Abstract: A voice coil motor 2 using a Dual Halbach Magnet Array has an outer magnet array 5 and an inner magnet array 6, wherein the inner magnet array 6 comprises axially magnetized magnets 6A, 6C and 6E and radially magnetized magnets 6B and 6D. Each of the axially magnetized magnets 6A, 6C and 6E of an inner magnet array 6 is formed of a monolithic magnet having ring-shape, whereas each of the radially magnetized magnets 6B and 6D of the inner magnet array 6 is formed of a plurality of split magnets divided in a circumferential direction. A fixing means 13 is provided to fix the radially magnetized magnets 6B and 6D and the axially magnetized magnets 6A, 6C and 6E of the inner magnet array 6 in an axially clamped manner.

Abstract: A voice coil motor 2 using a Dual Halbach Magnet Array has an outer magnet array 5 and an inner magnet array 6, wherein the inner magnet array 6 comprises axially magnetized magnets 6A, 6C and 6E and radially magnetized magnets 6B and 6D. Each of the axially magnetized magnets 6A, 6C and 6E of an inner magnet array 6 is formed of a monolithic magnet having ring-shape, whereas each of the radially magnetized magnets 6B and 6D of the inner magnet array 6 is formed of a plurality of split magnets divided in a circumferential direction. A fixing means 13 is provided to fix the radially magnetized magnets 6B and 6D and the axially magnetized magnets 6A, 6C and 6E of the inner magnet array 6 in an axially clamped manner.

Abstract: An absolute type position sensor, preferably of the magnetostrictive line type, and a semi-absolute type position sensor, preferably of the magnetic induction type, are operated in parallel with each other, and their moving portions are connected to each other. Position information, obtained by the absolute type position sensor, which is outside the range of a single pitch distance for the semi-absolute position sensor, is corrected, in accordance with a detected value obtained by the semi-absolute type position sensor, by a predetermined logic. In this way accurate absolute measurements can be made over a long range of motion with extremely high accuracy.