Ricoh Company, Ltd.

Mugijiroh Uno

Eisaku Murakami

Eiji Takenaka

Tetsuo Yamanaka

Toshihiro Sugiyama

Kazuhiro Yuasa

Satoru Komatsubara

Hiroshi Hosokawa

Hiroshi Saitoh

Yoshiaki Tanaka

Iwao Matsumae

Shuichi Endoh

Masami Tomita

Takeshi Uchitani

Hiroyuki Nagashima

Shin Hasegawa

Yutaka Takahashi

Toshio Koike

Takeshi Shintani

Naohiro Kumagai

Masanori Kawasumi

Atsushi Sampe

Masato Yanagida

Kazunori Karasawa

Tokuya Ohjimi

Hiroya Hirose

Kentaroh Matsumoto

A cleaning unit includes a first blade and a second blade. The first blade is in contact with an image carrier or a paper carrier and removes adhered substances remained on surface of these. The second blade has an abrasive layer that is formed by including abrasive particles in an elastic material and is disposed in the downstream side of the first blade. The second blade is allowed to be in contact with the image carrieror the paper carrier. Volume occupancy of abrasive particles in an area of contact of the second blade with either the image carrier or the paper carrier is not less than 50 percent and not more than 90 percent.

Cleaning unit and image forming apparatus having multiple cleaning blades

Cleaning unit, process cartridge, and image forming apparatus

A method for cleaning a charging brush which charges a drum including an electroconductive substrate and an insulating surface layer over the electroconductive substrate, including the steps of grounding the electroconductive substrate of the drum contacting a brush portion of the charging brush with the insulating surface of the drum while the charging brush and the drum are rotated and applying an alternating electric field to the brush portion of the charging brush to vibrate to brush portion to remove fouling adhered to the brush portion.

Method and apparatus for image forming capable of preventing a contamination of a brush-roller charger

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

A developer, process cartridge and electrophotographic apparatus that includes the process cartridge and developer, which has as component parts, a main toner body, and an additive that enhances the fluidity of the main toner body. A mixing ratio of the additive to the main toner body, ensures that a contact charger, will not become contaminated, with excess additive that bypasses a cleaning device. While the additive ensures a proper fluidity of the main body of the toner, an excessive amount of additive, beyond a predetermined range, is avoided, so as to prevent the additive from contaminating the contact charger, thus enhancing the lifespan of the contact charger while maintaining image quality.

Developer, process cartridge and electrophotographic image forming

In an electrophotographic image recording apparatus of the type using a single-ingredient type developer, i.e., toner, a latent image is electrostatically formed on a photoconductive drum or similar image carrier. A developing unit has a developing roller for conveying the toner deposited thereon, and an intermediate roller for conveying the toner transferred thereto from the developing roller and depositing it on the latent image to thereby produce a corresponding toner image. An image transfer unit transfers the toner image to a cut sheet. During the development of an area of the image carrier other than a latent image area, at least one of biases assigned to the developing roller and intermediate roller, respectively, 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. As a result, the toner existing on the intermediate roller is collected by the developing roller. This successfully prevents the toner from depositing on the intermediate roller except when required, and frees the image transfer unit from the deposition of the toner.

Electrophotographic recording apparatus configured to switch a bias

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

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

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 device which includes a first toner transporting roller, a second toner transporting roller to which toner is transported from the first toner transporting roller and an image bearing member such as a photoconductive drum or belt. Seals are located between the circumferential ends of one of the toner transporting rollers and a bottom portion of a toner hopper. When the seals are between the bottom of toner hopper and the first toner transporting roller, the first toner transporting roller is longer than the second toner transporting roller and the circumferential portions of the first toner transporting roller which contact the seals do not contact the second toner transporting roller. Alternatively, when the seals are between the bottom of toner hopper and the second toner transporting roller, the second toner transporting roller is longer than the first toner transporting roller and the circumferential portions of the second toner transporting roller which contact the seals do not contact the first toner transporting roller. Additionally, when the seals contact the second toner transporting roller, side seals may be placed against the ends of the first toner transporting roller. In both of these arrangements, the length of the second toner transporting roller is shorter than a length of an effective area of a photoconductive layer on the image bearing member.

Developing device having seals between a toner transport roller and the

Toner, and devices for electrostatically depositing a uniform

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Isehara, Japan

Mugijiroh Uno