Piezo print head

Brother MFC3360C(r) Piezo print heads (23) Brother... 

Piezo. This is the same basic print head technology as in continuous inkjet. The ink jet droplets are forced out through the nozzle after an electrical signal to the piezoelectric crystal causes a pressure wave to be set up in the ink (Figure 2.35b). The wave can be produced in the bend mode, as in Figure 2.35b or in a push or shear mode. An important variation on piezo technology is the Xaar... 

Figure 2.35 Cross sections of thermal/bubble Jet and piezo DOD print heads.

The advantages of an electrostatic inkjet are that it allows you to print a more concentrated fluid than the formulation that actually passes through the print head, and that the achievable resolution is not a function of the nozzle diameter so that potentially higher resolutions than piezo inkjet are possible. Additionally, very small drops can be formed while still using pigments, as the size of the drop... 

FORMULATING SOLVENT INKS FOR PIEZO DROP-ON-DEMAND PRINT HEADS... 

Piezo drop-on-demand print head s principle of operation is relatively simple in comparison to CIJ. The jetted fluid is held in balance between a shght negative pressure in the ink system, and capillary tension in small nozzles. Each nozzle is attached to a small chamber from which ink is ejected on demand when a piezo crystal coupled to that chamber flexes on apphcation of voltage. While the principle of operation is simple, producing a viable print head is not. The print heads themselves are complex constructions and have specific requirements on the fluid to enable rehable operation. 

State-of-the-art piezo-based drop-on-demand printers are produced by companies such as Xaar (UK), Konica Minolta (Japan), and Fujifilm Dimatix (US). These print heads have around 180 to 360 nozzles per inch and are designed to print at basic resolutions of up to 360 dpi with drop volumes down to about 40 pi (picoliter). This type of print resolution gives features equivalent to approximately 100 /xm track width on PET or PI substrates. However, Xaar s new generation "gray scale" heads allow variable drop volumes down to around 3 pi to give printed features of around 50 /xm or less. 

Droplet Dispensing, Figure 1 Principle of (a) a thermal bubble jet print-head and (b) a piezo-actuated inkjet printhead... 

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