Patents by Inventor Masahide Yamashita

Masahide Yamashita 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).

  • Publication number: 20050238980
    Abstract: A carrier composition, including a particulate magnetic material; and a layer located on a surface of the particulate magnetic material, wherein the layer is formed by heating a mixture containing a metal alkoxide; a resin having a hydroxyl group reacting with the metal alkoxide; and a particulate inorganic material.
    Type: Application
    Filed: March 2, 2005
    Publication date: October 27, 2005
    Inventors: Masahide Yamashita, Tomio Kondou, Kousuke Suzuki
  • Publication number: 20050141917
    Abstract: An image forming apparatus includes an image carrier, a charging device configured to uniformly charge a surface of the image carrier with a charging member applied with a bias of a first polarity (e.g. a negative polarity) for charging. A latent image forming device forms a latent image on the surface of the image carrier uniformly charged. A developing device develops a latent image by depositing toner grains of the first polarity on the latent image to thereby form a corresponding toner image. A transferring device forms an electric field between the image carrier and a moving member that serves as a movable contact with the image carrier to thereby transfer the toner image from the surface of the image carrier to the moving member or to a recording member nipped between the image carrier and the moving member. A polarity controlling device sets residual toner to a second polarity (e.g.
    Type: Application
    Filed: December 3, 2004
    Publication date: June 30, 2005
    Inventors: Shigekazu Enoki, Koji Suzuki, Yasushi Koichi, Osamu Ariizumi, Kumiko Hatakeyama, Koichi Kato, Masahide Yamashita, Toshiyuki Kabata, Jun Yura
  • Publication number: 20050079434
    Abstract: A carrier for a double component developer for developing latent electrostatic images at least contains a particulate core material having a weight average particle diameter (Dw) of from 25 to 45 ?m and a magnetic moment of from 65 to 90 Am2/Kg at 1 KOe and a resin layer located on the surface of the particulate core material. Further, the carrier has a breakdown voltage not less than 1,000 V.
    Type: Application
    Filed: October 12, 2004
    Publication date: April 14, 2005
    Inventors: Kousuke Suzuki, Tomio Kondou, Masahide Yamashita
  • Patent number: 6852459
    Abstract: A color toner composition including at least toner particles including at least a binder resin; a colorant and a release agent dispersed in the binder resin; and a titania as an external additive, wherein the colorant has an average dispersion particle diameter not greater than 0.5 ?m; the release agent and the binder resin are insoluble to each other; the toner particles satisfy the relationship: 0.05?Dw/D4?0.4, wherein Dw represents an average dispersion particle diameter of the release agent and D4 represents a weight-average particle diameter of the toner particles; and the titania has a segregation rate of from 0.5 to 5%.
    Type: Grant
    Filed: February 22, 2002
    Date of Patent: February 8, 2005
    Assignee: Ricoh Company, Ltd.
    Inventors: Kohki Katoh, Masanori Suzuki, Yohichiro Watanabe, Masahide Yamashita, Akihiro Kotsugai, Toyoshi Sawada, Keiko Shiraishi
  • Publication number: 20050008962
    Abstract: A color toner composition including at least toner particles including at least a binder resin; a colorant and a release agent dispersed in the binder resin; and a titania as an external additive, wherein the colorant has an average dispersion particle diameter not greater than 0.5 ?m; the release agent and the binder resin are insoluble to each other; the toner particles satisfy the relationship: 0.05?Dw/D4? 0.4, wherein Dw represents an average dispersion particle diameter of the release agent and D4 represents a weight-average particle diameter of the toner particles; and the titania has a segregation rate of from 0.5 to 5%.
    Type: Application
    Filed: August 6, 2004
    Publication date: January 13, 2005
    Inventors: Kohki Katoh, Masanori Suzuki, Yohichiro Watanabe, Masahide Yamashita, Akihiro Kotsugai, Toyoshi Sawada, Keiko Shiraishi
  • Publication number: 20050003292
    Abstract: A carrier including a manganese ferrite core material having a layer on its surface such that 0.1?K?30, where K=(S/M)×100, S and M represent the standard deviation and average of M2/(M1+M2), respectively, M ranging from 0.05 to 0.45, and M1 and M2 represent the content of iron and manganese, respectively, in a carrier particle. The carrier has a magnetization ranging from 45 to 75 emu/g at 1,000 Oe, a mass-averaged particle diameter, D4, ranging from 25 to 65 ?m and carrier particles having a particle diameter not greater than 12 ?m are included in an amount not greater than 0.3% by weight, and a ratio, D4/D1, ranging from 1 to 1.3, where D1 is a number-averaged particle diameter of the carrier.
