| 摘要 |
PURPOSE:To enable the spacing between the tow positions of a line setting member to be alternately changed between two values by a simple structure by rotating through a prescribed angle pulley provided with a line setting member mounting portion in a position with a prescribed distance of eccentricity from a rotational center by the rotation of a frame provided with a reference line setting member mounting portion. CONSTITUTION:A reference line setting member mounting portion is formed in a suitable position or set in an imaginary position and a normally and reversedly rotatable frame 12 is provided. A pulley 9 is provided which is equipped with a line setting member mounting portion having parallel axes arranged on the same plane at constant pitches from a reference axis passing the reference mounting portion as rotational centers and disposed in a position with a prescribed distance of eccentricity from the rotational centers by Xalpha/2 at X'th pitch in + (plus) direction and by -X'/2 in - (minus) direction both along the plane. The normal and reverse rotation of the frame 12 within the range of a prescribed angle theta rotates the pulley 9 through an angle (180 deg.-theta) in the reverse direction to the frame 12 to change the spacing between the two positions of line setting by a distance alpha.
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