Impulse jet method technologies
Impulse Jet can be sub-divided into two technologies: piezo and bubble jet. These technologies vary greatly in terms of application.
From the office to industry
Impulse jet printheads were originally developed for the office printer market. They are now in general use and achieve outstanding results. Although the concept of the impulse jet printing method appears to be relatively simple, it is worth mentioning that the original patents are from the 1970s.
The printing method was developed for printing on clean paper in an office environment with a consistent gap between the printhead and paper. Now it is also used in production environments where operating conditions are more difficult to control.
The piezo method was the first impulse jet printing method to be developed. Ink is fed into the nozzle with little pressure, so it is only kept in the nozzle by means of surface tension forces. If a drop is required, the piezo crystal is energised. The crystal then expands, which reduces the volume in the cavity and a drop is ejected from the nozzle.
The piezo crystal returns to its original size when the drop has fallen onto the material. The surface tension forces then draw more ink from the ink supply to refill the nozzle.
Resolution determined by nozzle configuration
Clustering a large number of nozzles can achieve the required print width and resolution, typically 8 or 16 dots per mm. The distance between the nozzles determines the print resolution.
Oil- or wax-based inks
As the ink is not continually agitated in the system, it must remain liquid in the nozzle but must dry on the printing surface. This is usually achieved with oil- or wax-based inks, which do not dry but are absorbed by the printing surface.