Having Feedback Or Environmental Control Patents (Class 347/133)
  • Patent number: 6989849
    Abstract: An exposure head is provided in which light beams from light emitting parts 63 pass through a transparent substrate 62 and are projected on an image carrier. The transparent substrate 62 has plain faces substantially parallel to each other, one of the faces being a face on which the light emitting parts 63 are formed and the other being a face from which light beams are projected. The transparent substrate 62 is provided, at position(s) other than the face on which the light emitting parts 63 are formed and than the face from which light beams are projected, with light quantity detecting means 100 for detecting the quantity of light emitted from said light emitting parts 63.
    Type: Grant
    Filed: August 11, 2003
    Date of Patent: January 24, 2006
    Assignee: Seiko Epson Corporation
    Inventors: Yujiro Nomura, Atsunori Kitazawa, Kiyoshi Tsujino
  • Patent number: 6975338
    Abstract: An image quality detecting apparatus detects image quality based on a specified image pattern formed on an image carrier. This apparatus includes a light-emitting device that radiates a spotlight on the image carrier, a lens, a scanning unit that scans the image pattern with the spotlight, and a photoelectric conversion element that detects a quantity of light reflected from the image pattern and the image carrier or light transmitted through the image pattern and the image carrier during the scanning. The image quality is detected by setting a diameter of the spotlight at least in a scanning direction to the reciprocal number of a spatial frequency or smaller in which human eyesight is the most sensitive, for example, to 1000 ?m or less.
    Type: Grant
    Filed: May 30, 2003
    Date of Patent: December 13, 2005
    Assignee: Ricoh Company, Ltd.
    Inventors: Shuji Hirai, Takeo Tsukamoto
  • Patent number: 6888556
    Abstract: An image forming apparatus having a photosensitive member, an exposure device having a laser emitting element that irradiates a laser beam, the laser beam being scanned on the photosensitive member line by line to form an electrostatic latent image on the photosensitive member, a developing device that supplies a developing agent to the electrostatic latent image to form a visible image, and a controller that controls the laser emitting element to irradiate the laser beam in a predetermined light amount. The controller further controls the laser emitting element to irradiate the laser beam in a reduced light amount every at least one line.
    Type: Grant
    Filed: March 20, 2003
    Date of Patent: May 3, 2005
    Assignee: Brother Kogyo Kabushiki Kaisha
    Inventor: Haruyuki Shimomura
  • Patent number: 6825863
    Abstract: An image forming apparatus having a photosensitive member, an exposure device having a plurality of laser emitting elements that each irradiate a laser beam onto the photosensitive member to form an elactrostatic latent image on the photosensitive member, a developing device that supplies a developing agent to the electrostatic latent image to form a visible image, and a controller that controls the irradiation of the plurality of laser emitting elements. The controller includes a determining device that determines which laser emitting element from the plurality of laser emitting elements is closest to reaching its end of operating life and a restricting device that restricts the irradiation of the laser emitting element determined closest to reaching its end of operating life.
    Type: Grant
    Filed: March 20, 2003
    Date of Patent: November 30, 2004
    Assignee: Brother Kogyo Kabushiki Kaisha
    Inventors: Haruyuki Shimomura, Hiroshi Koie
  • Publication number: 20040223169
    Abstract: An image expansion unit expands image data at a resolution higher than the actual resolution of an output apparatus, and a resolution conversion unit converts the expanded high-resolution data to data having the actual resolution of the output apparatus. An exposure setting unit outputs a reference pattern and a density sensor measures the density of this reference pattern. On the basis of the result of measurement, a laser-exposure correction table for an electrophotographic process is created in such a manner that the density of prescribed image data that is obtained by the resolution conversion will be the same before and after image formation. This table is set in a LUT. As a result, it is possible to prevent a situation in which the density and shape of an image are rendered non-uniform and to output a high-quality image in stable fashion.
    Type: Application
    Filed: April 19, 2004
    Publication date: November 11, 2004
    Applicant: CANON KABUSHIKI KAISHA
    Inventors: Jun Hirabayashi, Hiroshi Kaburagi
  • Patent number: 6810799
    Abstract: A printing machine with an electrophotographic device, having a photoconductor, a photoconductor drive and an illumination device. The electrophotographic unit can be provided with the substrate by a feed device. The photoconductor drive motor is adjusted by a controller and the feed device can be linearly adjusted by a feed device drive motor. In order to produce high-definition prints, especially images or lettering on plate-shaped substrates, the feed device drive motor is adjusted by a controller that is controlled by a master-slave controller via a setpoint feed. The controller for the photoconductor drive motor is also controlled by the master-slave controller via a setpoint feed and the master slave controller synchronizes the feeding speed of the feed device and the speed of movement of the photoconductor.
