Patents by Inventor Kenji Okado
Kenji Okado has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7855042Abstract: To provide a developer and an image forming method with each of which a high-resolution, high-definition image can be stably obtained over a long time period irrespective of an environment. The present invention provides a developer including at least: toner particles each containing at least a binder resin; and a composite inorganic fine powder, the developer being characterized in that: the composite inorganic fine powder has a peak at a Bragg angle (2?±0.20 deg) of each of 32.20 deg, 25.80 deg, and 27.50 deg in a CuK? characteristic X-ray diffraction pattern; and the half width of the X-ray diffraction peak at a Bragg angle (2?±0.20 deg) of 32.20 deg is 0.20 to 0.30 deg.Type: GrantFiled: May 30, 2007Date of Patent: December 21, 2010Assignee: Canon Kabushiki KaishaInventors: Takakuni Kobori, Kenji Okado, Masami Fujimoto, Katsuhisa Yamazaki, Syuhei Moribe, Daisuke Yoshiba
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Publication number: 20070224530Abstract: To provide a developer and an image forming method with each of which a high-resolution, high-definition image can be stably obtained over a long time period irrespective of an environment. The present invention provides a developer including at least: toner particles each containing at least a binder resin; and a composite inorganic fine powder, the developer being characterized in that: the composite inorganic fine powder has a peak at a Bragg angle (2?±0.20 deg) of each of 32.20 deg, 25.80 deg, and 27.50 deg in a CuK? characteristic X-ray diffraction pattern; and the half width of the X-ray diffraction peak at a Bragg angle (2?±0.20 deg) of 32.20 deg is 0.20 to 0.30 deg.Type: ApplicationFiled: May 30, 2007Publication date: September 27, 2007Applicant: CANON KABUSHIKI KAISHAInventors: Takakuni Kobori, Kenji Okado, Masami Fujimoto, Katsuhisa Yamazaki, Syuhei Moribe, Daisuke Yoshiba
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Patent number: 7070898Abstract: A toner having a favorable fixability, excelling in charge stability, and capable of forming a image of retaining a high image density and a high resolution in long-term use is provided. That is, the toner of the present invention is a toner obtained by polymerizing a polymerizable monomer composition comprising a polymerizable monomer and a colorant, in which the polymerizable monomer composition is polymerized using a polymerization initiator comprising a redox initiator which includes an organic peroxide with a 10-hour half-life temperature of 86° C. or higher and an reducing agent; the toner has a ratio of a weight-average particle diameter to a number-average particle diameter of 1.40 or less; and the toner has top of a main-peak in a molecular weight range of 5,000 to 50,000 in a molecular weight distribution measured using GPC of the THF-soluble part thereof, including t-butanol with a content of 0.1 to 1,000 ppm.Type: GrantFiled: December 4, 2003Date of Patent: July 4, 2006Assignee: Canon Kabushiki KaishaInventors: Tatsuya Nakamura, Kenji Okado, Akira Hashimoto, Keiji Komoto
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Patent number: 7024138Abstract: In an image forming apparatus having at least one single electrostatic latent image bearing member and a plurality of image forming units each having a replenishing developer cartridge and a developing assembly, at least one of the image forming units is a special-color image forming unit having a special-color replenishing developer cartridge containing a special-color replenishing developer, and at least one of the other image forming unit is a non-special-color image forming unit having a non-special-color replenishing developer cartridge containing a non-special-color replenishing developer. The special-color replenishing developer cartridge has a volume larger than the volume of the non-special-color replenishing developer cartridge, and the special-color replenishing developer contains a toner and a carrier.Type: GrantFiled: January 28, 2004Date of Patent: April 4, 2006Assignee: Canon Kabushiki KaishaInventors: Naotaka Ikeda, Kenji Okado, Kazumi Yoshizaki, Hironori Minagawa
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Patent number: 7016630Abstract: In an image forming apparatus having a powder transport mechanism including a powder container and a powder transport means which rotates relative to the powder container, the powder transport means has the rotation center substantially on the axis of the powder container, and the space between the inner wall surface of the powder container and the powder transport means is sealed with magnetic particles held by a magnetic-filed generation means. The magnetic particles have a specific saturation magnetization ?s and a specific value of A×?A where the residual magnetic flux density of the magnetic-field generation means is represented by A in a specific range and the magnetization intencity of the magnetic particles in a magnetic field with the residual magnetic flux density A is represented by ?A.Type: GrantFiled: May 3, 2004Date of Patent: March 21, 2006Assignee: Canon Kabushiki KaishaInventors: Kazumi Yoshizaki, Kenji Okado, Masashige Tamura, Naotaka Ikeda