    Type: Application
    Filed: May 13, 2004
    Publication date: January 6, 2005
    Inventors: Masahide Yamashita, Tomio Kondou, Kohsuke Suzuki
  • Publication number: 20040253528
    Abstract: A carrier including a magnetic core material and a layer located on a surface of the magnetic core material, wherein the carrier satisfies the following relationships (1) to (3): 0.90≦(&sgr;a/&sgr;b)<1.00 (1); 200≦(&sgr;b·&rgr;c)≦400 (2); 10≦(&sgr;b/&rgr;c)≦20 (3), wherein &sgr;b represents a magnetization of the carrier at 1,000 Oe, &sgr;a represents a magnetization of the carrier after frictionized with a cylindrical sleeve under a specific condition and &rgr;c represents a true specific gravity of the carrier, wherein the carrier has a weight-average particle diameter of about 25 to about 65 &mgr;m and includes carrier particles having a weight-average particle diameter not greater than about 12 &mgr;m in an amount of not greater than about 0.3% by weight, wherein a ratio between the weight-average particle diameter and a number-average particle diameter of the carrier is about 1 to about 1.3, and wherein an electric resistance is from about 1.0×109 to about 1.
    Type: Application
    Filed: January 30, 2004
    Publication date: December 16, 2004
    Inventors: Masahide Yamashita, Satoshi Mochizuki, Tomio Kondou, Kohsuke Suzuki
  • Publication number: 20040234876
    Abstract: A carrier for electrostatic development contains a core particle and a coating layer covering the core particle, and the core particle is a ferrite particle containing at least one of Zr in an amount of 0.005% by mass to 5% by mass and Bi in an amount of 0.001% by mass to 1% by mass. The carrier shows a sufficient resistance, is stably charged over a long period of time, can avoid roughness and irregular density in halftone images, prevents deposition of the carrier particles on a photoconductor, can satisfactorily reproduce character images and can produce high-quality images over a long period of time. The carrier is usable for constituting a developer, a container housing the developer, an image forming apparatus and process, and process cartridge using the developer.
    Type: Application
    Filed: March 12, 2004
    Publication date: November 25, 2004
    Inventors: Kousuke Suzuki, Tomio Kondou, Masahide Yamashita
  • Patent number: 6790575
    Abstract: A two component developer comprising a magnetic toner containing a binder resin and a magnetic particle, and a magnetic carrier containing a magnetic particle, wherein the magnetic toner has an average particle diameter of 4.0 to 10.0 &mgr;m, and contains 5 to 80 No. % of toner particles having particle diameter of 5 &mgr;m or less, and exhibits magnetization of 10 to 25 emu/g under magnetic field of 5 kiloersteds.
    Type: Grant
    Filed: March 21, 2002
    Date of Patent: September 14, 2004
    Assignee: Ricoh Company, Ltd.
    Inventors: Fumihiro Sasaki, Hiroaki Matsuda, Bing Shu, Maiko Kondo, Hiroshi Nakai, Hiroto Higuchi, Yasuaki Iwamoto, Yoshihiro Suguro, Hiroyuki Yoshikawa, Masahide Yamashita, Kazuyuki Yazaki
  • Patent number: 6743558
    Abstract: A carrier for electrophotographic developer essentially consisting of a core material of magnetic particles and thereon provided a resinous coating layer, wherein a weight-average particle-diameter(Dw) of the carrier ranges from 25 to 45 &mgr;m, the content of particles having diameter less than 44 &mgr;m is more than or equal to 75% by weight, the content of particles having diameter more than or equal to 62 &mgr;m is less than one percent by weight, the content of particles having diameter less than 22 &mgr;m is less than or equal to 7.0% by weight, the magnetic moment of the carrier at 1 kilo Oe of magnetic field is more than or equal to 76 emu/g. The carrier shows high optical density of image with no smearing of background area, good reproducibility in developing of small dots in image with no carrier deposition.
    Type: Grant
    Filed: May 1, 2002
    Date of Patent: June 1, 2004
    Assignee: Ricoh Company, Ltd.