    Type: Grant
    Filed: July 14, 2003
    Date of Patent: November 2, 2004
    Assignee: Schott Glas
    Inventors: Bernd Schultheis, Dieter Jung, Birgit Lattermann, Hermann Lemm
  • Patent number: 6795099
    Abstract: An image forming apparatus for forming an image by irradiating a charged surface of a photosensitive member with a laser beam depending on a picture signal to form an electrostatic latent image, visualizing the latent image with a recording agent, and transferring the visualized image onto a recording medium; includes a circumferential position detection unit for detecting a circumferential position of the photosensitive member irradiated with the laser beam and an APC circuit for controlling a light quantity of the laser beam so as to provide a target light quantity varying depending on the detected circumferential position.
    Type: Grant
    Filed: February 10, 2003
    Date of Patent: September 21, 2004
    Assignee: Canon Kabushiki Kaisha
    Inventors: Katsuhide Koga, Fumitaka Sobue
  • Patent number: 6750892
    Abstract: Based on the density of an image formed on a photosensitive member or an image recording medium, an amount of correction for uniformalizing the image density in a main scanning direction of a light beam is set. Based on the set amount of correction, the intensity of a light beam in an image region is corrected within a range of one main scan.
    Type: Grant
    Filed: July 13, 2001
    Date of Patent: June 15, 2004
    Assignee: Fuji Xerox Co., Ltd.
    Inventor: Takayoshi Suzuki
  • Patent number: 6750893
    Abstract: An image forming apparatus compensating for printing density of a toner image by adjusting a quantity of light to form the toner image in accordance with a variation of a resistance of a roller includes an electrical charge roller electrically charging a photosensitive drum, a laser scan unit projecting the image light on the photosensitive drum to form an electrostatic latent image corresponding to an input image, a development roller developing the electrostatic latent image formed on the photosensitive drum with toner to form the toner image, a transfer roller rotating in contact with the photosensitive drum and transferring the toner image to a sheet of paper when a predetermined voltage is supplied to the transfer roller, and a controller controlling the laser scan unit and varying the quantity of the image light projected from the laser scan unit in accordance with the variation of a resistance value of the transfer roller.
    Type: Grant
    Filed: May 29, 2002
    Date of Patent: June 15, 2004
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Su-jong Jeong
  • Patent number: 6710792
    Abstract: In a multibeam scanner, a control unit includes a velocity detecting circuit detecting a conveying velocity V of a photosensitive body; a comparison circuit comparing the detected conveying velocity V to a reference conveying velocity V0; a light intensity control circuit 93, a modulation circuit 94, an LD1 control circuit 95, and an LD2 control circuit 96. The LD1 control circuit 95 and LD2 control circuit 96 issue drive signals to laser diodes LD1 and LD2. The laser diodes LD1 and LD2 emit laser beams LB1 and LB2 that are modulated according to image signals outputted from the modulation circuit 94. The laser beams LB1 and LB2 are deflected by a polygon mirror onto the photosensitive body and perform a main scan over neighboring scanning lines SL1 and SL2, while the photosensitive drum is rotated. The light intensity from the laser diode LD1 is adjusted when the velocity of the photosensitive drum differs from a prescribed velocity in order to achieve a balanced image density.
    Type: Grant
    Filed: October 27, 2000
    Date of Patent: March 23, 2004
    Assignee: Brother Kogyo Kabushiki Kaisha
    Inventors: Koji Ito, Ryota Kato, Yutaka Hattori
  • Patent number: 6700595
    Abstract: An image forming apparatus includes an image bearing member, a latent image writing device that emits a plurality of laser beams, two adjacent laser beams of the plurality of laser beams partially overlapping in a sub-scanning direction, respectively, and forming a reference latent image on a surface of the image bearing member by performing repeated scanning of each laser beam on the surface of the image bearing member, a developing device that develops the reference latent image with toner into a reference toner image, and a detecting device that detects the density of the reference toner image. The quantity of light of each laser beam forming a subsequent latent image is adjusted according to the density of the reference toner image detected by the detecting device.
    Type: Grant
    Filed: March 21, 2002
    Date of Patent: March 2, 2004
    Assignee: Ricoh Company, Ltd.
    Inventors: Toshihiro Sugiyama, Hiroshi Ishii, Hiroshi Saitoh, Yuji Suzuki
  • Patent number: 6686943
    Abstract: An image formation apparatus for keeping secularly stable image quality for all image patterns if change in the charge amount of a developer caused by environment variation or over time or change in the photoconductor characteristic occurs in electrophotographic record apparatus. A test patch image formed on a photoconductor by a parallel electric field is detected by an image density sensor, the developing bias and the photoconductor surface potential are controlled so that the density detected by the image density sensor becomes constant, a test patch image formed on the photoconductor by a peripheral electric field is detected by the image density sensor with the control condition of the image density sensor maintained, and the light application amount in which an image area of a several-dot width adjacent a blank paper part is exposed to light is controlled so that the density detected by the image density sensor becomes constant.
