How the speaker works

How the speaker works

1. Magnetic speaker

There is an electromagnet with a movable iron core between the two poles of the permanent magnet. When there is no current in the coil of the electromagnet, the movable iron core is attracted by the two magnetic poles of the permanent magnet and remains stationary in the center; when there is current flow in the coil Obsolete, the movable iron core is magnetized and becomes a bar magnet.

As the direction of the current changes, the polarity of the bar magnet changes accordingly, causing the movable iron core to rotate around the fulcrum, and the vibration of the movable iron core is transmitted from the cantilever to the diaphragm (paper cone) to promote air thermal vibration.

2. Electrostatic speaker

It is a loudspeaker that uses the electrostatic force applied to the plate of a capacitor to work. In terms of its structure, the positive and negative poles face each other to form a capacitor shape, so it is also called a capacitive speaker.

Two thick and hard materials are used as fixed pole plates, which can transmit sound, and the middle pole plate uses a thin and light material as a diaphragm (such as aluminum film). Fix and tighten the periphery of the diaphragm to keep a considerable distance from the fixed pole. Even on the large diaphragm, it will not collide with the fixed pole.

3. Piezo speakers

A speaker that uses the inverse piezoelectric effect of piezoelectric materials to work is called a piezoelectric speaker. The phenomenon in which dielectrics (such as quartz, potassium sodium tartrate and other crystals) are polarized under pressure to cause a potential difference between the two ends of the surface is called the "piezoelectric effect." Its inverse effect, that is, the elastic deformation of the dielectric medium placed in the electric field, is called the "reverse piezoelectric effect" or "electrostriction".

4. Ion speaker

Under normal conditions, the molecular weight of air is neutral and uncharged. But after high-voltage discharge, they become charged particles. This phenomenon is called ionization. The ionized air is vibrated by audio voltage to generate sound waves, which is the principle of ion speakers.

5. Flame speaker

When the flame of air and gas burning passes through the electrode, the electrode is applied with a DC voltage and a high-frequency signal, and the flame is modulated by the audio signal to make a sound. The flame has almost no quality and the sound dynamics are better. But it has fatal shortcomings: unsafe and inconvenient