# US 6,737,209 B2 · Color image forming method using flattened toner > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,737,209 B2 - Document ID: US6737209B2 - Status: Granted - Kind: B2 - Application number: 10/172,690 - Filed: 2002-06-14 - Published: 2003-08-14 - Granted: 2004-05-18 - Earliest claimed: 2001-06-22 - Assignees: Konica Corporation - Inventors: Kunio Shigeta; Yotaro Sato; Satoshi Haneda - Web page: https://patentgrep.com/patent/US6737209B2 ## CPC - G03G 13/0133: {developing using a step for deposition of subtractive colorant developing compositions, e.g. cyan, magenta and yellow} - G03G 9/0827: {characterised by their shape, e.g. degree of sphericity} - G03G 2215/017: single rotation of recording member to produce multicoloured copy - G03G 2215/0497: Exposure from behind the image carrying surface - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A color image forming method in which a color toner image is formed through superposing toner images of three color toners of yellow, magenta, and cyan and a black toner, wherein each of the color toners is a flattened toner composed of particles each having an equivalent circle diameter d of 5 to 10 (μm) when viewed from a direction to make a projection area maximum, a thickness t of 1 to 4 (μm), and a flattening ratio d/t of 2 to 8 represented by a ratio of the equivalent circle diameter d to the thickness t, and the flattening ratio d/t of the particles of the color toners is larger than the flattening ratio dk/tK of the particles of the black toner. ## Claims ### Claim 1 A color image forming method for forming a color toner image, comprising the steps of: forming toner images of three color toners of yellow, magenta, and cyan and a black toner; and superposing the toner images, thereby forming the color toner image, wherein each of said color toners is a flattened toner composed of particles each having an equivalent circle diameter d of 5 to 10 (μm) when viewed from a direction to make a projection area maximum, a thickness t of 1 to 4 (μm), and a flattening ratio d/t of 2 to 8 represented by a ratio of said equivalent circle diameter d to said thickness t, and wherein the flattening ratio d/t of the particles of each of said three color toners is larger than a flattening ratio dk/tk of the particles of said black toner, where dk and tk represent an equivalent circle diameter and a thickness, respectively, of the particles of said black toner. ### Claim 2 (depends on 1) The color image forming method of claim 1, wherein the flattening ratio d/t of the particles of each of said three color toners is 2 to 4 times the flattening ratio dk/tk of the particles of said black toner. ### Claim 3 (depends on 1) The color image forming method of claim 1, wherein the equivalent circle diameter d of the particles of each of said three color toners of yellow, magenta, and cyan is 1.2 to 2 times the equivalent circle diameter dk of the particles of said black toner. ### Claim 4 (depends on 3) The color image forming method of claim 3, wherein a shape of coefficient of each of said three color toners when viewed from a direction to make a projection area maximum, is 0.95 to 1.00, where the shape of coefficient=(a circumferential length of a circle obtained from an equivalent circle diameter)/(a circumferential length of a projection image of a particle). ### Claim 5 (depends on 3) The color image forming method of claim 3, wherein a maximum deposition quantity of each of toner layers of said three color toners of yellow, magenta, and cyan is smaller than a toner layer of said black toner. ### Claim 6 (depends on 1) The color image forming method of claim 1, further comprising concurrently transferring the color toner image formed on an image forming body onto a transfer material after superposing the toner images of the three color toners of yellow, magenta, and cyan and the black toner on the image forming body to form the color toner image. ### Claim 7 (depends on 6) The color image forming method of claim 6, wherein when the color toner image is formed on the image forming body, the superposing step is carried out so that the toner image of said black toner comes to an upper side of the toner images of said color toners. ### Claim 8 (depends on 6) The color image forming method of claim 6, wherein a shape of coefficient of each of said three color toners when viewed from a direction to make a projection area maximum, is 0.95 to 1.00, where the shape of coefficient=(a circumferential length of a circle obtained from an equivalent circle diameter)/(a circumferential length of a projection image of a particle). ### Claim 9 (depends on 6) The color image forming method of claim 6, wherein a maximum deposition quantity of each of toner layers of said three color toners of yellow, magenta, and cyan is smaller than a toner layer of said black toner. ### Claim 10 (depends on 1) The color image forming method of claim 1, wherein the superimposing step comprises sequentially transferring toner images formed on a plurality of image forming bodies onto a transfer material to form the color image after forming the toner images of the three color toners of yellow, magenta, and cyan and the black toner on the plurality of image forming bodies, respectively. ### Claim 11 (depends on 10) The color image forming method of claim 10, wherein when the toner images are sequentially transferred onto the transfer material to form the color toner image, the superposing step is carried out so that the toner image of said black toner comes to an upper side of the toner images of said color toners. ### Claim 12 (depends on 10) The color image forming method of claim 10, wherein a shape of coefficient of each of said three color toners when viewed from a direction to make a projection area maximum, is 0.95 to 1.00, where the shape of coefficient=(a circumferential length of a circle obtained from an equivalent circle diameter)/(a circumferential length of a projection image of a particle). ### Claim 13 (depends on 10) The color image forming method of claim 10, wherein a maximum deposition quantity of each of toner layers of said three color toners of yellow, magenta, and cyan is smaller than a toner layer of said black toner. ### Claim 14 (depends on 1) The color image forming method of claim 1, wherein the superposing step comprises sequentially transferring toner images formed on a plurality of image forming bodies onto an intermediate transfer material to form the color toner image after forming the toner images of the three color toners of yellow, magenta, and cyan and the black toner on the plurality of image forming bodies, respectively, and the color toner image forming method further comprising concurrently transferring the color toner image onto a transfer material after forming the toner images of the three color toners of yellow, magenta, and cyan and the black toner on the plurality of image forming bodies, respectively. ### Claim 15 (depends on 14) The color image forming method of claim 14, wherein when the toner images are sequentially transferred onto the intermediate transfer material to form the color image, the superposing step is carried out so that the toner image of said black toner comes to an upper side of the toner images of said color toners. ### Claim 16 (depends on 14) The color image forming method of claim 14, wherein a shape of coefficient of each of said three color toners when viewed from a direction to make a projection area maximum, is 0.95 to 1.00, where the shape of coefficient=(a circumferential length of a circle obtained from an equivalent circle diameter)/(a circumferential length of a projection image of a particle). ### Claim 17 (depends on 14) The color image forming method of claim 14, wherein a maximum deposition quantity of each of toner layers of said three color toners of yellow, magenta, and cyan is smaller than a toner layer of said black toner. ### Claim 18 (depends on 1) The color image forming method of claim 1, wherein the thickness t of the particles of each of said three color toners is smaller than the thickness tk of the particles of said black toner. ### Claim 19 (depends on 18) The color image forming method of claim 18, wherein the thickness t of particles of each of said three color toners is 0.25 to 0.7 times the thickness tk of the particles of said black toner. ### Claim 20 (depends on 18) The color image forming method of claim 18, wherein a shape of coefficient of each of said three color toners when viewed from a direction to make a projection area maximum, is 0.95 to 1.00, where the shape of coefficient=(a circumferential length of a circle obtained from an equivalent circle diameter)/(a circumferential length of a projection image of a particle). ### Claim 21 (depends on 18) The color image forming method of claim 18, wherein a maximum deposition quantity of each of toner layers of said three color toners of yellow, magenta, and cyan is smaller than a toner layer of said black toner.