Canon Kabushiki Kaisha

Bridgestone Corporation

Yuichi Seki

Takashi Nakahara

Atsushi Nakagawa

Satoshi Endo

Mitsushige Murata

Keizo Isemura

Kuniyasu Kimura

Toshio Hayashi

Katsuhide Koga

Shoji Takahashi

Akihiko Sakai

Hiroaki Tomiyasu

Mitsuru Sakurai

Satoru Takezawa

Yoshihiro Funamizu

Takashi Sekiguchi

Masatoshi Tanabe

Atsushi Wada

Koichi Otaka

Shigeru Kasahara

Masaharu Sumiuchi

Hiroshi Takazawa

Toshinori Yabe

Jun'ichi Intoh

Masajiro Fujiwara

Eiko Wada

An apparatus includes a forming unit, a cleaning mechanism that cleans a transparent member of a scanning device of the forming unit, a counter that counts a number of image-formed sheets, which are sheets of a recording medium on which images have been formed by the forming unit, the counter performing counting with a first count value in a case where the forming unit performs image formation in a first mode and performing counting with a second count value larger than the first count value in a case where the forming unit performs image formation in a second mode higher in image forming speed than the first mode, and a control unit that controls the cleaning mechanism to clean the transparent member in response to the number of image-formed sheets counted by the counter reaching a predetermined number of sheets.

Image forming apparatus

An image forming apparatus comprises a semiconductor laser for emitting laser light for irradiating a photosensitive drum, BD for detecting laser light before irradiating the photosensitive drum to output BD signal as a reference for determining an initiation position of the photosensitive drum, and a laser circuit board. The laser circuit board causes the semiconductor laser to emit laser light detected by the BD with first light amount. When a BD sensor outputs the BD signal, a laser circuit board causes the semiconductor laser to emit the laser light with second light amount.

Image forming apparatus with current-controlled light emitting element

Surface identification processing is performed using a period of a BD signal when an amount of light incident on a BD sensor reaches an amount equal to or more than a threshold value, and the surface identification processing is not performed using the period of the BD signal in a state where the amount of light incident on the BD sensor is less than the threshold value. Thus, malfunction of the image forming apparatus due to failure of the surface identification processing is suppressed.

A light scanning apparatus, including: a light source configured to emit a light beam; a light intensity detection portion configured to detect a light intensity of the light beam; and a light intensity control portion configured to control the light intensity of the light beam based on a detection result of the light intensity detection portion, wherein the light intensity control portion supplies, in advance, to the light source, a bias current equal to or less than a threshold current at which the light source starts emitting the light beam, and supplies, to the light source, a switching current superposed on the bias current, the switching current being modulated in order to control light emission of the light source in accordance with an image signal, and wherein the light intensity control portion includes a bias current changing unit configured to change the bias current.

Light scanning apparatus

A light scanning apparatus, including: a light source; a light intensity detecting portion configured to detect a light intensity of the light beam emitted from the light source; and a light intensity controller configured to control the light intensity based on a detection result of the light intensity detecting portion, wherein the light intensity controller is configured to supply, in advance, to the light source, a bias current smaller than a threshold current at which the light source starts emitting the light beam, and is configured to control a supply of a drive current to the light source, the drive current being generated by superimposing, on the bias current, a switching current for controlling the light source in accordance with an image signal, and the light intensity controller includes a current stopping unit configured to stop a supply of the bias current and the drive current to the light source.

Light scanning apparatus and image forming apparatus

A light scanning apparatus, including: a light source configured to emit a light beam; a rotary polygon mirror configured to deflect the light beam emitted from the light source so that the light beam scans on a surface of a photosensitive member in a main scanning direction; a motor configured to rotate the rotary polygon mirror; and a rotational position detection unit configured to detect a magnetic flux change caused by rotation of the motor to generate a rotational position detection signal, wherein an emitting start timing of the light beam from the light source is determined based on the rotational position detection signal in order to maintain a writing start position of the light beam with respect to the photosensitive member in the main scanning direction.

Light scanning apparatus, image forming apparatus, and method of manufacturing light scanning apparatus

An image forming apparatus capable of controlling an amount of light beam to be a target value even when an emission characteristic of a light source varies. A photosensitive member is exposed to the light beam emitted form a light source. A light receiving element receives the light beam. Voltage for prescribing the driving current is set in a voltage setting unit. A voltage control unit controls the voltage so that the light amount of the light beam received by the light receiving element becomes a target light amount. A determination unit determines a correction parameter for correcting the voltage based on at least the voltage set in the voltage setting unit. A correction unit corrects the voltage set in the voltage setting unit with the correction parameter. A current supply unit supplies a driving current corresponding to the corrected voltage to the light source based on image data.