    Inventors: Kimitoshi Yamaguchi, Masahide Yamashita, Akihiro Kotsugai, Hiroaki Takahashi
  • Patent number: 6740461
    Abstract: A carrier is composed of carrier particles, each carrier particle having a core particle containing at least a magnetic material and a surface coating layer provided on the core particle containing at least a resin, the surface coating layer being constituted of a plurality of regions, the regions being separately formed and joined together to form a complex configuration, and having different phase lags when the surface coating layer is subjected to scanning by phase imaging measurement using a scanning probe microscope in a tapping mode, wherein a region having a phase lag over the average phase lag obtained from Eavg=&Sgr;(E(i)·S(i))/&Sgr;S(i) has an area SO, and SO and &Sgr;S(i) are in a relationship of 10%≦SO/&Sgr;S(i)×100≦90% when each region comprises a component A(i) having an area S(i) and a phase lag E(i), in which i represents the number of regions with different phase lags. A two-component developer employs the above-mentioned carrier.
    Type: Grant
    Filed: December 20, 2002
    Date of Patent: May 25, 2004
    Assignee: Ricoh Company, Ltd.
    Inventors: Masahide Yamashita, Masanori Suzuki, Yohichiroh Watanabe, Kazuhito Watanabe, Keiko Shiraishi, Kohki Katoh
  • Patent number: 6716561
    Abstract: A toner for developing electrostatic latent images, including a matrix of a first resin selected from polyester resins, polyol resins and mixtures thereof, a plurality of domains of a second resin dispersed in the matrix and containing a wax. The amount of the wax is 2-15% by weight based on the weight of the toner The matrix is substantially free of domains of the second resin having a maximum diameter of greater than 2.0 &mgr;m. A part of the domains containing the wax having a maximum diameter of at least 0.2 &mgr;m constitutes a part of an outer surface of the toner.
    Type: Grant
    Filed: November 27, 2001
    Date of Patent: April 6, 2004
    Assignee: Ricoh Company, Ltd.
    Inventors: Keiko Shiraishi, Masanori Suzuki, Yohichiroh Watanabe, Masahide Yamashita, Akihiro Kotsugai, Toyoshi Sawada, Kohki Katoh
  • Patent number: 6653037
    Abstract: A toner for developing latent electrostatic images is provided which contains, in a binder resin, at least a coloring agent formed from a metal material. A saturation magnetization of the toner is 0.01 to 10 emu/g, and a true specific gravity thereof is 1.33 to 1.62 g/m3. Also provided are an electrostatic charge image developer containing the toner for developing latent electrostatic images, an image forming device, and an image forming method using the toner for developing latent electrostatic images.
    Type: Grant
    Filed: November 19, 2001
    Date of Patent: November 25, 2003
    Assignee: Ricoh Company, Ltd.
    Inventors: Toyoshi Sawada, Masanori Suzuki, Kohki Katoh, Yohichiroh Watanabe, Masahide Yamashita, Akihiro Kotsugai, Keiko Shiraishi
  • Publication number: 20030180643
    Abstract: A developer for developing an electrostatic latent image, including a carrier which includes core particles, and a surface layer surrounding each of the core particles and containing an acrylic resin binder; and a toner which includes toner particles and an external additive of inorganic or organic fine particles present on each of the toner particles. Each of the toner particles comprises a colorant, a matrix of a first resin, and a plurality of domains of a second resin dispersed in the matrix and containing a wax. The first resin is substantially free of tetrahydrofuran insoluble matters and has a weight average molecular weight of 3,000 to 90,000.
    Type: Application
    Filed: March 20, 2003
    Publication date: September 25, 2003
    Inventors: Kohsuke Suzuki, Satoshi Mochizuki, Tomio Kondou, Masahide Yamashita, Tomomi Tamura, Takayuki Koike
  • Publication number: 20030165765
    Abstract: A carrier is composed of carrier particles, each carrier particle having a core particle containing at least a magnetic material and a surface coating layer provided on the core particle containing at least a resin, the surface coating layer being constituted of a plurality of regions, the regions being separately formed and joined together to form a complex configuration, and having different phase lags when the surface coating layer is subjected to scanning by phase imaging measurement using a scanning probe microscope in a tapping mode, wherein a region having a phase lag over the average phase lag obtained from Eavg=&Sgr;(E(i)·S(i))/&Sgr;S(i) has an area SO, and SO and &Sgr;S(i) are in a relationship of 10%≦SO/&Sgr;S(i)×100≦90% when each region comprises a component A(i) having an area S(i) and a phase lag E(i), in which i represents the number of regions with different phase lags. A two-component developer employs the above-mentioned carrier.
