Ricoh Company, Ltd.

Hiroshi Takashima

Koji Suzuki

Naoki Iwata

Shigekazu Enoki

Yuichi Ueno

Shinji Kato

Katsuhiro Kosuge

Tomoji Ishikawa

Kazuyuki Sugihara

Takayuki Maruta

Akihisa Itabashi

Jun Aoto

Hiroyasu Shijo

Yasuo Hirano

Fumio Kishi

Kazuo Nojima

Hiroyasu Sumida

Hiroshi Fukano

Takeshi Ogiwara

An image forming device includes a plurality of developing devices and a photosensitive drum. Each of the developing devices includes a developer carrying roller. One of the developing devices is moved to a developing position confronting the photosensitive drum which is formed with a latent image. A first developing bias including a d.c. component and an a.c. component is applied to the developer carrying roller and developer on the developer carrying roller is rendered in contact with the latent image on the photosensitive drum so that the latent image is developed. On the other hand, when the developer on the developer carrying roller comes in contact with and separates from the photosensitive drum due to the movement of the developing device, a second developing bias is applied to the developer carrying roller. The second developing bias generates an electric field where the developer on the developer carrying roller is more reluctant to move toward the photosensitive drum as compared with the first developing bias. The second developing bias may include only a d.c. component.

Color image forming device which changes developing bias when switching

A method of developing latent electrostatic images and a developer-bearing member for use in the method are disclosed, which method includes the steps of (a) forming numerous micro closed electric fields near the surface of a rotatable developer-bearing member which comprises an electroconductive support and a surface layer formed thereon comprising an electroconductive organic polymeric matrix and numerous minute charge-retainable insulating segments distributed at least one the surface of the surface layer, by electrically charging the surface of the charge-retainable insulating segments; (b) supplying a one-component type developer comprising toner particles to the rotatable developer-bearing member to hold the developer on the rotatable developer-bearing member to hold the developer on the rotatable developer-bearing member by the numerous micro closed electric fields; and (c) bringing the rotatable developer-bearing member near or into contact with a latent-electrostatic-image-bearing member which bears a latent electrostatic image to develop the latent electrostatic image with the one-component developer to a visible toner image.

Method of developing latent electrostatic images and developer-bearing

A developer carrier capable of forming microfields on the surface thereof and a method of producing such a developer carrier. A great amount of sufficiently charged one-component developer is carried on the surface of the developer carrier by the microfields and transported to a developing station for developing an electrostatic latent image. The developer carrier has a simple structure and is easy and economical to produce.

Developer carrier capable of forming microfields thereon and method of

A developing device develops a latent image electrostatically formed on an image carrier in a developing region to produce a corresponding visible image. The developing device includes a rotatable developer carrier for carrying a developer to the developing region and a charging device for forming small closed electric fields in the vicinity of the surface of the developer carrier. The developer is deposited on the surface of the developer carrier by the small closed electric fields. The developer carrier comprises a conductive base and dielectric bodies fixedly buried in recesses formed in the conductive base with each of the dielectric bodies having a predetermined cross-section which extends in a direction of a line normal to the surface of the developer carrier. Also, the developer carrier has a photoconductive surface which is charged by a charging device and selectively illuminated by an illuminating device to deposit a charge on the photoconductive surface which forms a great number of microfields on the photoconductive surface.

Developing apparatus using a developer carrier capable of forming

An image forming apparatus having a device capable of identifying an image orientation to allow adequate processing to be executed and a device capable of binding sheets by determining a binding position. When an image orientation cannot be identified on the basis of a predetermined reference object, it is identified on the basis of another object. When the image orientation of a reference image and the image orientations of the other images are not coincident, an adequate procedure is executed to avoid an undesirable result. An orientation of a document image matching a predetermined adequate binding position is surely and accurately determined.

Image forming apparatus having an image orientation identifying device

A developing apparatus using a developer carrier which is capable of forming microfields on the surface of the carrier. A great amount of sufficiently charged one-component developer is deposited on the surface of the developer carrier by the microfields and transported to a developing region to be supplied to an electrostatic latent image. The developer carrier has a plurality of surface portions, each having a particular characteristic, such that at least one surface portion holds a first charge while at least another surface portion holds a second charge that is equal to and of an opposite polarity to the first charge.

A developing apparatus having a rotatable toner carrier for transporting a toner to a developing region where it faces an image carrier on which a latent image has been electrostatically formed. The surface of the toner carrier is constituted by a mixture of conductive surface portions and dielectric surface portions and selectively holds a charge to form microfields. The toner having been charged is electrostatically deposited on the toner carrier by the microfields and transported to the developing region as the toner carrier moves. In the developing region where the toner carrier and the image carrier face each other while defining a developing gap therebetween, the toner electrostatically flies from the toner carrier to the latent image formed on the image carrier to thereby develop it.

A developer carrier constituting a developing roller which carries a developer on the surface thereof where numerous microfields are developed. The developing roller has a conductive base and a plurality of different kinds of substances each having a particular charging characteristic. The different kinds of substances show themselves on the surface of the base in a regular or irregular pattern, and each is charged to a particular polarity.

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Yono, Japan

Hiroshi Takashima