Ricoh Company, Ltd.

Junroh Uda

Hiromi Ogiyama

Ryuuichi Mimbu

Sadayuki Iwai

Ryuuichi Minbu

In a transfer nip roller operative to transfer an image from an image carrier to a recording medium, a ratio (We3/Wt3)/(We30/Wt30) is 0.47 or more, where We3 is an elastic workload and Wt3 is a total workload measured by applying a load on a covering portion under a load push-in condition of 3 mN/10 seconds, and We30 is an elastic workload and Wt30 is a total workload measured by applying a load on the covering portion under a load push-in condition of 30 mN/10 seconds.

Transfer nip roller, transfer device, and image forming apparatus

A transfer-separation device includes an intermediate transfer unit, a secondary transfer roller, a repulsive roller, a transfer unit, and a charge-eliminating/separating member. The secondary transfer roller and the repulsive roller form a nip through which the intermediate transfer unit and a recording medium pass. The transfer unit applies a bias voltage of a polarity identical to that of a toner image to the repulsive roller to secondarily transfer the toner image onto the recording medium. The charge-eliminating/separating member separates the recording medium from the intermediate transfer unit by removing charge therefrom. The volume resistance of the repulsive roller is greater than that of the secondary transfer roller. The surface resistance of the secondary transfer roller is equal to or greater than 10ohm.

Transfer-separation device and image forming apparatus

An image forming apparatus includes a plurality of toner-image forming units. Each toner-image forming unit includes a photosensitive drum and a charging unit that is arranged to abut against or remain detached from the photosensitive drum, and that electrically charges the photosensitive drum. Each of the toner-image forming units forms an image of a different color. At least one of the charging units functions as a corona charging unit and at least another one of the charging units functions as a non-contact charging unit.

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Kanagawa, Japan

Junroh Uda