Patent ID: 7825789

Claim:
A system for detecting whether a seat belt is worn, comprising: a contact type sensor and a non-contact type sensor installed in a seat belt buckle, wherein the contact type sensor is supplied with power from a vehicle battery even when an ignition key is on; a Body Control Module (BCM) for receiving a signal from the contact type sensor and transmitting the signal to a cluster; an airbag control unit for receiving a signal from the non-contact type sensor; and a seat belt control unit for receiving the signals from the cluster and the airbag control unit, and determining whether the seat belt is worn using the signal received from the cluster when an ignition key is off, and determining whether the seat belt is worn, using the signal received from the airbag control unit when the ignition key is on; wherein the seat belt control unit is configured to perform at least a slack removal function if it is determined that the seat belt is worn when the ignition key is on, and perform at least a parking function if it is determined that the seat belt is not worn when the ignition key is off, and wherein the seat belt control unit, after the ignition key is off, considers the signal received from the contact type sensor to be an error and ignores the signal of the contact type sensor, when final signals detected by the contact type sensor and the non-contact type sensor, respectively, before the ignition key is off, are different from each other.