One of the problems of modern electronics and electrical engineering is the conversion of electric current into mechanical movement and vice versa. It arises due to the different nature of mechanical movement and electric current. There are various approaches to solving this problem, each with its own class of devices. The piezoelectric technique is discussed next.
The essence of the piezoelectric effect and its main properties
The first reports on the piezoelectric effect were published in 1880 in France by the Curie brothers. They found that during mechanical deformation of quartz and some other crystalline materials by pressure, compression, stretching and torsion, an electric charge appears on it. The authors of the discovery called such charges piezoelectricity from the Greek word "crush". Accordingly, materials with such a property were assigned by them to the group of piezoelectrics.
A remarkable quality of the piezoelectric effect is its reversibility, as illustrated in Figure 1. In other words, any piezoelectric material not only creates an electric charge under pressure, but also begins to change its volume when in an electric field.
Piezoelectric devices are widespread in modern technology. This is facilitated by:
- cheapness, prevalence and ease of processing piezoelectric materials;
- good stability of their electrical and mechanical characteristics over time.
Of no small importance is the fact that the magnitude of both the charge itself and the mechanical displacements in some cases, they are sufficient for their direct use without the involvement of additional amplifiers.
Some areas of application
Here are just a few examples of piezoelectric technology for mass use.
The handheld piezo lighter went on mass sale back in the 70s. last century. The electricity that appears on the crystal when you press the key goes to the electrodes, between which, when discharged, a spark jumps and ignites the gas. Currently, gas stoves of middle and older models are equipped with built-in elements, Figure 2.
The piezo filter is popular in electronics due to the fact that, as a mechanical system, a piezo crystal has a very high vibrational figure of merit. As a result, it can significantly reduce the filter bandwidth and effectively separate signals from each other.
The sonar uses a crystal as an emitter of sounding acoustic waves and a signal receiver, reflected from any underwater obstacle (bottom, fish, driftwood, submarine, etc.), picture 3.
Micromovements of focusing elements of television cameras, electronic-mechanical switches of optical signals and other elements. Advantageous in that they create linear motion directly without intermediate transformation from rotary.
Mobile phone buzzers that vibrate a call in silent mode.
Piezo heads for inkjet printers to control the process of applying ink to paper.