Ink jet printers are far less complex than their laser-toting cousins. That's because ink jet printers are basically an updated version of that old office workhorse, the dot-matrix printer. Both ink jet and dot-matrix printers rely on a print head that slides back and forth across the face of the paper, composing letters and images from combinations of ink dots. The smaller the dots and the greater their density, the crisper the image. Dot-matrix printers transfer ink dots much as typewriters printed letters by striking an inked ribbon against the paper. Ink jet printers replace the ribbon and mechanical letter heads with a print head that blows the ink through as many as 160 tiny nozzles to form clusters of very small, precisely placed dots (see FIGURE 1).

The ink is stored in a cartridge. On some printers, only the cartridge needs be replaced; on many others, however, you must change the entire printhead. Here are tips for maintaining your printhead and the rest of your ink jet printer.

Keep your nozzles clean: Faint output, unprinted lines running across the page, or simply no visible printing at all indicate clogged nozzles. Many ink jet printers come with a nozzle-clearing function that blows ink through the nozzles to unclog them. Use this feature regularly, especially if your printer tends to sit unused for weeks at a time. If that doesn't clear them, you'll have to remove the printhead and clean it manually. Dampen a lint-free swab or cloth with isopropyl alcohol and gently wipe the nozzles to remove dried ink. Then retry the printer's auto cleaning function. If that doesn't work, replace the cartridge.

Power down properly: Always use your printer's power switchùrather than the switch on a surge protectorùto shut the unit down. Many ink jet printers have a printhead parking function that's triggered by the printer's own power switch.

Seal your cartridges properly: Keep ink fresh by storing extra cartridges in their factory-supplied containers. If you regularly switch between colour and black ink printheads, store the swapped-out cartridge in an old factory-supplied container or in a small, zip-lock bag.

Maintain your contacts: Over time, the metal contacts on the back of the printhead may oxidise and lose their conductivity through exposure to air. Use isopropyl alcohol and a lint-free swab to keep them cleanùespecially if the printhead was used and then removed and stored for a long period of time.

Use the right paper: Most ink jets print reasonably well on standard, 20-pound copier paper. But the type of paper you use strongly affects the quality of ink jet output. Some grades of paper absorb too much ink, causing either too light or too blurred an image. If you want the best image possible, use the paper recommended by your printer manufacturer.

Keep it clean: Periodically inspect the inside of your printer for scraps of paper or other debris. Unplug the printer, and use canned air and tweezers to remove anything that may smudge the output or otherwise gum up the works. If your printer's environment is very dirty, keep a plastic cover over the printer to extend its life and minimise downtime.

Don't be jammin': Ink jetsùespecially low-cost, relatively flimsy onesùare sensitive to paper position and weight. Always set your paper guides carefully, and never mix paper types in the same tray.

Get the latest driver: Like laser printers, many manufacturers' ink jet models will perform better if you equip them with up-to-date drivers. Find and download these drivers at the vendor's Web site.