| 摘要 |
A joint unit comprises a lock mechanism L in which a ball-like joint section 14 provided at the base end of an arm 13 is housed in a holder 12 formed at an end of a cylindrical case 10. As the joint section 14 is brought into pressed contact against an inner surface 12S of the holder, the lock mechanism L locks a pivotal angle. In the lock mechanism L, in response to a manual operation of a knob 19, a bolt 18 is caused to project into the case 10 and this pressing force is transmitted to a roller-like first pressing body 21 and then to a second pressing body 22 placed in contact therewith. Further, the pressing force from the first pressing body 21 is transmitted to a pressure block 16 and then the pressing force from this pressure block 16 brings the joint section 14 into pressed contact against the holder inner surface 12S. |
