1. Field of the Invention
The present invention relates to a seat belt system which is provided with a take-up apparatus for taking up a webbing to be placed around an occupant of an automobile in the form of layers around a take-up shaft.
2. Description of Prior Art
A seat belt system mounted in an automobile is provided with a take-up apparatus which takes up one end of the webbing that is used to secure an occupant and stores the webbing in the form of layers around a take-up shaft so that the occupant can pull the webbing out of the take-up apparatus and place the webbing.
Such a take-up apparatus is provided with an inertia lock mechanism which stops the webbing from being pulled out during emergency by inhibiting the rotation of the take-up shaft in the direction of pulling out of the webbing. Thus, the occupant is secured by the webbing at the time of a vehicle emergency.
However, when the rotation of the take-up shaft in the direction of pulling out of the webbing is inhibited during an emergency in this way, a high degree of tension is then applied to the webbing due to the inertia force of the occupant, and thus tightening occurs in the roll of webbing wound around the take-up shaft in layers. This causes the webbing to be pulled out from the take-up shaft even after the rotation of the take-up shaft in the direction of pulling out of the webbing has been inhibited.