What Is Thermal Inkjet Printing?

Thermal inkjet, or bubble jet, printing is the most popular type of consumer printing in use. Thermal inkjet technology was pioneered in the 1950s, but the first mass-produced inkjet printer was introduced in 1976. Hewlett-Packard (HP) introduced its DeskJet inkjet printer in 1988, and it became a popular home consumer item.

Function and Process

Inkjet printing involves shooting tiny particles (50 to 60 microns in diameter) of heated (or thermal) ink onto paper through nozzles (300 to 600 nozzles per print head) to create an image. Ink particles, or dots, are positioned precisely and create high-resolution images. The ink is then heated until a bubble is created and forced out by pressure onto the paper. The bubble collapses and cools, leaving behind an image. The resulting vacuum draws up more ink from a reservoir to replace the ejected ink.

Configurations

Thermal inkjet printers are available in one of two configurations: side-shooter and top-shooter. The type of shooter depends on the how the nozzles are aligned with the planar substrate. Canon printers employ side-shooter thermal inkjet printers while Lexmark and HP employ top-shooters.

Types

There are various types of thermal inkjet printing techniques, each forming images differently. They including drop on demand (DOD), thermal bubble and piezoelectric printing. DOD squirts minuscule droplets of heated ink through tiny nozzles at the rate of 5,000 squirts per second. The printer software dictates which nozzle will shoot droplets and when--depending on the image that is to be printed. Thermal bubble printing involves heating ink till it bursts out and forms a bubble on paper. Piezoelectric printing uses a piezo crystal that, when electrically charged, applies pressure on the ink reservoir. That, in turn, forces an ink particle out of the nozzle.

Advantages

Thermal inkjet printing has numerous advantages over laser printers. It allows for accurate and high-quality printing. Ink cartridges can be refilled when empty, a cost-effective alternative to purchasing brand-new cartridges. Inkjet printers are compact, quiet and easy to use.

Disadvantages

Disadvantages of thermal printing include color limitations (they typically use carbon-pigmented inks that do not produce optimal-quality color images); the need for constant maintenance (thermal power makes the print head susceptible to damage); and the requirement of heat-resistant paper for printing.

References

• InkGuides: How Inkjet Printers Work
• Stanford University: Piezoelectric Droplet Ejector
• Mimech: Inkjet and Bubble Printer Technology