Ricoh Company, Ltd.

Yuko Hayama

Hiroshi Itoh

Hirokazu Ishii

Satoshi Takano

Shunichi Oohara

Akio Kutsuwada

Haruji Mizuishi

Itaru Matsuda

Katsuhiko Miki

Osamu Takehira

Itaku Matsuta

Hakuti Mizuishi

A curl straightening method in an image apparatus including a fixing apparatus and a curl straightening apparatus is disclosed. The method includes calculating moisture content of a sheet before being supplied to the fixing apparatus; measuring a temperature of a heating unit and a pressurizing unit; calculating a temperature and moisture content of the sheet in the respective conveying sections; calculating a conveying time of the sheet in the respective conveying sections; calculating a residual strain of the sheet in the respective conveying sections from the calculated temperature and the moisture content of the sheet in the respective conveying sections, the calculated conveying time, and the stress relaxation characteristics of the sheet; calculating a final curl amount using the calculated residual strain of the sheet in the respective conveying sections; and controlling the curl straightening apparatus based on the final curl amount obtained.

Curl straightening method and image forming apparatus

An image forming apparatus includes: a curl correction device which corrects curl generated in a recording medium having passed through a fixing device; a temperature/humidity sensor unit which is installed in a conveying path between the fixing device and the curl correction device, and detects and outputs temperature and humidity near a surface of the recording medium; a calculation unit which calculates temperature and moisture content of the recording medium from the temperature and humidity output values output from the temperature/humidity sensor unit, and calculates curl correction efficiency of the curl correction device from the temperature and moisture content of the recording medium; a control value determination unit which determines a control value to perform a curl correction in the curl correction device, based on the curl correction efficiency calculated by the calculation unit; and a control unit which controls the curl correction device by the control value.

Image forming apparatus and curl correcting method

A sheet conveying apparatus, an automatic draft conveying apparatus, a paper feeding apparatus, and an image forming apparatus capable of preventing self-oscillation of a conveying roller. When rigidity of an oscillation system of the conveying roller is K [N/m], the distance between a supporting point of an arm and a section of the arm to which an axis of the conveying roller is attached is L [mm], and arm angle, which is formed between a sheet and a line segment connecting the supporting point of the arm to the section of the arm to which the axis of the conveying roller is attached on an assumed plane perpendicular to a direction of the axis of the conveying roller, is &#x3b8; [deg], &#x3b8;&#x2266;(Pse&#xd7;K)&#xd7;(1/L) is satisfied, where Pse=37500.

Image forming apparatus

A transfer separator comprises a transfer belt or other transfer mechanism for carrying and conveying a sheet to apply a toner image from an image carrier onto the sheet and separating the sheet from the image carrier. A bias application electrode applies a transfer bias to the transfer belt, wherein a relation of Lp.gtoreq.aV, and a=1 mm/KV is established when the minimum distance between the image carrier and surface of the bias application electrode is set to Lp (mm) and the maximum voltage applied to the bias application electrode is set to V (KV) . Preferably, the bias application electrode has a coated layer, and the difference in thickness resistance between the coated layer and the transfer belt is within two orders of magnitude. The hardness of the coated layer is preferably equal to or greater than the hardness of the transfer belt.

Transfer separator

In an image forming apparatus, a lubricant is fed to an image carrier on which a toner image is to be formed. An endless rotatable transfer member conveys a recording medium to which the toner image is to be transferred from the image carrier. The transfer member is capable of contacting the surface of the image carrier to which the lubricant has been applied. As a result, an adequate amount of lubricant is evenly applied to the transfer member to reduce the coefficient of friction of the surface of the transfer member, thereby enhancing the cleanability of the transfer member.

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Kanagawa, Japan

Yuko Hayama