Paper creasing device and printer

A paper creasing device comprising:

• a receiving member that is configured to receive paper thereon, the receiving member comprising a groove extending in a longitudinal direction of the receiving member, wherein the longitudinal direction of the receiving member corresponds to a paper width direction of the paper;
• a rotary blade that is movable along the groove;
• and
• a movement mechanism that is configured to move the rotary blade along the groove at a fixed height in a range between first and second edges of the paper in the paper width direction of the paper, the paper being placed on an upper surface of the receiving member,
• wherein when the paper is creased, the paper is sandwiched between the rotary blade and the groove, and the receiving member is formed such that a shearing force applied to the paper during the creasing is smaller in an outside range than in an inside range in the longitudinal direction of the receiving member, the outside range corresponding to at least one of the first and second edges of the paper that is located on a side where the rotary blade starts contacting the paper when the rotary blade moves along the groove,
• wherein the groove comprises a first groove width in the outside range and a second groove width in the inside range in the longitudinal direction of the receiving member, and
• wherein the first groove width is wider than the second groove width in a groove width direction of the groove, the groove width direction being perpendicular to the longitudinal direction of the receiving member.