| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a permanent electromagnetic chuck capable of easily adjusting a force for attracting a loaded article. Ž<P>SOLUTION: This permanent electromagnetic chuck includes a rectifying circuit 30 which has a coil 14 and a permanent magnet and rectifies all waves of an alternating current and outputs the rectified current without smoothening, a polarity switching circuit 32 which synchronizes with the frequency of the alternating current and switches the direction of a direct current which flowing to the coil 14, a rectifying circuit drive circuit 34 which receives the pulse signals synchronized with the frequency of the alternating current and drives the rectifying circuit 30, and a control unit 36 for controlling the polarity switching circuit 32 and the rectifying circuit drive circuit 34. The control unit 36 switches the electrifying direction by the polarity switching circuit 32 so that an opposing magnetic force occurs in the coil 14 against the magnetic force of a loading surface on which the maximum suction force is generated in synchronism with the frequency of the alternating current, transmits a predetermined quantity of pulse signals synchronized with the frequency of the alternating current to the rectifying circuit drive circuit 32, flows a direct current corresponding to the pulse signals to the coil 14, and de-energizes the magnetic force of the loading surface to adjust to adjust to a desired suction force. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
