A winding mechanism retains a sheet material in a state in which the sheet material
can be pulled out. The winding mechanism includes a flexible sheet material, a
winding shaft attached to one end of the sheet material, a force application device
that always applies a force to the winding shaft in a normal direction in which
the sheet material is wound around the winding shaft, and a braking device that
applies a braking force to the winding shaft only in the normal direction. In other
words, the winding mechanism applies an appropriate braking force to the winding
shaft when the sheet material is wound, but does not apply a braking force to the
winding shaft when the sheet material is pulled out.
