Ricoh Company, Ltd.

Iwao Matsumae

Yoshiaki Tanaka

Hiroshi Hosokawa

Eisaku Murakami

Hiroshi Saitoh

Tetsuo Yamanaka

Toshihiro Sugiyama

Kazuhiro Yuasa

Eiji Takenaka

Satoru Komatsubara

Shuichi Endoh

Mugijiroh Uno

Kazunori Bannai

Yoshinobu Sakaue

Noboru Kusunose

Shigekazu Enoki

Kozo Yamazaki

Kohta Takenaka

Mugijiro Uno

Eizi Takenaka

Mugiziroh Uno

An image forming apparatus is provided with a light scanning device that directs laser beams emitted from a plurality of laser light sources on to a plurality of photoconductive members via focusing device which includes optical elements and a deflecting device that deflects the beams in a main scanning direction; an image forming device which forms visible images of different colors from images written onto the photoconductive members by the light scanning device; and an intermediate transfer member or a recording sheet transport member capable of carrying the visible images formed on the photoconductive members. When in detection mode, a control device controls the correction of color registration errors between each color forms patterns on an intermediate belt by an image forming device, detects the patterns by a color registration error detection sensor, and stores the color registration error correction values obtained from the detection output of the sensor in a memory device. When forming images, the control device reads the color registration error correction values stored in the memory device, and carries out correction in accordance with the correction values via a writing start position correction device which deflects the laser position in the sub scanning direction.

Image forming apparatus

An optical scanning device includes a polygon mirror, a beam detector, a correcting unit, and a controller. The polygon mirror deflects and scans a light beam in a main scanning direction on a surface of an image carrier. The beam detector detects a beam position of the deflected light beam in a sub-scanning direction. The correcting unit calculates a correction amount of out-of-color registration based on the beam position, and corrects out-of-color registration in the sub-scanning direction based on the correction amount. The controller controls, during correction of out-of-color registration, a deflection speed of the deflector to be less than a deflection speed for writing a latent image on the surface of the image carrier.

Optical scanning device and image forming apparatus

A beam detecting unit detects at least one of a position of an optical beam in a sub scanning direction and a position of the optical beam in a main scanning direction. A color-misalignment correcting unit changes an optical-beam irradiating position on a photosensitive element based on a result of detection by the beam detecting unit. The beam detecting unit is arranged between an optical element that is closest to a corresponding photosensitive element and the corresponding photosensitive element.

Optical scanning device, image forming apparatus, optical scanning correcting method, and image forming method

An optical writing apparatus includes a deflecting part having a deflection plane for deflecting a plurality of light beams, a synchronization detection mirror for reflecting the plurality of light beams from the deflecting part, a synchronization detection part for detecting the timing for deflecting the plural light beams reflected from the synchronization detection mirror, and a housing for housing the deflecting part and the synchronization detection part. The synchronization detection part includes a lens for converging the plural light beams reflected from the synchronization detection mirrors, a light detection plate for detecting the plural light beams converged by the lens, and a holding member for holding the lens and the light detection plate.

Optical writing apparatus and image forming apparatus

In an image forming apparatus, a developing device operable with toner or single component type developer has a hard first developing roller and a soft second developing roller. Fine magnetic N-S poles are formed on the periphery of the first roller. The second roller conveys the toner, electrostatically transferred thereto from the first roller, to an image carrier. The device frees a toner image from deterioration due to toner particles charged to a polarity opposite to an expected polarity. The toner forms a uniform thin layer on the first roller and is uniformly charged. Toner for use with this type of developing device is also disclosed.

Developing device for an image forming apparatus

In an electrophotographic image forming apparatus of the type using single-ingredient type high resistance toner, a developing roller or similar toner conveyor roller is covered with a dielectric layer which is comparatively thick at opposite end portions than at an intermediate portion. A conductive or semiconductive elastic layer underlies the dielectric layer. With the above configuration, the dielectric layer is prevented from coming off the roller. This, coupled with the fact that the elastic layer does not contact a photoconductive element, eliminates current leaks and thereby extends the life of the roller and photoconductive element.

Method of coating a toner conveyor roller

A sheet feeding device for feeding sheets from a tray one by one and an image forming apparatus having the same are disclosed. A tray loaded with a stack of sheets, a separating member for separating a sheet paid out from the tray from the other sheets, and a driven conveyor roller are sequentially arranged around a single pick-up roller. With this arrangement, it is possible to reduce to a load to act on the sheet being conveyed by the pick-up roller and conveyor roller, and to prevent accidental continuous feed or simultaneous feed of a plurality of sheets.

