Piezoelectric Speaker

What Is a Piezoelectric Speaker?

The Piezoelectric speaker is known by several names, including piezo, buzzer, and crystal loudspeaker. It is a speaker that uses a piezoelectric effect to generate sound. Applying a voltage to a piezoelectric material creates the initial mechanical motion. Furthermore, diaphragms and resonators typically convert the signal into audible sound. Piezoelectric speakers are relatively easy to drive compared to other speaker designs. In ultrasound applications, piezoelectric speakers operate well in the 1-5 kHz range and up to 100 kHz.

Vibration Regions

In the piezoelectric speaker, according to the present invention, the vibration region may distribute the plurality of the portions of the common piezoelectric sheets. With this configuration, a compact speaker is formed integrally. If the pattern of the first and second electrodes formed on each of the plurality of the vibration region are the same, a stereo speaker forms. On the other hand, if at least one of the patterns and the sizes of the first and second electrodes formed on each of the plurality of the vibration and regions are different, a 2-way or 3-way speaker forms.

The Electrodes Structure

The first and second electrodes preferably include a layer mainly containing at least one type of indium tin oxide, indium zinc oxide, and zinc oxide, or a layer made of at least one polythiophene conductive polymer. More preferably, the first and second electrodes have a structure in which a layer mainly containing zinc oxide and a layer made of polythiophene conductive polymers overlap, as viewed in the lamination direction of the laminated body. The present invention is also directed to a speaker apparatus, including a frame and a piezoelectric speaker arranged on the front surface of the frame. According to the latest invention, the speaker apparatus is characterized by including the piezoelectric speaker mentioned above.

Usage

Piezoelectric speakers generate sound in digital quartz watches and other electronic devices. Also, engineers sometimes use them as tweeters in less-expensive speaker systems, such as computer speakers and portable radios. They also produce ultrasound in sonar systems. Piezoelectric speakers have several advantages over conventional loudspeakers. They are resistant to overloads that would usually destroy most high-frequency drivers. Also, people use them without a crossover due to their electrical properties. There are also disadvantages. Some amplifiers can oscillate when driving capacitive loads, like most piezoelectrics. This results in distortion or damage to the amplifier. Additionally, their frequency response, in most cases, is inferior to that of other technologies, especially concerning bass and midrange. This is why people generally use them in applications where volume and high pitch are more important than sound quality.

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