What is ink drop?
The minimum ink drop size is the most important technical parameter to pay attention for industrial and commercial printers. The images on the paper appears because of the smallest drops of colored ink ejected from the print head. The volume of an ink drop is measured in picoliters (pl), which is a trillionth of a liter or a millionth of a millionth. That is, to represent a picoliter, you have to divide a liter of ink by a million drops, and then divide the resulting drop by another million.
The volume of the drop determines the quality and the speed of the printer printed. To achieve a small drop size, printers have come a long way. 20 years ago they poured ink droplets as small as 80-90 pl, but now progress has come to the point where only one pl of ink can be thrown on paper. That is why advanced commercial and industrial label printers produce detailed images in which halftones, highlights, shades and contrasts can be seen. In addition, the smaller the drop, the less likely to get a smudge on the paper, hence the high print quality.
If one compares the pictures produced by printers with a drop of 3 pl and 1.5 pl, it turns out that the second device prints sharper images which do not cut the eye and are perceived naturally, there are also color transitions and penumbra.
At the same time, we should not forget that the printing result is influenced not only by the volume of the drop, but also by:
- the selected ink;
- the characteristics of the printing device.
The a small ink drop is not always a good thing. For example, for pigment or sublimation printing, a large drop volume is important. The fact is that the pigment consists of particles and if you pour it into a printer that has a minimum drop of 1.5 pl, then the ink will simply clog the nozzles and the device will no longer print without special cleaning.
It turns out that, choosing a printing device, you should not look at individual parameters, but evaluate it comprehensively, and also take into account the purposes for which you need it. If you want a home photo lab, of course, buy a device with a minimal ink drop, so the pictures are of high quality and pleasing to the eye.
Large and small ink drops
The successful compromise of quality and speed depended on the ability of the printing device to use varying amounts of ink in different areas of the image. Manufacturers have taken a responsible approach to this challenge and found suitable options for both printing technologies.
Epson and Brother were able to achieve variable drop volume printing by adjusting the current pulse. The greater the strength of the electrical charge that affects the piezo element, the larger the volume of the drop produced. And, of course, vice versa. The printing device processes print jobs and determines the areas of the page where small and large volume drops will be used before printing even begins.
The greater the strength, And, of course, vice versa. The printing device processes print jobs and determines the areas of the page where low and high volume droplets will be used before printing even begins.
Thermal inkjet printing
Printers that work using this particular technology can take two approaches to generating different sized drops. The first is to control the volume of gas that forms when heated and pushes out the corresponding volume of ink. This requires two heating elements for each nozzle, which is understandably inconvenient and not always possible.
To make printing with different droplets available, design changes were needed. The printhead of thermal jet printers began to be arranged according to the checkerboard principle. The printhead on one side are designed to form small droplets and on the other side to form large droplets. Thus, if it is necessary to print the background, one row is used and, accordingly, the other row is used to print highlights and various details.
Different approach
The approach to the formation of different-sized drops, although different, but in their aim the manufacturers are the same. They look for compromises between the possibilities of the devices and the needs of the users in order to avoid graininess, to render shades and smoothness of gradation better, and not to sacrifice the speed for the sake of quality. And they do it quite well.
