Ricoh Company, Ltd.

Nippon Oil Company

Haruo Iimura

Shinji Aoki

Keigo Nakamura

Yasuhiko Ogino

Shinya Tanaka

Akihiko Kanemoto

Naomi Sugimoto

Yasuyuki Takiguchi

Kazuchika Saeki

Kenya Yokoi

Takamichi Enomoto

Tadashi Kasai

Takehiro Toyooka

Masahide Nakaya

Tomokazu Takeuchi

Shigeki Iida

Fuyuhiko Matsumoto

Hiroyuki Takahashi

Hiroyuki Itoh

Wasaburo Ohta

Takeo Yamaguchi

Sumio Kamoi

Hiroyuki Ito

Masakatsu Shimoda

Takaaki Miyashita

Toru Miyabori

An image forming apparatus includes a nip forming member and a transfer bias output device that outputs a transfer bias to form a transfer electric field in a transfer nip between the nip forming member and an intermediate transfer member. Upon transfer of a composite toner image including a particular toner image onto a recording medium in the transfer nip, the transfer bias output device outputs the transfer bias including a first superimposed bias in which a direct current (DC) component is superimposed on an alternating current (AC) component. Upon transfer of the composite toner image without the particular toner image onto the recording medium in the transfer nip, the transfer bias output device outputs one of the transfer bias including a second superimposed bias having a peak-to-peak value of the AC component smaller than that of the first superimposed bias and the transfer bias including only the DC component.

Image forming apparatus

An image forming apparatus includes a transfer member configured to abut against an image carrier for carrying a toner image to form a transfer nip; and a power supply configured to output a bias voltage for transferring the toner image on the image carrier onto a recording medium nipped in the transfer nip. The bias voltage includes a first voltage for transferring the toner image from the image carrier onto the recording medium in a transfer direction and a second voltage having an opposite polarity of the first voltage, the first and the second voltages being alternately output. A time-averaged value of the bias voltage is set to a polarity in the transfer direction and is set in the transfer direction side with respect to a median between a maximum and a minimum of the bias voltage.

Image forming apparatus and image forming method

An image forming apparatus includes an image bearer to bear a toner image, a toner image forming device to form the toner image on the image bearer, a nip forming device to contact the image bearer to form a transfer nip between the image bearer and the nip forming device, a transfer bias output device to output a transfer bias including a DC component and an AC component to transfer the toner image from the image bearer onto a recording medium interposed in the transfer nip, and a controller operatively connected to the transfer bias output device to adjust a frequency f of the AC component of the transfer bias in accordance with an image area ratio A such that the frequency f is at its minimum with a predetermined image area ratio Amin %, where Amin % is greater than 0 but lower than an image area ratio of a solid image.

Image forming apparatus including a transfer bias output device

According to an embodiment, provided is a transfer device including: a nip forming member that abuts against a surface of an image carrier carrying a toner image; and a transfer voltage application unit that applies a transfer voltage including a DC component and an AC component. The transfer voltage is an alternating voltage in which a supply voltage having polarity in a transfer direction and a return voltage having polarity opposite. A time average value Vave of the transfer voltage is set to be at polarity in the transfer direction and is set to be closer to a peak value Vt of the supply voltage relative to a center value Voff between a maximum and minimum value. An absolute value of the peak value Vr of the return voltage is set to be larger than an absolute value of the time average value Vave.

Transfer device with transfer voltage unit and image forming apparatus using the same

[Problem to be solved] To provide an image forming apparatus for suppressing formations of white spots and achieving high quality images, while obtaining sufficient image densities in both of the recessed parts and the projected parts of a recording medium surface. [Solution] An image forming apparatus includes a transfer memberthat abuts against a surface of an image carrier carrying a toner image and forms a transfer nip, and a power supplythat outputs a voltage (transfer bias) for causing the toner image on the image carrier to be transferred onto a recording medium P nipped in the transfer nip. The voltage is switched alternatingly between a transfer direction voltage for causing the toner image to be transferred from the image carrier onto the recording medium and a voltage having an opposite polarity of the transfer direction voltage when the toner image on the image carrier is to be transferred onto the recording medium. A time-averaged value (V) of the voltage is set to a transfer direction polarity that causes the toner image to be transferred from the image carrier onto the recording medium, and is set more in the transfer direction than a median voltage (V) between a maximum and a minimum of the voltage.