    Type: Grant
    Filed: July 12, 2002
    Date of Patent: February 3, 2004
    Assignees: Hitachi Printing Solutions, Ltd., Hitachi Ltd.
    Inventors: Masayoshi Ishii, Keisuke Kubota, Teruaki Mitsuya, Shintaro Yamada
  • Patent number: 6650849
    Abstract: After forming solid patch images under various patch generating conditions (E, Vb), the optical densities of the respective patch images are measured by a patch sensor, and patch generating conditions matching with a higher-density side target density (OD=1.2) are extracted as “higher-density side correlation data.” Further, line patch images are formed under various patch generating conditions (E, Vb), the optical densities of the respective line patch images are measured by the patch sensor, and patch generating conditions matching with a lower-density side target density (OD=0.2) are extracted as “lower-density side correlation data.” An optimal exposure energy and an optimal developing bias are set based on one piece of correlation data (E2, Vb(3)) belonging to said product set of the higher-density side correlation data and the lower-density side correlation data.
    Type: Grant
    Filed: January 11, 2002
    Date of Patent: November 18, 2003
    Assignee: Seiko Epson Corporation
    Inventor: Hidetsugu Shimura
  • Publication number: 20030210319
    Abstract: An image forming apparatus using a multi-scan system is capable of forming an image at a high speed. An exposure device scans a surface of the photo conductor by light beams emitted by a plurality of light-emitting elements so as to simultaneously form a plurality of electrostatic latent images at a plurality of positions on the photo conductor, a pitch of the light beams in a sub scanning direction being smaller than a beam diameter defined by a value of an intensity of the light beam at which an intensity level of each light beam is 1/e2 of an intensity level at a center thereof, the electrostatic latent image being formed also at a position where the plurality of light beams overlaps with each other. A code of a plurality of levels is produced from image data in accordance with a pattern detection matrix. A pulse with output from the pattern detection processing means is produced with reference to pulse width data which designates a pulse width of each light beam previously set in response to the code.
    Type: Application
    Filed: March 18, 2003
    Publication date: November 13, 2003
    Inventor: Toshio Ohide
  • Patent number: 6639617
    Abstract: An image forming apparatus and an image forming method for preventing reducing of density of an image transferred to the recording paper due to dropping in a temperature, without providing a temperature sensor. The current detecting unit detects an electric current value generated at the time a test voltage is applied to a transferring member which is provided for transferring a developed image on a photoconductive drum to the paper. The detected current value is input and stored by a printer controller. The printer controller determines an exposure time, based on the stored current value, by reference to a table for determining an exposure time. The printer controller causes the exposure time to be long when the stored current value is small or large.
    Type: Grant
    Filed: May 6, 2002
    Date of Patent: October 28, 2003
    Assignee: Murata Kikai Kabushiki Kaisha
    Inventor: Tadahiro Yokogawa
  • Publication number: 20030184638
    Abstract: An image forming apparatus having a photosensitive member, an exposure device having a plurality of laser emitting elements that each irradiate a laser beam onto the photosensitive member to form an elactrostatic latent image on the photosensitive member, a developing device that supplies a developing agent to the electrostatic latent image to form a visible image, and a controller that controls the irradiation of the plurality of laser emitting elements. The controller includes a determining device that determines which laser emitting element from the plurality of laser emitting elements is closest to reaching its end of operating life and a restricting device that restricts the irradiation of the laser emitting element determined closest to reaching its end of operating life.
    Type: Application
    Filed: March 20, 2003
    Publication date: October 2, 2003
    Applicant: BROTHER KOGYO KABUSHIKI KAISHA
    Inventors: Haruyuki Shimomura, Hiroshi Koie
  • Publication number: 20030156180
    Abstract: An image forming apparatus for forming an image by irradiating a charged surface of a photosensitive member with a laser beam depending on a picture signal to form an electrostatic latent image, visualizing the latent image with a recording agent, and transferring the visualized image onto a recording medium; includes a circumferential position detection unit for detecting a circumferential position of the photosensitive member irradiated with the laser beam and an APC circuit for controlling a light quantity of the laser beam so as to provide a target light quantity varying depending on the detected circumferential position.
