| 摘要 |
PROBLEM TO BE SOLVED: To improve measuring accuracy for a transition in a surface velocity.SOLUTION: A velocity transition measuring device comprises: a laser driver 4 oscillating a semiconductor laser 1; a calculation unit 7 calculating a run length of a binary signal obtained by binarizing an interference waveform contained in an output from a photodiode 2 converting an output from the semiconductor laser 1 to an electric signal; and an arithmetic unit 8 computing a transition in a surface velocity of a web 11 from a calculation result of the calculation unit 7. The calculation unit 7 binarizes the interference waveform synchronously with a sampling clock, measures the run length of the binary signal in each of a reference period and a comparison period, creates a run length frequency distribution for each of the reference period and the comparison period, and calculates a total number of run lengths equal to or higher than a threshold Th for each of the reference period and the comparison period from the frequency distribution. |
