 Speaker
| 65 - Analysis of Static Thrust of a Voice Coil Motor |
Module:TR |
2011-01-17 |
| Coreless linear actuators are used for the head drive of electronic packaging
machines and precision stages, both of which require high accuracy positioning.
Static thrust has a great effect on accurate positioning, since it varies
with the translation position of an actuator. Also, static thrust varies
with the amount of current, so it is important to obtain the static thrust
at each supply current from the analysis. This note presents the use of
magnetic field analysis to obtain static thrust characteristics of a voice
coil motor at different translation positions and different supply currents. |
 | 9 - Sound Pressure Analysis of a Loudspeaker UP! | Module:DS,TR | 2012-04-10 | A loudspeaker produces sound when the voice coil makes the vibrator vibrate. The general requirement of the loudspeaker is to produce uniform sound over a wide range of the frequencies.
Lorentz force is generated in the coil when the magnetic field of a permanent magnet acts on the current flowing through the voice coil, and produces sound by making the vibrator vibrate. In order to evaluate the sound with good accuracy, it is necessary to handle the resonance phenomenon between the Lorentz force and the speaker's eigenmode properly. The eigenmode and Lorentz force distribution change depending on the place where the core and coil are wound, so high accuracy calculations need to be carried out using the finite element method (FEM).
This Application Note presents how the frequency characteristics of sound pressure can be obtained using the constant Lorenz force on the voice coil, regardless of the frequency.
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