Ricoh Company, Ltd.

Bridgestone Corporation

Naoto Kochi

Takehide Mizutani

Hirokazu Ishii

Yuuji Wada

Kenji Sugiura

Shinya Tanaka

Junpei Fujita

Atsushi Nagata

Naohiro Kumagai

Kazuki Yogosawa

Seiichi Kogure

Keigo Nakamura

Hiroyoshi Haga

Tatsuya Ohsugi

Takahiro Suzuki

Osamu Ichihashi

Atsushi Nakamoto

Ryo Hasegawa

Masakazu Imai

Katsuhito Haruno

Hiroki Nakamatsu

Haruki Nagata

Naomi Sugimoto

Yuji Kato

Yasufumi Takahashi

Kazuosa Kuma

Takahiro Konishi

Tsutomu Kato

Eiji Ichihara

A transfer device includes an intermediate transfer belt configured to bear a toner image and rotate, a transferor configured to contact the intermediate transfer belt via a recording medium and form a transfer nip, a guide configured to guide the recording medium conveyed to the transfer nip, and a pressure reducing device. The intermediate transfer belt is shaped as an endless belt. The pressure reducing device is configured to reduce pressure-contact force of the transferor against the intermediate transfer belt as the recording medium advances in the transfer nip. Therefore, a trailing end of the recording medium does not move toward the intermediate transfer belt when the trailing end of the recording medium has passed the guide.

Transfer device and image forming apparatus incorporating same

An image forming apparatus including an image bearer, a transfer-bias power source, an environment sensor, and a controller. The controller controls the transfer-bias power source to change the DC component and the AC component, according to the at least one of temperature and humidity detected by the environment sensor and a duty of the transfer bias. The duty is A/(A+B)&#xd7;100[%] where A denotes an area on a return-directional side to move toner from the recording sheet back to the image bearer, relative to a center value (Voff) of a maximum value and a minimum value of the transfer bias in one cycle of a waveform of the transfer bias, and B denotes an area on a transfer-directional side to move the toner from the image bearer to the recording sheet, relative to the center value (Voff) in the one cycle.

Image forming apparatus

An improved image forming apparatus includes an image bearer, a nip forming member, a transfer power source, and a controller. The controller switches a transfer mode between a first mode to transfer the toner image onto a first type sheet having a surface smoothness higher than a surface smoothness of a second type sheet and a second mode to transfer the toner image onto the second type sheet. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of greater than or equal to 50% that is a duty on the side of the opposite-peak value in the first mode. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of less than 50%, which is different from the opposite-peak duty of the first mode, in the second mode.

Image forming apparatus and image forming method

An image forming apparatus includes a developing device, an image bearer, a transfer rotator, a blade contacting a surface of the transfer rotator, and a controller to control the developing device, the image bearer, and the transfer rotator. A first toner pattern image is formed on the image bearer, transferred onto the transfer rotator, and passed past the blade at least twice together with rotation of the transfer rotator in at start-up of the image forming apparatus. A second toner pattern image is formed on the image bearer after the start-up and during passage of a non-image area in which toner images are not formed. A range of the first toner pattern image is wider than a range of the second toner pattern image in a width direction perpendicular to a direction of travel of the image bearer.

Transfer rotator and image forming apparatus comprising the same

An image forming apparatus includes an image bearer to bear a toner image, a nip forming member contacting the image bearer to form a transfer nip, and a transfer power source. The transfer bias has a transfer peak value to electrostatically move toner from the image bearer to the recording sheet and an opposite-peak value to electrostatically move less toner from the image bearer to the recording sheet than the transfer peak value. An opposite-peak duty of the transfer bias is less than 50%. The opposite-peak duty is tr/T&#xd7;100% where T is one cycle of the transfer bias and tr is a time period during which the transfer bias is on a side of the opposite-peak value relative to an offset voltage of the transfer bias in the one cycle T.

Image forming apparatus and image forming method for controlling a secondary transfer bias according to recording sheet type

A transfer device includes an image bearer, a rotatable body, a solid lubricant assembly, and a guide. An image bearer bears an image. The rotatable body forms a transfer nip with the image bearer to rotate in contact with a recording medium. An image on the image bearer is transferred onto the recording medium at the transfer nip. The solid lubricant assembly includes a solid lubricant and extends in a longitudinal direction of the rotatable body. The solid lubricant assembly applies a solid lubricant to at least one of the rotatable body and the image bearer. The guide guides the recording medium and positions the solid lubricant assembly.

An image forming apparatus including an image bearer; a nip forming member, a nip width changing device, a power source; and a controller. The controller switches between a first mode and a second mode according to a predetermined condition. In the first mode, a duty of the transfer bias is a first duty and a width of a transfer nip is a first width. In the second mode, the duty of the transfer bias is a second duty lower than the first duty and the width of the transfer nip is a second width greater than the first width. The duty is (T&#x2212;Tt)/T&#xd7;100% where T denotes one cycle of the transfer bias, and Tt denotes a time period, in which the transfer bias is on a transfer-directional side relative to a time-averaged value of the transfer bias, in the one cycle.

