Glossary · Part

UV printing

Piezo print head

A type of print head in which a tiny component pushes the ink out of the nozzle using an electrical voltage, entirely without heat. That is why it is suitable for UV ink.

Explained in more detail

Piezo crystals deform when voltage is applied. This movement creates a pressure pulse in the ink chamber that ejects a droplet. The shape of the voltage curve (waveform) controls droplet size and speed. Unlike the thermal inkjet in office printers, the ink is not heated, which is why piezo heads can handle viscous UV inks. Well-known head series include Epson XP600, TX800, I1600 and I3200 as well as Ricoh Gen5 and Gen6, and they differ in nozzle count, speed and lifespan.

Where does the term come from?

"Piezo" comes from the Greek "piezein", meaning to press or squeeze. The brothers Pierre and Jacques Curie discovered the piezoelectric effect in 1880: certain crystals generate voltage under pressure and, conversely, deform when voltage is applied.

In practice

• Because the ink is not heated, piezo heads can also handle viscous inks such as UV ink, varnish and primer.
• Cold makes UV ink thicker; a room at 18 to 22 °C helps all nozzles fire evenly.
• Variable drop sizes (greyscale printing) give finer gradients; the smallest drop size is given in the data sheet in picolitres (pl).
• Epson calls its piezo technology "Micro Piezo", meaning the same principle in its own design.

Not to be confused

Not to be confused with the thermal inkjet (bubble jet) of many office printers: there, a heating element creates a vapour bubble that ejects the droplet. That does not work with UV ink.

Frequently asked questions

Why do UV printers use piezo print heads?

Piezo heads eject the droplets mechanically, without heat. UV ink is more viscous than office ink and would change when heated, which is why thermal heads are unsuitable.

What is the difference between XP600 and i3200?

The XP600 originally comes from a photo printer and has 1,080 nozzles; the i3200 is an industrial head with 3,200 nozzles. The i3200 prints faster, but as a spare part it costs several times as much.