Patent ID: 7859140
Filing Date: 2010-12-28
Classification: H02K

Abstract:
1. A permanent magnet member for a voice coil motor, the permanent magnet member being a planar permanent magnet member and comprising a magnet body and a corrosion-resistant film formed on a surface of the magnet body, the permanent magnet member having a top surface and a bottom surface opposing each other; wherein at least one of the top and bottom surfaces is formed with a recess in a thickness direction; and a deepest part in the recess and a tangent plane thereof have a distance of 5 to 75 μm therebetween, the permanent magnet member comprises a shorter periphery, a longer periphery located at a position separated from the shorter periphery by a predetermined distance, and a pair of side peripheries connecting the shorter and longer peripheries to each other, and has a fan-shaped planar form; the maximum value of a thickness of the permanent magnet member exists along a peripheral part comprising the shorter periphery, longer periphery, and side peripheries; and the minimum value of the thickness of the permanent magnet member exists in an area surrounded by the peripheral part.