| 摘要 |
PROBLEM TO BE SOLVED: To enable adjusting an initial posture (initial angle) of a backrest while appropriately securing a lumbar support function.SOLUTION: A backrest 4 has a back inner shell 18, and the back inner shell 18 is connected to a back support 14 so as to rotate around both right and left ends of a lumbar support part 22. The lower end of the back inner shell 18 is connected to a back frame 13 through an initial angle adjusting device 15. A pin-like lock pin of an operation tool 40 is penetrated into the lower end of the back inner shell 18, and the initial posture of the backrest 4 is gradually changed by changing the support position of the lock pin. Since the longitudinal position of the lumbar support part 22 is not changed by changing the initial posture of the backrest 4, a sense of pressure and support deficiency with the change of the initial posture are not generated.SELECTED DRAWING: Figure 9 |
