TRANSFER DEVICE AND IMAGE FORMING APPARATUS

• Main Authors: KATO TSUTOMU, KATO YUJI, ICHIHASHI OSAMU, MIZUTANI TAKEHIDE, TANAKA SHINYA
• Format: Patent
• Language: English; Japanese
• Published: 17.09.2015
• Subjects: CINEMATOGRAPHY; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; HOLOGRAPHY; MAGNETOGRAPHY; PHOTOGRAPHY; PHYSICS

PROBLEM TO BE SOLVED: To provide a transfer device that prevents the occurrence of abnormal images resulting from discharge at a transfer nip.SOLUTION: A transfer device 20 includes a transfer member 30 that forms a transfer nip N, and a power source 39 that supplies a transfer bias for transferring a toner image on an image carrier 21 to a recording material S held at the transfer nip. The power source can supply either one of a first transfer bias or a second transfer bias to the transfer nip, and has contact width changing means 60 for extending, when the first transfer bias is supplied, the contact width between the transfer member and the image carrier on the upstream side in a recording material conveyance direction compared with the case where the second transfer bias is supplied; the first transfer bias is a transfer bias in which a bias in a transfer direction to transfer a toner image from an image carrier side to a recording material side and a bias having a polarity opposite to that of the bias in the transfer direction are alternately switched; the second transfer bias is a transfer bias comprising only the bias in a transfer direction to transfer a toner image from the image carrier side to the recording material side. 【課題】転写ニップにおける放電による異常画像の発生を防止する転写装置の提供。【解決手段】転写装置２０は、転写ニップＮを形成する転写部材３０と、転写ニップ内に挟み込んだ記録材Ｓに対して像担持体２１上のトナー像を転写するための転写バイアスを供給する電源３９とを有し、電源は、第一の転写バイアスまたは第二の転写バイアスのいずれかを転写ニップへ供給可能であり、第一の転写バイアスを供給するとき、第二の転写バイアスを供給するときよりも、記録材搬送方向上流側における転写部材と像担持体との接触幅を広げる接触幅変更手段６０を有し、第一の転写バイアスは、トナー像を像担持体側から記録材側に転写させる転写方向のバイアスと、転写方向のバイアスと逆極性のバイアスとが交互に切り替わる転写バイアスであり、第二の転写バイアスは、トナー像を像担持体側から記録材側に転写させる転写方向のバイアスのみからなる転写バイアスとしている。【選択図】図２