An image forming apparatus includes an image bearer, an image forming device to form a toner image on the image bearer with toner, a power source to output a bias to transfer the toner image onto a recording medium, and control circuitry. The circuitry controls the power source to decrease a peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when a time-averaged voltage of the bias is on a transfer side of transferring the toner to the recording medium, from a median value of maximum and minimum voltages of the bias. The circuitry controls the power source to increase the peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when the time-averaged voltage of the bias is on a return side of returning the toner to the image bearer, from the median value.

An image forming apparatus includes a transfer power supply and a controller. The controller is configured to execute control for an end-portion voltage that is a DC voltage of a transfer bias at a time of transferring a toner image to an end portion of a recording sheet and a body-portion voltage that is a DC voltage of a transfer bias at a time of transferring a toner image to a body portion on a rear side of an end portion of a recording sheet, such that the end-portion voltage is set to be higher than the body-portion voltage in the DC transfer bias and a value obtained by dividing the end-portion voltage by the body-portion voltage in the superimposed transfer bias is set to be smaller than a value obtained by dividing the end-portion voltage by the body-portion voltage in the DC transfer bias.

Image forming apparatus having transfer bias power controller

An image forming apparatus includes an image bearer; a toner image forming device; an intermediate transferor; a primary transfer power source; a secondary transfer nip forming device; and a secondary transfer power source to output a secondary transfer bias. One of two peak values of the secondary transfer bias is a transfer peak value to provide a greater transfer-directional force to move toner from the intermediate transferor toward the recording medium in the secondary transfer nip. An absolute value of the transfer peak value is greater than an absolute value of the primary transfer bias.

Image forming apparatus and transfer bias control

An image forming apparatus includes a plurality of image bearers, a transfer bias member, and a power source. When the transfer bias member transfers a color toner image onto a recording sheet, a second peak value of a peak-to-peak of a transfer bias, which is smaller than a first peak value of the peak-to-peak in an electrostatic force to move toner from the image bearers or an intermediate transfer body to the recording sheet, is zero or has a first polarity to generate the electrostatic force in a transfer direction to move toner from the image bearers or the intermediate transfer body to the recording sheet. When the transfer bias member transfers a monochromatic toner image including only black toner onto the recording sheet, the second peak value is zero or has a second polarity to generate an electrostatic force in an opposite direction to the transfer direction.

An image forming apparatus, including an image bearer configured to bear a toner image; a transfer device disposed opposing to the image bearer; and a transfer bias power source. The transfer bias power source is configured to output a transfer bias to transfer the toner image onto a recording medium. The transfer bias is a superimposed bias that cyclically alternates between a transfer-directional bias to transfer the toner image from the image bearer onto the recording medium and an opposite-directional bias in an opposite direction of the transfer direction. A ratio of a time period of application of the opposite-directional bias to a total time period of one cycle of the output transfer bias is greater than 50%. The transfer bias power source changes a value of a direct current voltage in the superimposed bias according to a linear velocity of the image bearer.

An image forming apparatus includes an image bearer, a transfer device contacting the image bearer to form a transfer portion, a transfer bias power source, and a controller. A ratio of a time period of application of the opposite-directional bias to a total time period of one cycle of the AC component of the superimposed bias is greater than 50%. A ratio of a value of the DC component of the superimposed bias output within a region ranging from a leading end of the recording medium to a predetermined length to a value of the DC component of the superimposed bias output outside the region is greater than a ratio of a value of the AC component of the superimposed bias output within the region to a value of the AC component of the superimposed bias output outside the region.

An image forming apparatus includes an image forming station, an intermediate transfer body, a transfer device, a transfer pressure applicator, and a controller. The image forming station forms a toner image. The toner image formed by the image forming station is transferred onto the intermediate transfer body. The transfer device transfers the toner image from the intermediate transfer body onto a recording medium. The transfer pressure applicator applies a secondary transfer pressure to the recording medium upon transfer of the toner image and to apply a lower secondary transfer pressure upon transfer of a toner image including a special color toner than that upon transfer of a toner image without the special color toner. The controller is operatively connected to the transfer pressure applicator to control the transfer pressure applicator.

An image forming apparatus includes an image bearer, a nip forming device, a contact-and-separation device, a thickness information retrieving device, and a controller. The contact-and-separation device moves the image bearer and the nip forming device to contact and separate from each other. The controller controls the contact-and-separation device based on information on a thickness of a recording medium obtained by the thickness information retrieving device such that in a case in which a thickness of a preceding recording medium and a thickness of a successive recording medium are different in continuous printing in which a plurality of recording media is printed out continuously, the contact-and-separation device adjusts a space between the image bearer and the nip forming device when the preceding recording medium exits the transfer nip to a preset size corresponding to the thickness of the successive recording medium that enters the transfer nip.

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Tokyo, Japan

Naoto Kochi