| 摘要 |
Each element (A1, A2, A3, A4 ... An) in a stack of elements is connected to the adjacent element by two crossways-running hinge joints (G12, H12; G23; G34, H34 ...) in such a way that, between each two elements, two axes of rotation (e1 or c2 and f1 or d2; e2 or c3 and f2 or d3; ...) are defined along opposite edges of the elements. Each element can thus be turned optionally with respect to the neighbouring element about either one of the two mutually opposite axes of rotation so that the stack can be unfolded in two alternative ways. |
