Ricoh Company, Ltd.

Chikara Imai

Susumu Tatsumi

Tadahiro Eda

Kazuyuki Sugihara

Yasushi Koichi

Nobuyuki Koinuma

Yuji Sawai

Yoshio Takamiya

Koji Suzuki

Yutaka Koizumi

Hajime Oyama

Kazumi Suzuki

Kiyoshi Sakai

Tsukuru Kai

Nobuyuki Yanagawa

Sadao Takahashi

Shigeru Suzuki

Kazuhisa Sudo

Makoto Obu

Koji Sakamoto

Manabu Mochizuki

Ichiro Kadota

Katsuo Sakai

Hisashi Shoji

Takeshi Takemoto

Takashi Bisaiji

Shigekazu Enoki

Mitsuo Tanaka

Norimasa Sohmiya

Koji Hirakura

Kouji Ishigaki

Hideaki Ema

Wataru Yasuda

Kenji Karashima

Hisao Kurosu

Noriyuki Usui

Moriyuki Koike

Kentaro Matsumoto

Hiroyuki Okamoto

Kazuhiro Kimura

Satoshi Otomura

Kazuhiko Yuki

Yohichiroh Miyaguchi

Atsushi Shinozaki

Masaki Tokuhashi

Asami Mae

Kohji Hirakura

Nobuaki Kondou

A multi color image forming apparatus includes a plurality of stations arranged side by side for forming unique mono-color toner images using mono-color developers each having a different mono-color toner. Each of the plurality of stations includes an image bearing member for bearing a latent image, and a developing device for visualizing the latent image into the mono-color toner image. A conveying device is provided to convey a transfer medium. A transfer device is provided to transfer the mono-color toner images from the image bearing members to the transfer medium. Charge ability of prescribed mono-color toner included in the mono-color developer used in the upstream station is smaller than that used in the downstream station.

Toner transfer back suppressing color image forming apparatus

A developing method of the present invention develops a latent image formed on an image carrier with a two-ingredient type developer, which consists of toner grains and magnetic carrier grains for supporting the toner grains. A developer carrier faces the image carrier and accommodates magnetic field forming device therein for causing the developer to deposit on the developer carrier. The developer is conveyed to a developing zone formed between the image carrier and the developer carrier. The latent image is developed by a magnet brush including free toner grains, which part from brush chains formed by the carrier grains when the brush chains start rising on the developer carrier in the developing zone. The method insures a high-density, smooth solid image. A device for practicing the method is also disclosed.

Developing device and image forming apparatus using the same

An electrophotographic image forming apparatus of the present invention deposits charged toner on a latent image formed on a photoconductive drum or similar image carrier to thereby produce a corresponding toner image. The apparatus includes a toner flying device for electrostatically conveying the toner along the conveying surface of a conveyance board to one end of the conveyance board. The toner is caused to fly toward the image carrier from the end of the conveyance board.

Image forming apparatus including electrostatic conveyance of charged toner

An image forming apparatus including a photoconductive drum, a charger which charges the photoconductive drum, an exposing device which irradiates light to the charged photoconductive drum for forming an electrostatic latent image on the photoconductive drum, a developing device which has two component developer which includes magnetic toner and magnetic carriers and a transfer charger to transfer the developed image to a sheet of paper. The bias voltages of the charger, the developing device and the transfer charger are applied from a common high voltage power source. A developing starting voltage of the developing device is higher than a residual voltage of the photoconductive drum.

Developing device for image forming apparatus

An image forming apparatus capable of forming both of erasable images and images to be stored, and increasing the number of times that a single sheet with an image can be repetitively decolorized and reused. The apparatus includes a photoconductive element for electrostatically forming a latent image representative of image data. A developing device develops the latent image formed on the photoconductive element by either of an ordinary undecolorizable toner and a decolorizable toner.

Image forming apparatus capable of forming an erasable image

An image density control method for an image forming apparatus of the type forming a latent image of a document image on a photoconductive element and developing the latent image by a toner to produce a toner image by an electrophotographic procedure. A background pattern whose density is substantially the same as the background density of a document, i.e., a light pattern is illuminated to electrostatically form a latent image thereof on the photoconductive element. The latent image is developed by the toner, and the density of the resultant toner image is optically sensed by an image density sensor. A change in background density due to contamination or an increase in background potential, for example, is detected. Based on the detected change in background density, a quantity of light for imagewise exposure or similar factor dictating the developing ability is corrected, i.e., it is controlled to the light side if the density has been shifted to the dark side. The detection of the background density and the control for correction are effected only when the charge retaining ability of the photoconductive element is stable.

