| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a seat belt device for a vehicle that can accurately detect a failure in a circuit for controlling an electric motor and driving of the motor. <P>SOLUTION: A microcomputer 40 rotates an electric motor 20 normally in an emergency for winding up a seat belt 12 to protect an occupant. In the rotation control for the electric motor 20, the microcomputer 40 determines a duty ratio based on a value of the current that flows in the motor 20 that has been detected by a current detection resistance 35 and controls switching elements SW1 to SW4 in a bridge circuit 30 to turn on/off by a pulse train signal with the determined duty ratio. Immediately after an ignition switch is turned on, the microcomputer 40 rotates the motor 20 reversely by the duty control and determines a failure in a current detection circuit including the current detection resistance 35 when the duty ratio is not in a predetermined range. <P>COPYRIGHT: (C)2004,JPO&NCIPI</p> |