Sheet feeding device and image forming apparatus having the same

In an electrophotographic recording apparatus of the type using a single-ingredient type developer, i.e., toner, a developing device has a developing roller for conveying the toner deposited thereon, and an intermediate roller for conveying the toner transferred theretofrom the developing roller and depositing it on a latent image electrostatically formed on an image carrier to thereby produce a corresponding toner image. During the development of an area of the image carrier other than a latent image area, a bias assigned to the developing roller is switched over to thereby form an electric field different in direction from an electric field assigned to the formation of the toner image between the two rollers. Further, before the rotation of the image carrier is stopped, the bias assigned to the developing roller is again switched in order to form the electric field for the formation of the toner image between the rollers. As a result, a toner layer is formed on the intermediate roller. Subsequently, the rotation of the image carrier is stopped. The device obviates defective images ascribable to the adhesion of the image carrier and intermediate roller while eliminating background contamination and wasteful toner consumption.

Developing device for an electrophotographic recording apparatus

An image forming device which allows reducing a linear velocity ratio of a developing roller against a sensitive body, which enables a pole pitch of a magnetic field generating layer to be miniaturized, and which generates a uniform and adequately thick toner layer on the developing roller. A toner regulating element formed by a sheet metal material having elasticity and non-magnetic characteristics elastically contacts a surface of the developing roller. The developing roller has an elastic body layer and a magnetic field generating layer having a minute pole pitch. The toner regulating elements serves to regulate a thickness of the toner layer without vibration induced from the pole pitch of the magnetic field generating layer. Thus, the toner layer can be uniform and of an adequate thickness, and reducing the linear velocity ratio of the developing roller against the sensitive body does not generate any drawbacks.

Image forming device for forming a uniform toner layer on a developing

In an image forming apparatus using a corona discharge type charging device and a contact type image transferring device, a toner deposited on a photoconductive element in the form of a black stripe is prevented from being transferred to the image transferring device; otherwise, the toner would be transferred from the image transferring device to the rear of the following recording medium. Because the toner forming the black stripe is limited to the toner charged to a polarity opposite to an expected polarity, toner consumption ascribable to the stripe is reduced.

Image forming apparatus with bias control to prevent undesirable toner

An image forming apparatus including a developing device having various components with specific relationships between their lengths. There is an image bearing member such as a photoconductive drum or belt having a photosensitive layer. The photosensitive layer has a length A. A first toner transporting roller has two ends, the length between the two ends being defined as B. Additionally, there is a second toner transporting roller, disposed between and contacting both the image bearing member and the first toner transporting roller. The length of the second toner transporting roller being defined as C. The components of the image forming apparatus are constructed such the length of the second toner transporting roller is less than or equal to the lengths of both the first toner transporting roller and the photosensitive layer of the image bearing member. This means that the relationships A&gt;C and B&gt;C may exist. As an alternative, B is approximately equal to C with A being greater than both B and C. As a further alternative, A, B and C are each approximately equal to each other.

Developing device having the lengths of two toner transporting rollers

A developing apparatus is capable of providing stable charging ability for a developer and stable transfer ability for transferring the developer to a photoreceptor for electronic photography to prevent residual positive images and stain of texture which appear on a toner image. A first toner transfer roller 23 has a core supported to be rotatable and a sheet type insulation layer wound around the outer periphery of the core. The insulation layer is made of elastic rubber in which magnetic material having a specified particle size is uniformly dispersed and the magnetic material is formed with ferromagnetic substance such as magnet and magnetized in advance. The first toner transfer roller 23 attracts toner T by actuating magnetism on the insulation layer since the magnetic material added to the insulation layer is magnetized.

Developing apparatus for electronic photographic recording equipment,

In an image forming apparatus, a developing device has a first developer carrier for depositing a developer thereon, a regulating member for regulating the amount of the developer deposited on the first developer carrier, and a second developer carrier having an elastic surface, and contacting the first developer carrier while biting into it by a predetermined amount. The developer is provided with a preselected degree of fluidity. Hence, even when the same portion of the surface of the second developer carrier runs a plurality of times past a position where the two developer carriers contact each other without any developer being fed from the second developer carrier to an image carrier, the first developer carrier can surely strip the developer from the second developer carrier. As a result, a developer on which a predetermined amount of charge is deposited is transferred from the first developer carrier to the second developer carrier. This successfully protects images from defects. Particularly, when the developer has a zinc stearate content of greater than 0.1 wt %, it is possible to prevent the developer from melting and adhering to a member which regulates the developer.

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Tokyo, Japan

Iwao Matsumae