    Type: Application
    Filed: February 10, 2003
    Publication date: August 21, 2003
    Applicant: Canon Kabushiki Kaisha
    Inventors: Katsuhide Koga, Fumitaka Sobue
  • Patent number: 6603496
    Abstract: A dot-matrix image-forming device such as an electrophotographic printer alters the size of a dot according to the surrounding dot pattern, thereby compensating for the tendency of isolated dots or small groups of dots to be undersized due to characteristics of the image formation process. Alternatively, the device may add dots to or delete dots from a contiguous group of dots to achieve substantially the same effect. Preferably, the device both adds or deletes dots and alters the dot size. This compensation scheme enables the total area occupied by dots in a given image region to be proportional to the number of dots in the region, regardless of the dot density and arrangement in the region.
    Type: Grant
    Filed: October 30, 2001
    Date of Patent: August 5, 2003
    Assignee: Oki Data Corporation
    Inventors: Akira Nagumo, Toshiki Sato
  • Publication number: 20030133001
    Abstract: An electrophotographic device with a laser power correction device (and method therefor) includes a laser power detection sensor retractably disposed relative to a laser beam optical path of a laser beam, a laser power adjusting device for controlling laser power of the laser beam based on an output from the laser power detection sensor, and a controller for inserting the laser power detection sensor into the optical path and applying laser power correction when a total laser beam activation time has reached a predetermined time and printing is stopped.
    Type: Application
    Filed: January 10, 2003
    Publication date: July 17, 2003
    Applicant: Hitachi Printing Solutions, Ltd.
    Inventors: Yasuyuki Horie, Katsumi Ishizawa, Souichi Nakazawa
  • Patent number: 6558136
    Abstract: A micropump underpressure control device, working in conjunction with a micropump having an inlet and an outlet. The micropump underpressure control device comprises a control valve and a transmission tube. The control valve is installed at a supply pipe leading to the micropump and further comprises a case with a membrane, a valve assembly, a connecting rod and a spring. The membrane is exposed to pressure from the outlet of the micropump and accordingly deformed, via the connecting rod controlling opening and closing of the valve assembly, so that working liquid is allowed to proceed to the inlet of the micropump or blocked. The transmission tube transmits pressure at the outlet of the micropump to the membrane. On an opposite side, the membrane is pressed on by working liquid and by the spring. Thus pressure at the inlet of the micropump is controlled, being kept smaller than or equal to pressure at the outlet of the micropump by a fixed difference.
    Type: Grant
    Filed: November 29, 2001
    Date of Patent: May 6, 2003
    Assignee: Industrial Technology Research Institute
    Inventor: Yu-Yin Peng
  • Publication number: 20030058325
    Abstract: An electrophotographic apparatus includes a controller having an image processor and an image storage unit. The controller is connected to a recording head having a light source and a light source driver, and to a surface electrometer. Based on surface potentials of a latent image area on a photoreceptor measured by the surface electrometer, the image processor of the controller processes image signals stored in the image storage unit or controls the light source driver to correct the intensity of a light beam emitted from the light source.
    Type: Application
    Filed: September 6, 2002
    Publication date: March 27, 2003
    Applicant: Dainippon Screen Mfg. Co., Ltd.
    Inventor: Tamio Fukui
  • Patent number: 6538678
    Abstract: A high quality image forming apparatus capable of outputting a quality image at a high speed is provided, with which no unevenness is generated on an image and a fog or a change in density is less likely to occur. An exposing unit is operated by an over-filled scanner method for exposure by a rotational polygon mirror that reflects lights on a surface narrower than an incident beam width, and forms an electrostatic latent image by back area exposure for exposing a non-image part.
    Type: Grant
    Filed: July 5, 2001
    Date of Patent: March 25, 2003
    Assignee: Canon Kabushiki Kaisha
    Inventors: Takahiro Nakase, Jun Asai, Yuji Kamiya
  • Patent number: 6538683
    Abstract: An object of the present invention is to solve a problem in which in an image forming apparatus which performs pulse width modulation, when the maximum pulse width is changed to change the maximum density, the exposure amount in patch formation also changes to make it difficult to accurately control the patch and maintain gradation characteristics. To achieve this object, the maximum pulse width of pulse width modulation can be changed. It is determined whether a patch is to be formed. For normal image formation, the maximum pulse width is set to a changed value. For patch formation, the maximum pulse width is set at a predetermined value, and an image is formed.
    Type: Grant
    Filed: October 26, 1999
    Date of Patent: March 25, 2003
    Assignee: Canon Kabushiki Kaisha
    Inventor: Yuichi Ikeda
  • Patent number: 6529223
    Abstract: An object of the present invention is to provide an image forming apparatus that has an image bearing body, charging device for charging the image bearing body, and exposing device for exposing the image bearing body charged by the charging device, wherein the exposing device illuminates a light beam for each of pixels corresponding to a non-imaged portion of a pixel matrix having plural rows and plural columns, and wherein, when it is assumed that a width of one pixel in the pixel matrix is A and a distribution width in a half value of a maximum potential value of potential distribution formed in OFF of light beam illumination of one pixel is Wv, a following relationship is satisfied: 0.6≦Wv/A≦1.4.
