Sheet conveying device and image forming apparatus with the same

A sheet conveying device comprising:

• a plurality of first conveyance rollers disposed coaxially with one another;
• a plurality of second conveyance rollers that face the respective plurality of first conveyance rollers, the plurality of second conveyance rollers being disposed coaxially with one another, the plurality of second conveyance rollers being configured to conveying a sheet while sandwiching the sheet between the second conveyance rollers and the first conveyance rollers to be rotated;
• and
• a stiffening roller disposed coaxially with an axis of at least either of the first and second conveyance rollers, wherein
• the stiffening roller includes a first stiffening roller and a second stiffening roller, the first stiffening roller applying a conveying force to the sheet and having a larger diameter than the conveyance rollers coaxially disposed with the first stiffening roller, the second stiffening roller applying a smaller conveying force to the sheet than the conveying force to the sheet by the first stiffening roller and having a larger diameter than the conveyance rollers coaxially disposed with the second stiffening roller, and
• the first stiffening roller and the second stiffening roller each have a same outer diameter.

A sheet conveying device comprising:

• a plurality of first conveyance rollers disposed coaxially with one another;
• a plurality of second conveyance rollers that face the respective plurality of first conveyance rollers, the plurality of second conveyance rollers being disposed coaxially with one another, the plurality of second conveyance rollers being configured to convey a sheet while sandwiching the sheet between the second conveyance rollers and the first conveyance rollers to be rotated;
• and
• a stiffening roller disposed coaxially with either or both of the first and second conveyance rollers, the stiffening roller having a diameter larger than a diameter of either or both of the first and second conveyance rollers, wherein
• the stiffening roller includes a first stiffening roller and a second stiffening roller, the first stiffening roller applying a conveying force to the sheet, the second stiffening roller applying a smaller conveying force to the sheet than the conveying force to the sheet by the first stiffening roller,
• the first stiffening roller and the second stiffening roller are configured to integrally rotate with the respective conveyance rollers, the first and second stiffening rollers being disposed coaxially with the respective conveyance rollers, and
• a friction coefficient of a surface of the second stiffening roller is smaller than a friction coefficient of a surface of the first stiffening roller.