US Patent 7922342 Rotational member of projector with improved retention

A rotational member inhibitable from coming off a support member is obtained. This rotational member includes a rotational portion rotatably mounted on a support member, a pair of arcuate portions provided on a side of the rotational portion closer to the support member to extend from the rotational portion and opposed to each other and a hook portion so provided as to extend from a circumferential end of at least one of the pair of arcuate portions in an outward direction intersecting with a mounting direction for the rotational portion for engaging with the support member.