Ricoh Company, Ltd.

Hideya Furuta

Yoshihiro Sakai

Mitsuru Mamizuka

Yutaka Koizumi

Katsuo Sakai

Kazushige Taguchi

Kenichi Mizuma

Kazunori Bannai

Noriyuki Kimura

Tsukasa Adachi

Yasunori Kawaishi

Itsuo Ikeda

Satoshi Shinguryo

Kazusige Taguchi

Nobuo Kasahara

Nobuyuki Yanagawa

Tadao Koike

Minoru Sugiyama

Tatsuo Hirono

Hideki Kamiyama

Yoshimine Horiuchi

Makoto Ohsaki

Leo Munakata

Reo Munakata

Toyoji Ishikawa

Shinju Nagatsuna

Ituso Ikeda

Fumitaka Fujieda

An image forming apparatus of the type forming a toner image on a photoconductive drum or similar image carrier, transferring it to a paper or similar transfer medium via an intermediate transfer body, e.g., belt, and fixing it on the medium by a fixing device is disclosed. Just after the transfer of a toner image of the last color which is to lie over the other toner images on the intermediate transfer belt, the peripheral speed of the belt is switched to a comparatively low speed matching a fixing and paper transport speed. At this instant, the belt is moved away from the drum. The length of the transfer medium and the distance between a paper transfer position and a fixing position is compared. For a relatively short transfer medium, the peripheral speed of the belt is not switched to the low speed.

Image forming apparatus for fixing a toner image at a first speed or at

An image forming apparatus includes an intermediate transfer member which moves in one direction with a surface thereof facing and contacting an image carrier so as to transfer toner images for multiple colors from the image carrier to the intermediate transfer member to form at least one toner image page having the multiple colors superimposed thereon. An image transfer device transfers the toner image page on the intermediate transfer member to a recording medium or sheet, and a cleaning device, which is movable into contact with or away from the intermediate transfer member at predefined times, cleans the intermediate transfer member. The cleaning device is positioned so that a distance from an intermediate transfer nip portion entrance part to the cleaning device in the moving direction of the intermediate transfer member is greater than a length of the intermediate transfer member occupied by one or more toner image pages and a distance from the intermediate transfer nip entrance part to an intermediate transfer nip exit part.

Image forming apparatus cleaning an intermediate transfer member

An image forming apparatus has an image scanner, a sensor for determining that the image sensor has scanned the front edge of a document, and a controller using main scanning line synchronizing signals and an output signal of the sensor as reference signals. In response to the reference signals, the controller causes at least a writing unit to start writing each image data of particular color and causes a transfer medium driving circuit to start driving a transfer medium. The apparatus allows image components of different colors to be transferred to the transfer medium one above the other in accurate registration.

Image forming apparatus using a synchronized transfer medium driver

Image forming apparatus

A color image forming apparatus has a plurality of developing units each including a developing sleeve and storing a developer of particular color. The developing sleeve is located to face a photoconductive element or similar image carrier. When the supply of the developer from the developing sleeve to the image carrier begins or ends, a magnet brush formed on the sleeve by the developer is slowly brought into or out of contact with the image carrier. As a result, a load acting on the image carrier due to the brush contacting it is slowly applied and cancelled. This eliminates changes in the moving speed of the image carrier and thereby insures desirable image quality.

Color image forming apparatus which accelerates or decelerates the

An image forming apparatus has a device for sequentially forming a plurality of images by repeatedly performing an optical writing operation a plurality of times on a photosensitive body face every predetermined timing; a device for sequentially overlapping and transferring the images; a detector for detecting a timing shift from a time point of a command for starting the optical writing operation each time to a start time point of the actual writing operation; and a device for correcting the timing shift to overlap and transfer the images.

Image forming apparatus for the synchronizing of laser writer with

An image forming apparatus has a plurality of developing containers for developing an electrostatic latent image of a latent image carrier by toners having colors different from each other except for black; a black developing container for color for storing black toner for color and operated when the developed image on the latent image carrier every color is overlapped and transferred onto a transfer material to provide a color image; a black developing container for a monochromatic image for storing black toner for a monochromatic image and operated when the monochromatic image is obtained; and a device for arranging the respective developing containers such that the developing containers are opposite to the latent image carrier. The other image forming apparatuses are also shown.

Image forming apparatus having a separate black developer stored for a

A device for use in electrostatographic image recording equipment for retaining and transporting a paper sheet, document or similar sheet member. A transporting member is implemented as an endless belt. An AC voltage is applied to the belt to form a charge density pattern on the surface of the belt, while the charge density pattern sets up a non-uniform electric field in close proximity to the surface of the belt. The non-uniform electric field urges the sheet member against the belt and thereby allows it to be surely transported by the belt to a predetermined position without being dislocated.

