Patents by Inventor Tatsuhiko Chiba
Tatsuhiko Chiba 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: 7560212Abstract: The present invention provides a magnetic toner which is hardly influenced by an environment, and with which an image with high quality and excellent resolution can be stably even under low humidity. In the magnetic toner of present invention: I) a ratio of an iron element content to a carbon element content present on the toner particle surface is less than 0.0010; II) 50 number % or more of toner particles satisfy a relationship of D/C?0.02 (C: projected area diameter of toner particles, D: minimum value for a distance between a magnetic iron oxide fine particle and the toner particle surface); and III) 40-95 number % of toner particles satisfy a structure where 70 number % or more of the magnetic iron oxide fine particles in the respective toner particles are present up to a depth of 0.2 time as far as C from the toner particle surface.Type: GrantFiled: March 18, 2008Date of Patent: July 14, 2009Assignee: Canon Kabushiki KaishaInventors: Tatsuhiko Chiba, Michihisa Magome, Eriko Yanase, Takeshi Kaburagi
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Publication number: 20080171277Abstract: The present invention provides a magnetic toner which is hardly influenced by an environment, and with which an image with high quality and excellent resolution can be stably even under low humidity. In the magnetic toner of present invention: I) a ratio of an iron element content to a carbon element content present on the toner particle surface is less than 0.0010; II) 50 number % or more of toner particles satisfy a relationship of D/C?0.02 (C: projected area diameter of toner particles, D: minimum value for a distance between a magnetic iron oxide fine particle and the toner particle surface); and III) 40-95 number % of toner particles satisfy a structure where 70 number % or more of the magnetic iron oxide fine particles in the respective toner particles are present up to a depth of 0.2 time as far as C from the toner particle surface.Type: ApplicationFiled: March 18, 2008Publication date: July 17, 2008Applicant: Canon Kabushiki KaishaInventors: Tatsuhiko Chiba, Michihisa Magome, Eriko Yanase, Takeshi Kaburagi
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Patent number: 7371494Abstract: The present invention provides a magnetic toner which is hardly influenced by an environment, and with which an image with high quality and excellent resolution can be stably even under low humidity. In the magnetic toner of present invention: I) a ratio of an iron element content to a carbon element content present on the toner particle surface is less than 0.0010; II) 50 number % or more of toner particles satisfy a relationship of D/C?0.02 (C: projected area diameter of toner particles, D: minimum value for a distance between a magnetic iron oxide fine particle and the toner particle surface); and III) 40-95 number % of toner particles satisfy a structure where 70 number % or more of the magnetic iron oxide fine particles in the respective toner particles are present up to a depth of 0.2 time as far as C from the toner particle surface.Type: GrantFiled: September 13, 2004Date of Patent: May 13, 2008Assignee: Canon Kabushiki KaishaInventors: Tatsuhiko Chiba, Michihisa Magome, Eriko Yanase, Takeshi Kaburagi
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Patent number: 7043175Abstract: In an image forming system, an image-bearing member having a photoconductor layer comprising an Si-based non-single crystal material is charged at a relatively low potential of 250 to 600 volts by a contact charging member in the presence of electroconductive fine powder. An electrostatic latent image formed on the image-bearing member is developed with a magnetic toner which includes magnetic toner particles comprising at least a binder resin and a magnetic iron oxide, and inorganic fine powder and electroconductive fine powder present at the surface of the magnetic toner particles. The magnetic toner has a weight-average particle size of 3-10 ?m and an average circularity of 0.950 to 0.995, and contains 0.05 to 3.00% of isolated iron-containing particles.Type: GrantFiled: November 15, 2001Date of Patent: May 9, 2006Assignee: Canon Kabushiki KaishaInventors: Keiji Komoto, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Michihisa Magome, Akira Hashimoto, Takeshi Kaburagi
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Publication number: 20050089785Abstract: The present invention provides a magnetic toner which is hardly influenced by an environment, and with which an image with high quality and excellent resolution can be stably even under low humidity. In the magnetic toner of present invention: I) a ratio of an iron element content to a carbon element content present on the toner particle surface is less than 0.0010; II) 50 number % or more of toner particles satisfy a relationship of D/C?0.02 (C: projected area diameter of toner particles, D: minimum value for a distance between a magnetic iron oxide fine particle and the toner particle surface); and III) 40-95 number % of toner particles satisfy a structure where 70 number % or more of the magnetic iron oxide fine particles in the respective toner particles are present up to a depth of 0.2 time as far as C from the toner particle surface.Type: ApplicationFiled: September 13, 2004Publication date: April 28, 2005Applicant: CANON KABUSHIKI KAISHAInventors: Tatsuhiko Chiba, Michihisa Magome, Eriko Yanase, Takeshi Kaburagi
