Characterization of thermal inkjet droplets jitter

Abstract

Due to the randomness in the nucleation process of vapor bubbles and the instability of ink drop breakup in the thermal inkjet drop ejector, the drop velocity varies slightly from drop to drop, such a variation is called the jitter of the droplets. Droplet jitter causes variations in drop volume, satellite drop formation, and drop placement error on the receiving substrate, which limit the high accuracy printing application for thermal inkjet. Traditionally, a multipleexposure method is used to photograph the droplets in flight, which is unable to measure jitters of every drop due to the low sampling rate. In this study, a laser-based high-speed flying drop measurement system is used to study the jitter. We tentatively propose a simple model to explain the cause of droplet jitter, which is related to the latency phenomenon, the randomness in droplet formation and the difference in droplets velocity. The jitter is recorded under different driving conditions and the distribution of jitter is analyzed. As a conclusion, the conditions for operation to achieve lower jitter are determined. Under certain driving conditions, the jitter can be reduced by 90%.

Recent advances in inkjet-printing technologies for flexible/wearable electronics

“…42 Due to the random nature of the vapor bubble in the nucleation process and the instability of the droplet, which may cause a breakup of the ink droplet in the sprayer, the velocity of the droplet varies slightly between each other, generally known as droplet jitter. 43 Droplet jitter can lead to droplet volume variation, satellite-liked drop formation, and droplet placement errors on the receiving substrate, which greatly limit the applications of inkjet technology where high-pre-cision is required. Traditionally, multiple-exposures are often used to capture the droplets in flight.…”

“…However, the low sampling rate makes it impossible to accurately measure the jitter of each drop. Wang et al 43 proposed a simple model to interpret the cause of droplet jitter by using a laser-based measurement system to study the jitter. The location of the bubble nucleation is restricted by pits and cavities, so heterogeneous nucleation can easily occur.…”

Simulation of a Hemispherical Chamber for Thermal Inkjet Printing

“…Here, the nozzle with a bottom diameter of 13 µm ejected the liquid column fastest. After the ink droplet was broken, the jitter range became more significant, and the ejected liquid column did not reach 10 pL in volume [32]. It is important to note that a nozzle with a top diameter of 17 µm ejects a slower liquid column with a larger volume, further prolonging the ink filling time.…”

Design of H-Shape Chamber in Thermal Bubble Printer

“…Therefore, the research on thermal bubble inkjet printing has become the hot topic again. The main reason is that the thermal bubble printing relies on heating resistors within 3 μs to instantaneously heat the ink to more than 300 °C, and the overall temperature of the whole chamber only rises about 5-10 °C [6,7], so most cells will not be inactivated by heating, in which the average survival rate is more than 90%. Piezoelectric inkjet printing can achieve an extremely high ejection frequency (up to 30 kHz) [8,9].…”