| 摘要 |
PROBLEM TO BE SOLVED: To measure a sure lead-out length by correction even when axial play occurs in rotation of a reel and to suppress the axial play in rotation of the reel by circumferential contact. SOLUTION: A lead-out length of a string 7 wound around an annular recess 39 of a reel 33 is measured on the basis of detection of the amount of rotation of the reel 33. Ribs 34a and 34b project from the inner peripheral edge 33a and the outer peripheral edge 33b of the upper side 33c of the reel 33 shaped like a cylinder. A plurality of bodies 41 to be detected are disposed radially at equal intervals on the upper side 33c. Detecting bodies 42 disposed on an annular printed circuit board 32 retained on a main-body housing 31a with springs 35 interposed detect capacitances with the bodies 41 to be detected.
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