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Patent number: 6879793Abstract: To provide a method for forming images in which the image bearing member and the toner carrying member are arranged with a gap of 100 ?m to 250 ?m, and the equation (1) and equation (2) are satisfied. (1) 22?(the frequency of the alternating current component of the alternating electric field/the peripheral speed of the toner carrying member)×the maximum electric field intensity at the time of developing?1.20. (2) 8?(the frequency of the alternating current component of the alternating electric field/the peripheral speed of toner carrying member)×(the fluidity index of Carr/the floodability index of Carr)?50. According to the method for forming images of the present invention, it is possible to obtain a high quality image without generating fog and light shielding while attaining a uniform halftone with a high image density even over long-term.Type: GrantFiled: June 18, 2003Date of Patent: April 12, 2005Assignee: Canon Kabushiki KaishaInventors: Tatsuhiko Chiba, Michihisa Magome, Keiji Komoto, Kaori Hiratsuka, Takeshi Kaburagi
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Publication number: 20040018028Abstract: To provide an method for forming image in which the image bearing member and the toner carrying member are arranged with a gap of 100 &mgr;m to 250 &mgr;m; equation (1) and equation (2) are satisfied: (1) 22≦(the frequency of the alternating current component of the alternating electric field/the peripheral speed of the toner carrying member)×the maximum electric field intensity at the time of developing≦120; (2) 8≦(the frequency of the alternating current component of the alternating electric field/the peripheral speed of toner carrying member)×(the fluidity index of Carr/the floodability index of Carr)≦50. According to method for forming image of the present invention, it is possible to obtain a high quality image without generating fog and light shielding while attaining a uniform halftone with a high image density even in a long-term use.Type: ApplicationFiled: June 18, 2003Publication date: January 29, 2004Applicant: CANON KABUSHIKI KAISHAInventors: Tatsuhiko Chiba, Michihisa Magome, Keiji Komoto, Kaori Hiratsuka, Takeshi Kaburagi
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Patent number: 6653035Abstract: A magnetic toner exhibiting stable performances under various environmental conditions is formed of toner particles each comprising at least a binder resin and iron oxide dispersed therein. Relative to the dry specific gravity (A) of the magnetic toner, the magnetic toner is characterized by a specific gravity distribution of toner particle fractions obtainable through wet sedimentation and including: at most 15 wt. % of a fraction having a specific gravity of above (A)×1.000 and at most (A)×1.025, 0.1-20 wt. % of a fraction having a specific gravity of above (A)×0.975 and at most (A)×1.000, at least 30 wt. % of a fraction having a specific gravity of above (A)×0.950 and at most (A)×0.975, 0.1-20 wt. % of a fraction having a specific gravity of above (A)×0.925 and at most (A)×0.950, and at most 15 wt. % of a fraction having a specific gravity of above (A)×0.900 and at most (A)×0.925.Type: GrantFiled: July 26, 2002Date of Patent: November 25, 2003Assignee: Canon Kabushiki KaishaInventors: Keiji Komoto, Tatsuya Nakamura, Tatsuhiko Chiba, Michihisa Magome, Akira Hashimoto, Takeshi Kaburagi, Eriko Yanase
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Patent number: 6638674Abstract: A magnetic toner is formed of magnetic toner particles each comprising a binder resin, an iron oxide, a sulfur-containing polymer, and inorganic fine powder blended with the magnetic toner particles, the toner having a weight-average particle size (D4) of 3-10 &mgr;m, and either (a) an average circularity of at least 0.970, and a magnetization of 10-50 Am2/kg (emu/g) at a magnetic field of 79.6 kA/m (1000 oersted), or (b) toner particles which retain carbon in an amount of A and iron in an amount of B at surfaces thereof, satisfying: B/A<0.001, and containing at least 50% by number of magnetic toner particles of D/C≦0.02, wherein C represents a particle projection area-equivalent circle diameter and D represents a minimum distance between a surface of the magnetic toner particle and iron oxide particles contained therein.Type: GrantFiled: July 25, 2001Date of Patent: October 28, 2003Assignee: Canon Kabushiki KaishaInventors: Keiji Komoto, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Michihisa Magome, Akira Hashimoto, Takeshi Kaburagi, Eriko Yanase