An image forming apparatus includes an image carrier to carry a toner image, a transfer member to form a transfer nip by contacting the image carrier surface, and a power supply to output a voltage to the recording material captured in the transfer nip so as to transfer the toner image formed on the image carrier surface. The voltage is switching alternately between a voltage in the transfer direction and a voltage opposite to the voltage in the transfer direction, and a time average value (Vave) of the voltage is set to have a polarity of the transfer direction, and is set to a value in the transfer voltage side, and a change mode to change a cycle of the voltage output from the power supply can be changed based on the toner deterioration information which determines the deterioration status of the toner.

A transfer device includes an image carrier that carries a toner image; a nip forming member that forms a transfer nip between the nip forming member and the image carrier by contacting with a front surface of the image carrier; and a transfer bias applying unit that applies a transfer bias, thereby transferring the toner image carried on the image carrier to a recording material at a position of the transfer nip. The transfer bias applying unit applies the transfer bias in which an AC component and a DC component are superimposed and in which a peak-to-peak voltage of the AC component is larger than 6 times an absolute value of a voltage of the DC component.

Transfer device, image forming apparatus, and transfer method

An image forming apparatus includes a transfer bias generator including a transfer bias supply that supplies a transfer bias to a transfer nip formed between an image carrier and a first rotary body, and a controller that detects a toner adhesion amount at a predetermined region of the image carrier located immediately upstream from the transfer nip and having a predetermined length in a moving direction of the image carrier. The transfer bias generator outputs at least an alternating current component under one of constant voltage control and constant current control and changes a target output value of the alternating current component according to the toner adhesion amount detected by the controller.

Described herein is a transfer device that transfers a visualized image formed on an image carrier onto a recording medium. The transfer device includes an image carrier that carries a toner image, a contacting member that contacts the image carrier via a recording medium and a power source that outputs a transfer bias to transfer the toner image from the image carrier onto the recording medium at a transfer nip formed between the image carrier and the contacting member. The transfer bias has a direct current component and an alternating current (AC) component superimposed on the direct current component. The transfer device also includes a controller that controls the power source such that the controller controls a level of the direct current component output from the power source by a constant current control.

Transfer device and image forming apparatus

A transfer device includes a controller that controls a transfer bias supply to cause a transfer bias to increase, between an image carrier and a first rotary body disposed opposite the image carrier, a potential of the first rotary body toward an opposite polarity to a charge polarity of toner of a toner image on the image carrier to be higher than a potential of the image carrier, and to change, on the basis of identified recording medium type, a returning peak value which is one of a peak value of positive polarity and a peak value of negative polarity of the transfer bias and which generates an electric field that causes the toner having moved to the recording medium from the image carrier to return to the image carrier from the recording medium in a transfer nip.

Transfer device and image forming apparatus incorporating same

An image forming apparatus includes an image carrying member to carry a toner image, a nip forming member to form a transfer nip with the image carrying member, and a transfer bias outputting unit to output a transfer bias to transfer the toner image from the image carrying member to a recording medium. The transfer bias is composed of a direct current (DC) component and an alternating current (AC) component, and a least one of the DC component and the AC component is subjected to constant voltage control. When constant current control is conducted at a timing other than when the toner image is being transferred from the image carrying member to the recording medium, a detection bias voltage at the transfer nip is detected, and the voltage of at least one of the DC component and the AC component is controlled based on the detected detection bias voltage.

Growing community of inventors

Kanagawa, Japan

Haruo Iimura