Device for transporting sheet members using an alternating voltage

An image forming apparatus has a device for performing a scanning operation using a laser beam by a polygon mirror at a predetermined timing; a writing device for sequentially forming a plurality of images by repeatedly performing an optical writing operation a plurality of times on a photosensitive body; a transfer device for sequentially overlapping and transferring the plurality of images onto a transferred member; and a device for starting the optical writing operation each time by the writing device from the same polygon mirror face. The photosensitive body is constructed by a photosensitive body belt and the optical writing operation is started from the same polygon mirror face approximately every integral multiple of one rotation of a driving roller for the photosensitive body.

A color recording apparatus has an electric charge carrier which is circulatingly movable, an electrostatic latent image forming unit for forming a latent image which corresponds to an original image on the carrier, a development unit for developing the latent image; a transfer unit for transferring the developed image formed on the carrier to a record paper in a transfer process, a conveyor for conveying the record paper forward and backward with respect to the transfer unit, and a control unit which repeats control operations for controlling the latent image forming unit to form a latent image on the carrier, for controlling the development unit to develop the latent image, for controlling the conveyor to convey the record paper forward, for controlling the transfer unit to transfer the developed image to the record paper, and for controlling the conveyor to convey the record paper backward at least for one time. The control unit controls the conveyor prior to the transfer process so that the record paper is positioned at a point which is a predetermined distance before a transfer point and that a forward movement of the record paper is started on the basis of an information signal which is output in response to a state of starting an electrostatic latent image forming operation each time the transfer process is carried out.

Color recording apparatus

A plurality of photosensitive drums are arranged such that color-separated light images of an original document are formed respectively thereon. The photosensitive drums are independently driven under equal conditions by a single drive source for preventing image colors, i.e., image positions, from being shifted out of registry on an image transfer sheet.

Mechanism for driving photosensitive drums

A color copier scans an original carrying a multi-color image in one direction to form toner images of different color components thereof on respective photosensitive drums while moving a transfer sheet in the opposite direction to transfer in registration thereon the several toner images and thereby form a composite color image of the original without reversing the rotational direction of the drums. After the latent image on a given drum is developed with a toner of a respective color, the drum is quenched to remove residual charge by irradiating it with light of a color which is not significantly absorbed by the toner on the drum. The quenching light color differs as between different drums, and for a given drum the quenching light color differs from the color of the light used to form the latent image on that drum.

Color copier

An optical system for a color copier in which light images of blue, green and red produced by color separation are formed one on each of three photoconductive elements, then developed by toner of associated colors, and then transferred one upon another onto a paper. A first mirror is disposed in an optical path to which light representative of an image of an original document is led through an image-forming lens and a mirror group. Light reflected by the first mirror is focused onto a first photoconductive element. Light transmitted through the first mirror is split by a second mirror which is located in a position for intercepting a part of the width of a slit for exposure. Light reflected by the second mirror is focused onto a second photoconductive element. Further, light outside the range of the second mirror is reflected by a third mirror to be focused onto a third photoconductive element. The first mirror has a spectral characteristic which reflects light of one of three colors, i.e., blue, green and red while transmitting light of the other two colors. All of the first to third mirrors comprise total reflection mirrors, or only the first mirror comprises a half-mirror. A reflection from the first mirror is of a particular color to which the photoconductive elements show the smallest amount of reaction. Light of wavelengths outside a predetermined range of each color which is to be reflected by any of the mirrors is cut by using the reflection characteristic of the mirror (as well as a transmission characteristic in the case of the half-mirror) and the transmission characteristics of a filter which is associated with the mirror.

Optical system for color copier

In a color copying apparatus including a plurality of photosensitive members and a mounting table driven by a pulley, in which an original mounted on the mounting table is illuminated to expose the respective photosensitive members with reflected light from the original to thereby form latent images thereon while the mounting table travels and these images, after developed, are transferred overlappingly onto a transfer paper to produce a color copy, a distance between exposing positions for adjacent photosensitive members is an integer multiple of a peripheral length of the pulley.

Color copying apparatus

A color electrophotographic copying process utilizing the Carlson process. A colored original to be copied is color-separated and read by a solid-state image pickup device. Color compensation or gradation compensation is carried out on the basis of the data read by the solid-state image pickup device. When the color compensation is effected, amounts of masking are determined on the basis of the data read by the solid-state image pickup device, and the color-separated latent images are partially erased in an area-modulating manner dependent on the determined amounts of masking with an eraser having a light-emitting dot array. When the gradation compensation is effected, the latent images are partially erased with the eraser in an area-modulating manner dependent on the determined amounts of masking, or an appropriate gradation reproduction curve is selected on the basis of the data read by the solid-state image pickup device.

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Yokohama, Japan

Hideya Furuta