HP (Hewlett-Packard) 540 Printer User Manual


 
Thermal Inkjet Technology
The HP DeskJet printer family uses Thermal Inkjet II (TIJ II) technology.
This technology centers on a disposable print cartridge which propels ink
out of 50 nozzles (48 nozzles on the color print cartridge). The basic
principle of TIJ II is to apply heat to a tiny measure of ink until it expands
and is propelled through a nozzle.
This is achieved by first filling a small reservoir, known as the firing
chamber, with ink. The next step is to heat the ink with a thin-film resistor
layered above the firing chamber. As the ink heats up, it expands to form a
bubble. As the bubble continues to expand and burst, it is forced through
the nozzle located below the firing chamber.
This process is repeated up to 5,000 times per second and creates
residual heat in the resistor which must be removed. A layer of silicon
placed above the resistor transfers the residual heat from the resistor.
Cooling Layer of Silicon
Heated Thin-Film Resistor
Firing Chamber
Nozzle
Propelled Ink Droplet
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