Abstract
Three dimensional (3D) printing technology is rapidly evolving such that printing speed is now a crucial factor in technological developments and future applications. For printing heads based on the inkjet concept, the number of nozzles on the print head is a limiting factor of printing speed. This paper offers a method to practically increase the number of nozzles unlimitedly, and thus to dramatically ramp up printing speed. Fluid reservoirs are used in inkjet print heads to supply fluid through a manifold to the jetting chambers. The pressure in the reservoir’s outlet is important and influences device performance. Many efforts have been made to regulate pressure inside the fluid reservoirs so as to obtain a constant pressure in the chambers. When the number of nozzles is increased too much, the regulation of uniform pressure among all the nozzles becomes too complicated. In this paper, a different approach is taken. The reservoir is divided into an array of many micro-reservoirs. Each micro-reservoir supports one or a few chambers, and has a unique structure with auto-pressure regulation, where the outlet pressure is independent of the fluid level. The regulation is based on auto-compensation of the gravity force and a capillary force having the same dependence on the fluid level; this feature is obtained by adding a wedge in the reservoir with a unique shape. When the fluid level drops, the gravitational force and the capillary force decrease with it, but at similar rates. Terms for the force balance are derived and, consequently, a constant pressure in the fluid micro-reservoir segment is obtained automatically, with each segment being autonomous. This micro reservoir array is suggested for the enlargement of an inkjet print head and the achievement of high-speed 3D printing.
Highlights
Inkjet technology has made continuous developments since the 1950s [1]
In 1977, the emergence of the drop on demand (DOD) concept [2] quickly paved the way for affordable home printers
Certain three dimensional (3D) printers are based on inkjet technology, and nowadays 3D printing may become a revolutionary technology in many disciplines
Summary
Inkjet technology has made continuous developments since the 1950s [1]. In 1977, the emergence of the drop on demand (DOD) concept [2] quickly paved the way for affordable home printers. The problem had been addressed extensively [14,15,16,17,18], with various solutions developed and patented to regulate the pressure in the reservoir, keeping the chamber pressure unchanged during the decrease in ink level in the print head. Such solutions included the use of pistons, membranes, springs, variable volume structure in the ink reservoir for expanding as ink is drawn out, and many more concepts. Combining the above elements results in an immediate printing of an entire layer and high-speed 3D printing
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