has a mechanism to vary its driving force, and the driving force of the developer agitation member is changed by a control unit according to the information of the number of times of image formation from a counter.

Abstract: Image forming histories when decolorization toner is used by a first counter or a second counter and when ordinary toner is used are counted respectively, and image forming histories of a decolorization developing device and an ordinary developing device are counted by a third counter or a fourth counter, and life control is executed for expendables, and adjustment of process conditions is controlled.

Abstract: A toner is formed of toner particles including a polyester resin as a principal component, and at least a colorant and a charge control agent, and externally added inorganic fine particles and organic fine particles. The toner has a volume-average diameter of 4 to 10 ?m, contains the charge control agent at 0.1 to 1.5%, and has an acid value of 2 to 33 mgKOH/g. The charge control agent exhibits a number-basis isolation percentage of at most 10% with respect to the toner particle. The charge control agent, the inorganic fine particles and organic fine particles exhibit number-basis isolation percentages from the toner particles satisfying a following relationship: 30%>inorganic fine particles>organic fine particles>charge control agent>0%.

Abstract: A developing agent contains a toner particle having a substantially spherical polymer phase selected from any one of acrylic bases, styrene bases or styrene-acrylic bases and a polyester based resin phase to coat the polymer phase such that at least a part thereof is exposed. It becomes possible to improve the low temperature fixability, by using the developing agent.

Abstract: In an image forming apparatus, a developer agitation member has a mechanism to vary its driving force, and the driving force of the developer agitation member is changed by a control unit according to the information of the number of times of image formation from a counter.

Abstract: A developing agent comprising color toners and a cyan toner, the color toners including a yellow toner, a magenta toner, and a black toner, wherein the black toner comprises a binder resin containing a crystalline polyester resin, and the yellow toner, the magenta toner and the cyan toner each comprise a binder resin containing no crystalline polyester resin.

Abstract: Of developing agents each having a binder containing a polyester resin having an acidic value, wax having a softening point higher than that of the binder, and wax having a softening point lower than that of the binder, the acidic value of a black developing agent is made higher than that of a color developing agent.

Abstract: A developing agent comprising color toners and a cyan toner, the color toners including a yellow toner, a magenta toner, and a black toner, wherein the black toner comprises a binder resin containing a crystalline polyester resin, and the yellow toner, the magenta toner and the cyan toner each comprise a binder resin containing no crystalline polyester resin.

Abstract: A toner is formed of toner particles including a polyester resin as a principal component, and at least a colorant and a charge control agent, and externally added inorganic fine particles and organic fine particles. The toner has a volume-average diameter of 4 to 10 ?m, contains the charge control agent at 0.1 to 1.5%, and has an acid value of 2 to 33 mgKOH/g. The charge control agent exhibits a number-basis isolation percentage of at most 10% with respect to the toner particle. The charge control agent, the inorganic fine particles and organic fine particles exhibit number-basis isolation percentages from the toner particles satisfying a following relationship: 30%>inorganic fine particles>organic fine particles>charge control agent>0%.

Abstract: A developing agent comprising color toners and a cyan toner, the color toners including a yellow toner, a magenta toner, and a black toner, wherein the black toner comprises a binder resin containing a crystalline polyester resin, and the yellow toner, the magenta toner and the cyan toner each comprise a binder resin containing no crystalline polyester resin.

Abstract: Image forming histories when decolorization toner is used by a first counter or a second counter and when ordinary toner is used are counted respectively, and image forming histories of a decolorization developing device and an ordinary developing device are counted by a third counter or a fourth counter, and life control is executed for expendables, and adjustment of process conditions is controlled.

Abstract: A developing agent comprising color toners and a cyan toner, the color toners including a yellow toner, a magenta toner, and a black toner, wherein the black toner comprises a binder resin containing a crystalline polyester resin, and the yellow toner, the magenta toner and the cyan toner each comprise a binder resin containing no crystalline polyester resin.

Abstract: The invention provides a developing agent that includes color toners and a black toner. The color toners include a yellow toner, a magenta toner and a cyan toner. Each of the yellow toner, the magenta toner and the cyan toner contains, as a binder resin, a mixture of an H form of polyester mainly containing higher molecular components polyester, and an L form of polyester mainly containing lower molecular components of polyester. The black toner contains, as a binder resin, a mixture of an H form of polyester mainly containing higher molecular components of polyester, and an L form of polyester mainly containing lower molecular components polyester, and a crystalline polyester resin.

Abstract: In a toner of the present invention containing binder resin and a coloring agent, the toner is comprised a mixture of first toner and second toner which are different in the binder resin from each other, and only either of the first toner and second toner contains crystalline polyester resin.

Abstract: Disclosed is a developing agent using a binder resin including a styrene-acrylic-series resin, a crystalline polyester resin, a first wax having a melting point higher than the softening point of the crystalline polyester resin, and a second wax having a melting point lower than the softening point of the crystalline polyester resin.

Abstract: A developing agent comprising color toners and a cyan toner, the color toners including a yellow toner, a magenta toner, and a black toner, wherein the black toner comprises a binder resin containing a crystalline polyester resin, and the yellow toner, the magenta toner and the cyan toner each comprise a binder resin containing no crystalline polyester resin.

Abstract: A developing agent comprising a binder resin containing a crystalline resin having a crystallinity of 10 to 50%, and the temperature at the DSC heat absorption peak of the developing agent in the heating step differs from the temperature at the DSC heat generation peak of the developing agent in the cooling step.

Abstract: A developing agent comprising color toners and a cyan toner, the color toners including a yellow toner, a magenta toner, and a black toner, wherein the black toner comprises a binder resin containing a crystalline polyester resin, and the yellow toner, the magenta toner and the cyan toner each comprise a binder resin containing no crystalline polyester resin.

Abstract: A binder resin includes a first polyester resin having a high softening point Sp1, a second polyester resin having a softening point Sp2 higher than the softening point Sp1, a first wax having a melting point Mp1 higher than the softening point Sp2, and a second wax having a melting point Mp2 lower than the softening point Sp2.

Abstract: In a color image forming method comprising the steps of forming a primary transferring image comprising plural developer images in different colors on an intermediate transferring belt by repeating the process to develop and transfer developer images on an intermediate transferring belt and forming a secondary transferring image by transferring the primary transferring image on a transfer paper, absolute values of tribo-charge amount of plural kinds of developers are 10 to 30 ?C/g, and an absolute value of tribo-charge amount of a developer used lastly for the development is larger than that of a developer first used for the development and a difference between them is more than 2 ?C/g×(number of developers used ?1).