Image forming apparatus of electrophotographic system

An image forming apparatus controls a semiconductor laser such that first and second light beams among multiple light beams are successively incident on a BD sensor and measures the time interval between BD signals that correspond to the first and second light beams and are output from the BD sensor. Two light emitting elements that output two light beams for which the ratio between the light powers of two light beams detected by the detection unit falls within a predetermined range are set as light emitting elements that are to emit the first and second light beams when the time interval is to be measured. This suppresses measurement errors when measuring the interval between light beams emitted from two light emitting elements and improves correction accuracy for the image writing start positions of the light emitting elements.

An exposure apparatus according to this invention uses both a first light source which outputs a light beam corresponding to a drive current corresponding to image information, and a second light source to irradiate the surface of a photosensitive drum with a plurality of light beams. The second laser light source irradiates the photosensitive drum with a laser beam in accordance with a drive current corresponding to a correction value according to which unevenness of potential characteristics due to unevenness of sensitivity of the surface of the photosensitive drum is reduced. The same region on the surface of the photosensitive drum is irradiated with laser beams which are output from the first and second laser light sources onto the photosensitive drum in superposition.

Exposure apparatus with correction for variations in sensitivity and image forming apparatus using the same

An image forming apparatus comprises a light source, a photosensitive member and a control unit. The light source turns on in response to a driving current supplied based on image data. An electrostatic latent image is formed on the photosensitive member by exposing the photosensitive member to a light beam output from the light source turned on. The control unit controls the value of the driving current supplied to the light source in accordance with a driving state of the light source so that the value of the driving current supplied to the light source differs and changes with the passage of time in accordance with the driving state of the light source prior to the driving current being supplied to the light source.

Electrophotographic-type image forming apparatus

An optical scanning apparatus includes a light source, rotational polygonal mirror, correction data calculating unit, modification computing unit, and adjustment unit. The adjustment unit adjusts drive current supplied to the light source using the correction data calculated by the correction data calculating unit when a first of a plurality of modes is selected or using the correction data calculated by the modification computing unit when a second of the plurality of modes is selected.

Optical scanning apparatus, light power control method, and image forming apparatus for adjusting drive current supplied to the light source

This invention is an optical scanning apparatus comprises a plurality of beam generating units adapted to generate beams; an optical unit adapted to collimate axes of the beams generated by the plurality of beam generating units to scan at intervals corresponding to a recording direction along a image bearing member; a detection unit adapted to detect a beam interval between the plurality of beams collimated by the optical unit; a driving unit adapted to change the beam interval by driving the optical unit; a first control unit adapted to drive/control the driving unit so as to make the detected beam interval become a predetermined value; and a second control adapted to drive/control the driving unit in accordance with a rotation position of the image bearing member.

Optical scanning apparatus and image forming apparatus

An optical scanning apparatus includes an approximation formula determination unit, a sensitivity correction value determination unit and a bias current controller. The approximation formula determination unit determines an nth-order approximation formula and an mth-order approximation formula, which represent the sensitivity characteristic of the image carrier along the main-scanning direction thereof, from sensitivity data representing the sensitivity of each area obtained by dividing the surface of the image carrier into a plurality of areas. The sensitivity correction value determination unit determines a sensitivity correction value, which is a correction value of sensitivity in each area, from the nth-order approximation formula and mth-order approximation formula. The bias current controller controls a bias current in accordance with the sensitivity correction value. A switching current controller controls a switching current in accordance with the sensitivity correction value and a current value that is for obtaining a target amount of light.

Optical scanning apparatus, method of controlling amount of light, and image forming apparatus

Disclosed are a frequency modulation apparatus and a frequency modulation method for generating an image clock that is used for turning on/off a laser beam that scans an image bearing member, such as a photosensitive drum. The frequency modulation apparatus divides, into a plurality of segments for each pixel, a main scan line on an image bearing member, and calculates auxiliary clock periods based on a reference clock period and variable-magnification coefficients corresponding to the segments. Then, the frequency modulation apparatus generates image clocks for the respective segments based on an initial predesignated period value and the obtained auxiliary clock periods. Furthermore, the frequency modulation apparatus includes a detecting device for detecting a difference between a reference value stored in a memory and an actual laser irradiation location, and corrects a shift in the laser irradiation location in accordance with the detection results obtained by the detecting device.

Frequency modulation apparatus and frequency modulation method

In an image forming apparatus which requires the user to manually input sheet medium information, (when a bundle of sheets which include a plurality of types of print media are to be printed, the user must manually input setups of the image forming apparatus for each individual print medium. In manual setups by the user, some setups require user's knowledge about print media. When the user has made wrong setups, a print result cannot be obtained under an appropriate control condition Furthermore, when information about a print medium is sensed by the sensor without manual setups, the information cannot be often precisely detect depending on the type and thickness of the print medium, an environment, and the like, and it is consequently difficult to attain optimal image formation. It is an object of this invention to attain optimal image formation, saving user labor and shortening the print time by using a radio tag attached to the sheet medium. An image forming apparatus which forms an image on a sheet medium, has means for reading information from a information holding means, such as a minuscule radio chip, attached to the sheet medium, and means for manually inputting information of the sheet medium, and controls an image forming condition using either information.

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Saitama, Japan

Yuichi Seki