Patents by Inventor Masatsugu Fujiwara

Masatsugu Fujiwara 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).

  • Patent number: 6537716
    Abstract: A toner for developing electrostatic images is comprised of a binder resin and a wax. The binder resin contains as a primary component a polyester resin having a soft segment. The wax has, in its endothermic peaks at the time of temperature rise and exothermic peaks at the time of temperature drop in the DSC curve measured using a differential scanning calorimeter; (i) an endothermic onset temperature within the range of from 50° C. to 110° C.; (ii) at least one endothermic peak P1 within the range of from 70° C. to 130° C. at the time of temperature rise; and (iii) a maximum exothermic peak at the time of temperature drop, within the range of plus-minus 9° C. of the endothermic peak P1.
    Type: Grant
    Filed: December 4, 1996
    Date of Patent: March 25, 2003
    Assignee: Canon Kabushiki Kaisha
    Inventors: Shinji Doi, Hirohide Tanikawa, Hiroaki Kawakami, Masatsugu Fujiwara, Tsutomu Onuma
  • Patent number: 5824442
    Abstract: A toner for developing electrostatic images has toner particles containing a binder resin and a colorant, and fine titanium oxide particles or fine alumina particles. The surfaces of the fine titanium oxide particles or fine alumina particles have been subjected to an organic treatment and have a methanol wettability half value of 55% or more.
    Type: Grant
    Filed: August 28, 1997
    Date of Patent: October 20, 1998
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hirohide Tanikawa, Hiroaki Kawakami, Masatsugu Fujiwara, Kazunori Kato
  • Patent number: 5707770
    Abstract: A toner for developing electrostatic images has toner particles containing a binder resin and a colorant, and fine titanium oxide particles or fine alumina particles. The surfaces of the fine titanium oxide particles or fine alumina particles have been subjected to an organic treatment and have a methanol wettability half value of 55% or more.
    Type: Grant
    Filed: November 8, 1995
    Date of Patent: January 13, 1998
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hirohide Tanikawa, Hiroaki Kawakami, Masatsugu Fujiwara, Kazunori Kato
  • Patent number: 5614344
    Abstract: A toner for developing electrostatic images contains toner particles containing at least a binder resin and a colorant as well as a fine powder comprised of base particles on which crystalline low resistance tin oxide films are formed. The crystalline low resistance tin oxide contains less than 100 ppm of antimony, arsenic and phosphorus, and has an oxygen deficiency structure. The toner is excellent in strength and can consistently give high quality images under any environmental conditions.
    Type: Grant
    Filed: June 13, 1995
    Date of Patent: March 25, 1997
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroaki Kawakami, Shinji Doi, Hirohide Tanikawa, Masatsugu Fujiwara, Kazunori Kato
  • Patent number: 5389487
    Abstract: An image forming process is disclosed which uses a non-magnetic one-component type developer comprising a finder resin and a releasing agent having specific properties. The developer has such advantages as being excellent in low-temperature fixability as well as anti-offset property.
    Type: Grant
    Filed: May 3, 1994
    Date of Patent: February 14, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroaki Kawakami, Shinji Doi, Keita Nozawa, Masatsugu Fujiwara, Masashi Jimbo
  • Patent number: 5384224
    Abstract: A toner for developing an electrostatic image is constituted by a binder resin and a hydrocarbon wax having a weight-average molecular weight of 800 to 3600. The toner is provided with good fixation characteristics including low-temperature fixability and anti-high temperature offsetting if the toner shows a storage modulus of at least 1.times.10.sup.3 dyn/cm.sup.2, a loss modulus in the range of 5.times.10.sup.2 -5.times.10.sup.4 dyn/cm.sup.2 and a ratio of loss modulus/storage modulus (loss tangent) of below 0.9 as measured under conditions of a frequency of 0.1 Hz and a temperature of 200.degree. C.; and the toner provides a DSC curve, as measured by a differential scanning calorimeter, showing an onset temperature of heat absorption of at most 105.degree. C. and a heat-absorption peak temperature in the range of 90.degree.-120.degree. C. on temperature increase, and a heat evolution peak temperature in the range of 62.degree.-75.degree. C. and a heat evolution peak intensity ratio of at least 2.times.10.
