| 摘要 |
<P>PROBLEM TO BE SOLVED: To enhance the follow-up performance of a foot board for a foot. <P>SOLUTION: A coil spring 16 has a lower end fixed to a base part of a base 10 and has an upper end fixed to a lower surface of a foot board 20 to elastically hold the foot board 20 at an initial position. The coil spring 16 is conical to have a larger outside diameter on the side nearer to the lower end, and the coil spring has an ineffective range extended from the lower end side to shorten an effective range as being compressed. Within a pivotal range from the initial position to an upper limit position of the foot board 20, the coil spring 16 is released to give the foot board 20 an urging force with linear characteristics toward the initial position direction. Meanwhile, within a pivotal range from the initial position to a lower limit position, the coil spring 16 is compressed to give the foot board 20 an urging force with linear characteristics toward the initial position direction in a range from the initial position to an intermediate position and to give the foot board 20 an urging force with nonlinear characteristics toward the initial position direction in a range from the intermediate position to the lower limit position. <P>COPYRIGHT: (C)2012,JPO&INPIT |
