Ricoh Company, Ltd.

Kenji Sengoku

Junpei Fujita

Hiroyoshi Haga

Yasunobu Shimizu

Hiromi Ogiyama

Tomokazu Takeuchi

Osamu Ichihashi

Ryuuichi Mimbu

Shinya Tanaka

Kenji Sugiura

Seiichi Kogure

Mitsuru Takahashi

Kazuki Yogosawa

Yuuji Wada

Takehide Mizutani

Katsuya Kawagoe

Tatsuya Ohsugi

Ryuichi Minbe

Keigo Nakamura

Hirokazu Ishii

Naohiro Kumagai

Yuji Kato

Yasufumi Takahashi

Kunio Hasegawa

Junichi Ichikawa

Ryuichi Minbu

Jumpei Fujita

An image forming apparatus includes an image bearing member to bear a toner image charged with a predetermined polarity, and a power source to apply a bias to a transfer portion to transfer the toner image from the image bearing member to a recording medium, a polarity of the bias being changed alternately. The toner image formed with toner of a plurality of colors is transferred in a color mode and the toner image formed with toner of a single color is transferred in a monochrome mode. The bias includes a peak voltage with a polarity that returns toner from the recording medium to the image bearing member. An absolute value of the peak voltage in the color mode is equal to or greater than an absolute value of the peak voltage in the monochrome mode.

Image forming apparatus with a controller to set transfer bias

A cleaning device includes an upstream cleaner, an upstream cleaner, and a collection member. The upstream cleaner is configured to remove toner from a surface of a cleaning target. The downstream cleaner is disposed downstream from the upstream cleaner in a direction of movement of the surface of the cleaning target. The downstream cleaner is configured to remove toner from the surface of the cleaning target. The collection member is configured to collect toner from the downstream cleaner.

Cleaning device and image forming apparatus incorporating same

A cleaning device includes a cleaner, a casing, and an exit seal. The cleaner is configured to remove toner from a cleaning target. The casing accommodates the cleaner. The exit seal is attached to the casing and has a free end contacting the cleaning target at a position downward from the cleaner in a direction of movement of the cleaning target and an attached end attached to the casing. A space is disposed between a surface of the cleaning target and an opposite face of the exit seal opposite the cleaning target. The space includes an opening at a lateral end of the exit seal. The exit seal contacts the cleaning target from a trailing direction of the exit seal and seals the opening at at least an attached end side of the exit seal.

An image forming apparatus includes a housing and a belt assembly. The belt assembly includes a plurality of rollers, a belt, a belt first support, and a belt second support. The belt assembly is detachably attachable relative to the housing. The plurality of rollers includes a rotary shaft. The belt is entrained around the plurality of rollers and rotated in a certain direction. The belt first support supports the rotary shaft of the plurality of rollers at a first end in a width direction thereof and is movable in a direction of twist and fixedly supported by the housing. The belt second support is fixedly supported by the housing and supports the rotary shaft of the plurality of rollers at a second end opposite the first end in the width direction.

Image forming apparatus

An image forming apparatus includes a transfer device to transfer a toner image from an image bearing member onto a recording medium, disposed opposite the image bearing member, a transfer bias power source to apply, between the image bearing member and the transfer device, a superimposed transfer bias in which a direct current (DC) component and an alternative current (AC) component are superimposed to transfer the toner image borne on the image bearing member to the recording medium, and a controller to change the superimposed bias that the transfer bias power source applies. The controller changes the levels of the DC component and the AC component of the superimposed transfer bias in a color mode from that in a monochrome mode to secure a return electric field in the superimposed transfer bias by which the toner is returned from the recording medium to the image bearing member.

A method of transferring an image includes the steps of; bringing an image bearer bearing an image thereon as a transfer origin in contact with a transferring objective (onto which the image is transferred) as a transfer destination; moving at least one of the image bearer and the transferring objective in a prescribed direction; and sequentially transferring the image borne on the image bearer onto the transferring objective in a contacting section in which the image bearer and the transferring objective contact each other in a direction in which the image does not pass through the contacting section.

Method of transferring image and image transferring system and image forming apparatus with same

A transfer device including an image carrier; a transfer member disposed facing the image carrier; a transfer electrical field generator including a direct-current (DC) power source to generate a DC voltage and an alternating current (AC) power source to generate an AC voltage; and a controller. The transfer electrical field generator forms the transfer electrical field between the image carrier and the transfer member using the DC voltage and the AC voltage, to transfer the toner image on the image carrier, charged to a predetermined polarity, onto the recording medium. The controller controls the AC voltage source so that, the AC voltage output from the AC voltage source when a leading edge of the recording medium is positioned in the transfer electrical field is set larger than the AC voltage when the portion of the recording medium other than the leading edge is positioned in the transfer electrical field.

