A laser printer is shown in figure 933 laser printers

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Unformatted text preview: lent. However due to impact printing, chain/band printers are noisy in operation and often use a cover to reduce the noise level. A chain/band printer is shown in Figure .9.32. Since chain/band printers use inked ribbon to produce printed output, they are usually monochrome. Typical speeds of chain/band printers are in the range of 400 to 3000 lines per minute. Laser Printers Laser printers are page printers that print one page at a time. The main components of a laser printer are a laser beam source, a multi-sided mirror, a photoconductive drum and toner (tiny particles of oppositely charged ink). To print a page of output the laser beam is focused on the electro statically charged drum by the spinning multi-sided mirror. The mirror focuses the laser beam on the surface of the drum in such a manner that it creates the patterns of characters/images to be printed on the page. As the drum is photoconductive, a difference in electric charge is created on those parts of the drum surface that are exposed to the laser beam. As a result, the toner, which is composed of oppositely charged ink particles, sticks to the drum in the places the laser beam has charged the drum's surface. The toner is then permanently fused on the paper with heat and pressure to generate the printed output. The drum is then rotated and cleaned with a rubber blade to remove the toner sticking to its surface to prepare the drum for the next page printing. A laser printer is shown in Figure 9.33. Laser printers produce very high quality output because they form characters by very tiny ink particles. The most common laser printers have resolutions of 600 dpi, whereas some high-end laser printers have resolutions of 120 dpi. Because of their high resolution, these printers give excellent graphics art quality. Since laser printers produce printed output as patterns generated by the laser beam, they can print any shape < characters that a programmer can describe. This allows the printer to print many special charact...
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