Device for locking and unlocking and automotive vehicle seat with such a device

An automotive seat has a backrest that inclines back and forward and is locked at a selected angle by a locking hook operating in conjunction with a sliding bolt. The hook rotates between an unlocked position and a locked position. The mechanism incorporates a signaling device that gives or receives a mechanical signal. The signaling device is linked in parallel and operates in conjunction with the cam to give an indication of the locked/unlocked seat back. In a further embodiment the locking/unlocking mechanism may be coupled to further devices e.g. overriding locking mechanism or light indicator.