| 摘要 |
PROBLEM TO BE SOLVED: To prevent a member to be supported from being suddenly jumped up by the reaction force of a reaction force applying mechanism at the time of unlocking operation and to facilitate assembling. SOLUTION: This lock mechanism comprises plural lock holes 7 formed in a back support lever and positioned on the same radius with respect to a turning shaft, a lock member 8 fitted to be slid in the direction of going in and out of the lock holes 7 to lock tilting of the back support lever 5, a switching means 9 for pressing the lock member 8 to be kept in the state of fitting in the lock hole 7 when it is in the locking position and separating from the lock hole 7 to force the lock member 8 to be slid when in the unlocking position, a position holding means capable of holding the switching means 9 in the unlock position, an unlock energizing means 10 for elastically energizing the lock member 8 to be pulled out of the lock hole 7, and a lock energizing means 11 for elastically energizing the switching means 9 toward the lock positon more strongly than the unlock energizing means 10. Then, the mechanism is operated by an operating lever near the seat.
|
