Patent ID: 8231529

Claim:
An arm structure comprising: a support member in which a longitudinal insertion hole through which a support post is inserted longitudinally, a slit portion communicating with the longitudinal insertion hole for an entire length, and a lateral insertion hole penetrating said support member laterally through the slit portion are formed; a shaft member inserted through the lateral insertion hole of said support member; at least one bar-shaped arm inserted through an insertion hole formed in said shaft member; and a cam provided in said arm, said cam being slidable in a long side direction of said arm and revolving integrally with said arm, wherein it is constituted so that by turning said arm around its axis thereby to make said cam revolve, the slit portion of said support member is narrowed thereby to diameter-reduce the longitudinal insertion hole, leading to restriction of rotation of said arm around the support post, and restriction of sliding of said arm in the long side direction of said arm and of rotation of said arm by said shaft member.