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Patent number: 6635398Abstract: A dry toner has toner particles containing at least a binder resin, a colorant and a wax component and an external additive. The binder resin contains a component derived from a monomer selected from butadiene, isoprene and chloroprene. The toner has a main Tg from 40° C. to 70° C. When specific surface area measured by the BET method in an environment of 23° C. atmospheric temperature and 65% relative humidity is represented by A (m2/g) and specific surface area measured by the BET method in an environment of 50° C. atmospheric temperature and 3% relative humidity is represented by B (m2/g), the toner satisfies the following relationship: 0.8≦A≦4.0, 0.80≦(B/A)≦1.05. The toner has a circle-corresponding number-average particle diameter D1 from 2 to 10 &mgr;m, an average circularity from 0.950 to 0.995 and a circularity standard deviation less than 0.040. The toner has a main-peak molecular weight from 2,000 to 100,000 and contains a THF-insoluble matter from 5 to 60% by weight.Type: GrantFiled: October 25, 2000Date of Patent: October 21, 2003Assignee: Canon Kabushiki KaishaInventors: Keiji Komoto, Tsutomu Kukimoto, Tatsuhiko Chiba, Akira Hashimoto
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Patent number: 6596452Abstract: A magnetic toner comprising magnetic toner particles containing at least a binder resin, a magnetic material containing a magnetic iron oxide, and a release agent. The magnetic toner has a weight-average particle diameter of from 3 &mgr;m to 10 &mgr;m, a magnetization intensity (saturation magnetization) of from 10 Am2/kg to 50 Am2/kg (emu/g) under application of a magnetic field of 79.6 kA/m (1,000 oersteds), an average circularity of 0.970 or more, a ratio of weight-average particle diameter to number-average particle diameter, of 1.40 or less, iron and an iron compound which stand liberated from the magnetic toner particles at a liberation percentage of from 0.05% to 3.00%, and a resin component having a tetrahydrofuran-insoluble matter in an amount of from 3% by weight to 60% by weight. Also disclosed is an image-forming method making use of the magnetic toner.Type: GrantFiled: February 21, 2001Date of Patent: July 22, 2003Assignee: Canon Kabushiki KaishaInventors: Michihisa Magome, Tsutomu Kukimoto, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Akira Hashimoto, Keiji Komoto
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Patent number: 6544708Abstract: An image forming method using a dry toner and exhibiting good quick-start and power economization characteristics is provided. The image forming method includes a heat-pressure fixing step using a rotatable electromagnetic induction heat-generation type heating member. The toner used therein is characterized by a moisture content of at most 3.00 wt. %, and viscoelasticities as represented by a storage modulus at 110° C. of G′ (110° C.) and a storage modulus at 140° C. of G′ (140° C.) satisfying: G′ (110° C.)≦1.00×106 dN/m2, and G′ (140° C.)≧7.00×103 dN/m3.Type: GrantFiled: March 27, 2001Date of Patent: April 8, 2003Assignee: Canon Kabushiki KaishaInventors: Keiji Komoto, Hiroaki Kawakami, Tatsuhiko Chiba, Atsuyoshi Abe, Yuji Moriki, Michihisa Magome, Satoshi Handa, Kiyokazu Suzuki
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Publication number: 20030064309Abstract: A magnetic toner exhibiting stable performances under various environmental conditions is formed of toner particles each comprising at least a binder resin and iron oxide dispersed therein. Relative to the dry specific gravity (A) of the magnetic toner, the magnetic toner is characterized by a specific gravity distribution of toner particle fractions obtainable through wet sedimentation and including: at most 15 wt. % of a fraction having a specific gravity of above (A)×1.000 and at most (A)×1.025, 0.1-20 wt. % of a fraction having a specific gravity of above (A)×0.975 and at most (A)×1.000, at least 30 wt. % of a fraction having a specific gravity of above (A)×0.950 and at most (A)×0.975, 0.1-20 wt. % of a fraction having a specific gravity of above (A)×0.925 and at most (A)×0.950, and at most 15 wt. % of a fraction having a specific gravity of above (A)×0.900 and at most (A)×0.925.Type: ApplicationFiled: July 26, 2002Publication date: April 3, 2003Inventors: Keiji Komoto, Tatsuya Nakamura, Tatsuhiko Chiba, Michihisa Magome, Akira Hashimoto, Takeshi Kaburagi, Eriko Yanase
