Theoretical investigation of the influence of nozzle diameter variation on the fabrication of thin film transistor liquid crystal display color filters

Printing technologies have gained widespread attention from industry as an alternative to expensive photolithographic processes. Among the various kinds of printing technologies, piezoelectric drop-on-demand (piezo-DOD) inkjet printing is regarded as a promising patterning method because of its inherent simplicity and very low levels of material waste generation, especially for display industries such as thin film transistor liquid crystal displays and polymer light emitting diode displays. However, its key engineering difficulty is the variation of droplet volume across the nozzles in a piezo-DOD inkjet printhead, which causes visible swathe marks on a printed display screen. In this paper, it is suggested that the occurrence of these swathe marks could result from the influence of the mechanical nozzle tolerance, i.e., the variation in nozzle diameter of the piezo-DOD printhead. The effect of the mechanical nozzle tolerance on droplet velocity and volume is investigated using mathematical models. Finally, the future research and development direction of piezo-DOD inkjet printing technology for the large area flat panel display industry are discussed.