Information Technology Reference
In-Depth Information
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Figure.3 15
A headset microphone works well for voice input software use.
Quick Review
1
Name three kinds of pointing devices.
2
Besides numbers, letters, and symbols, what other kinds of keys are found on a keyboard and what do they do?
3
What hardware is required for audio input?
4
What is the difference between a digital video camera and a webcam?
Selecting and Using Output Devices
Output devices make the computer's processed information available to a
human user. Without output devices, there would be little reason to have
a computer, because it wouldn't produce anything you could use. The
most common types of output devices are display screens, printers, and
speakers.
Display Screens
A
display screen
is a video screen that the computer uses to provide
information to a human user. A display screen can be built into a device,
as it is with smartphones, tablets, and notebook PCs, or it can be a sepa-
rate unit (a monitor), as it is with the majority of desktop PCs.
display screen
A video screen that a computer
uses to provide output to a human user.
Display screens create their images by filling in tiny dots called
pixels
with different colors. The pixels are so small and so close together that
the human eye sees them as continuous color gradients rather than indi-
vidual blocks. Monitors differ in the technology they use to illuminate
those pixels.
pixel
An individual colored dot in a raster graphic
or on a display screen.
Built-in display screens are thin and flat, and most of them use
liquid
crystal display (LCD)
technology. Most modern stand-alone monitors
are also LCD, like the one shown in Figure 3.16. This technology has
two polarized filters, with a liquid crystal substance between them. One
filter is at an angle, so light doesn't pass through it automatically. When
electricity hits a crystal, it twists, refracting the light so that it passes
liquid crystal display (LCD)
A flat-screen
display technology that passes electricity through
liquid crystals to create a display image.
