Piezo ceramic elements buzzer is in an ionic crystal, positive and negative ions.which are regularly arranged alternately to form a crystal lattice. This creates an intrinsic electric moment, a polarized charge appears on the surface of the piezo crystal, and because the piezo crystal is exposed to the air over time, the charge is neutralized by the alien ions in the air that fall onto the crystal face. Therefore, both the polarization surface charge and the electric moment do not appear. However, when the piezo crystal is mechanically deformed, the crystal lattice changes. Thus, the electric moment changes and the surface when polarization charges by value. Thus, the positive or negative charge on the surface has a measurable increment (increase or decrease), which is the amount of electricity produced by the piezoelectric effect.
Detection method of piezo ceramic bimorph buzzer: The method of detecting the piezoelectric ceramic buzzer with a mechanical multimeter is turning the multimeter to 2. 5v, and gently pinch both sides of the buzzer with the left thumb and index finger. Holding two test leads on the right, the red pen is connected to the metal piece, and the black pen is placed on the surface of the piezo buzzer. Then the left thumb and the index finger are pressed slightly, and then relaxed. The piezo buzzer produces two voltage signals of opposite polarity, so that the pointer swings to the right → returns to zero → swings to the left → returns to zero, and the swing is about 0. 1~0. 15v.
If you exchange the test pen position and re-experiment, the order of the pointer swing is: swing to the left → return to zero → swing to the right → return to zero. Under the same pressure, the larger is the pointer swing, the highersensitivity of the diaphragm piezo element. If the pointer does not move, it indicates that the piezo buzzer is leaking or damaged inside. The capacitance of the buzzer can be directly measured by the digital capacitance meter, and the capacitance should be in the range of 0.005~0. 02∧f.