Droplet ejection performance of a monolithic thermal inkjet print head

Abstract

This paper presents a simulation study of the droplet ejection performance of a thermal inkjet print head. The geometry of the print head comprises a dome-shaped ink chamber, a nozzle guide and a ring-shaped heater integrated on each chamber. The design eliminates direct contact between the heater and the ink, thus minimizing heater burnout. The ink manifold, ink chamber and nozzle are aligned, thus facilitating higher nozzle density. The model simulates thermal bubble dynamics including nucleation and growth of thermal bubbles caused by a thermal pulse. The model was validated by comparing model predictions with experimental results for a previously reported print head design. Then, the model was used to simulate the droplet ejection performance of the proposed inkjet print head. Effects of print head geometry including nozzle diameter, nozzle length, chamber size, heater dimensions and location, thermal conductivity of the passivation layer, operating conditions including total thermal energy and pulse width, properties of the ink including density, viscosity and surface tension on the performance of the inkjet device are investigated. The influence of these parameters on the drop volume and velocity, threshold energy and tail length of the ejected droplets is studied.

Effects of actuating waveform, ink property, and nozzle size on piezoelectrically driven inkjet droplets

“…l and r, a task often not attainable experimentally. Similar to the trend reported previously (Asai 1992;Sen and Darabi 2007), Fig. 12 indicates that B d and V d decreases linearly with increasing l. To gather further insight into the ink ejection process, the corresponding shapes of the ejected droplet and the meniscus at the nozzle opening are also shown as the photo images in Fig.…”

“…Available commercial inkjet technologies in terms of actuating mechanisms can be currently distinguished into electrostatic (Meinhart and Zhang 2000), thermal (Asai et al 1987(Asai et al , 1988Asai 1992;Chen et al 1998;Tseng et al 2002;Sen and Darabi 2007), acoustic (Elrod et al 1997), and piezoelectric inkjet (PIJ) printheads (Bogy and Talke 1984;Fromn 1984;Shield et al 1987;Chen et al 1999Chen et al , 2002Yeh 2001;Wu et al 2004;Liou et al 2008). Among them PIJ technique has advantages such as superb in the control of droplet volume, more flexible in the ink compatibility, and higher range in the operation frequency.…”

A Level-Set Method for Simulation of a Thermal Inkjet Process

“…Also, the bubble pressure was evaluated from a simplified model as proposed by Asai et al [2], and the liquid temperature field was assumed as one-dimensional, which is not suitable for general thermal inkjet applications such as including the generation of multiple bubbles. A number of other numerical studies of thermal inkjets, which have been based on a simplified model or an empirical correlation for the bubble pressure as well as one-dimensional formulation for temperature field, have been reported in the literature [7][8][9]. In this article, a numerical method is presented for computing the whole process of the thermal inkjet, including bubble growth and collapse as well as ink ejection and refill, without employing any simplified formulation for bubble growth and temperature field.…”

Research on a large power thermal bubble micro-ejector with induction heating

“…The working principle of thermal bubble driven is based on the explosive evaporation (van den Broek and Elwenspoek 2008). Sen and Darabi (2007) researched a thermal inkjet printhead with a monolithically fabricated nozzle plate and self-aligned ink feed hole. Experiments with a 50 μm diameter nozzle show ink ejection with an average ink dot diameter of about 110 μm.…”