However an impact printer is noisy in operation and

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Unformatted text preview: er certain lighting conditions. This is because unlike the phosphors used in CRT monitors, the liquid crystals do not glow when charged, so there is not enough contrast between the images and their background to make them clearly legible under all lighting conditions. To take care of this problem, some LCD monitors put a light source behind the screen. Although this makes the screen easier to read, the light source requires additional power, which can be a problem for portable computer systems that often run on battery. Printers Printers are the most commonly used Output devices today for producing hard-copy output. There are many ways to classify a wide variety of printers available today. The most commonly used ways are: 1. Printing technology used. According to this classification, the common types of printers are dot-matrix printers, ink-jet printers, drum printers, chain/band printers and laser printers. 2. Approach of printing. According to this classification, printers are classified as impact printers and non-impact printers. Impact printers use the approach of hammering a typeface against paper and inked ribbon to produce printed output. Nonimpact printers do not hit or impact a ribbon to print. They use thermal, electrostatic, chemical or inkjet technology to produce printed output. Impact printers can produce multiple copies by using carbon in a single print cycle, which is not possible with a non-impact printer. However, an impact printer is noisy in operation and normally uses covers to reduce the noise level. Non-impact printers are quiet in operation. 3. Speed of printing. According to this classification, printers are classified as character printers, line printers and page printers. As the names imply, a character printer prints one character at a time, a line printer prints one line at a time, and a page printer prints an entire page at a time. Accordingly, printer speeds are measured in characters-per-second (cps) for character printers, lines-per-min...
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