Inkjet Printer Information (2)
The Difference - Thermo Bubble-Jet vs. Piezo-Jet

The picture to the right is another illustration of an inkjet printer nozzle. A droplet of ink is propelled out of the nozzle to print when the control signal is applied to the control device.

The very first difference between Thermo Bubble-Jet and Piezo-Jet technology can be discovered in the specs of a typical Canon and an Epson inkjet printer. Canon inkjet printers typically have 256, 512 or even 1024 nozzles per group (color) of nozzles, but Epson printers typically have 60 or 120 nozzles per group. This is a significant difference that has its implications.

The Printing Speed Implication

Obviously, when the nozzle density is higher (higher nozzle count) the printer is able to print more pixels per unit of time. With fewer nozzles the print head has to make more trips over the medium to print the same number of pixels and this takes more time to do. There is no implication to the final resolution (pixels per inch) of the print as it is determined by how fine of the step is when the stepping motor advances to print the next round of pixels. Epson printers typically are slower for this reason.

The Ink Formulation Implication

The ink for Thermobble-Jet is considerably more difficult to formulate than for Piezo-Jet. Just think of sugar water. The water is the solution and the sugar is the colorant. It will be super heated (300 - 400 degree Fahrenreiht) in a Thermo Bubble-Jet nozzle. The water content for sure will be vaporized to leave sugar to be charred into carbon to clog the nozzle. This is one of the reasons Epson ink is completely incompatible with Canon, HP and just about every other brands. You can feed sugar water to Epson printers and it will not clog the print head. If you do that to a Thermo Bubble-Jet printer it may be an instant death of the print head.

The Clogging Implication

There is a reason why Epson printers are made with 60 - 120 nozzles per group of nozzles. It is difficult to make with more. When Piezo crystal bends (by the electrical signal) it can only create a relatively small force to expel ink out of the nozzle. The piezo crystal has to be made larger to generate large enough expelling force. The Thermo Bubble-Jet on the other hand can expel ink with an explosive force. The nozzles can be made much smaller in higher density as long as the ink is formulated to withstand the heat.

Piezo-jet nozzles are naturally easier to get clogged because the expelling force is intrinsiclly small. But Thermo Bubble-Jet nozzles can be as easily clogged if the ink used is inferiorly formulated in terms of the ability to withstand the heat.

The basic requirement for formulating Ink for Thermo Bubble-Jet and for Piezo-Jet is completely different. There is no such a universal ink that works for both technologies.

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