Ink jet printers have made rapid technological advices in the recent years. The printer, although it has been around for years, has become more affordable for customers. Inkjets have the ability to produce colour which makes them more popular. The tend to be more expensive to maintain than laser printers. Cartridges need to be changed more often and (expensive) special coated paper is required to produce high quality output. When comparing cost per page, inkjets cost ten times more than laser printers. Research in inkjet technology is making advances with each new product showing improvements in performance and output quality. Inkjet printing is a non-impact method. Liquid ink is emitted from nozzles onto the paper, using various colours to build up an image. Inkjets operate at a minimum of 300dpi, meaning there are at least 2,475 dots across the page. In the future, fabrication advances will allow faster frequencies, delivering resolutions up to 1200dpi. The most common type of inkjet is the "drop on demand" (D.O.D.). Small droplets of ink are squirted onto the paper through tiny nozzles. The amount of ink put on the page is determined by the driver software that dictates which nozzles to shoot and when. Nozzles are hair fine and were clogged in the early models. One disadvantage is the tendency of the ink smudging after immediately being printed. Though smudging has improved over the years. Thermal technology is used in most inkjets. Heat is used to fire ink onto the paper. Thermal inkjets currently have print heads containing 300 to 600 nozzles. Print speeds are between 4 to 8 pages per minute for monochrome text and 2 to 4 pages per minute for colour text and graphics. Epison inkjets technology uses a piezo method. The process allows more control over the shape and size of ink droplet release. It allows for smaller droplet size and higher nozzle density. Unlike the thermal technology, the ink does not have to be heated and cooled between each cycle.