Discovering Computers
Chapter 6
Output
Ch 1 – Introduction
Ch 2 – Internet & WWW
Ch 3 – Application Software
Ch 4
Processor
Control
Control
Unit
Unit
Arithmetic
Arithmetic
Logic
(ALU)
Logic Unit
Unit (ALU)
Instructions
Data
Information
Input
Devices
Ch 5
Data
Information
Instructions
Data
Information
Ch 8 – System Software
Storage
Devices
Ch 7
Output
Devices
Ch 6
2
Output what?
Information processed,
organized,
meaningful,
useful data
text
graphics
video
audio
3
Output device conveys information
speakers
display
printer
5
Display
devices
Printers
Speakers,
headphones,
ear buds
Interactive
whiteboards
Forcefeedback
game
controllers
Data
projectors
Tactile
output
6
What is a display device?
 Output device that visually conveys text,
graphics, and video information
 Information on display device is called
soft copy
 Monitor houses display device as a separate
peripheral
CRT (Cathode Ray Tube) Monitors
What is a CRT monitor?
 Contains cathode-ray
tube (CRT)
 Screen coated with tiny dots
of phosphor material
 Each dot consists of a red,
green, and blue phosphor
 Common sizes are 15, 17, 19,
21, and 22 inches
 Viewable size is diagonal
measurement of actual
viewing area
What is an LCD monitor?


Uses liquid crystal display
Mobile devices that contain
LCD displays include
 Notebook computer, Tablet
PC, desktop computer,
portable media player,
smart phone, and PDA
Using multiple LCD monitors


Some users position
two or more monitors
side-by-side or stacked
Allows users to run
multiple applications
simultaneously
What is a plasma monitor?
 Displays image by applying voltage to layer of gas
 Larger screen size and richer colors than LCD,
but plasma monitors are more expensive
The graphics processing unit (GPU)
controls the display of graphics
13
Interactive screen
More and more electronic screens are used to interact
with the computer rather than just reflect
information delivered by the computer.
Interactive screen
The quality of a display depends on:
Resolution
Dot pitch
Refresh rate =
Response time
Color depth
15
What is resolution?
Number of
horizontal and
vertical pixels in a
display device

Higher resolution
makes image
sharper, displays
more text on screen

800 x 600
most common
1280 x 1024
maximum
resolution of most
monitors
600 vertical
pixels
800
horizontal
pixels
Total 480,000 pixels
2048 x 1536
maximum for
high-end monitors
17
What is dot pitch?
Measure of the
distance between
pixels
Sometimes called pixel
pitch
Smaller the distance
between the pixels,
the sharper the
image
Use a monitor with a
dot pitch of .29
millimeters or lower
to minimize eye
fatigue
18
What is bit depth?
Number of bits a video
card uses to store
information (color) of
each pixel
Also called
color depth
Determines number
of different colors
The greater the number
of bits (color depth) , the
better are colors of the
image
8-bit video
card
Uses 8 bits to
store information
about each pixel
Can display 256
different colors
24-bit video
card
Uses 24 bits to
store information
about each pixel
Can display 16.7
million colors
28 =
2x2x2
x2x2x
2x2x2
= 256
colors
224 =
16.7 million
colors
19
What is important in a monitor?

Price of a display is the biggest part of the
computer price

Screen resolution: more pixels – sharper picture

Dot pitch: distance between neighboring pixels

Color depth: more bytes to carry the color of a
pixel

Refresh rate is speed at which monitor redraws
images on screen

Energy consumption
Television
From 3 channels to 300
From analog to digital
From TV to HDTV
Next is streaming
What is digital television (DTV)
Many programs can be
broadcast on a single
digital channel
DTV uses digital signals to produce
crisper, higher-quality output
on LCD and plasma televisions
What is high-definition television
HDTV)?
High resolution
HDTV
(high-definition television)
is the most advanced form
of digital TV
Great for game playing, watching movies, and browsing the Internet
Using a computer to deliver television
•
•
•
Just a few years ago it seemed far-fetched:
there was not much video online that was
legal and non-pornographic; broadband
wasn’t available
That has changed. Here are some videostreaming websites: iPlayer, Hulu, YouTube
that stream billions of videos per month
Ordinary people want a cable that will allow
them to connect their computers to their
television sets
24
Three-dimensional TV is coming
Three-dimensional TV works by projecting two images
filmed from slightly different angles onto the
screen.
Battery-powered glasses ($150 for two sets) alternately
darken each lens, so each eye sees only one of two
images
“Monsters v Aliens”, “Avatar”, “My Bloody Valentine
3D”, televised sport will gain the most.
Sport is the “killer application” of today's TV
25
What is the ENERGY STAR program?


