Patent attributes
A rotation shaft assembly includes a pivot assembly including a common rotation shaft, and a lock member, a first connection member, a second connection member, and a third connection member disposed at the common rotation shaft. The first connection member, the second connection member, and the third connection member are configured to be connected to a first member, a second member, and a third member, respectively. The lock member has a locked state that enables the first connection member and the second connection member to rotate synchronously, and an unlocked state that enables the first connection member and the second connection member to rotate independently with respect to each other.