    Type: Grant
    Filed: May 30, 2001
    Date of Patent: March 4, 2003
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hironori Ohwaki, Toshiyuki Ehara, Masaya Kawada
  • Patent number: 6529222
    Abstract: An optical scanning system for a printer.
    Type: Grant
    Filed: November 1, 1999
    Date of Patent: March 4, 2003
    Assignee: Samsung Electronics Co. Ltd.
    Inventor: Seung-deog An
  • Patent number: 6507354
    Abstract: An image forming apparatus which writes an electrostatic image onto a photoconductor by laser light. An image writing resolution is set and a controller controls writing laser power according to the set image writing resolution. The controller also controls the writing laser power for a high resolution mode to be greater than the writing laser power for a low resolution mode.
    Type: Grant
    Filed: March 7, 2000
    Date of Patent: January 14, 2003
    Assignee: Ricoh Company, Ltd.
    Inventor: Masumi Sato
  • Patent number: 6504558
    Abstract: An image forming apparatus which includes a light source for emitting a light beam modulated according to an image signal and an optical deflector for repeatedly deflecting the light beam. A focussing optical system focuses the light beam deflected by the optical deflector on a surface to be scanned to form a light spot there, the surface being scanned repeatedly in a main-scanning direction. A photosensitive member is arranged at the surface and exposed selectively to the light spot, the photosensitive member having an image forming region and blank regions arranged at opposite ends of the image forming region. A developing unit causes toner to adhere to unexposed areas of the selectively exposed photosensitive member and develops an image. A photodetector receives part of the light beam emitted from the light source and an automatic power control circuit controls an output power of the light source on the basis of an output of the photodetector.
    Type: Grant
    Filed: July 26, 2000
    Date of Patent: January 7, 2003
    Assignee: Canon Kabushiki Kaisha
    Inventor: Hidemi Takayama
  • Patent number: 6480213
    Abstract: The CPU counts the number of printings made with use of a photosensitive member so as to monitor the usage of the photosensitive member. When executing printing, the CPU determines a modulating rate, which is based on the reducing rate and some correction of the rate in accordance with the usage of the photosensitive member, with reference to a table. The CPU sets the determined modulating rate to the pulse modulating section. The pulse modulating section executes pulse modulation at the set modulating rate, and thus generates video data used for the printing operation of the print processing section.
    Type: Grant
    Filed: August 22, 2001
    Date of Patent: November 12, 2002
    Assignee: Toshiba Tec Kabushiki Kaisha
    Inventor: Satoshi Hasegawa
  • Publication number: 20020135656
    Abstract: An image forming apparatus includes an image bearing member, a latent image writing device that emits a plurality of laser beams, two adjacent laser beams of the plurality of laser beams partially overlapping in a sub-scanning direction, respectively, and forming a reference latent image on a surface of the image bearing member by performing repeated scanning of each laser beam on the surface of the image bearing member, a developing device that develops the reference latent image with toner into a reference toner image, and a detecting device that detects the density of the reference toner image. The quantity of light of each laser beam forming a subsequent latent image is adjusted according to the density of the reference toner image detected by the detecting device.
    Type: Application
    Filed: March 21, 2002
    Publication date: September 26, 2002
    Inventors: Toshihiro Sugiyama, Hiroshi Ishii, Hiroshi Saitoh, Yuji Suzuki
  • Patent number: 6445401
    Abstract: In a light power modulating system for modulating output power of a laser diode, an output power of the laser diode is monitored and a voltage signal corresponding to the detected output power is output. An image signal output system is provided to form an image signal representative of a thickness density of an image to be formed, and a modifying system modifies the image signal such that a changing rate of the image signal between a lower value and a higher value is lowered. A differential amplifier outputs an amplified difference between the modified image signal and the voltage signal, and a driving current to be supplied to the laser diode is generated based on the amplified difference output by the differential amplifier.
    Type: Grant
    Filed: December 27, 2000
    Date of Patent: September 3, 2002
    Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
    Inventor: Shoji Iwazaki
  • Publication number: 20020113856
    Abstract: Based on the density of an image formed on a photosensitive member or an image recording medium, an amount of correction for uniformalizing the image density in a main scanning direction of a light beam is set. Based on the set amount of correction, the intensity of a light beam in an image region is corrected within a range of one main scan.
    Type: Application
    Filed: July 13, 2001
    Publication date: August 22, 2002
    Applicant: Fuji Xerox Co., Ltd.
    Inventor: Takayoshi Suzuki
  • Patent number: 6433804
    Abstract: A method in which a multilevel character generator (22) is adjusted using a single correction factor (KF) during an automatic compensation operation such that high-quality printed images can be obtained also in the instance of modified printing conditions.
