The signals cause fluctuations in the opposing magnetic forces between the magnet and the coil, making it move back and forth through the attached diagram.
What matters is that the material can create a magnetic field strong enough tho move they could. You can learn about speaker magnet strength here.
If not, move on to the deeper explanation below. As we already explained, magnetic speakers are made up of a permanent magnet and a magnet created by the coil as current goes through it it is essentially an electromagnet.
These magnets work as a pair and interact with each other as two physical magnets would do. The electromagnet is put in a magnetic field created by the physical magnet and as each produces its own magnetic fields, they oppose each other.
Just like two normal speakers, the positive pole of the permanent magnet attracts the negative pole of the electromagnet. On the other hand, the negative pole of the permanent magnet repels the negative pole of the electromagnet and causes a shift in the magnetic forces hitting the voice coil. The direction of the attraction and repulsion changes with the shift in the polar orientation of the electromagnet.
When the polar orientation switches, the alternating electric signal constantly pushes back the magnetic force between the permanent magnet and the voice coil.
This makes the coil rapidly vibrate back and forth, making the speaker cone move in different patterns. The coil movement then creates vibrations in the air, resulting in audio signals sound is nothing but vibrating air. The strength and frequency of the magnetic forces determine the distance and rate that the voice coils move.
In other words, the magnetic forces regulate the vibrations created by the diaphragm. So how does the fluctuation make the speaker coil move back and forth? The electromagnet is positioned in a constant magnetic field created by a permanent magnet. These two magnets -- the electromagnet and the permanent magnet -- interact with each other as any two magnets do. The positive end of the electromagnet is attracted to the negative pole of the permanent magnetic field, and the negative pole of the electromagnet is repelled by the permanent magnet's negative pole.
When the electromagnet's polar orientation switches, so does the direction of repulsion and attraction. In this way, the alternating current constantly reverses the magnetic forces between the voice coil and the permanent magnet. This pushes the coil back and forth rapidly, like a piston. When the coil moves, it pushes and pulls on the speaker cone. This vibrates the air in front of the speaker, creating sound waves.
While one electromagnet is fixed, the other one is placed on a movable membrane. The fixed electromagnet plays the role which permanent magnets do in ordinary speakers. Both the coils are placed in close proximity to each other. They are excited by a common source signal like a common amplifier. Electromagnetic fields are created by the coils upon excitation. The magnetic fields created by the coils cause mutual interaction between them.
It causes the coils to alternately attract and repel one another. One of the coils receives an excitation signal directly from the source. While the other coil receives the source signal in an indirect way, preferable via a bridge rectifier. The coils may be in the form of conventional wound wires. Or it can be formed on a printed circuit board in the form of flat spirals. The resulting speaker is very lightweight. It is well suited for use in cars, aeroplanes, and other optimizations in which weight minimization is important.
There are other speakers which do not use magnets at all. For instance, Piezo speakers. Piezo speakers use the piezoelectric effect. They are similar to the above-mentioned process. They generate mechanical vibration by applying an electrical signal to a piezoelectric crystal. Buzzers in wristwatches generally use piezo speakers. Magnets are used to make an opposing magnetic field which creates vibrations. This makes the cone or panel of the speaker move. The vibrations are the sounds we hear.
As a convention, speakers generally contain large magnets inside of them. Bigger magnet means more vibrations. Because a larger magnet would imply stronger opposing magnetic field leading to more vibrations.
There are many other factors which are involved. This is especially true with the growing popularity of super lightweight and powerful magnets. These magnets are generally made of neodymium.
As we have already seen, neodymium magnets are really powerful although they are small and lightweight. In this segment we saw the role of magnets in speakers. We saw that the sound is produced by the interaction of two magnetic fields.
At least one of the two magnetic fields is the result of an electromagnet. To convert an electrical signal to an audible sound, speakers contain an electromagnet. It is a metal coil which creates a magnetic field when an electric current flows through it. The electrified coil has the properties of a normal permanent magnet. There is, however, one particularly handy property. When the direction of the current in the coil is reversed, the poles in the magnet gets flipped.
This electromagnet reacts with the permanent magnet in the speakers. In speakers, where the manufacturer avoids installing a permanent magnet, a second electromagnet take its place. Inside the speaker, the electromagnet is placed in front of the permanent magnet.
The permanent magnet is placed in a compact and fixed position whereas the electromagnet is mobile. As currents of electricity pass through the coil of the electromagnet, the direction of its magnetic field changes rapidly.
This means that it is attracted to and repelled from the permanent magnet rapidly in alternate turns, vibrating back and forth. These vibrations lead to sound produced in speakers.
Conventionally the size of the magnet influences the quality of sound. However, with neodymium magnets, we have lighter magnets which are powerful in quality. Also we saw that mostly magnets in speakers are round.
0コメント