Patent ID: 7963420

Claim:
A case, comprising: a shaft disposed at either one of a cover or a case body; a shaft inserting portion substantially equal in length to the shaft and disposed at the other of said cover or case body, said shaft being inserted into the shaft inserting portion such that the cover turns with respect to the case body to open the case; and urging means for urging the cover in an opening direction, a viscous material being disposed between an outer peripheral surface of the shaft and an inner circumferential surface of the shaft inserting portion such that the cover is slowly opened with respect to the case body, wherein an engaging projection is disposed at said shaft inserting portion and an engaged recess engageable with said engaging projection is disposed at said shaft to enlarge a contact area between said shaft and the shaft inserting portion via the viscous material, and said viscous material is disposed between an outer peripheral surface of said engaging projection and an inner circumferential surface of said engaged recess to be turned on the axis with respect to said engaging projection.