Piezoelectric Crystals

Question	Answer
A piezoelectric crystal is a material that expands and contracts when an electric current is applied. The piezoelectric effect converts this mechanical stress or vibration into electrical signals.	E.g. Epson printers. A piezoelectric crystal is located at the back of the ink reservoir of each nozzle. The crystal receives an electric charge which causes it to vibrate. When the crystal vibrates it releases ink from the reservoir, then more ink is brought into the reservoir to replace the ink just gone.
Piezoelectric crystals are used in a wide range of products and systems as either actuators or transducers.	Image: musical_card (image/jpg)
Actuator - A device for controlling a mechanism or system. E.g. A musical Greetings card Pressure => Sound	How it works: The music module is activated by opening the card, which removes an insulating tongue from between a pair of switch contracts on the module. The piezoelectric crystal acts as a tiny speaker driver allowing it to generate a pre-programmed sound stored on an integrated circuit mounted on the module.
Transducer - A device that converts a signal from one form to another E.g. An electrical drum kit Pressure => Sound	When an electronic drum pad is struck, a voltage change is triggered in the embedded piezoelectric transducer. The resultant signals are translated into digital waveforms, which produce the desired percussion sound assigned to that particular trigger pad.

Resource summary

	Created by Poppy Venables about 11 years ago