    Type: Grant
    Filed: March 4, 1993
    Date of Patent: January 24, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hirohide Tanikawa, Hiroaki Kawakami, Masatsugu Fujiwara, masashi Jinbo, Tsutomu Onuma
  • Patent number: 5364722
    Abstract: A toner for developing electrostatic images is prepared from a binder resin and a hydrocarbon wax. The toner is provided with improved fixability and anti-offset characteristic by controlling the thermal characteristic of the hydrocarbon wax so as to provide a DSC (differential scanning calorimeter) curve, showing an onset temperature of heat absorption in the range of 50.degree.-110.degree. C. and at least one heat absorption peak P1 in the range of 70.degree.-130.degree. C. giving a peak temperature T.sub.P1 on temperature increase, and showing a maximum heat evolution peak temperature in the range of T.sub.P1 .+-.9.degree. C. on temperature decrease. Correspondingly, the toner provides a DSC curve showing a rising temperature of heat absorption of at least 80.degree. C., an onset temperature of heat absorption of at most 105.degree. C. and a heat absorption peak temperature in the range of 100.degree.-120.degree. C.
    Type: Grant
    Filed: September 10, 1992
    Date of Patent: November 15, 1994
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hirohide Tanikawa, Hiroaki Kawakami, Masatsugu Fujiwara, Masashi Jinbo, Tsutomu Onuma
  • Patent number: 5213933
    Abstract: A positively chargeable magnetic toner comprises positively chargeable magnetic toner particles having at least a binder resin, a magnetic substance and a charge controlling agent; wherein the binder resin contains (A) a vinyl polymer having carboxyl groups, acid anhydride groups, partial esters thereof or mixtures of the groups and having and an acid value of 5 to 30, and (B) a copolymer obtained by polymerizing at least a diolefin monomer and a vinyl monomer; and wherein the charge controlling agent contains (C) a quaternary ammonium salt and (D) a nigrosine dye or a triphenylmethane dye, the ratio by weight among the components (A), (B), (C) and (D) being within the range of (A):(B):(C):(D)=80 to 30:70 to 20:2.0 to 0.5: 2.0 to 0.1 relative to 100 parts of the total weight of the components (A) and (B). The present invention also provides an image forming process, an image forming apparatus and a facsimile apparatus, all of which use the positively chargeable magnetic toner.
    Type: Grant
    Filed: May 28, 1991
    Date of Patent: May 25, 1993
    Assignee: Canon Kabushiki Kaisha
    Inventors: Ichirou Osaki, Keita Nozawa, Kuniko Kobayashi, Masatsugu Fujiwara, Masayoshi Shimamura
  • Patent number: 5202213
    Abstract: A developer for developing electrostatic latent images, comprising a mixture of toner and fine powder of silicic acid wherein the mixture has a ratio of B/A of 0.9 or larger provided that the mixture contains A wt. % thereof of the silicic acid fine powder, and contains B wt. % thereof of the silicic acid fine powder after the mixture has been passed through a 200 mesh-sieve.
    Type: Grant
    Filed: January 21, 1992
    Date of Patent: April 13, 1993
    Assignee: Canon Kabushiki Kaisha
    Inventors: Toshiaki Nakahara, Hirohide Tanikawa, Satoshi Yoshida, Masatsugu Fujiwara, Kiichiro Sakashita
  • Patent number: 5014089
    Abstract: A developer for developing electrostatic images, containing a magnetic toner having a binder resin and magnetic powder, the developer containing 17-60% by number of magnetic toner particles of 5 microns or smaller, containing 1-23% by number of magnetic toner particles of 8-12.7 microns, and containing 2.0% by volume or less of magnetic toner particles of 16 microns or larger; wherein the magnetic toner has a volume-average particle size of 4-9 microns, and the magnetic toner particles of 5 microns or smaller have a particle size distribution satisfying the following:N/V=-0.04N+k,wherein N denotes % by number of magnetic toner particles of 5 micron or smaller, V denotes % by volume of magnetic toner particles of 5 microns or smaller, k denotes a positive number of 4.5-6.5, and N denotes a positive number of 17-60.
