Ricoh Company, Ltd.

Kenji Karashima

Hisashi Fuzisaki

Manabu Mochizuki

Noriyuki Usui

Kentaro Matsumoto

Asami Mae

Mayumi Yoshida

Kazuhiko Yuuki

Masakuni Konja

Kohichi Yamazaki

Hajime Oyama

Haruji Mizuishi

Chikara Imai

Yasushi Akiba

Kazuhiko Yuki

An image forming apparatus and method in which a transfer device is provided in a position separated from an image carrier. A transfer sheet is conveyed along and contacting a part of a circumferential surface of the image carrier facing the transfer device when transferring a toner image from the image carrier to the transfer sheet. A conveying guide is included to guide and covey the transfer sheet separated from the image carrier to a fixing unit. The conveying guide includes a guiding member to direct the conveying direction of the transfer sheet upward when the leading edge of the transfer sheet contacts the guiding member and to convey the transfer sheet at a part of the conveying guide or the guiding member in a position higher than the position of the leading edge of the transfer sheet contacting the conveying guide or the guiding member, so that the contact area between the transfer sheet and the image carrier increases, and so that the transfer sheet separates from the image carrier without a discharging of a charge on the transfer sheet.

Image forming apparatus with a device and a method to increase contact

A contact type image transferring device and method incorporated in an image forming apparatus for cleaning a residual toner on a transfer roller. The transfer roller is in contact with a photoconductive drum at a first force and forms nip between the roller and the drum. A sheet of paper passes through the nip and a toner image on the drum is transferred to the sheet of paper. When the sheet of paper is not at the nip, the transfer roller is moved such that the force of the roller against the drum is a second force which is different from the first force. A cleaning bias voltage is applied to the roller and toner on the roller is transferred to the drum.

Apparatus and method for cleaning a transfer device of an image forming

A contact type image transferring system and method incorporated in an image forming apparatus for cleaning residual toner on a transfer roller. The transfer roller is in contact with a photoconductive drum and forms a nip between the roller and the drum. A sheet of paper passes through the nip and a toner image on the drum is transferred to the sheet of paper. A power source applies a first bias current which has the same polarity as regularly charged toner to the transfer roller from when the image carrier starts its rotation after an inputting of a print start request until the sheet reaches the nip. Then the power source applies a second bias current having the same polarity as the first bias current to the transferring device when the sheet is at the nip to transfer the toner image on the image carrier to the sheet.

Method for cleaning a transfer device of an image forming apparatus

An image forming apparatus in which a transfer device is provided in a position separated from an image carrier. A transfer sheet is conveyed along and contacting a part of a circumferential surface of the image carrier facing the transfer device when transferring a toner image from the image carrier to the transfer sheet. A conveying guide is included to guide and covey the transfer sheet separated from the image carrier to a fixing unit. The conveying guide includes a guiding member to direct the conveying direction of the transfer sheet upward when the leading edge of the transfer sheet contacts the guiding member and to convey the transfer sheet at a part of the conveying guide or the guiding member in a position higher than the position of the leading edge of the transfer sheet contacting the conveying guide or the guiding member, so that the contact area between the transfer sheet and the image carrier increases.

Image forming apparatus with a device to increase contact area between a

An image forming apparatus including a photoconductive drum, a charger which charges the photoconductive drum, an exposing device which irradiates light to the charged photoconductive drum for forming an electrostatic latent image on the photoconductive drum, a developing device which has two component developer which includes magnetic toner and magnetic carriers and a transfer charger to transfer the developed image to a sheet of paper. The bias voltages of the charger, the developing device and the transfer charger are applied from a common high voltage power source. A developing starting voltage of the developing device is higher than a residual voltage of the photoconductive drum.

Developing device for image forming apparatus

A contact type image transferring system and method, incorporated in an image forming apparatus, for cleaning a residual toner on a transfer roller. The transfer roller is in contact with a photoconductive drum and forms a nip between the roller and the drum. A sheet of paper passes through the nip and a toner image on the drum is transferred to the sheet of paper. When the sheet of paper is not at the nip, not only a transfer voltage but also a charging voltage is applied at a same time. The polarities of the voltages applied to the charger and to the transfer roller cause the toner on the transfer roller to be removed.

Apparatus for cleaning a transfer device of an image forming apparatus

A contact type image transferring system and method incorporated in an image forming apparatus for cleaning residual toner on a transfer roller. The transfer roller is in contact with a photoconductive drum and forms a nip between the roller and the drum. A sheet of paper passes through the nip and a toner image on the drum is transferred to the sheet of paper at the nip. When the sheet of paper is not at the nip, a first transfer voltage is applied to the transfer roller for 3 to 20 seconds after a paper feed jam is corrected. The polarity of the voltage causes the toner on the transfer roller to be removed. Then a second transfer voltage is applied to the transfer roller which has a polarity which is opposite to the polarity of the first transfer voltage. The voltage difference between the transfer roller and photoconductive drum may be formed by applying bias voltages to both the photoconductive drum and the transfer roller.

A developing apparatus having an improved construction for a developer carrying roller, particularly the developing roller which applies developer to a photosensitive body which carries a latent image. The developing roller or developer carrying roller includes a dielectric surface having a groove or grooved surface thereon formed, for example, by engraving, with the groove preferably extending along a central portion of the roller corresponding to the width of the latent image forming area of the photosensitive body. Preferably, the groove imparts a surface roughness in the axial direction of the roller in the range of 5-30 .mu.m, with the width of the groove not greater than 400 .mu.m. The roller may be formed such that adjacent grooved portions are immediately adjacent one another, or a smoothed flat portion may be interposed between adjacent grooved portions.

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Kawasaki, Japan

Kenji Karashima