Patents by Inventor Keita Maejima

Keita Maejima 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: 20160044745
    Abstract: A heater controller and heater control method is disclosed. The hater controller includes a detector, a determination circuit, a limiting circuit, a selection circuit, and a driving circuit. The detector detects a temperature of the heating object, which is heated by the heater. The determination circuit determines turn-on ratio for the heater for every control cycle of AC voltage, based on the surface temperature of the heating object and a target temperature of the heating object. The limiting circuit limits the turn-on ratio of current control cycle when the control method of previous control cycle is phase control. The selection circuit selects control pattern to control the heater, based on the turn-on ratio, and the driving circuit applies a heater driving signal to the heater.
    Type: Application
    Filed: August 7, 2015
    Publication date: February 11, 2016
    Inventors: Shuntaro NAKAYAMA, Keita MAEJIMA, Ryota KUBOKAWA
  • Publication number: 20150370216
    Abstract: An image forming apparatus includes a heat generator configured to generate heat in the image forming apparatus; a converter including a capacitor to convert AC power supplied from an external power supply into DC power for a load unit; a thermoelectric transducer configured to convert the generated heat into DC power for the load unit; a detector configured to detect a voltage of the AC power; and a controller configured to cause the converter to continue supplying the DC power to the load unit when a first elapsed time elapsed since the detected voltage drops below a rated voltage is shorter than a first time period shorter than an upper limit of a period of time over which the capacitor is dischargeable, and cause the thermoelectric transducer to supply the DC power to the load unit when the first elapsed time exceeds the first time period.
    Type: Application
    Filed: June 22, 2015
    Publication date: December 24, 2015
    Applicant: RICOH COMPANY, LIMITED
    Inventors: Norikazu OKADA, Takaaki SHIRAI, Takuma KASAI, Keita MAEJIMA, Tomoyuki YAMASHITA, Ryohta KUBOKAWA, Satoru TAO, Homare EHARA
  • Publication number: 20150261151
    Abstract: A fixing device includes a pressure rotator pressed against a fixing rotator to form a fixing nip therebetween, through which a recording medium bearing a toner image is conveyed. A first heater is disposed opposite and heats a first heated span on the fixing rotator spanning in an axial direction thereof. A second heater is disposed opposite and heats a second heated span on the fixing rotator spanning in the axial direction thereof. A temperature sensor unit is disposed opposite an outer circumferential surface of the fixing rotator and includes a first temperature detection element to detect a first temperature of the first heated span on the outer circumferential surface of the fixing rotator and a second temperature detection element to detect a second temperature of the second heated span on the outer circumferential surface of the fixing rotator.
    Type: Application
    Filed: March 9, 2015
    Publication date: September 17, 2015
    Applicant: Ricoh Company, Ltd.
    Inventors: Yasunori Ishigaya, Keita Maejima
  • Patent number: 9116479
    Abstract: A fixing control device includes an image detection unit that determines presence of an image in each of areas obtained by division of an image formation region in which the image is formed, a heater selection unit that selects from heaters of a fixing device heaters at positions corresponding to areas in which the presence of the image is determined, a heating amount computation unit that computes a heating amount of a heating area heated by each of the selected heaters in a fixing region corresponding to the image formation region, a change amount computation unit that computes an amount of change of the heating amount between adjoining ones of the heating areas, and a heating amount correction unit that corrects one of the heating amounts of the adjoining heating areas so that the amount of change after the correction is less than a predetermined threshold.
    Type: Grant
    Filed: March 14, 2014
    Date of Patent: August 25, 2015
    Assignee: Ricoh Company, Ltd.
    Inventors: Hiroaki Umezawa, Shiho Shimosaka, Katsunori Kume, Koh Tokumaru, Osamu Kizaki, Noboru Sugiura, Norikazu Okada, Atsuki Iwata, Keita Maejima, Tomoyuki Yamashita
  • Publication number: 20150177684
    Abstract: An image forming apparatus includes a heat-generating component, a power generation device including a thermoelectric element, a heat radiation device, a cooling device, a temperature detector that detects a temperature increase of the heat-generating component, and a controller. The heat radiation device includes a first radiator plate interposed between the heat-generating component and a surface of the thermoelectric element and a second radiator plate attached to another surface of the thermoelectric element. The cooling device cools the first radiator plate. The controller controls operations of the cooling device and the power generation device by operating the cooling device if the detected temperature increase reaches at least a predetermined threshold value, and causing the power generation device to generate power without operating the cooling device to cool the first radiator plate passively if the detected temperature increase falls below the predetermined threshold value.