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Patent number: 6936394Abstract: An electrostatic latent image on an image-bearing member is developed with a two-component developer comprising a toner and a carrier stored in a developer vessel while supplying as required a replenishing developer to the developer vessel. The replenishing developer comprises 1 wt. part of a carrier and 2-50 wt. parts of a toner, wherein the carrier is a magnetic fine particle-dispersed resin carrier comprising at least inorganic compound particles and a carrier binder resin, and the toner has a weight-average particle size of 3 to 10 ?m and contains 1 to 40 wt. % of solid wax.Type: GrantFiled: February 25, 2002Date of Patent: August 30, 2005Assignee: Canon Kabushiki KaishaInventors: Kenji Okado, Yushi Mikuriya, Kazumi Yoshizaki, Naotaka Ikeda
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Patent number: 6855469Abstract: In a full-color image-forming method having at least a charging step, a latent-image-forming step, a developing step of developing an electrostatic latent image by the use of a developer; a transfer step, and a fixing step, the developer comprises a plurality of color developers and a black developer. The color developers are each a two-component developer for full-color image formation which has i) a color toner having color toner particles containing at least a binder resin, a colorant and a wax and ii) a carrier for the color developer. The black developer is a two-component developer for full-color image formation which has i) a black toner having black toner particles containing at least a binder resin, carbon black and a wax and ii) a carrier for the black developer. The carrier for the black developer has a larger absolute value of charge quantity when the same toner is used, than the respective carriers for the color developers.Type: GrantFiled: October 22, 2002Date of Patent: February 15, 2005Assignee: Canon Kabushiki KaishaInventors: Naotaka Ikeda, Kenji Okado, Yushi Mikuriya, Shinya Yachi, Kazumi Yoshizaki, Katsuyuki Nonaka
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Publication number: 20040258434Abstract: In an image forming apparatus having a powder transport mechanism including a powder container and a powder transport means which rotates relative to the powder container, the powder transport means has the rotation center substantially on the axis of the powder container, and the space between the inner wall surface of the powder container and the powder transport means is sealed with magnetic particles held by a magnetic-filed generation means. The magnetic particles have a specific saturation magnetization &sgr;s and a specific value of A×&sgr;A where the residual magnetic flux density of the magnetic-field generation means is represented by A in a specific range and the magnetization intencity of the magnetic particles in a magnetic field with the residual magnetic flux density A is represented by &sgr;A.Type: ApplicationFiled: May 3, 2004Publication date: December 23, 2004Applicant: Canon Kabushiki KaishaInventors: Kazumi Yoshizaki, Kenji Okado, Masashige Tamura, Naotaka Ikeda
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Publication number: 20040191659Abstract: A toner having a favorable fixability, excelling in charge stability, and capable of forming a image of retaining a high image density and a high resolution in long-term use is provided. That is, the toner of the present invention is a toner obtained by polymerizing a polymerizable monomer composition comprising a polymerizable monomer and a colorant, in which the polymerizable monomer composition is polymerized using a polymerization initiator comprising a redox initiator which includes an organic peroxide with a 10-hour half-life temperature of 86° C. or higher and an reducing agent; the toner has a ratio of a weight-average particle diameter to a number-average particle diameter of 1.40 or less; and the toner has top of a main-peak in a molecular weight range of 5,000 to 50,000 in a molecular weight distribution measured using GPC of the THF-soluble part thereof, including t-butanol with a content of 0.1 to 1,000 ppm.Type: ApplicationFiled: December 4, 2003Publication date: September 30, 2004Inventors: Tatsuya Nakamura, Kenji Okado, Akira Hashimoto, Keiji Komoto
