| 摘要 |
PROBLEM TO BE SOLVED: To make a rotary shaft light and preventing it from being deformed by providing a driving shaft where the rotary shaft is put through inside so as to be rotatable, rotating the rotary shaft by means of the motor of an erecting device and erecting a bottom to be the rotary center of the rotary shaft. SOLUTION: The driving shaft constituting the erecting device is arranged in a center part in an axial direction of the rotary shaft 10 of a back bottom 1. Then, the driving shaft 20 is a large diameter circular pipe with respect to the rotary shaft 10, the rotary shaft 10 is put through its inside so as to be freely rotatable and the both play ends of the arm 21 of the erecting device are integratedly welded. The rotary shafts 10 of parts positioned on the both sides of the driving shaft 20 are supported at a bed frame 4 side with a bracket so as to be freely rotatable. Thus, when the back bottom 1 is erected, the back bottom 1 is rotated with the rotary shaft 10 as a rotary center. Therefore, loading such as the weight, etc., of the upper half body of a user is added to the rotary shafts 10 and concentrated on the center part of the rotary shaft 10 as bending loading. But, the center part of the rotary shafts 10 are reinforced by the driving shaft 20 so that deformation, etc., does not occur. |
