Patents by Inventor Yuki Karaki

Yuki Karaki 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: 6485875
    Abstract: A toner is constituted by at least a binder resin, a colorant and a wax. The binder resin has been formed from monomers including a vinyl monomer and polyester-forming monomers containing at least a polybasic carboxylic acid having three or more carboxyl groups or its anhydride, and comprises at least a hybrid resin comprising a vinyl polymer unit and a polyester unit.
    Type: Grant
    Filed: October 26, 2000
    Date of Patent: November 26, 2002
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yuki Karaki, Hiroshi Yusa, Takashige Kasuya, Yoshihiro Ogawa
  • Patent number: 6300024
    Abstract: A toner is principally constituted by a binder resin, a colorant and a wax. The toner has a maximum heat-absorption peak of 60-135° C. as measured by differential scanning calorimetry (DSC). The toner further has a viscoelastic characteristic measured at an angular frequency of the toner of 6.28 rad/sec including: a temperature giving a loss molecules G″ of 3×104 Pa of 90-115° C., a temperature giving a loss modulus G″ of 2×104 Pa of 95-120° C., a temperature giving a loss modulus G″ of 1×104 Pa of 105-135° C., a tan &dgr; (loss modulus G″/storage modulus G′) when G″=1×104-3×104 Pa of 0.6-2.0, a storage modulus at 170° C. (G′ (170° C.)) of 1×102-1×104 Pa, a loss modulus at 170° C. (G″ (170° C.)) of 1×102-1×104 Pa, and a ratio of a tan &dgr; at 170° C. (tan &dgr;170) to a tan &dgr; at 150° C. (tan &dgr;150) (tan &dgr;170/tan &dgr;150) of 1.05-1.6.
    Type: Grant
    Filed: June 28, 2000
    Date of Patent: October 9, 2001
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroshi Yusa, Satoshi Yoshida, Takashige Kasuya, Yuki Karaki
  • Patent number: 6214509
    Abstract: The objects of the present invention are to provide a toner excellent in transferability, little remaining on the photosensitive member and causing no defective image in roll-aided transfer (or at least such a phenomenon is well-controlled), and also to provide an image forming method using the same toner. The above objects are achieved when the toner contains a binder resin and colorant, inorganic fine particles, and a hydrotalcite compound shown by the formula: M1y12+M2y22+ . . . Mjyj2+L1x13+L2x23+ . . . Lkxk3+(OH)2.(X/n)An−.mH2O  (1) wherein 0<[X=(x1+x2+ . . . xk)]≦0.5; Y=(y1+y2+ . . . +yj)=1−X; j and k are each an integer of 2 or larger; M13+, M23+, . . . and Mj2+ are divalent metallic ions different from each other; L13+, L23+ . . .
    Type: Grant
    Filed: May 13, 1999
    Date of Patent: April 10, 2001
    Assignee: Canon Kabushiki Kaisha
    Inventors: Takashige Kasuya, Tsutomu Kukimoto, Satoshi Yoshida, Hiroshi Yusa, Manabu Ohno, Tsuyoshi Takiguchi, Yuki Karaki, Satoshi Handa, Masanori Ito
  • Patent number: 6033817
    Abstract: A toner for developing an electrostatic image is disclosed which has at least one endothermic peak in the temperature region of 120.degree. C. or below in differential thermal analysis and contains, in its particles having particle diameters of 3 .mu.m or larger, not less than 93% by number of particles having a circularity of at least 0.90 and less than 30% by number of particles having a circularity of at least 0.98. The toner does not cause the re-transfer under high transfer current conditions and can realize the formation of good images with high image density. Also, an image forming method using the toner is disclosed.
    Type: Grant
    Filed: July 29, 1997
    Date of Patent: March 7, 2000
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hiroshi Yusa, Motoo Urawa, Keita Nozawa, Yuki Karaki, Kazuo Maruyama
  • Patent number: 5912101
    Abstract: A toner for forming an image has toner particles containing at least a colorant, a binder resin and a wax. The toner has (i) a circularity distribution in which the toner has an average circularity of 0.900 to less than 0.965, contains 20 to 60% by number of particles with a circularity of less than 0.95 and has a mode circularity of 0.90 or more; and (ii) a particle size distribution in which the toner has a circle-equivalent average diameter of 2.0 to 10.0 .mu.m and has at least one peak of frequency by number in the region of a circle-equivalent diameter of 0.6 to 3.0 .mu.m and at least one peak of frequency by number in the region of a circle-equivalent diameter of from more than 3.0 .mu.m to 10.0 .mu.m. The wax has an endothermic main peak as measured by DSC of 60 to 120.degree. C. The binder resin contains THF soluble matter and 0 to 5.0% by weight of THF insoluble matter.
    Type: Grant
    Filed: April 6, 1998
    Date of Patent: June 15, 1999
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yuki Karaki, Hiroshi Yusa, Takashige Kasuya, Kazuo Maruyama, Masao Takano
  • Patent number: 5840457
    Abstract: A magnetic black toner for electrophotography, includes: (a) magnetic black toner particles containing a binder resin, a magnetic material in 30-200 wt. parts per 100 wt. parts of the binder resin, and a first solid wax, and (b) first inorganic fine powder. The first solid wax (ii) provides a DSC heat-absorption main peak in a range of 60.degree.-120.degree. C., and (iii) shows a molecular weight distribution factor Mw/Mn of 1.0-2.0. The binder resin (iv) has a THF (tetrahydrofuran)-insoluble content of at most 5 wt. %, and (v) contains a THF-soluble content showing a GPC molecular weight distribution including a content (M1) of 40-70% in molecular weights of below 5.times.10.sup.4, a content (M2.ltoreq.M1) of 20-45% in molecular weights of 5.times.10.sup.4 -5.times.10.sup.5, and a content (M3<M2) of 2-25% in molecular weights exceeding 5.times.10.sup.5. (vi) The magnetic black toner exhibits a tan .delta. of 0.5-3.0 in a range of 150.degree.-190.degree. C. and a tan .delta. at 150.degree. C.
    Type: Grant
    Filed: July 30, 1997
    Date of Patent: November 24, 1998
    Assignee: Canon Kabushiki Kaisha
    Inventors: Motoo Urawa, Keita Nozawa, Hiroshi Yusa, Takashige Kasuya, Yuki Karaki, Kazuo Maruyama, Masao Takano
  • Patent number: 5774771
    Abstract: An image forming method has a developing step of developing an electrostatic latent image by the use of a developer to form a toner image on an electrostatic latent image bearing member, a primary transfer step of transferring the toner image onto an intermediate transfer member to which a voltage is applied, and a secondary transfer step of transferring onto a transfer medium the toner image held on the intermediate transfer member, while a transfer means to which a voltage is applied is pressed against the transfer medium. The developer has a toner. The toner is a black toner having at least i) black toner particles formed of a binder resin with a colorant dispersed therein and ii) an inorganic fine powder. The black toner has the value of shape factor SF-1 of 110<SF-1.ltoreq.180, the value of shape factor SF-2 of 110<SF-2.ltoreq.140, and the value of ratio B/A of 1.
    Type: Grant
    Filed: February 9, 1996
    Date of Patent: June 30, 1998
    Assignee: Canon Kabushiki Kaisha
    Inventors: Tsutomu Kukimoto, Motoo Urawa, Kenji Okado, Toshiyuki Ugai, Keita Nozawa, Satoshi Yoshida, Yuki Karaki