Voice coil motors are a special form of linear motion motor, and also famous for its working principle which similar to the loudspeaker. Voice coil motor has a simple structure, low volume and noise, in the meanwhile, its specific thrust, acceleration, response speed and accuracy are also excellent. Besides, voice coil motor is also reliable and easy to maintain. Therefore, voice coil motors are widely applied to hard disk drive (HDD), optical disk drive (ODD), scanner, lens focusing, laser cutting, vibrating motor of mobile phone, medical equipment and spaceflight apparatus. Even to this day, a great deal of Neodymium magnets is still serving as voice coil motor magnets which utilized as servo drive of seeking and focusing mechanism in hard disk drive (HDD) and the optical disk drive (ODD)

Working Principle of Voice Coil Motor

According to Ampere’s force law, force F suffered by current-carrying wires in the magnetic field is determined by magnetic induction B, current I and included angle θ between magnetic field and current direction. When the length of current-carrying wire and magnetic induction being kept constant, the force is directly proportional to the current, and voice coil motor is right based on this principle. Place a conducting coil into the magnetic field, and magnetic conduction cylinder which inside the coil and external permanent magnets will form a magnetic circuit. Coil will be subjected to the magnetic field after energized the coil, therefore generate an axial force on the coil. It should be noted that the direction of force is affected by the current direction in coil.

About Voice Coil Motor Magnets

The magnetization pattern of ring-shaped voice coil motor magnets in cylindrical voice motor should via radial direction, and most of them are built by several pieces of diametrically magnetized arc magnet. By comparison with arc magnet array, radially oriented ring magnets will exhibit more uniformly distribution in the magnetic field.

SDM team can not only provide sintered radially oriented magnet, but also manufacture hot-pressed/hot-deformed magnets which have more superior magnetic field distribution and consistency.