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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: 6447969Abstract: A toner is formed of toner particles each comprising a binder resin and iron oxide particles dispersed therein. The toner particles are characterized by uniform but non-surface-exposed dispersion of the iron oxide particles within the toner particles as represented by (i) a carbon content (A) and an iron content (B) giving a ratio B/A<0.001 at surfaces of the toner particles as measured by X-ray photoelectron spectroscopy, (ii) an average circularity of at least 0.970, and (iii) at least 50% by number of toner particles satisfying D/C≦0.02, wherein C denotes a projection area-equivalent circular diameter of each toner particle and D denotes a minimum distance of iron oxide particles from a surface of the toner particle, based on a sectional view of the toner particle as observed through a transmission electron microscope (TEM).Type: GrantFiled: May 30, 2000Date of Patent: September 10, 2002Assignee: Canon Kabushiki KaishaInventors: Masanori Ito, Tsutomu Kukimoto, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Michihisa Magome, Akira Hashimoto, Keiji Komoto
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Publication number: 20020115011Abstract: In an image forming system, an image-bearing member having a photoconductor layer comprising an Si-based non-single crystal material is charged at a relatively low potential of 250 to 600 volts by a contact charging member in the presence of electroconductive fine powder. An electrostatic latent image formed on the image-bearing member is developed with a magnetic toner which includes magnetic toner particles comprising at least a binder resin and a magnetic iron oxide, and inorganic fine powder and electroconductive fine powder present at the surface of the magnetic toner particles. The magnetic toner has a weight-average particle size of 3-10 &mgr;m and an average circularity of 0.950 to 0.995, and contains 0.05 to 3.00 % of isolated iron-containing particles.Type: ApplicationFiled: November 15, 2001Publication date: August 22, 2002Inventors: Keiji Komoto, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Michihisa Magome, Akira Hashimoto, Takeshi Kaburagi
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Publication number: 20020055052Abstract: A magnetic toner capable of exhibiting stable chargeability regardless of environmental change is formed of magnetic toner particles each comprising at least a binder resin, an iron oxide and a sulfur-containing polymer, and inorganic fine powder blended with the magnetic toner particles. The magnetic toner is also provided with good developing performance and high transferability by satisfying a weight-average particle size (D4) of 3-10 &mgr;m, an average circularity of at least 0.970, and a magnetization of 10-50 Am2/kg (emu/g) at a magnetic field of 79.6 kA/m (1000 oersted). The magnetic toner is further characterized in that 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, and the magnetic toner contains at least 50% by number of magnetic toner particles satisfying a relationship of D/C≦0.Type: ApplicationFiled: July 25, 2001Publication date: May 9, 2002Inventors: Keiji Komoto, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Michihisa Magome, Akira Hashimoto, Takeshi Kaburagi, Eriko Yanase
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Publication number: 20020048713Abstract: An image forming method using a dry toner and exhibiting good quick-start and power economization characteristics is provided. The image forming method includes a heat-pressure fixing step using a rotatable electromagnetic induction heat-generation type heating member. The toner used therein is characterized by a moisture content of at most 3.00 wt. %, and viscoelasticities as represented by a storage modulus at 110° C. of G′ (110° C.) and a storage modulus at 140° C. of G′ (140° C.) satisfying: G′ (110° C.)≦1.00×106 dN/m2, and G′ (140° C.)≧7.00×103 dN/m3.Type: ApplicationFiled: March 27, 2001Publication date: April 25, 2002Inventors: Keiji Komoto, Hiroaki Kawakami, Tatsuhiko Chiba, Atsuyoshi Abe, Yuji Moriki, Michihisa Magome, Satoshi Handa, Kiyokazu Suzuki
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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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Publication number: 20010028988Abstract: A magnetic toner comprising magnetic toner particles containing at least a binder resin, a magnetic material containing a magnetic ion oxide, and a release agent. The magnetic toner has a weight-average particle diameter of from 3 &mgr;m to 10 &mgr;m, a magnetization intensity (saturation magnetization) of from 10 Am2/kg to 50 Am2/kg (emu/g) under application of a magnetic field of 79.6 kA/m (1,000 oersteds), an average circularity of 0.970 or more, a ratio of weight-average particle diameter to number-average particle diameter, of 1.40 or less, iron and an iron compound which stand liberated from the magnetic toner particles at a liberation percentage of from 0.05% to 3.00%, and a resin component having a tetrahydrofuran-insoluble matter in an amount of from 3% by weight to 60% by weight. Also disclosed is an image-forming method making use of the magnetic toner.Type: ApplicationFiled: February 21, 2001Publication date: October 11, 2001Inventors: Michihisa Magome, Tsutomu Kukimoto, Tsuyoshi Takiguchi, Tatsuhiko Chiba, Akira Hashimoto, Keiji Komoto