| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To detect a drawing out amount or a winding amount of a seat belt with sufficient resolving power even in a seat belt device in which a motor and a spindle are not always connected. <P>SOLUTION: The retractor R for the seat belt is used, which includes a belt movement amount detection device B provided with a magnetic field variation means 1; a magnetic sensor 2 for detecting magnetic variation; and a rotation amount detection means 3 for receiving output of the magnetic sensor 2 and detecting a rotation amount of a spindle. The magnetic field variation means 1 is constituted such that a transmission part 1a for transmitting the magnetic field and a shielding part 1b for shielding the magnetic field are alternately provided on a circular disc 1c interlocked and rotated with rotation of the spindle for winding a belt in a circumferential direction. In the magnetic sensor 2, a permanent magnet 2a and a hall IC2b are arranged opposed to each other so as to clamp the magnetic field variation means. Since output current of the hall IC2b also becomes alternate output of size in response to rotation of the magnetic field variation means 1, a rotation amount of the belt can be accurately detected by counting the variation. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
