Speaker working principle

Electrodynamic loudspeaker, also known as the moving coil loudspeaker; it is using the electric principle of electro acoustic transducer; it is currently use most, the most extensive speaker, the reason mainly three:
1. electric loudspeaker, structure is simple, the manufacture is easy, and oneself do not need a large space, leading to price cheap, can be a lot of popularity.

2.This type of loudspeaker can be done with good performance, and the frequency response can be obtained in the medium frequency band.

3.In the continuous improvement of this type of speakers, the development history of speakers for decades, is the speaker design, technology, materials, continuous improvement of the history, but also the performance of the history of the times.

    Most of the shape of the electric loudspeaker is a conical, spherical dome; a conical speaker (speaker cone).

The structure can be divided into three parts:

    1>The vibration system comprises a diaphragm, a voice coil, the damper, dust cover, etc.;

    2>The magnetic circuit system includes a guide plate, a guide plate, a guide plate, a magnet, etc.;

    3>The auxiliary system comprises a frame, blank holder, wire rack, phase turunda.

    According to Faraday's law, when the current carrying conductor through a magnetic field, by an electro dynamic and its direction with Fleming's left hand rule, force and current, magnetic field direction perpendicular to each other, by force and current, wire length, magnetic flux density is proportional to. When the voice coil input AC current, the voice coil is subjected to an alternating driving force to produce alternating movement, driven by the paper basin vibration, repeatedly push air and sound.

    The force that causes the vibration of the electric loudspeaker to vibrate, that is, the magnetic field on the current carrying conductor, which we call the force effect of the electric transducer, the size of which is determined by the following formula:

    F=B L i

    Type: B for the magnetic gap of the magnetic induction density (intensity), the unit for N / (A.m) < Newton >, also known as Tesla (T)

    L For voice coil wire length, unit: meter

    I for the current flowing through the voice coil unit: Ampere

    F for the magnetic field on the voice coil of the force, the unit: Newton

    However, in electronic music scene by the force of the movement at the same time, due to cut magnetic gap of the magnetic line of force to generate induced electromotive force in the voice coil, the effect we call it for electrodynamic transducer electrical effects, the size of the induced electromotive force:

    е=Вiν

    In the formula: V is the vibration speed of the voice coil, the unit is: M / S

    By induction coil EMF, unit: v

    The electric power effect and the electric effect are simultaneously present, accompanied by the same.

Other speakers working principle:

〈1〉Magnetic loudspeaker: also known as reed Speaker its structure as shown in Figure 4, in the permanent magnet poles between a movable iron core of the electromagnet, when no current in the coil of the electromagnet, permanent magnets, magnetic poles level attraction attraction by the movable iron core, in the central remain stationary; when in the current flowing through the coil, a movable core is magnetized, and become a bar magnet. With the change of the direction of the current, the polarity of the bar magnet changes, so that the movable core can rotate around the fulcrum, the vibration of the movable core is transmitted by the cantilever to the vibrating film (paper basin).

〈2〉Electrostatic loudspeaker: it is by added to the capacitor plate on the static electricity and the speaker, the structure, a capacitor like from the positive and negative electrodes are opposite, so it is also called as condenser loudspeaker. As shown in figure, there are two thick and hard materials as a fixed plate, the plate can be through the sound, the middle of a plate with a thin and light material for vibrating film (such as aluminum film). Will diaphragm fixed around, taut and with fixed pole to maintain a considerable distance, even in the large diaphragm on, nor cause the collision with the fixed pole.

    A DC voltage (called bias) between two electrodes. If the two electrodes are coupled with the output voltage of the amplifier, the output voltage is overlapped to form an alternating current, which is caused by the change of the attraction of the poles.

    The advantages of the electrostatic speaker is the whole vibration film in phase vibration, the film is light, distortion is small, it can replay the very crisp sound, has a very good analytical, detail, sound fidelity. Its disadvantages are low efficiency, high voltage DC power supply, easy to vacuum, the vibration film will increase the distortion will increase, not suitable for listening to rock, heavy metal music, the price is relatively expensive some.

〈3〉Piezoelectric speaker: the use of piezoelectric materials for the inverse piezoelectric effect and the work of the speaker called the piezoelectric speaker. Dielectric (such as quartz and sodium potassium tartrate crystal) under the pressure of polarization potential difference between the two surfaces of the phenomenon, known as the pressure electric effect. Its inverse effect, that is, in the electric field of the dielectric will occur elastic deformation, known as the inverse piezoelectric effect or.

    Compared with the electric type loudspeaker, the piezoelectric speaker does not need the magnetic circuit, and compared with the static electricity, the structure is simple and the price is cheap, but the disadvantage is that the distortion is large and the work is not stable.

〈4〉Ion speakers: in general, the molecular weight of the air is neutral, not charged. But after high pressure discharge, it becomes a charged particle, which is called free. The principle of a sound wave, which is the principle of the ion speakers, is generated by the use of the free air in the audio frequency.

    In order to be ionized, the high frequency voltage of 20MHz is to be added, and the signal voltage is overlapped on it. Visible, ion loudspeaker is composed of high-frequency oscillation, modulated audio signal, discharge cavity and horn composition.

    Discharge cavity with the diameter of 8mm quartz rod in the center hole, into a quartz tube, an electrode inserted in, another electrode is shown, a cylindrical sleeve in a quartz tube outside, due to the adoption of the silent discharge form, only the center of the needle electrode lossy can be replaced regularly the center electrode. The difference between the ion speakers and other speakers is that there is no film, so the transient and high frequency characteristics are good, but the structure is too complex.

〈5〉Flame Speaker: when the air and gas burning flame through the electrode, the electrode with a DC voltage and high frequency signal, the flame is modulated by the audio signal and sound. The flame is almost no mass, and the sound is very dynamic. But it has a fatal flaw: it's not safe, inconvenient.

〈6〉Air modulated Speaker: also known as air current speaker. It is the use of compressed air as energy, the use of audio frequency current modulation of the voice of the speaker. It consists of a gas chamber, valve, horn and magnetic modulation. Flow of compressed air from an air chamber through the valve in, by the external audio signal modulation, airflow fluctuation according to the external audio signal and change, at the same time be modulated airflow coupled via the horn, to improve the system efficiency. It is mainly used for high intensity noise environment test of sound source or long-distance broadcast, etc..

〈7〉Magnetic distortion speaker. This is a special kind of strong magnet, which can vibrate under the action of magnetic field.