Information Technology Reference
In-Depth Information
assigns a transistor to control each pixel, resulting in higher resolution and quicker response
to changes on the screen. TFT LCD monitors have displaced the older CRT technology and
are commonly available in sizes from 12 to 30 inches. A number of companies are capable
of providing multimonitor solutions that enable users to see a wealth of related information
at a single glance, as shown in Figure 3.13.
Figure 3.13
A Four-Screen Wide Display
(Source: © Justin Pumfrey/Getty
Images.)
Organic Light-Emitting Diodes
Organic light-emitting diode (OLED)
technology is based on research by Eastman Kodak
Company and is appearing on the market in small electronic devices. OLEDs use the same
base technology as LCDs, with one key difference: Whereas LCD screens contain a fluores-
cent backlight and the LCD acts as a shutter to selectively block that light, OLEDs directly
emit light. OLEDs can provide sharper and brighter colors than LCDs and CRTs, and be-
cause they don't require a backlight, the displays can be half as thick as LCDs and used in
flexible displays. Another big advantage is that OLEDs don't break when dropped. OLED
technology can also create three-dimensional (3-D) video displays by taking a traditional
LCD monitor and then adding layers of transparent OLED films to create the perception of
depth without the need for 3-D glasses or laser optics.
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Printers and Plotters
One of the most useful and popular forms of output is called
hard copy
, which is simply paper
output from a printer. The two main types of printers are laser printers and inkjet printers,
and they are available with different speeds, features, and capabilities. Some can be set up to
accommodate paper forms, such as blank check forms and invoice forms. Newer printers
allow businesses to create customized printed output for each customer from standard paper
and data input using full color. Ticket-receipt printers such as those used in restaurants,
ATMs, and point-of-sale systems are in wide-scale use.
The speed of the printer is typically measured by the number of pages printed per minute
(ppm). Like a display screen, the quality, or resolution, of a printer's output depends on the
number of dots printed per inch (dpi). A 600-dpi printer prints more clearly than a 300-dpi
printer. A recurring cost of using a printer is the inkjet or laser cartridge that must be replaced
periodically—every few thousand pages for laser printers and every 500 to 900 pages for
inkjet printers. Figure 3.14 shows a laser printer.
Laser printers are generally faster than inkjet printers and can handle more volume
than inkjet printers. Laser printers print 15 to 50 pages per minute (ppm) for black and white
and 4 to 20 ppm for color. Inkjet printers print 10 to 30 ppm for black and white and 2 to
10 ppm for color.
For color printing, inkjet printers print vivid hues and with an initial cost much less than
color laser printers. Inkjet printers can produce high-quality banners, graphics, greeting cards,
letters, text, and prints of photos. Hewlett-Packard introduced the CM8060 inkjet printers
with a stationary print head that uses 60,000 nozzles to spray ink as the paper moves.