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Publication number: 20040184838Abstract: In an image forming apparatus having at least one single electrostatic latent image bearing member and a plurality of image forming units each having a replenishing developer cartridge and a developing assembly, at least one of the image forming units is a special-color image forming unit having a special-color replenishing developer cartridge containing a special-color replenishing developer, and at least one of the other image forming unit is a non-special-color image forming unit having a non-special-color replenishing developer cartridge containing a non-special-color replenishing developer. The special-color replenishing developer cartridge has a volume larger than the volume of the non-special-color replenishing developer cartridge, and the special-color replenishing developer contains a toner and a carrier.Type: ApplicationFiled: January 28, 2004Publication date: September 23, 2004Applicant: Canon Kabushiki KaishaInventors: Naotaka Ikeda, Kenji Okado, Kazumi Yoshizaki, Hironori Minagawa
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Patent number: 6641967Abstract: A carrier for electrophotography and a two component type developer using the carrier. The carrier is composed of magnetic particles of a magnetic ferrite component represented by Formula: (Fe2O3)X(MnO)Y(A)Z. An image forming method is also disclosed which uses the two component type developer.Type: GrantFiled: March 28, 2002Date of Patent: November 4, 2003Assignee: Canon Kabushiki KaishaInventors: Tsuyoshi Takiguchi, Kenji Okado, Tetsuya Ida
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Publication number: 20030122918Abstract: In a full-color image-forming method having at least a charging step, a latent-image-forming step, a developing step of developing an electrostatic latent image by the use of a developer; a transfer step, and a fixing step, the developer comprises a plurality of color developers and a black developer. The color developers are each a two-component developer for full-color image formation which has i) a color toner having color toner particles containing at least a binder resin, a colorant and a wax and ii) a carrier for the color developer. The black developer is a two-component developer for full-color image formation which has i) a black toner having black toner particles containing at least a binder resin, carbon black and a wax and ii) a carrier for the black developer. The carrier for the black developer has a larger absolute value of charge quantity when the same toner is used, than the respective carriers for the color developers.Type: ApplicationFiled: October 22, 2002Publication date: July 3, 2003Applicant: Canon Kabushiki KaishaInventors: Naotaka Ikeda, Kenji Okado, Yushi Mikuriya, Shinya Yachi, Kazumi Yoshizaki, Katsuyuki Nonaka
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Publication number: 20030091922Abstract: An electrostatic latent image on an image-bearing member is developed with a two-component developer comprising a toner and a carrier stored in a developer vessel while supplying as required a replenishing developer to the developer vessel. The replenishing developer comprises 1 wt. part of a carrier and 2-50 wt. parts of a toner, wherein the carrier is a magnetic fine particle-dispersed resin carrier comprising at least inorganic compound particles and a carrier binder resin, and the toner has a weight-average particle size of 3 to 10 &mgr;m and contains 1 to 40 wt. % of solid wax.Type: ApplicationFiled: February 25, 2002Publication date: May 15, 2003Inventors: Kenji Okado, Yushi Mikuriya, Kazumi Yoshizaki, Naotaka Ikeda
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Patent number: 6548218Abstract: Magnetic particles for charging means disposed in contact with an electrophotographic photosensitive member for charging the electrophotographic photosensitive member based on a voltage applied thereto are provided as particles of a ferrite component represented by the following formula (1): (Fe2O3)X(A)Y(B)Z (1), wherein A denotes at least one metal oxide component selected from the group consisting of Li2O, MnO and MgO, B denotes at least one metal oxide component different from A; X, Y and Z denote numbers representing mol ratios and satisfying the following conditions: 0.2<X<0.95, 0.01<Y<0.5, X+Y≦1, and 0≦Z<0.79. The magnetic particles show an excellent charging performance, particularly in injection charging, without causing a difficulty, such as soiling or pinhole leakage of the photosensitive member.Type: GrantFiled: June 19, 1995Date of Patent: April 15, 2003Assignee: Canon Kabushiki KaishaInventors: Tsutomu Kukimoto, Kenji Okado, Shuichi Aita, Tsuyoshi Takiguchi
