Writing instrument

A thermochromic ink writing instrument comprising a body extending along an axis, the body having a first end and a second end opposed to the first end along the axis, the first end being provided with a writing tip and with an eraser, wherein the writing tip is fed with thermochromic ink, wherein the writing tip is fixed with regard to the body and the eraser is movable along the axis with regard to the body, and the thermochromic ink writing instrument further comprises a helical-cam propelling mechanism configured to move the eraser along the axis between a retracted position and a protruding position, wherein the helical-cam propelling mechanism includes a first part and a second part, and wherein the thermochromic ink writing instrument further comprises a return spring configured to axially push the eraser toward the first part.

A thermochromic ink writing instrument comprising a body extending along an axis, the body having a first end and a second end opposed to the first end along the axis, the first end being provided with a writing tip and with an eraser, wherein the writing tip is fed with thermochromic ink, wherein the writing tip is fixed with regard to the body and the eraser is movable along the axis with regard to the body, and the thermochromic ink writing instrument further comprises a helical-cam propelling mechanism configured to move the eraser along the axis between a retracted position and a protruding position, wherein the helical-cam propelling mechanism includes a first part and a second part, wherein the thermochromic ink writing instrument further comprises a writing body having the writing tip, wherein the first part is hollow, a support extends inside the first part and is axially coupled with the second part, and the support supports and restricts a movement of the writing body.