    Type: Grant
    Filed: June 21, 2001
    Date of Patent: August 13, 2002
    Assignee: Océ Printing Systems GmbH
    Inventors: Volkhard Maess, Martin Schleusener
  • Patent number: 6418280
    Abstract: An electrophotographic apparatus has a detector, for detecting a surface potential on the photosensitive member, a determination unit, for employing the detection results obtained by the detector to determine an electrification amount for the electrification unit and an exposure control value for the exposure unit, for determining the electrification amount for the electrification unit, so that a dark portion potential on the photosensitive member is substantially a target dark portion potential selected from multiple target dark portion potentials, for determining a first exposure control value for the exposure unit, so that a light portion potential, which is based on the determined electrification amount and which is formed on the photosensitive member by the electrification unit and the exposure unit, is substantially a first target light portion potential, and for determining, in accordance with the first exposure control value and the selected target dark portion potential, a second exposure control val
    Type: Grant
    Filed: March 13, 2001
    Date of Patent: July 9, 2002
    Assignee: Canon Kabushiki Kaisha
    Inventor: Yuji Kamiya
  • Patent number: 6417876
    Abstract: A control unit of an image forming apparatus for controlling exposure energy includes a reference image storage unit storing a plurality of reference images, an image recognition unit comparing image information consisting of a plurality of pieces of pixel information with data stored in the reference image storage unit, an exposure energy density storage unit storing an exposure energy density for each reference image stored in the reference image storage unit, an exposure energy density determination unit based on data from the image recognition unit and data in the exposure energy density storage unit an exposure energy density to be applied to a dot position corresponding to each piece of the pixel information, and a laser drive driving a laser of an exposure unit based on data from the exposure energy density determination uni. Accordingly, the image forming apparatus can be provided which exhibits an excellent image reproducibility for images with various dot densities.
    Type: Grant
    Filed: June 8, 2000
    Date of Patent: July 9, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshinori Nakajima, Tetsuro Toyoshima, Tadashi Iwamatsu, Nobuyuki Azuma, Yoshinori Mutou
  • Publication number: 20020044189
    Abstract: The invention provides an image forming apparatus which, in case of switching to an exposure amount reduction mode for executing the image formation with an exposure amount reduced from that in the normal image formation in order to prevent ghost image generation resulting from the exposure memory effect of the photosensitive member, corrects a look-up table for gradational correction for the intermediate density or is provided with a look-up table for the exposure amount reduction mode.
    Type: Application
    Filed: August 24, 2001
    Publication date: April 18, 2002
    Inventors: Kenichiro Kitajima, Yuichiro Toyohara
  • Patent number: 6344866
    Abstract: A light beam scanner unit includes a light beam generating unit for generating light beams at a fixed power, a polygon mirror for reflecting light beams generated from the light beam generating means toward a surface to be scanned, thereby scanning it, and a light beam power sensing unit for sensing light beam power for scanning a surface to be scanned with the polygon mirror. This light beam scanner unit further has a mirror contamination sensing unit for sensing contamination of the polygon mirror by comparing a sensing result obtained from the light beam power sensing unit when light beams are emitted by the light beam generating unit with a preset reference value.
    Type: Grant
    Filed: August 8, 2001
    Date of Patent: February 5, 2002
    Assignee: Toshiba TEC Kabushiki Kaisha
    Inventors: Kenichi Komiya, Koji Tanimoto, Naoaki Ide, Jun Sakakibara
  • Publication number: 20020008754
    Abstract: An object of the present invention is to provide an image forming apparatus that has an image bearing body, charging device for charging the image bearing body, and exposing device for exposing the image bearing body charged by the charging device,
    Type: Application
    Filed: May 30, 2001
    Publication date: January 24, 2002
    Inventors: Hironori Ohwaki, Toshiyuki Ehara, Masaya Kawada
  • Patent number: 6339441
    Abstract: The present invention relates to an electrophotographic apparatus which has a photosensitive member, first light emitting means and second light emitting means, detecting means, and control means and the control means variably adjusting the light emitting amount of the first light emitting means and the light emitting amount of the second light emitting means so that a ratio between the light emitting amount of the first light emitting means and the light emitting amount of the second light emitting means becomes a predetermined value.
    Type: Grant
    Filed: December 9, 1999
    Date of Patent: January 15, 2002
    Assignee: Canon Kabushiki Kaisha
    Inventor: Kazuo Suzuki
  • Publication number: 20010033319
    Abstract: The present invention relates to an electrophotographic apparatus which has a photosensitive member, first light emitting means and second light emitting means, detecting means, and control means and the control means variably adjusting the light emitting amount of the first light emitting means and the light emitting amount of the second light emitting means so that a ratio between the light emitting amount of the first light emitting means and the light emitting amount of the second light emitting means becomes a predetermined value.
