The printer

Chapter The printer

Teach Yourself Electricity and Electronics Third Edition Book
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Teach Yourself Electricity and Electronics Third Edition Book

  • yellow, green, blue, indigo, violet). Saturation is the “richness” of color; the higher thesaturation, the more intense a given hue appears. The “techies” use numbers from180 to 180 to represent hue, and from 0 to 100 to represent saturation. Another wayto specify color is according to the red/green/blue (RGB) scheme, in which each colorhas an intensity number independent of the other two, and ranging from 0 to 255, cor-responding to the binary number range 00000000 to 11111111.Interlacing (or lack thereof) is important in a desktop monitor. A noninterlacedmonitor is better than an interlaced one if you’re working with fast-moving graphic im-ages. Interlacing translates into a lower refresh rate (number of times the entire imageis renewed). A low refresh rate can cause noticeable flickering in the image, and can beespecially disruptive in applications where rapid motion must be displayed. A good re-fresh-rate specification is 70 Hz or more. For applications not involving much motion,60 or 66 Hz is adequate for some people, but others complain of eye fatigue becausethey can vaguely sense the flicker. Most people find 56-Hz refresh rates too slow forcomfort in any application.If you’re concerned about the extremely-low-frequency (ELF) electromag-netic fields produced by CRT monitors, you might consider buying a unit that hasbeen designed to reduce this “radiation” or buying a stand-alone LCD display panelinstead (LCDs do not emit significant ELF). There is disagreement among experts asto the actual danger posed by ELF emission. It’s a good idea to arrange your work-station so your eyes are at least 18 inches away from the screen of a CRT monitor,and if you are working near other computer users, workstations should be at least 3feet apart.The printerA computer printer is an electromechanical device that produces hard copy (textand images on paper). The most common printers are dot-matrix, thermal, inkjet,and laser.Dot-matrix printersThe “horse and buggy” of the printing family is the dot-matrix printer. This type ofprinter is the least expensive, in terms of both the purchase price and the long-termoperating cost. Dot-matrix printers produce fair print quality for most manuscripts,reports, term papers, and theses. The mechanical parts are rugged, and mainte-nance requirements are minimal.Older dot-matrix printers are noisy in operation; newer machines are quieter. Butnone of them have the typeset-grade image quality of more expensive printers. Dot-ma-trix printers can render some simple graphic images, but the quality is fair at best, andit can take a long time to print a single image. Dot-matrix printers cannot reproduce de-tailed artwork or photographs with acceptable quality.Thermal printersA thermal printer uses temperature-sensitive dye and/or paper to create hard copy textand images. Some thermal printers produce only black-and-white images, while otherscan render full color. Thermal printers are often preferred by traveling executives The printer633