| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce false detection of diameter errors in an optical fiber as much as possible, and to reduce loss of the optical fiber due to unnecessary discarding. <P>SOLUTION: In the middle of a process for drawing the optical fiber 10, at least two outer-diameter-measuring devices 3A and 3B are placed at prescribed intervals in the drawing direction, and a control unit (judging means) 50 is installed. Each measuring device measures the outer diameter of the optical fiber, and the control unit retrieves signals D1 and D2 from the individual measuring device with a prescribed time difference and compares the signals. The control unit sets the prescribed time differenceΔt1 as the time required for a certain point on the drawn optical fiber to move between the measuring devices 3A and 3B, compares the signals retrieved from the individual measuring devices at the prescribed time difference and, when individual measuring devices output the same defect signals, judges that a diameter error may have occurred in the optical fiber. Meanwhile, when the individual measuring devices output the same defect signals with a time difference corresponding to the propagation speed of vibration, the signals are judged false detection caused by fiber oscillation, and the judgement that the diameter error has occurred is canceled. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