    Type: Application
    Filed: December 9, 1999
    Publication date: October 25, 2001
    Inventor: KAZUO SUZUKI
  • Patent number: 6307579
    Abstract: A first polygonal motor correction value and a first drum motor correction value are provided to the polygonal motor and the photosensitive drum motor so that an image formed by a printer unit has a 100% magnification on the basis of data provided from a reference pattern generating unit which generates an ideal pattern data having no magnification error. Next, a document, on which a predetermined pattern is printed, is scanned by a scanner unit, and then, a second polygonal motor correction value and a carriage motor correction value are provided to the polygonal motor and the carriage motor so that an image printed using the printer unit has a 100% magnification.
    Type: Grant
    Filed: March 6, 2000
    Date of Patent: October 23, 2001
    Assignee: Toshiba Tec Kabushiki Kaisha
    Inventor: Akihiko Kida
  • Patent number: 6297839
    Abstract: A light beam scanner unit includes a light beam generating unit for generating light beams at a fixed power, a polygon mirror for reflecting light beams generated from the light beam generating means toward a surface to be scanned, thereby scanning it, and a light beam power sensing unit for sensing light beam power for scanning a surface to be scanned with the polygon mirror. This light beam scanner unit further has a mirror contamination sensing unit for sensing contamination of the polygon mirror by comparing a sensing result obtained from the light beam power sensing unit when light beams are emitted by the light beam generating unit with a preset reference value.
    Type: Grant
    Filed: March 31, 2000
    Date of Patent: October 2, 2001
    Assignee: Toshiba Tec Kabushiki Kaisha
    Inventors: Kenichi Komiya, Koji Tanimoto, Naoaki Ide, Jun Sakakibara
  • Patent number: 6292206
    Abstract: An electrophotographic image forming apparatus including an LED (Light Emitting Diode) array head and a method of generating data for correcting the quantities of light to issue form the LEDs of the LED array head are disclosed. Only the quantity of light that actually contributes to development is uniformed throughout the LEDs. This reduces the scatter of a dot area in a latent image and thereby enhances image quality while insuring the sufficient resolution of the LEDs.
    Type: Grant
    Filed: December 24, 1998
    Date of Patent: September 18, 2001
    Assignee: Ricoh Company, Ltd.
    Inventors: Atsushi Takehara, Katsuhiko Maeda
  • Patent number: 6288733
    Abstract: An image forming apparatus includes a photoreceptor, an exposure device for exposing the photoreceptor with a laser beam dot by dot so as to form a dotted latent image on the photoreceptor, and a developing device for developing the dotted latent image with developer. The apparatus also includes a dot diameter correcting device for correcting a diameter of the dot formed on the photoreceptor. The dot diameter correcting device includes an image patch producing device for forming an image patch having a specific dot pattern with a laser beam having a predetermined power strength by the exposure device, an image patch detector for detecting a density level of the image patch formed on the photoreceptor, and a memory for storing data of laser power strengths with correlation to the detected density levels. With this structure, a controller controls laser power strength of the exposure device based on the correlated data stored in the memory and the density level detected by the image patch detector.
    Type: Grant
    Filed: March 28, 2000
    Date of Patent: September 11, 2001
    Assignee: Konica Corporation
    Inventors: Kazuhiro Nakazawa, Yasushi Koshimura, Toru Komatsu, Koichi Gunji
  • Patent number: 6285385
    Abstract: In the electrophotographic method of the present invention employing a photosensitive member and forming an electrostatic latent image by a charging step and a light beam irradiating step, in order to improve the dot reproducibility in the output image to thereby obtain an image with excellent gradation property, the amount of potential attenuation in the depth direction at light beam irradiation for one pixel of the photosensitive member is set so as to be not less than 65% but less than 135% of the amount of potential attenuation in the depth direction at the continuous light beam irradiation.
    Type: Grant
    Filed: December 21, 1999
    Date of Patent: September 4, 2001
    Assignee: Canon Kabushiki Kaisha
    Inventors: Hironori Owaki, Koji Yamazaki, Toshiyuki Ehara, Tetsuya Karaki, Kunimasa Kawamura
  • Patent number: 6266074
    Abstract: Provided is a light emitting apparatus capable of preventing light emitting elements made of an organic compound from being affected by moisture in an ambience, thereby increasing their lifetime, and suitably applicable to an exposure section of the electrophotographic method. Temperature sensors are set next to a light emitter array which is an array of many light emitting elements made of the organic compound. A drive control unit of the array is composed of CPU, ROM, RAM, and I/O ports. The CPU carries out control of each unit according to input data of image information etc. and also carries out pre-heat control for the light emitting elements. The temperature sensors detect the temperature of the light emitting elements and the CPU, receiving their detection output, turns the light emitting elements or a heating element provided separately, on and off so that a detected temperature value becomes a predetermined value in a waiting state without the input data.
