Types of Sound Components and Piezoelectric Sound Components | Basic Knowledge

Type of sound components
Type of piezoelectric sound component
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Type of sound components

Sound components are divided into mechanical and electrical types. The mechanical type produces sound with the application of mechanical shocks to the sound source. This type is used, for example, in bicycle bells, other types of bells, gongs, and similar devices. The electrical type produces sound by vibrating the sound source part with the application of electrical signals such as voltage and current. The electric type is further divided into piezoelectric, electromagnetic (magnetic), and electrodynamic (dynamic) types.

Piezoelectric type

This is a sound component for which a sound element (piezoelectric diaphragm) made by pasting together piezoelectric ceramics and a metal plate is embedded into a resonator (for example, a plastic case, etc.).
The piezoelectric diaphragm vibrates with the input of AC signals into a piezoelectric element, generating sound.

The feature of this type is that power consumption (drive method) is low (voltage type).
It can be configured with few components. This gives it the advantages of being lighter in weight and easier to make thinner.

Electromagnetic (Magnetic) Type

The electromagnetic type uses a diaphragm and electromagnet embedded in a resonator to generate sound by vibrating the diaphragm with changes in the magnetic field of the electromagnet.

The feature of this type is that power consumption (drive method) is high (current type).
As it requires many components, it is also heavier and it is difficult to make it thinner.

Electrodynamic (Dynamic) Type

The electrodynamic (dynamic) type uses a magnetic field generated by a coil with input signals to vibrate a cone and thereby generate sound.

The feature of this type is that it is possible to obtain distortion-free sound over a wide band compared to the piezoelectric and electromagnetic types.
However, the size of the cone becomes bigger and the structure also becomes more complicated. Accordingly, the overall product is larger and heavier.

Type of piezoelectric sound component

What Is a Piezoelectric Sounder?

Piezoelectric Sounder is a piezoelectric diaphragm assembled in a plastic case (Resonant cavity) and is classified into External Drive Type and Self Drive Type.

What Is a Piezoelectric Buzzer?

Piezoelectric Buzzer is a self drive type piezoelectric sounder with built-in oscillation circuit.
It generates consistent single tone sound just by applying D.C.voltage.

Differences between Buzzers and Sounders

To put it briefly, we can distinguish buzzers and sounders by the fact that buzzers have a piezoelectric circuit while sounders do not have a circuit.
Sounders are generally grouped together with buzzers. However, we at Murata distinguish between them as follows.

Type	Definition
Diaphragms	A device for which electrodes are affixed to both sides of a piezoelectric ceramic and then polarized with that, and then bonded to one or both sides of a metal plate There are two types depending on the electrode pattern: one for an external drive and one for a self drive Ceramic only on one side of the metal plate: Unimorph type Ceramic on both sides of the metal plate: Bimorph type
Sounders	A device for which a piezoelectric diaphragm is embedded into a plastic case (resonator); there is no built-in drive circuit There is a nominal value for the basic sound frequency that produces a loud sound, but it is not limited to this; it is also possible to freely produce sound depending on the signal conditions input externally
Buzzers	A device for which an oscillation circuit is built into the case of the piezoelectric sounder or a device used in combination with an external dedicated oscillation circuit Sound can be generated just by connecting a DC voltage (for example, a dry battery) to an oscillation circuit, but it is fixed to one sound frequency
Speakers	A device that expands the frequency band at which a high S.P.L can be generated compared to the above three types by using a specially designed diaphragm while flattening the frequency dependence of the SPL at the same time There is no built-in drive circuit It is possible to create a stereo sound source by using two devices