| 摘要 |
PROBLEM TO BE SOLVED: To provide the cam curve which can not only lessen starting load but also enlarge the movable range of a slave body in a limited development length. SOLUTION: The movement of a slave pin 24 is regulated accordingly by a cam curve 20, the slave pin stands still at three point (tele, middle and wide) set over the cam curve 20 so as to allow positioning to be performed. The slave pin 24 starts relatively moving in accordance with a cam groove 22 while making each stay point as a starting point. Starting load at the wide point W can be lowered by forming the starting inclined angleθ2 of the cam curve at the wide point W where static friction force is applied, smaller than an inclined angleθ2 ' at the middle of the cam curve connecting the wide point W with a middle point M (θ2 <θ2 '), and the specified quantity of movement required between the wide point W and the middle point M can thereby be secured. Besides, since starting load has been reduced, a small energy saving motor can thereby be used.
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