Patent attributes
Upper support portions 4 are respectively provided at respective upper end sections of a pair of support columns 1, 1′ such that the position of the upper support portions can be adjusted in an up-down direction. Lower support portions 5 are respectively provided at respective lower end sections of a pair of support columns 1, 1′ such that the position of the lower support portions can be adjusted in an up-down direction. A pair of wires 13, 13 is provided to extend between the lower support portion 5 and the upper support portion 4 of the support column 1. Another pair of wires 13, 13 is provided to extend between the lower support portion 5 and the upper support portion 4 of the support column 1′.