| 摘要 |
The frame is used mainly for furniture which folds flat without dismantling and for this purpose has four joints the axles of which are parallel to each other. They cut with theoretical straight line extension a projection plane vertical to the axle direction in four fixed points. The square or triangle formed by the four fixed notional point (A,B,C,D) is constructed to ensure that any two sides adjoining at a notional point (a, b, or b, c, or c, d or d, a) are of different length and that the sum (a+c or b+d) of the length of two sides lying opposite to each other are equal for both pairs of these sides. |
