What is the relationship between the printhead waveform and the ink in a white ink direct-to-substrate printer?

There is a close relationship between the printhead waveform and the ink in white ink direct-to-substrate printers; this relationship is primarily influenced by a combination of factors, including the ink’s speed of sound, viscosity, and density. Different inks produce different waveforms, requiring the printhead to have flexible waveforms to adapt to various inks. The purpose of the printhead waveform file is to control the operation of the printhead’s piezoelectric ceramic by adjusting the waveform (including the rising edge, dwell time, and falling edge), thereby influencing the ejected ink droplets. This adjustment ensures that ink is ejected stably and uniformly, thereby improving print quality and efficiency.

Specifically, the sound velocity, viscosity, and density of the ink affect the printhead waveform in the following ways:

‌Sound Velocity‌: Generally, ink with a higher specific gravity has a faster sound velocity. For example, the sound velocity of water-based ink is typically higher than that of oil-based ink. This means that for the same printhead, when using inks of different densities, the waveform must be adjusted to accommodate the varying sound velocities.

‌Viscosity‌: Differences in ink viscosity affect the speed and stability of ink flow within the printhead waveform. Higher-viscosity inks require longer decay times to ensure stable printhead operation, which may increase the difficulty of optimizing the inkjet waveform.

‌Density Value‌: The speed of sound also varies when using inks of different densities. Given that the size of the printhead’s piezoelectric elements is fixed, the pulse width of the drive waveform is typically the only parameter that can be adjusted to achieve optimal pulse peak performance.

In summary, the printhead waveform for direct-to-substrate white inkjet printers must be adjusted according to the characteristics of the ink being used to ensure printing stability and optimize print quality.