Transfer device and image forming apparatus

An image forming apparatus includes an image forming unit; an intermediate transfer member; a secondary transfer member to form a secondary transfer nip with the intermediate transfer member and the secondary transfer member; a biasing mechanism to bias the secondary transfer member toward the intermediate transfer member; a cam member rotatable between a first position, at which a predetermined space is formed in the secondary transfer nip, and a second position, at which the secondary transfer member and the intermediate transfer member contact each other; and a contact-separation controller configured to put the cam member in the first position before entry of the recording medium into the secondary transfer nip, rotate the cam member toward the second position when the recording medium enters the secondary transfer nip, and change a start timing of rotation of the cam member in accordance with a thickness of the recording medium.

Image forming apparatus including a cam member to separate a transfer member

An image forming apparatus includes an image bearing member, an image forming unit for forming a toner image and a toner pattern comprising toner not to be transferred onto a recording medium for adjustment of a density of toner on a surface of the image bearing member, a nip forming member contacting the surface of the image bearing member to form a transfer nip therebetween, a transfer bias applicator for applying a transfer bias in which an alternating current component and a direct current component are superimposed to transfer the toner image onto the recording medium in the transfer nip, a first cleaning device to mechanically remove toner remaining on the image bearing member after passing through the transfer nip. The transfer bias applicator applies a charge eliminating bias to remove charge from toner in the toner pattern when the toner pattern passes through the transfer nip.

An image forming apparatus includes: a belt unit that includes a belt-shaped image carrier stretched around and driven to rotate by a plurality of rollers; a belt tensioning unit that includes a tensioning member that is brought into contact with an image carrying surface of the belt-shaped image carrier and applies tension to the belt-shaped image carrier; and a cleaning unit that includes a cleaning member that is brought into contact with the image carrying surface of the belt-shaped image carrier and cleans the image carrying surface. The cleaning unit is supported by the belt tensioning unit in an attachable and detachable manner.

Image forming apparatus and belt tensioning unit

An image forming apparatus includes an image carrier; a facing member facing the image carrier via a transfer position; a power supply to output a voltage between a first position on the image carrier side and a second position on the facing member side; a resistance detector to detect electrical resistance between the first position and the second position via the transfer position; and a controller to switch between a first transfer mode in which the power supply outputs a direct current voltage, and a second transfer mode in which the power supply outputs a superimposed voltage. When a toner image on the image carrier is transferred onto a recording medium at the transfer position, the controller selects either the first transfer mode or the second transfer mode. When the resistance detector detects the electrical resistance, the controller selects the first transfer mode.

An image forming apparatus includes a transfer unit configured to transfer a toner image onto a recording medium; a power supply unit configured to output one of an alternating-current-based voltage including at least an alternating-current voltage and a direct-current voltage to the transfer unit; and a power supply control unit configured to cause the power supply unit to start switching to the alternating-current-based voltage a first time after the power supply unit stops outputting the direct-current voltage in the case that output of the power supply unit is switched to the alternating-current-based voltage, and cause the power supply unit to start switching to the direct-current voltage a second time after the power supply unit stops outputting the alternating-current-based voltage in the case that output of the power supply unit is switched to the direct-current voltage. The second time is longer than the first time.

Image forming apparatus, image forming system, and transfer method

An image forming apparatus, includes an image bearer to bear a toner image; a transfer member to transfer the toner image; a transfer bias applicator to apply a transfer bias to the transfer member, the transfer bias applicator including a direct current voltage source to apply a direct current transfer bias constituted by a direct current voltage to the transfer member; and a superimposed voltage source to apply a superimposed transfer bias in which an alternating current voltage is superimposed on a direct current voltage to the transfer member; and a controller to switch between a direct current transfer mode during which the direct current transfer bias is applied to transfer the toner image and a superimposed transfer mode during which the superimposed transfer bias is applied to transfer the toner image while the direct current voltage source and the superimposed voltage source are off.

An image forming apparatus includes a controller and a transfer device including a power source to output a superimposed bias in which an AC voltage is superimposed on a DC voltage, a first electrode, a second electrode disposed opposite the first electrode with an image bearing member interposed therebetween to form a transfer electric field to transfer a toner image on the image bearing member to a recording medium. The controller including a CPU adjusts the transfer electric field and a transfer speed. One of the first electrode and the second electrode is connected to the power source, and the other is grounded. The controller adjusts the transfer speed such that in a case in which an oscillating electric field of the transfer electric field is strong, a maximum transfer speed is slower than the maximum transfer speed in a case in which the oscillating electric field is weak.

Image forming apparatus which uses an AC voltage and/or a DC voltage at a transfer nip depending on a surface roughness of a recording sheet

An image forming apparatus includes an image bearing member to bear a toner image on a surface thereof, a transfer unit including a transfer device to transfer the toner image onto a recording medium, disposed opposite the image bearing member, a direct current (DC) power source to apply, between the image bearing member and the transfer device, a DC bias to form a first transfer electric field to transfer the toner image onto the recording medium, and a power supply module detachably attachable relative to the image forming apparatus. The power supply module includes an AC-DC superimposed bias power source to apply, between the image bearing member and the transfer device, a superimposed bias in which an alternating voltage is superimposed on a DC voltage to form a second transfer electric field to transfer the toner image onto the recording medium.

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Kanagawa, Japan

Kenji Sengoku