Ricoh Company, Ltd.

Ricoh Printing Systems, Ltd.

Masayoshi Nakayama

Yoshitaka Fujinuma

Tatsuya Kubo

Susumu Tateyama

Takuma Higa

Kazuaki Kamihara

Masaki Sukesako

Yuichi Aizawa

Kohei Matsumoto

Tomohide Takenaka

Hiroyuki Kunii

Hiroyoshi Haga

Tsutomu Nakagawa

Masahiro Katoh

Shinya Tanaka

Kenji Sugiura

Hirokazu Ishii

Naohiro Kumagai

Takashi Suzuki

Junpei Fujita

Seiichi Kogure

Kazuki Yogosawa

Yuuji Wada

Toshihiro Sugiyama

Shinichi Akatsu

Toshitaka Yamaguchi

Hisao Okada

Tatsuya Ohsugi

Masakazu Terao

Wakana Itoh

Masashi Tachi

Jyunya Sakuraba

Susumu Takeyama

Hitoshi Yamamoto

Tadashi Kasai

Teruaki Mitsuya

Hirobumi Ooyoshi

Emiko Shiraishi

Makoto Yasuda

Keisuke Kubota

Kazumi Kobayashi

Takehide Mizutani

Kunio Hasegawa

Hiroyuki Mabuchi

Takamasa Ozeki

Yohhei Watanabe

Masaaki Imahori

Tsutomu Kato

Keita Sone

Mutsuki Morinaga

Jun Hitosugi

Takatsugu Komori

Takashi Rokutanda

Hiroyuki Kunil

Yoshimi Saitoh

An image forming apparatus includes a latent image bearer to bear a latent image, a potential sensor having a vibrator driven by a drive frequency to detect a surface potential of the latent image bearer, a developer bearer to bear developer that develops the latent image on the latent image bearer, and a power supply to apply a superimposed voltage obtained by superimposing an alternating voltage on a direct current voltage on the developer bearer. The frequency of the alternating voltage is not a multiple of the drive frequency and is a value obtained by adding a predetermined value to a multiple of the driving frequency.

Image forming apparatus and voltage application method

An electrophotographic image forming apparatus includes a latent image bearer to rotate and bear a latent image, a charging device to charge the a latent image bearer, a developing device to develop the latent image with developer including toner and use a developing voltage including an AC component, and a lubricant applicator to apply lubricant onto a surface of the latent image bearer. An amount of the lubricant applied by the lubricant applicator onto the latent image bearer per centimeter in an axial direction of the latent image bearer is equal to or greater than 0.845 mg for a running distance of 1.0 kilometer of the latent image bearer, and a difference between a largest value and a smallest value of the developing voltage is in a range of 200 V to 400 V.

Image forming apparatus

An image forming apparatus includes an image bearer, a transfer member, and a power source. The image bearer includes a plurality of layers. The transfer member forms a transfer nip between the image bearer and the transfer member. The power source outputs a transfer bias to transfer a toner image from the image bearer onto a recording sheet in the transfer nip. The transfer bias alternates between a transfer-side bias that causes the toner image to move from the image bearer to the recording sheet, and an opposite-side bias different from the transfer-side bias. A duty ratio of a time period, during which the opposite-side bias is output, relative to one cycle of a waveform, is greater than 50%.

An image forming apparatus includes an image bearer, an image forming device, a toner concentration detector, a toner supply device, an image density detector, and a controller including a memory device. At a predetermined timing before image formation is started, the controller adjusts a developing potential to adjust an image density of a detection toner image on the image bearer and drives the toner supply device or the developing device to adjust a toner concentration in the developing device. After the image formation is started, the controller drives the toner supply device to adjust the toner concentration, and, in a predetermined sheet interval, adjusts the target concentration based on the image density of the detection toner image formed in a non-image area of the image bearer. When the toner concentration is higher than the target concentration plus a threshold, the controller suspends image formation and readjusts the developing potential.

Image forming apparatus comprising image density detector and toner concentration detector

An image forming apparatus includes a first electric charging unit having an electric discharge wire to uniformly electrify a surface of the electrostatic latent image bearer, a second electric charging unit having a second electric discharge wire to execute a pre-electric charge removal electric charging process by electrifying the surface of the electrostatic latent image bearer subsequent to a transfer process to transfer a toner image, and a first electric charge removing device to diselectrify the surface of the electrostatic latent image bearer by irradiating it with electric charge removing light subsequent to the pre-electric charge removal electric charging process. The first electric charge removing device is disposed within an electric discharge region of the second electric discharge wire on a downstream side of an extreme upstream edge of the electric discharge region of the second electric discharge wire in a rotational direction of the electrostatic latent image bearer.

