A Deep─Dive Into Epson’s Advanced Micro Piezo Inkjet Technology And Spherical Droplet Accuracy Using Meniscus Control
Epson's inkjet printing technology is used in home, office, and commercial and industrial printers.
Since Epson’s printing systems form images by directly depositing microscopic droplets of ink on sheets of paper or other media, they generate virtually no waste ink, are far superior to analog and laser printing systems in terms of the environment and efficiency, and can theoretically print on almost any medium.
Let's look at the Micro Piezo inkjet technology that powers every Epson inkjet printer.
Advantages Of Epson Printing Technology
There are two main ways of ejecting ink from a printer. The first is thermal technology, which uses a heater to heat the ink and form bubbles that cause the ink to be ejected.
The other is piezo technology, which applies voltage to change the shape of piezoelectric elements, the mechanical motion of which ejects the ink. Micro Piezo printheads are extraordinarily durable because they are not subjected to heat-induced functional deterioration.
They are compatible even with inks that would undergo changes of material properties if heated. Printers with piezo technology can use a wide variety of inks, including dye and pigment inks.
Micro Piezo Printheads
Epson Micro Piezo printheads achieve superb placement accuracy with fast ejection of up to 50,000 droplets per second by controlling the meniscus at the tip of each nozzle and by using variable size dot technology (VSDT ). VSDT controls the volume of ejected ink droplets by precisely controlling the voltage wave form that drives the piezoelectric elements.
Meniscus Control
This technology harnesses the motion of precisely controlled piezoelectric elements to control the meniscus.
By rapidly suppressing the residual vibration of the meniscus, it holds down the mist caused by residual vibration and ensures straight ejection of large and small ink droplets that are nearly perfect spheres and land with superb placement accuracy.
Variable Size Dot Technology
By precisely controlling the voltage wave form that drives the piezoelectric elements, VSDT controls the volume of the ink in ejected droplets. Ink droplets as small as 1.5 picoliters, or one one-trillionth of a liter, can be deposited in precisely the amounts and locations needed. Since each nozzle can selectively eject ink droplets in a range of sizes, users can enjoy fast output and beautiful image expression with virtually no graininess.
Creating Advanced Printheads
Many issues had to be overcome to create Epson Micro Piezo printheads with all the advantages they offer.
One challenge was coming up with an ink ejection mechanism using piezoelectric elements. Generally, piezoelectric elements with smaller surface area have less displacement than those with greater surface area, if they are of the same thickness.
Therefore, increasing the level of resolution means less displacement of piezoelectric elements and less ink that can be ejected from the nozzle at one time.
Increasing piezoelectric element displacement is essential to selectively ejecting ink droplets of varying sizes.
The thinner the piezoelectric elements, the greater their displacement under the same applied voltage. However, thinner piezoelectric elements are more fragile and thus hard to fabricate and handle.
To solve the problem, Epson adopted a Multi-Layer Piezo, consisting of a stack of thin piezoelectric elements, as an actuator.
We then developed a MACH (Multi-layer Actuator Head) printhead to eject ink through vertical vibration of the piezoelectric elements.
This approach realized high density and responsiveness and dramatically advanced inkjet printing.
