Tapered Magnet Voice Coil Motor
Original Publication Date: 1980-Jun-01
Included in the Prior Art Database: 2005-Feb-13
Presently used alnico magnets are magnetized after the whole magnetic circuit is assembled. Rare earth or ceramic magnets are usually magnetized by the magnet manufacturer and shipped to the user in the magnetized state. The use of these high coercivity magnets complicates the design and assembly of the magnetic circuit. Two basic rare earth magnet configurations are shown in Figs. 1 and 2. The magnet length (1) is constant; that is the two large surfaces are parallel to each other. A typical voice coil motor (VCM) assembly is shown in Fig. 3. B 1I is very difficult to control dimensions A, B, and C to the extent that there are no air gaps after assembly. This would result in loss of magnetic flux in the working gap, due to higher reluctance of the magnetic circuit.