    Type: Grant
    Filed: May 25, 1990
    Date of Patent: May 7, 1991
    Assignee: Canon Kabushiki Kaisha
    Inventors: Kiichiro Sakashita, Toshiaki Nakahara, Hirohide Tanikawa, Naoki Matsushige, Satoshi Yoshida, Masatsugu Fujiwara, Yasuo Mitsuhashi
  • Patent number: 4999272
    Abstract: An image forming method, comprising the steps of: providing an electrophotographic photosensitive member comprising an organic photoconductor, and a toner-carrying member carrying thereon a magnetic toner disposed opposite to the photosensitive member with a predetermined clearance in a developing region; the photosensitive member comprising at least two species of charge-generating substances and carrying thereon a digital and an analog electrostatic images; carrying the magnetic toner on the toner-carrying member to the developing region while regulating the magnetic toner so as to provide a thickness smaller than the clearance, the magnetic toner having a specific particle size distribution and a volume-average particle size of 4-10 microns; and developing the electrostatic images with the magnetic toner.
    Type: Grant
    Filed: August 25, 1989
    Date of Patent: March 12, 1991
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hirohide Tanikawa, Toshiaki Nakahara, Satoshi Yoshida, Masatsugu Fujiwara, Kiichiro Sakashita
  • Patent number: 4985327
    Abstract: A developer for developing electrostatic images, comprising a non-magnetic toner, the toner containing 17-60% by number of non-magnetic toner particles of 5 microns or smaller, containing 1-30% by number of non-magnetic toner particles of 8-12.7 microns, and containing 2.0% by volume or less of nonmagnetic toner particles of 16 microns or larger; wherein the non-magnetic toner has a volume-average particle size of 4-10 microns, and the non-magnetic toner particles of 5 microns or smaller have a particle size distribution satisfying the following formula:N/V=-0.04N+k,wherein N denotes % by number of non-magnetic toner particles of 5 microns of smaller, V denotes % by volume of non-magnetic toner particles of 5 microns or smaller k denotes a positive number of 4.5-6.5, and N denotes a positive number of 17-60.
    Type: Grant
    Filed: May 22, 1990
    Date of Patent: January 15, 1991
    Assignee: Canon Kabushiki Kaisha
    Inventors: Kiichiro Sakashita, Hirohide Tanikawa, Satoshi Yoshida, Toshiaki Nakahara, Naoki Matsushige, Masatsugu Fujiwara, Yasuo Mitsuhashi
  • Patent number: 4957840
    Abstract: A developer for developing electrostatic images, comprising a magnetic toner comprising a binder resin and magnetic powder, the developer containing 17-60% by number of magnetic toner particles of 5 microns or smaller, containing 1-23% by number of magnetic toner particles of 8-12.7 microns, and containing 2.0% by volume or less of magnetic toner particles of 16 microns or larger; wherein the magnetic toner has a volume-average particle size of 4-9 microns, and the magnetic toner particles of 5 microns or smaller have a particle size distribution satisfying the following formula:N/V=-0.04N+k,wherein N denotes % by number of magnetic toner particles of 5 micron or smaller, V denotes % by volume of magnetic toner particles of 5 microns or smaller, k denotes a positive number of 4.5-6.5, and N denotes a positive number of 17-60.
    Type: Grant
    Filed: October 25, 1988
    Date of Patent: September 18, 1990
    Assignee: Canon Kabushiki Kaisha
    Inventors: Kiichiro Sakashita, Toshiaki Nakahara, Hirohide Tanikawa, Naoki Matsushige, Satoshi Yoshida, Masatsugu Fujiwara, Yasuo Mitsuhashi