Patent ID: 6923398

Claim:
A winding mechanism comprising: a 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, wherein the braking device comprises: an inner revolution member that is attached to the winding shaft and rotatable in unison with rotations of the winding shaft, the inner revolution member including concave sections that recede toward a center rotation; an outer revolution member that is rotatable and generally encircles the inner revolution member, the outer revolution member defining an inner wall section that is provided with an arcuate rack section; planetary gear members that are stored in the concave sections of the inner revolution member and engage the arcuate rack section; a case member that stores the outer revolution member; and a viscous fluid that fills a gap formed between the outer revolution member and the case member, wherein rotations of the planetary gears are restricted when the inner revolution member is rotated in the normal direction by rotations of the winding shaft in the normal direction.