    Type: Application
    Filed: December 22, 2014
    Publication date: June 25, 2015
    Applicant: RICOH COMPANY, LTD.
    Inventors: Takaaki SHIRAI, Satoru TAO, Takuma KASAI, Norikazu OKADA, Homare EHARA, Keita MAEJIMA, Tomoyuki YAMASHITA, Ryohta KUBOKAWA
  • Publication number: 20140270835
    Abstract: A fixing control device includes an image detection unit that determines presence of an image in each of areas obtained by division of an image formation region in which the image is formed, a heater selection unit that selects from heaters of a fixing device heaters at positions corresponding to areas in which the presence of the image is determined, a heating amount computation unit that computes a heating amount of a heating area heated by each of the selected heaters in a fixing region corresponding to the image formation region, a change amount computation unit that computes an amount of change of the heating amount between adjoining ones of the heating areas, and a heating amount correction unit that corrects one of the heating amounts of the adjoining heating areas so that the amount of change after the correction is less than a predetermined threshold.
    Type: Application
    Filed: March 14, 2014
    Publication date: September 18, 2014
    Applicant: RICOH COMPANY, LTD.
    Inventors: Hiroaki UMEZAWA, Shiho SHIMOSAKA, Katsunori KUME, Koh TOKUMARU, Osamu KIZAKI, Noboru SUGIURA, Norikazu OKADA, Atsuki IWATA, Keita MAEJIMA, Tomoyuki YAMASHITA
  • Patent number: 8761625
    Abstract: A fixing device includes: a heat generating rotating member including a heat generating layer; an exciting coil to inductively heat the heat generating layer; a degaussing coil generating an electrical current in response to a magnetic flux generated by the exciting coil and generating a magnetic flux in an opposite direction; an exciting coil controller configured to control energization of the exciting coil by using PWM signals; a degaussing coil controller determining necessity of switching the degaussing coil and to control energization of the degaussing coil. When the degaussing coil controller switches ON/OFF state of the degaussing coil, the exciting coil controller controls ON time periods of the PWM signals so as to be within a range from minimum to maximum values of the ON time periods of the PWM signals corresponding to the ON/OFF state of the degaussing coil stored in a storage unit.
    Type: Grant
    Filed: August 8, 2011
    Date of Patent: June 24, 2014
    Assignee: Ricoh Company, Limited
    Inventors: Yushi Miyata, Keita Maejima
  • Publication number: 20120051775
    Abstract: A fixing device includes: a heat generating rotating member including a heat generating layer; an exciting coil to inductively heat the heat generating layer; a degaussing coil generating an electrical current in response to a magnetic flux generated by the exciting coil and generating a magnetic flux in an opposite direction; an exciting coil controller configured to control energization of the exciting coil by using PWM signals; a degaussing coil controller determining necessity of switching the degaussing coil and to control energization of the degaussing coil. When the degaussing coil controller switches ON/OFF state of the degaussing coil, the exciting coil controller controls ON time periods of the PWM signals so as to be within a range from minimum to maximum values of the ON time periods of the PWM signals corresponding to the ON/OFF state of the degaussing coil stored in a storage unit.
    Type: Application
    Filed: August 8, 2011
    Publication date: March 1, 2012
    Inventors: Yushi MIYATA, Keita Maejima
  • Patent number: 7633508
    Abstract: A reference-data storing unit stores reference data for determining whether to display image data by overwriting display data. A data converting unit converts the image data into display image data. A transparency determining unit determines whether a first pixel value of the display image data obtained through a color conversion by the data converting unit coincides with a second pixel value of the reference data stored in the reference-data storing unit. A data transfer unit that transfers, when it is determined that the first pixel value coincides with the second pixel value, the display image data to a display address space.
    Type: Grant
    Filed: August 31, 2006
    Date of Patent: December 15, 2009
    Assignee: Ricoh Company, Limited
    Inventors: Eiji Enami, Keita Maejima, Hironobu Kurihara, Yuichi Yomogida
  • Publication number: 20070057961
    Abstract: A reference-data storing unit stores reference data for determining whether to display image data by overwriting display data. A data converting unit converts the image data into display image data. A transparency determining unit determines whether a first pixel value of the display image data obtained through a color conversion by the data converting unit coincides with a second pixel value of the reference data stored in the reference-data storing unit. A data transfer unit that transfers, when it is determined that the first pixel value coincides with the second pixel value, the display image data to a display address space.
    Type: Application
    Filed: August 31, 2006
    Publication date: March 15, 2007
    Inventors: Eiji Enami, Keita Maejima, Hironobu Kurihara, Yuichi Yomogida