| 摘要 |
PROBLEM TO BE SOLVED: To provide a brushless linear motor having a small detecting error of a speed even when a distance between a permanent magnet and a magnetic sensor is changed. SOLUTION: A movable element 2 has permanent magnets 21 arranged along an advancing direction so that a plurality of poles alternately become heteropolar. A stator 1 has a plurality of oils 11 opposed to the poles of the element 2 and arranged along the advancing direction of the element 2. Positions of the poles of the element 2 are detected by magnetic sensors 31. Timing of energizing the coils 11 is controlled in response to the position of the element 2 detected by the sensor 31. A time interval of a change point of the polarity of the pole of the magnet 21 provided at the element 2 to be detected by the sensor 31 is obtained. The moving speed of the element 2 is obtained by dividing the mean value of the time intervals of every continuous even number of magnets 21 by the distance of the adjacent poles. |
