Topic: Output devices
1. lesson: Workstation, Monitors
2. lesson: Monitors (Price, Screen size, Aperture grill pitch (dot pitch), Maximum resolution,
Refresh rate, Safety standards, Power-saving features, On-screen menu), CRT and LCD
technology
3. lesson: Printers, flowchart (to choose a printer)
4. lesson: Revision (questions about monitors and printers)
Output devices
WORKSTATION
It is common for people to spend long periods of time in front of a computer. This can be harmful
to their health unless they follow a few simple guidelines. It is important that they remain relaxed
and comfortable and that they avoid eyestrain. To achieve this, they must have appropriate
furniture, lighting, and computer equipment -and must make sure that it is positioned correctly.
Chair should be adjustable and provide good back support. Printer should be more than a metre
away from you as quiet as possible. Monitor screen should level with your eyes. Make sure it is
flicker-free, and that you can read everything easily. Avoid any glare from the window. Lamp
should light your work and not the screen.
The term workstation is sometimes used to describe a very powerful desktop computer but also it
refers to the furniture and environment used for working with a computer.
MONITORS
A monitor is the most common type of output device. It displays the output from the computer on
a screen. The display image on a monitor screen can be thought of as being made up of a series of
dots. The quality of the image depends on a number of factors including: the number of dots (the
resolution), the space between dots (the aperture grill pitch (or dot pitch)), how often the dots are
refreshed by the beam of light (the refresh rate), the size of the dots (the size of the screen and the
resolution).
If you describe a (or your) monitor, mention the following:
Price
The price mainly depends on the screen size but also on aperture grill pitch, resolution, and the
number of controls.
Screen size
The size of the screen is the diagonal distance from one corner to another. The actual area for
images is smaller than this. Common monitor sizes are 15-inch, 17-inch, 19-inch and 21-inch.
Aperture grill pitch (dot pitch)
This controls the space between the dots which make up the image. The less space between the
dots, the better the display. Most monitors offer 0.25mm dot pitch but some go as high as
0.31mm or as low as 0.22mm.
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Maximum resolution
The quality of the display depends on the number of dots which make up the image. The more
dots, the better the display.
Refresh rate
The monitor refreshes the image on the screen all the time. The faster this happens, the less the
screen flickers. You should have a refresh rate of at least 72Hz.
Safety standards
These are international standards to control harmful signals.
Power-saving features
The power the monitor uses automatically reduces when it is not in use.
On-screen menu
Digital controls on the screen allow you to adjust the image.
Give details about your monitor:
Screen size
Aperture grill pitch
Maximum resolution
Refresh rate
Price
Have you noticed how much your computer screen flickers? This may be because your computer
monitor uses CRT technology. This kind of technology offers colour and high-resolution pictures
for relatively little money but the monitors are large, use a lot of energy, can flicker and emit
electromagnetic radiation.
In recent years flat screens have become increasingly popular. Users talk of benefits such as more
desk space, how easy they are to adjust for tilt and height, crisper, clearer images and the total
elimination of screen flicker. It’s like having a different PC, they say, a new window on the
world.
Most flat screens are based on LCD technology which has a lot of benefits over CRT
technology:
 LCDs are flat, CRT monitors are not, so LCDs require much less space
 LCDs use less power than CRTs
 LCDs are distortion-free while typical CRTs are curved, which may cause image distortion
 most LCD displays use a TFT system offering a wider angle of vision and high-quality
images.
But there is one major drawback to flat screens: their cost. They are expensive compared with
CRT monitors. Prices are falling, however, and they’ll soon find their way into homes, schools
and businesses.
Monitor manufacturers like Philips, Apple, Sharp or Panasonic offer compatible flat screens
including built-in stereo speakers, headphone connection, and a USB port. Some models can also
be removed from the stand and mounted on the wall. They come with stylish designs for a variety
of applications. LCDs range from small-size PC screens and TVs to large-screen projectors.
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Questions:
What does `LCD' stand for? What type of computers use LCD displays?
What does the price of a computer depend on?
What is the common monitor size?
What is the function of aperture grill pitch (dot pitch)?
What is the common dot pitch?
What is maximum resolution?
What is refresh rate?
PRINTERS
A printer is a very common output device. It is used to print the computer output on paper.
Colour printers are available but sometimes printing is done using a mono printer that prints only
in black.
There are many different types of printer. These include for example inkjet, mono laser, and dye
sublimation printers. The more you pay, the better the printer.
Inkjet printers are the cheapest, but their print quality is not as good as the other two types of
printer. They are expensive to run compared to mono laser printers, but are able to print in colour.
Inkjets are the noisiest of the three types of printer.
Mono laser printers are more expensive than inkjet printers but give you a better quality of
black and white output. They cannot print in colour, but are the fastest type of printer and cost the
least to run.
Dye sublimation printers are the most expensive type of printer, but their print quality is
extremely high. They are quiet in operation, but are relatively slow and very expensive to run.
Dot-matrix printers use pins to print the dots required to shape a character. They print text and
graphics and nowadays some of them can print up to 450 characters per second (cps); however,
they produce relatively low resolution output - 72 or 144 dots per inch. They are slower than laser
printers but much cheaper.
Plotters are a special kind of printer. Plotters use ink and fine pens held in a carriage to draw
very detailed designs on paper. They are used for construction plans, engineering drawings and
other technical illustrations.
Questions:
How many types of printer do you know?
What printers are quieter than dot-matrix printers?
What type of printer do you have?
What is the print quality like?
How fast is it?
Does it cost a lot to run?
How noisy is it?
Is it expensive?
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Look at the flowchart for choosing a printer and answer following questions:
When should you buy an inkjet printer?
When should you buy a mono laser printer?
When should you buy a colour inkjet printer?
When should you buy a colour laser printer?
When should you buy a dot-matrix printer?
TO CHOOSE A PRINTER
Do you need to print
on multi-part forms?
YES
Buy a dot-matrix printer
NO
Do you need to
print in colour?
YES
NO
Buy an inkjet printer
Buy a colour laser printer
NO
Are print speed or
quality important?
NO
YES
Do you need
a fast printer?
Buy a colour inkjet printer
YES
Buy a mono laser printer
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