Image density control method for an image forming apparatus

A method of removing a film from a photoconductive element of a color copier or similar image forming apparatus. At a suitable time when an image forming mode operation for forming a toner image on the photoconductive element is not under way, an amount of cleaning agent great enough to scrape a film off the photoconductive element is transported to a region between the photoconductive element and a cleaning sleeve. Subsequently, the amount of cleaning agent to be transported to such a region is reduced. This sequence of steps is repeated a plurality of times.

Method of removing a film from an image carrier of an image forming

A method of removing a film which undesirably forms on a photoconductive element or similar image carrier of an image forming apparatus such as an electrophotographic copier, printer or facsimile machine. The method is implemented by a cleaning device having a cleaning sleeve which removed toner particles remaining on the image carrier after image transfer. In a film removing mode which is executed when an image forming mode for forming a toner image on the image carrier is not under way, the cleaning sleeve is rotated at a lower speed than in an ordinary cleaning mode so as to feed a greater amount of cleaning agent to a cleaning region. The rotation speed of image carrier and that of the cleaning sleeve are controlled in such a manner as to feed a predetermined adequate amount of cleaning agent for the removal of a film to the cleaning region at all times.

Method of removing a film from an image carrier

An image density control method for an image forming apparatus controls any of various image forming conditions such as toner density on the basis of a result of image density detection which is executed in a pattern detection mode. A plurality of pattern detection modes are provided each for developing the latent image of a pattern having a reference voltage under a different potential for development. A development gamma characteristic representative of a characteristic relationship between the amount of toner deposited on the resulting toner image representative of the pattern and the potential for development on the basis of the results of detection which are individually associated with the plurality of pattern detection modes. The image forming condition is controlled such that the determined development gamma characteristic substantially coincides with a target development gamma characteristic.

An electrophotographic apparatus is operable selectively in an image-forming mode and a checking mode. In the checking mode, a region of a photosensitive body or drum having a uniform surface potential is developed by a developing unit at a plurality of different developing bias voltages into toner amount detecting regions.

Electrophotographic apparatus

A dual mode method for controlling the density of a toner image is disclosed for an electrophotographic process. In the first mode, an electrostatic latent image is formed on a photosensitive member from a reference pattern having a predetermined reflectance, the latent image is developed, the density of the developed image is detected, and this density information is used to replenish toner to the developer. A second mode can be actuated in which the photosensitive member is excited to form a region of approximately saturating residual potential which is then developed under a predetermined bias potential, the density of the thus developed image is detected and the density information is used to determine whether the developing step is functioning properly.

Dual mode image density controlling method

Light reflected from a reference pattern having a predetermined reflectivity is focused to a photoconductive element to form a latent image thereon. A degree of deposition of a toner on the latent image is sensed by a sensor and the toner supply to a developing unit is controlled in response to an output of the sensor. A fatigue standard is selected taking into account a fatigue characteristic particular to the photoconductor, so that a bias voltage applied to a developing roller in the developing unit is varied in response to the selected fatigue standard.

Toner supply control method for electrophotographic copier

A method for controlling an electrophotographic copying process in order to maintain the quality of copy images uniform as well as excellent even if the gamma characteristics of a photosensitive member including a photoconductive material such as AsSe or halogen doped SeTe has been changed due to changes in temperature of the photosensitive member is provided. A main feature of the method resides in using different combinations of process variables including charging amount, exposure amount and developing bias voltage level depending upon whether the temperature of the photosensitive member goes higher or lower than a predetermined reference level.

Reproduction process control method

An original to be copied is placed in a given position. An exposure optics including a movable part is employed to focus an optical image of slitwise segment of the original on a photosensitive member. The photosensitive member moves in a given direction and at a given speed throughout the exposure. The location where the image of slitwise segment of the original is focused moves through the space of the arrangement at a given speed and in a direction opposite from the direction of movement of the photosensitive member throughout the exposure. Consequently, the location corresponding to the initiation of the exposure is situated downstream as viewed in the direction of movement of the surface of the photosensitive member while the location corresponding to the end of the exposure is situated upstream as viewed in the same direction. Upon termination of the exposure, the photosensitive member continues its movement which is the same as during the exposure while the movable part of the exposure optics returns to its start position.

Process of exposing photosensitive member

An electrophotographic copying process and apparatus fast in operation and capable of making reproduced images having substantially the same image density is provided. In accordance with the present invention, pre-exposure is carried out only when a photosensitive member is to be used for image formation after elapsing a predetermined time period during which the photosensitive member has been kept unused. The present invention is fast in operation and minimal in power consumption because the pre-exposure is skipped when unnecessary. However, since pre-exposure is effected when necessary, the image density may be maintained at constant.

Electrophotographic copying process and apparatus having means for

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Tokyo, Japan

Chikara Imai