Encourages manufacturers to create energy-efficient
devices that require little power when not in use
Monitors and devices meeting guidelines display
ENERGY STAR label
What is an audio output device?

Computer component that produces music, speech,
or other sounds

Speakers and headsets are common devices
Voice output occurs when
you hear a person’s voice or
when the computer talks to
you through the speakers
• Some Web sites dedicate themselves
to providing voice output
• VoIP uses voice output and voice
input
28
Headphones are
speakers that
cover your head
or are placed
outside of the
ear
Ear buds (also
called
earphones) rest
inside the ear
canal
29
Some speakers are specifically designed to play
audio from a portable media player
 Wireless speakers
30
Printers and other
output devices
Printers
What is a printer?



Output device that
portrait
produces text and
graphics on a physical
medium (paper, film,
fabric)
The result is the hard
copy, or printout
Two orientations:
portrait
landscape
landscape
Nonimpact printer
forms characters and graphics on a piece of
paper without actually striking the paper
Ink-jet
printers
Photo
printers
Mobile
printers
Label and
postage
printers
Laser
printers
Plotters
Thermal
printers
Largeformat
printers
34
Ink-jet printer
 Ink-jet printer
sprays tiny
drops of liquid
ink onto paper
 Prints in
black-andwhite or color
on a variety of
paper types
How does an ink-jet printer work?
print head
print cartridge
firing
chamber
ink dot
bubble
resistor
nozzle
Step 1. A
Step 2. The
small resistor
heats the ink,
causing the
ink to boil and
form a vapor
bubble.
vapor
bubble
forces the
ink through
the nozzle.
ink
Step 3. Ink
drops onto
the paper.
Step 4. As the vapor
bubble collapses,
fresh ink is drawn
into the firing
chamber.
A photo printer produces color
photo-lab-quality pictures
• Most use ink-jet technology
• PictBridge allows you to print photos
directly from a digital camera
• Print from a memory card and
preview photos on a built-in LCD
screen
37
Highspeed
High
price
Highquality
Laser
printer
Blackandwhite
Color
39
How does a laser printer work?
A thermal printer generates images by pushing
electrically heated pins against the heat-sensitive
paper
Thermal waxtransfer printer
Dye-sublimation
printer
41
A mobile printer is a
small, lightweight,
battery-powered
printer that allows a
mobile user to print
from a mobile device
42
A label printer is a small printer that prints on
adhesive-type material
A postage
printer prints postage stamps
43
What is a plotter?


Sophisticated printer used to produce high-quality
drawings
Large-format printer creates photo-realistic-quality
color prints
A multifunction peripheral (MFP) is a single
device that prints, scans, copies, and sends faxes
 Sometimes called an all-in-one device
45
Impact printer
dot-matrix:
produces printed
images when tiny
wire pins strike
ribbon
band: prints fully
formed characters
using a hammer
mechanism
What is a line printer?
 High-speed impact
printer that prints
entire line at a time
Some line printers
are band printers
Others are shuttlematrix printers
Characteristics of a Printer
Price
Cost
per page
Speed
Portable/
Stationary
Resolution
System compatibility
Color vs.
black- white
Graphics and
photo printing
Paper types and sizes
Wireless capability
What is the resolution of a printer?

Sharpness and clarity

Measured by number of dots per inch (dpi) printer
can output
Terminals
What is a terminal?
Device that performs both input and output
dumb
terminals
intelligent
terminals
specialpurpose
terminals
50
What is a facsimile (fax) machine?
Device that transmits and receives documents over
telephone lines
What is a fax modem?

Extension that allows you to send and receive
electronic documents over Internet as faxes
internal fax card
in system unit
external fax
modem
fax machine
An interactive whiteboard is a touch-sensitive device,
resembling a dry-erase board, that displays the
image on a connected computer screen
53
Force-feedback sends
resistance to the device
in response to actions of
the user
Tactile output provides
the user with a physical
response from the device
54
What is a data projector?

Device
that takes
text and
images
from
computer
screen and
projects
them onto
larger
screen
Output Devices for Physically Challenged
What is the
Magnifier?

Windows
Magnifier
enlarges
text and
other
items on
screen
Output Devices for Physically Challenged
What other output options are available for visually
impaired users?
 Change Window settings,
(increase the size or
change color of text) to
make words easier to read

Blind users can work with
Windows Vista’s Narrator

Braille printer outputs
information in Braille
onto paper
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