    Type: Grant
    Filed: October 18, 1999
    Date of Patent: July 24, 2001
    Assignee: Canon Kabushiki Kaisha
    Inventors: Noboru Koumura, Yukio Nagase, Izumi Narita, Seiji Mashimo
  • Publication number: 20010005214
    Abstract: In an electrophotographic image formation apparatus that plural lines on a surface of a photosensitive body are simultaneously scanned by plural laser beams for image formation, image deterioration due to differences among light quantities of the plural laser beams is correctly prevented by a simple and cost-effective structure. The present invention aims to lower the image deterioration due to laser start characteristics as much as possible, and especially to realize high-speed image formation without degrading highlight reproducibility and fine line reproducibility.
    Type: Application
    Filed: January 19, 2001
    Publication date: June 28, 2001
    Inventors: Kenichi Nakagawa, Kazuo Suzuki
  • Patent number: 6204870
    Abstract: Plural lines on a surface of a photosensitive body of an electrophotographic image formation apparatus are simultaneously scanned by plural laser beams for image formation. Each of a pair of semiconductor lasers 11a and 11b biased in an ON state is independently turned on. A surface potential of the photosensitive body in each case is measured by a measurement unit such as a surface potential sensor 30, a surface potential detection circuit 31 and an A/D conversion circuit 32. Based on the measured result, an operational current of each laser is determined by a CPU 33 such that the surface potential of the photosensitive body becomes a target-potential, e.g., 220V to 230V. An image pattern difficult to be influenced by the laser start characteristic and an image pattern easy to be influenced by the laser start characteristic are formed, and the formed image patterns are respectively measured so that the current supplied at no beam emission time is controlled according to the measured results.
    Type: Grant
    Filed: September 8, 1999
    Date of Patent: March 20, 2001
    Assignee: Canon Kabushiki Kaisha
    Inventors: Kenichi Nakagawa, Kazuo Suzuki
  • Patent number: 6198497
    Abstract: A first embodiment of an adjustment circuit for a laser diode output power compensator includes a feedback circuit for adjusting the laser diode output power compensator so that the output power of the laser diode is substantially constant. The feedback circuit includes a photodiode for measuring the output power of a VCSEL diode. The signal from the photodiode is coupled to a first amplifier. The difference between the signal from the photodiode and a first reference value is amplified and coupled through electronic switches to selectively charge one of multiple capacitors. The multiple capacitors are each coupled to one of a drive current source, a compensation current source, and a voltage controlled resistor, each of which are voltage controlled. A second amplifier is used for amplifying the difference between the signal from the photodiode and a second reference value to charge a capacitor coupled to a voltage controlled bias current source.
    Type: Grant
    Filed: June 3, 1998
    Date of Patent: March 6, 2001
    Assignee: Hewlett-Packard
    Inventor: Phillip R. Luque
  • Patent number: 6195108
    Abstract: An image formation apparatus of the present invention forms an electrostatic latent image on a moving photosensitive belt by a laser beam produced by a laser device. A belt edge detector 1 detects an edge portion (belt edge) of a photosensitive belt 100 in a main scanning direction. A virtual edge detection circuit 2 generates a virtual edge detection signal 2A which changes a generation timing in accordance with a change of a detection timing of the belt edge detected by the belt edge detector 1. The generation timing of the virtual edge detection signal 2A does not almost follow the detection timing of the belt edge which changes by flaws and non-linearity of the belt edge, and changes in accordance with a slow change of the detection timing. A synchronizing signal generation circuit 3 and a driving circuit 4 drives the laser device so as to start a writing of an image data by the laser beam in synchronization with the virtual edge detection signal.
    Type: Grant
    Filed: July 19, 1999
    Date of Patent: February 27, 2001
    Assignee: NEC Corporation
    Inventor: Hiromasa Kanno
  • Patent number: 6169563
    Abstract: In an image recording apparatus provided with an optical unit having a plurality of laser diodes; a driving circuit is provided to drive the plurality of laser diodes in accordance with image output signals applied with a predetermined first bias; and a beam intensity measuring element is provided to measure a beam intensity of each of beams emitted from the plurality of laser diodes. When the beam intensity measuring element measures the beam intensity of each of beams emitted from the plurality of laser diodes, the driving circuit switches the first bias applied to at least one of the plurality of laser diodes to a second bias smaller than the first bias.
    Type: Grant
    Filed: May 18, 1999
    Date of Patent: January 2, 2001
    Assignee: Konica Corporation
    Inventor: Masato Doi