    Type: Application
    Filed: December 20, 2002
    Publication date: September 4, 2003
    Inventors: Masahide Yamashita, Masanori Suzuki, Yohichiroh Watanabe, Kazuhito Watanabe, Keiko Shiraishi, Kohki Katoh
  • Publication number: 20030096183
    Abstract: A color toner composition including at least toner particles including at least a binder resin; a colorant and a release agent dispersed in the binder resin; and a titania as an external additive, wherein the colorant has an average dispersion particle diameter not greater than 0.5 &mgr;m; the release agent and the binder resin are insoluble to each other; the toner particles satisfy the relationship: 0.05≦Dw/D4≦0.4, wherein Dw represents an average dispersion particle diameter of the release agent and D4 represents a weight-average particle diameter of the toner particles; and the titania has a segregation rate of from 0.5 to 5%.
    Type: Application
    Filed: February 22, 2002
    Publication date: May 22, 2003
    Inventors: Kohki Katoh, Masanori Suzuki, Yohichiro Watanabe, Masahide Yamashita, Akihiro Kotsugai, Toyoshi Sawada, Keiko Shiraishi
  • Patent number: 6566026
    Abstract: A toner including mother toner particles including at least two resins A and B and a wax each of which is incompatible with the others; and an external additive including at least one of a particulate inorganic material and a particulate resin, wherein the resins and wax form a sea-island structure in which the resin B is present like islands in a sea of the resin A and the wax is substantially included in the resin B while dispersed therein, and wherein the resin A does not include a component insoluble in tetrahydrofuran and has a weight average molecular weight of from 10,000 to 90,000.
    Type: Grant
    Filed: June 26, 2001
    Date of Patent: May 20, 2003
    Assignee: Ricoh Company,. Ltd.
    Inventors: Yohichiroh Watanabe, Masanori Suzuki, Masahide Yamashita, Keiko Shiraishi, Kazuhito Watanabe, Kohki Katoh, Toyoshi Sawada, Takuya Saito
  • Publication number: 20030073021
    Abstract: A two component developer comprising a magnetic toner containing a binder resin and a magnetic particle, and a magnetic carrier containing a magnetic particle, wherein the magnetic toner has an average particle diameter of 4.0 to 10.0 &mgr;m, and contains 5 to 80 No. % of toner particles having particle diameter of 5 &mgr;m or less, and exhibits magnetization of 10 to 25 emu/g under magnetic field of 5 kiloersteds.
    Type: Application
    Filed: March 21, 2002
    Publication date: April 17, 2003
    Inventors: Fumihiro Sasaki, Hiraoki Matsuda, Bing Shu, Maiko Kondo, Hiroshi Nakai, Hiroto Higuchi, Yasuaki Iwamoto, Yoshihiro Suguro, Hiroyuki Yoshikawa, Masahide Yamashita, Kazuyuki Yazaki
  • Publication number: 20030054279
    Abstract: A carrier for electrophotographic developer essentially consisting of a core material of magnetic particles and thereon provided a resinous coating layer, wherein a weight-average particle-diameter(Dw) of the carrier ranges from 25 to 45 &mgr;m, the content of particles having diameter less than 44 &mgr;m is more than or equal to 75% by weight, the content of particles having diameter more than or equal to 62 &mgr;m is less than one percent by weight, the content of particles having diameter less than 22 &mgr;m is less than or equal to 7.0% by weight, the magnetic moment of the carrier at 1 kilo Oe of magnetic field is more than or equal to 76 emu/g. The carrier shows high optical density of image with no smearing of background area, good reproducibility in developing of small dots in image with no carrier deposition.
    Type: Application
    Filed: May 1, 2002
    Publication date: March 20, 2003
    Inventors: Kimitoshi Yamaguchi, Masahide Yamashita, Akihiro Kotsugai, Hiroaki Takahashi
  • Publication number: 20030036010
    Abstract: A toner for developing a latent electrostatic image to a toner image, including a binder resin, and a magnetic material which is blackened by coating the surface of a magnetic powder with a coloring agent, the magnetic material being in an amount of 10 wt. % to 40 wt. % of the entire weight of the toner, a method of forming an image, using a two-component developer containing the toner, an image formation apparatus using the two-component developer, and a toner container containing therein the toner, and an image formation apparatus equipped with the toner container are proposed.
    Type: Application
    Filed: April 5, 2001
    Publication date: February 20, 2003
    Inventors: Masanori Suzuki, Yohichiroh Watanabe, Masahide Yamashita, Kazuhito Watanabe, Keiko Shiraishi, Kohki Katoh