Method of forming composite color image

Abstract

The present invention provides a composite color image forming method. The method includes electrically charging a latent image-holding member; exposing the charged latent image-holding member to light to form an electrostatic latent image; developing the electrostatic latent image with a two-component developer containing toner particles of one color and a carrier to form a toner image on the latent image-holding member; primarily transferring the toner image from the latent image-holding member to an intermediate transfer member; repeating the electrically charging, the exposing, the developing, and the primarily transferring, while the toner particles are replaced with toner particles of different color, to form a composite color image on the intermediate transfer member; and secondarily transferring the composite color image from the intermediate transfer member to a recording medium. The carrier contains magnetic substance-dispersed core particles in which a magnetic substance is dispersed in a resin, and a coating layer that coats the surface of each of the magnetic substance-dispersed core particles at a covering rate of 95% or more. In addition, the carrier has a degree of circularity of 0.970 or more. The intermediate transfer member is a belt that has a substrate whose Young's modulus is in the range of 3,000 to 6,500 MPa. During the primary transferring, primary transfer nip pressure is in the range of 8 to 20 gf/cm, and a value (T/P) obtained by dividing a primary transfer current value T (μA) by a processing speed P (mm/sec) is from 0.08 to 0.18.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be described in detail based on the following figures, wherein:

FIG. 1 is a diagram schematically illustrating the structure of an exemplary embodiment of an image forming apparatus used in the invention;

FIG. 2A is a cross-sectional view schematically illustrating the structure of an intermediate transfer belt 100a usable in the invention;

FIG. 2B is a cross-sectional view schematically illustrating the structure of an intermediate transfer belt 100b usable in the invention;

FIG. 3A is a plan view schematically illustrating an example of an electrode having a circular plan shape; and

FIG. 3B is a cross-sectional view schematically illustrating the electrode of FIG. 3A.

Claims

1. A method of forming a composite color image, comprising: electrically charging a latent image-holding member;exposing the charged latent image-holding member to light to form an electrostatic latent image;developing the electrostatic latent image with a two-component developer containing toner particles of one color and a carrier to form a toner image on the latent image-holding member;primarily transferring the toner image from the latent image-holding member to an intermediate transfer member;repeating the electrically charging, the exposing, the developing, and the primarily transferring, while the toner particles are replaced with toner particles of different color, to form a composite color image on the intermediate transfer member; andsecondarily transferring the composite color image from the intermediate transfer member to a recording medium;the carrier comprising magnetic substance-dispersed core particles in which a magnetic substance is dispersed in a resin, and a coating layer that is made of a resin and that coats the surface of each of the magnetic substance-dispersed core particles at a covering rate of about 95% or more, the carrier having a degree of circularity of about 0.970 or more, the intermediate transfer member being a belt that has a substrate whose Young's modulus is in the range of about 3,000 to about 6,500 MPa, andduring the primary transferring, primary transfer nip pressure being in the range of about 8 to about 20 gf/cm, and a value (T/P) obtained by dividing a primary transfer current value T by a processing speed P being in the range of about 0.08 to about 0.18 μA.sec/mm.

2. A method of forming a composite color image, comprising: electrically charging a latent image-holding member;exposing the charged latent image-holding member to light to form an electrostatic latent image;developing the electrostatic latent image with a two-component developer containing toner particles of one color and a carrier to form a toner image on the latent image-holding member;primarily transferring the toner image from the latent image-holding member to an intermediate transfer member;repeating the electrically charging, the exposing, the developing, and the primarily transferring, while the toner particles are replaced with toner particles of different color, to form a composite color image on the intermediate transfer member; andsecondarily transferring the composite color image from the intermediate transfer member to a recording medium;the carrier comprising magnetic substance core particles that have surface roughness, or mean spacing between protrusions, Sm of about 2.0 μm or less, and surface roughness, or arithmetic average roughness, Ra of about 0.1 μm or more, and a coating layer that is made of a resin and that coats the surface of each of the magnetic substance core particles at a coating content of about 3 to 10 percent by mass relative to the total mass of the magnetic substance core particles, the carrier having a degree of circularity of about 0.970 or more,the intermediate transfer member being a belt that has a substrate whose Young's modulus is in the range of about 3,000 to about 6,500 MPa, andduring the primary transferring, primary transfer nip pressure being in the range of about 8 to about 20 gf/cm, and a value (T/P) obtained by dividing a primary transfer current value T by aprocessing speed P being in the range of about 0.08 to about 0.18 μA.sec/mm.