Roller, roller unit, paper feeder provided with roller or roller unit, and image reader

A rotationally driven retarding roller unit disposed adjacent to a rotationally driven separation roller in a paper feeder, the retarding roller unit comprising:

• a roller;
• and
• a wheel having a center axial line, the wheel including M arc-shaped long holes (where M is an integer greater than or equal to 4) in each of N layers (where N is an integer greater than or equal to 2) which are circular and concentric to the center axial line of the wheel and spokes between the arc-shaped long holes in each layer, the spokes in one layer not overlapping in a circumferential direction with the spokes in an adjacent layer,
• wherein, when the wheel is not deformed by an external force, a width of the arc-shaped long holes in an outermost one of the layers in a radial direction of the wheel from a first end of each of the arc-shaped long holes in the circumferential direction to a second end thereof in the circumferential direction is uniform and is greater than a width of the arc-shaped long holes in one of the layers that is adjacent to the outermost one of the layers in the radial direction, and each of the spokes of the one of the layers that is adjacent to the outermost one of the layers extends along a plane passing through a center in the circumferential direction of one of the arc-shaped long holes of the outermost one of the layers and the center axial line,
• wherein an outer circumferential surface of the wheel is in contact with an inner circumferential surface of the roller, and
• wherein, when the roller is in contact with the separation roller, an abutting portion of an outer circumferential surface of the roller warps to fit to an exterior shape of the separation roller, and the wheel rotates to a position at which a deformed one of the arc-shaped long holes deforms along a plane which passes through a center axial line of the separation roller, the center axial line of the wheel, a center in the circumferential direction of the deformed one of the arc-shaped long holes, and at least one of the spokes.

A rotationally driven retarding roller disposed adjacent to a rotationally driven separation roller in a paper feeder, the retarding roller comprising:

• a cylindrical roller having an innermost layer that is circular and concentric to a center axial line of the roller, and an outermost layer that is circular and concentric to the center axial line of the roller, the innermost layer being adjacent to the outermost layer,
• wherein each of the innermost layer and the outermost layer includes at least four arc-shaped long holes and spokes between the arc-shaped long holes, the spokes in the innermost layer not overlapping in a circumferential direction with the spokes in the outermost layer,
• wherein, when the roller is not deformed by an external force, a width of the arc-shaped long holes in the outermost layer in a radial direction of the roller from a first end of each of the arc-shaped long holes in the circumferential direction to a second end thereof in the circumferential direction is uniform and is greater than a width of the arc-shaped long holes in the innermost layer in the radial direction, and each of the spokes of the one of the layers that is adjacent to the outermost one of the layers extends along a plane passing through a center in the circumferential direction of one of the arc-shaped long holes of the outermost one of the layers and the center axial line, and
• wherein, when the cylindrical roller is in contact with the separation roller, an abutting portion of an outer circumferential surface of the cylindrical roller warps to fit to an exterior shape of the separation roller, and the cylindrical roller rotates to a position at which a deformed one of the arc-shaped long holes deforms along a plane which passes through a center axial line of the separation roller, the center axial line of the cylindrical roller, a center in the circumferential direction of the deformed one of the arc-shaped long holes, and at least one of the spokes.