1. Piezoelectric oscillator and piezoelectric ceramic frequency control device

Polarized piezoelectric ceramics, also known as piezoelectric oscillators, have an inherent vibration frequency determined by their size. By utilizing the inherent vibration frequency and piezoelectric effect of piezoelectric oscillators, stable electrical oscillations can be achieved. When the frequency of the applied voltage is the same as the natural vibration frequency of the piezoelectric oscillator, it will cause resonance and greatly increase the amplitude. This process generates strain through the reverse piezoelectric effect in the alternating electric field, and the strain in turn generates current through the positive piezoelectric effect, achieving maximum conversion between electrical and mechanical energy. By utilizing the characteristic of piezoelectric oscillators, various devices such as filters and resonators can be manufactured.

These devices have low cost, small size, no moisture absorption, long lifespan, good frequency stability, higher equivalent quality factor than LC filters, wide frequency range, high accuracy, especially when used in multi-channel communication, amplitude modulation reception, and various wireless communication and measurement instruments to improve anti-interference ability. So currently, a considerable portion of electromagnetic oscillators and filters have been replaced, and this trend is still evolving.

2. Piezoelectric transformer

A piezoelectric transformer is prepared by utilizing the characteristic of converting electrical and mechanical energy through the piezoelectric effect. It consists of two parts: the input end and the output end, with their polarization directions perpendicular to each other. The input terminal polarizes along the thickness direction and undergoes longitudinal vibration after applying alternating voltage. Due to the reverse piezoelectric effect, there will be a high voltage output at the output terminal.

Piezoelectric ceramic transformer is a new type of solid-state electronic device. Compared with traditional electromagnetic transformers, it has the advantages of simple structure, small volume, light weight, large transformer ratio, good stability, no electromagnetic interference and noise, high efficiency, high energy density, high safety, no winding, non combustible, no magnetic leakage phenomenon, and electromagnetic radiation pollution.

According to the working modes of piezoelectric ceramic transformers, they can be divided into the following categories: Rosen type piezoelectric ceramic transformers, thickness vibration mode piezoelectric ceramic transformers, radial vibration mode piezoelectric ceramic transformers, etc.

In recent years, some piezoelectric transformers with better performance have emerged, such as Rosen type piezoelectric ceramic transformers with three-order vibration modes at two input terminals and high-power multi-layer piezoelectric ceramic transformers. At present, piezoelectric ceramic transformers are mainly used in power devices such as AC-DC and DC-DC, as well as high-voltage generating devices, such as cold cathode tubes, neon tubes, laser tubes and small X-ray tubes in liquid crystal displays, high-voltage electrostatic spraying, high-voltage electrostatic flocking, and driving radar display tubes.

3. Piezoelectric transducer

Piezoelectric transducers utilize the piezoelectric and inverse piezoelectric effects of piezoelectric ceramics to achieve the mutual conversion of electrical and acoustic energy. A piezoelectric ultrasonic transducer is one of them, which is an underwater acoustic device that emits and receives ultrasonic waves. A piezoelectric transducer in water, under the action of sound waves, induces charges at both ends of the transducer, which is called a sound wave receiver; If an alternating electric field is applied to a piezoelectric ceramic sheet, the sheet will sometimes become thinner and thicker, while generating vibration and emitting sound waves, which is called an ultrasonic transmitter.

Piezoelectric transducers are also widely used in industry for underwater navigation, ocean exploration, precision measurement, ultrasonic cleaning, solid state inspection, medical imaging, ultrasonic diagnosis, and ultrasonic disease treatment. Another application field of piezoelectric ultrasonic transducers today is telemetry and remote control systems, with specific application examples mainly including piezoelectric ceramic buzzers, piezoelectric igniters, ultrasonic microscopes, etc.

4. Piezoelectric ultrasonic motor

Piezoelectric ultrasonic motor is a new type of micro motor that utilizes the inverse piezoelectric effect of piezoelectric ceramics to generate ultrasonic vibration, amplifying the micro deformation of materials through resonance, and driving it by the frictional force between the vibrating and moving parts, without the need for conventional electromagnetic coils.

Compared with traditional electromagnetic motors, it has the characteristics of low cost, simple structure, small size, high power density, good low-speed performance (can achieve low speed operation without the need for a reduction mechanism), large torque and braking torque, fast response, high control accuracy, no magnetic and electric fields, no electromagnetic interference and noise, etc.

Piezoelectric ultrasonic motors are widely used in precision instruments, aerospace, automatic control, office automation, micro mechanical systems, micro assembly, precision positioning and other fields due to their own characteristics and performance advantages. At present, Japan is at the forefront of technology in this field, and has widely used piezoelectric ultrasonic motors for autofocus in cameras and camcorders, forming a large-scale series of products.