1. Thermal or bubble jet
2. Piezo drop on demand.
In these technologies the pressure applied to the ink reservoir is not continuous, but is only intermittently applied when a droplet is needed.
Thermal Inkjet or Bubble Jet Technology:The Bubble Jet printer uses a small heating element to create pressure droplets on demand within the ink reservoir. The small quantity of ink present in each nozzle is heated by a resistive heating element actuatted by the digital data stream. The ink boils creating a bubble whcih forces an equivalant volume of ink droplet through the nozzle and on to the substrate.
Thermal inkjets offer low cost print heads but suffer from slow speed. In thermal inkjet printers two variations are available- side shooter thermal inkjet and rear shooter thermal inkjet.
Thermal printers are well suited for low volume printing. The system restricts the use of binder containing pigment inks. The major problem with the thermal inkjet is the high nozzle and resister failure rate resulting from rapid thermal cycling. The high temperatures cause often decomposition of ink components, which leads to nozzle clogging. Therefore, only thermally stable inks can be used. Poor quality production results are possible. Finally, compared to Piezi systems the droplet size is larger resulting in low resolution. Main players in bubble jet printer manufacturing are Canon, Encad, Color Wings, HP and Direct Imaging Systems.