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Publication number: 20030008226Abstract: A carrier for electrophotography and a two component type developer using the carrier. The carrier is composed of magnetic particles of a magnetic ferrite component represented by Formula: (Fe2O3)X(MnO)Y(A)Z. An image forming method is also disclosed which uses the two component type developer.Type: ApplicationFiled: March 28, 2002Publication date: January 9, 2003Inventors: Tsuyoshi Takiguchi, Kenji Okado, Tetsuya Ida
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Patent number: 6465144Abstract: A magnetic toner includes: magnetic toner particles each comprising at least a binder resin and magnetic toner, and inorganic fine powder. The magnetic toner has an average circularity of at least 0.970, and a magnetization of 10-50 Am2/kg at a magnetic field of 79.6 kA/m. The magnetic powder comprises at least magnetic iron oxide. The magnetic toner particles retain carbon in an amount of A and iron in an amount of B at surfaces thereof as measured by X-ray photoelectron spectroscopy, satisfying: B/A<0.001. The binder resin comprises a resin formed by polymerization of a monomer comprising at least styrene monomer. The magnetic toner has a residual styrene monomer content of less than 300 ppm, and contains at least 50% by number of toner particles satisfying a relationship of: D/C≦0.Type: GrantFiled: March 8, 2001Date of Patent: October 15, 2002Assignee: Canon Kabushiki KaishaInventors: Akira Hashimoto, Kenji Okado, Tsutomu Kukimoto, Tatsuya Nakamura, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Michihisa Magome, Keiji Komoto
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Patent number: 6372400Abstract: A carrier for use in electrophotography has carrier cores comprising a binder resin and metal compound particles dispersed therein, and a coating resin for coating the surfaces of the carrier cores. Water adsorption TH2O-H (% by weight) after the carrier has been left in an environment of 30° C./80%RH, water adsorption TH2O-L (% by weight) after the carrier has been left in an environment of 23° C./5%RH, and particle surface area Sm (cm2/g) of the carrier satisfy the following relationship: 6.00×10−6≦TH2O-H/(100×Sm)≦1.50×10−5, and 1.00×10−6≦TH2O-L/(100×Sm)≦5.50×10−6.Type: GrantFiled: June 29, 2000Date of Patent: April 16, 2002Assignee: Canon Kabushiki KaishaInventors: Kazumi Yoshizaki, Kenji Okado, Makoto Kanbayashi, Yushi Mikuriya
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Publication number: 20020037470Abstract: A carrier for electrophotography and a two component type developer using the carrier.Type: ApplicationFiled: August 30, 2001Publication date: March 28, 2002Inventors: Tsuyoshi Takiguchi, Kenji Okado, Tetsuya Ida
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Publication number: 20020009661Abstract: A magnetic toner includes: magnetic toner particles each comprising at least a binder resin and magnetic toner, and inorganic fine powder. The magnetic toner has an average circularity of at least 0.970, and a magnetization of 10-50 Am2/kg at a magnetic field of 79.6 kA/m. The magnetic powder comprises at least magnetic iron oxide. The magnetic toner particles retain carbon in an amount of A and iron in an amount of B at surfaces thereof as measured by X-ray photoelectron spectroscopy, satisfying: B/A<0.001. The binder resin comprises a resin formed by polymerization of a monomer comprising at least styrene monomer. The magnetic toner has a residual styrene monomer content of less than 300 ppm, and contains at least 50% by number of toner particles satisfying a relationship of: D/C≦0.Type: ApplicationFiled: March 8, 2001Publication date: January 24, 2002Inventors: Akira Hashimoto, Kenji Okado, Tsutomu Kukimoto, Tatsuya Nakamura, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Michihisa Magome, Keiji Komoto
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Patent number: 6316157Abstract: A non-metallic black toner is disclosed. The toner has toner particles containing at least a binder resin, a carbon black and an organometallic compound, and an external additive. The toner particles contain 10 to 200 ppm of at least one kind of alkali metal element and at least one kind of organometallic compound. The toner particles further contain a polyester resin. The non-metallic black toner has a weight-average particle diameter of 4 to 11 &mgr;m, the following loss tangents tan &dgr; shown by dielectric loss factor ∈″/dielectric constant ∈′ at frequencies of 5×104 Hz and 105 Hz: tan &dgr; (5×104 Hz)≦0.0125 tan &dgr; (105 Hz)≦0.0105, a Carr's flowability index of 50 or more, and a Carr's floodability index of 65 or more. Also, an image forming method is disclose using the black toner.Type: GrantFiled: July 5, 2000Date of Patent: November 13, 2001Assignee: Canon Kabushiki KaishaInventors: Junko Yoshikawa, Kenji Okado, Masaaki Taya, Yushi Mikuriya, Kazumi Yoshizaki, Yasushi Katsuta, Kenichi Nakayama