Image forming apparatus including electric charge removing device and method of forming image

An image forming apparatus includes a latent image bearer; a developing device containing two-component developer and including a developer bearer, a development voltage source, and a toner concentration detector; a toner supply device to supply toner to the developing device; a transfer device; and a controller to keep a toner concentration in the developer in the developing device at a target toner concentration during image formation. The controller executes forced toner consumption in which the developing device supplies the toner to the latent image bearer the toner at a predetermined forced toner consumption timing, while inhibiting the toner supply device from supplying toner. When the toner concentration falls to a prescribed toner density lower than the target toner concentration, the controller completes the forced toner consumption and executes a post-consumption toner supply operation.

An image forming apparatus includes a latent image bearer that carries a latent image and a developer carrier including a developer carrying member that carries a developer on a surface thereof. The developer carrier conveys the developer to a developing position opposite to the latent image bearer by moving the developer carrying member so as to develop the latent image carried by the latent image bearer. In a startup operation after a stop operation performed during a developing operation by the developer carrier, the developer carrying member is rotated for a predetermined time while the latent image bearer is set in a stopped state before starting a rotation.

Image forming apparatus and method in which a developer carrying member is rotated for a predetermined time during a startup or removal operation

An image forming apparatus includes multiple image forming units each including a latent image bearer and a developing device, a transfer device to transfer toner images from the latent image bearers onto a surface of endless rotary member, a cleaner to clean the surface of the endless rotary member, and a control unit to execute a forcible toner consumption process to forcibly consume degraded toner stored in applicable one or more developing devices. The forcible toner consumption process includes a step of forming a toner image formed for forced consumption in a non-image region of the latent image bearer with an amount of toner corresponding to a difference between an image area ratio of a developed image and a prescribed threshold when the image area ratio of the developed image is lower than the prescribed threshold.

Image forming apparatus and method having a forcible toner consumption process

An image forming apparatus includes: an image forming unit that includes a developing unit with a developing roller to form an image using toner; a controller; and a detection unit that detects a plurality of toner patches formed at different densities on an image carrier by the image forming unit. The controller controls the image forming unit to form the toner patches on the image carrier so that each interval between the toner patches is equal to or greater than a length corresponding to a circumference length of the developing roller.

Image forming apparatus and image forming method for advanced control of image density

A developing device that can discharge developer by an amount of developer in the developing device increased by a carrier supplemented into the developing device includes a supply transport screw and a receiving transport screw in a top and bottom positional relationship, the rotational axes of the supply transport screw and the receiving transport screw are mutually parallel in relation to an image support member. The developing device also includes an inclined transport screw arranged at an incline between one end of the supply transport screw and an other end of the receiving transport screw. The developing device also includes a supply unit for supplying new carrier into a casing and a discharge port and discharge unit for discharging part of the developer housed in the casing to the outside, the discharge port provided on a part of the casing corresponding to an upper part of the inclined transport screw.

Developing device and image forming apparatus that include a developer transport amount regulation part

An image forming apparatus includes an image carrier, a developer carrier, a runout measurement information storage unit to store runout measurement information of the image carrier and the developer carrier, including runout amounts on the circumference of the image and developer carriers in a development area, a development gap measurement information storage unit to store information obtained by measuring a development gap when runout measurement points of the image and developer carriers face each other, and a development electric field strength control unit to obtain each development electric field strength based on the runout measurement information and the development gap measurement information, and determine control contents of development electric field strength control to cause the entire development electric field strengths to fall within an acceptable range of a target electric field strength to perform the control contents.

Image forming apparatus and method of controlling development electric field strength therein

An image forming apparatus is provided, which forms a releasing agent absorption toner image on an in-between printed sides area of a moving surface of an image carrier in the duplex printing mode. When the in-between printed sides area of the moving surface enters a transfer position at which a toner image is transferred from the image carrier to a recording medium, the transferring operation of transferring the toner image from the image carrier to a recording medium is interrupted to keep the releasing agent absorption toner image on the in-between printed sides area of the moving surface of the image carrier.

Apparatus including a re-transfer unit to re-transfer a recording medium and method of image forming

Developing device and image forming apparatus including inclined transport screw

A development apparatus includes a first developer chamber configured to store and supply the developer, a first developer bearer configured to convey the developer supplied from the first developer chamber to a first development domain, defined by a portion of the first developer bearer facing a latent image bearer, to develop the latent image, a second developer bearer configured to convey the developer passed through the first development domain to a second development domain, defined by a portion of the second developer bearer facing the latent image bearer, to develop the latent image, a second developer chamber configured to recover the developer passing through the second development domain and store the recovered developer, and a transfer prevention member provided between the second developer chamber and the second developer bearer to reduce a transfer of the developer from the second developer chamber to the second developer bearer.

Development apparatus having two developer bearers and two development chambers

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Ibaraki, Japan

Masayoshi Nakayama