PURPOSE: To attain volume saving and ease of assembling by providing a mechanism folding two vertically divided reflection mirrors toward the reflecting face side and a mechanism limiting the folding angle and fixing the angle.

CONSTITUTION: Reflection mirrors 1a, 1b are divided and folded into an upper reflection mirror 1a and a lower reflection mirror 1b around a turning support 11 by loosening the joint bolt of the split face and a lock mechanism of a supporting rod 2 limit a folding angle. Then a primary radiator supporting base 7 is fixed by loosening the lock mechanism constituted with a primary radiator support 5 and a supporting rod 6 and folding the support 7 around a turning support 13 to tighten the lock mechanism of the support 6. In this case, the folded reflection mirror 1 is supported with buffer by a buffer mechanism 12 at the tip of the supporting base 7 and fixed stable while keeping a prescribed folded angle by operating the lock mechanism at folding of the supporting rod 2.