Piezo plates can be classified into several common types based on the number of terminals, the position of the feedback electrode, and the shape design of the ceramic plate and metal plate.
The upper-left image shows a standard piezo plate, which is a two-terminal circle type. This is the most common basic structure and is usually composed of a circular ceramic plate and a metal plate.
The lower-left image shows a piezo plate with the feedback electrode located at the center. It is a three-terminal circle type with center feedback. In addition to the main driving terminals, this structure also includes a feedback terminal, which can be used to provide a feedback signal to the circuit.
The upper-right image shows a piezo plate with the feedback electrode located near the side edge. It is a three-terminal circle type with brim feedback. Its function is similar to that of a three-terminal feedback piezo plate, but the feedback electrode is placed at the side. This type may be selected depending on different product structures and circuit requirements.
The lower-right image shows a piezo plate with a circular ceramic plate and a square metal plate. It is a two-terminal square type. This type of piezo plate is often used in applications that require a specific mounting method or mechanical layout.
In addition, for applications that require a higher sound pressure level, such as sirens, some manufacturers use a double-sided piezo plate structure. This structure usually has stainless steel or brass placed in the middle, allowing the piezo plate to generate a higher sound pressure level than a single ceramic plate.
