Moving iron element; finite element analysis; internal components; cavity structure; acoustic performance.
In recent years, with the rapid development of the earphone industry, music lovers have higher and higher requirements for the sound quality of earphones, so simple dynamic earphones can no longer meet the demand. As a result, running-wireless-earbuds-bluetooth-for-sports-earbuds-bluetooth-5-0-product/”>headphones with moving coil and moving iron have increasingly entered the field of vision of music lovers. The thick mid-bass of the moving coil unit and the clear and bright treble of the moving iron unit have gradually become a perfect combination.
The moving coil unit is relatively mature at present, but most people know little about the moving iron unit. Therefore, this paper introduces the internal structure and working principle of the moving iron unit in detail, and through the finite element analysis, let you deeply understand the design focus of the moving iron unit. Through this article, not only beginners can understand the moving iron unit, but also the designer of the moving iron unit can shorten the design cycle and reduce the design cost through finite element simulation.
1 Internal structure of moving iron unit
Figure 1 is the internal structure of the moving iron unit. It can be seen from the figure that the internal components are: upper cover, lower cover, PCB, diaphragm, voice coil, square iron, magnet, armature and driving rod. There is a sound hole on the side of the upper cover, and the position of the sound hole will change with the actual sound output position after the earphone is installed. Generally, the upper cover is made of metal material; the lower cover is used to fix the square iron, and the general material is metal material. It is sealed with the upper cover; there are two solder joints on the PCB for welding the headphone cable; the edge of the diaphragm is generally made of TPU material with good elasticity, and the middle is made of metal material; the material of the voice coil is copper wire, in order to improve high frequency, it can also be plated with Silver wire; square iron material is generally nickel-iron alloy; magnet material is generally Alnico; armature and driving rod are generally nickel-iron alloy.
2 The working principle of the moving iron unit
The working principle of the moving iron unit: when the voice coil has no signal input, the shrapnel maintains a balanced state in the magnetic field. When the electric signal is sent to the voice coil, the armature will be magnetic and vibrate up and down in the magnetic field, thereby driving the driving rod through the driving rod. The diaphragm vibrates to make a sound. The U-shaped armature of the moving iron unit is similar to a lever structure, one end is fixed on the square iron, and the other end is suspended and connected to the driving rod. Therefore, a slight movement of the armature in the magnetic field will amplify at the end, and then the amplified signal will be transmitted to the diaphragm, which is the reason for the higher sensitivity of the moving iron unit.
3 Finite element analysis of moving iron unit
Since the main advantage of the moving iron unit is high frequency, this paper takes the treble moving iron unit as the model for analysis. Due to the small size of the moving iron unit, it has high requirements for material accuracy. In order to more accurately and effectively analyze the influence of the main components of the moving iron and the cavity on the acoustic performance, through the finite element analysis, by entering the 3D model of the moving iron unit, the input material properties, perform modal analysis, and simulate the frequency response curve. Figure 2 is the simulation model of the moving iron unit.
Post time: Aug-16-2022
