Transcript Output Devices

Input Devices
Backing Storage
PROCESSOR
Main Memory
Output Devices
Output Devices
Translates signals from the computer into a humanreadable form.
• Printers
• Plotters
• Monitor
• VDU
• Liquid Crystal Display (LCD)
• Thin Film Transistor (TFT)
• Sound Card
• Graphics Card
• Specialised output device for disabled users and virtual
reality
• Output devices for Multimedia
Printers
A device which is used to produce a printout (Hard Copy)
for the output from a computer.
• Laser Printer
• Inkjet Printers
• Photo Printers
Laser Printer
Use a special powder called toner to produce the image
on the paper. A laser beam is used to project the image
of the page to be printed onto a cylinder known as a
drum.
Inkjet Printer
A type of printer that sprays tiny streams of quick-drying
ink onto paper.
The number of holes on the print head determines the
printers resolution.
Photo Printer
photo printer is a printer (usually an inkjet printer) that is
specifically designed to print high quality digital photos
on photo paper. These printers usually have a very high
number of nozzles and are capable of printing droplets
as small as 2 picoliters.
(trillionth part of a litre)
Laser vs Inkjet
Resolution
A printers accuracy is known as its resolution. Resolution measured in
dots per inch (dpi).
Inexpensive colour laser printer will be
between 1200 x 600 dpi to 2400.
And a higher-end colour laser will have
a resolution between 2400 x 1200 dpi
to 2400.
Laser prints from 4 to 32
ppm
Inexpensive inkjet printer will be
between 1200 x 1200 dots per inch
(dpi) to 2400
And a higher-end inkjet printer will
have a resolution between 2400 x
1200 dpi to 4800.
A lasers printer ranges from
£100 - £2000.
An inkjet prints from 2 to 15
ppm
An inkjet ranges from £30 £300.
Toner can range from £30 £200 (3000 – 8000 pages)
Ink cartridges range from
£10-£15 (500 – 900 pages)
Cost
Capital cost is how much it cost to purchase the printer.
Running cost is how much it costs to use the printer.
A lasers printer ranges from
£100 - £2000.
An inkjet ranges from £30 £300.
Toner can range from £30 £200 (3000 – 8000 pages)
Ink cartridges range from
£10-£15 (500 – 900 pages)
Plotter
A printing device that draws images on paper using ink
pens or pencils.
Plotters are capable of producing very accurate large
scale drawings and are most often used in computer
aided design (CAD).
Monitors
Monitor accepts video signals directly from the computer
and displays the output on a screen.
A high resolution monitor will be able to show very fine
detail on the screen compared to a low resolution.
Types of monitors:
Cathode Ray Tube (CRT)
Liquid Crystal Display (LCD)
Cathode Ray Tube (CRT)
Most common type of monitor. The electron gun in a
video display monitor that generates the focused beam
that creates an image on the monitor's screen.
Liquid Crystal Display (LCD)
Consists of thin layer of fluid sandwiched between two
sheets of plastic. Complicated wiring is used to apply
voltage to different parts of the screen.
Thin Film Transistor (TFT)
A type of LCD flat panel display screen in which each
pixel is controlled by one to four transistors.
The TFT technology provides the best resolution of all
the flat panel techniques, but it is also the most
expensive. TFT screens are sometimes called active
matrix LCDs.
Advantages LCD
• LCD are smaller and lighter. (Portable)
• LCD use less power (15-20 watts) Ideal for laptops and
palmtops.
• LCD do not flicker or give out static electricity or any
other type of radiation.
• Do not suffer reduction in viewable size – 17 inch LCD
screen has full view of 17 inch.
Loudspeakers
Most computers have built-in loud speakers or can be
connected to one or more loudspeakers.
Sound Card
Sound is analogue in nature, it is continuously varying
quantity. Computers work in digital quantities. In order
to output sound from a computer the sound must be
changed from digital to analogue.
This process is called digital to analogue conversion.
(DAC)
Speakers would
be plugged into
the sound card
socket.
Graphics Card
Device which controls the quality of output on a monitor.
Graphic card contain a large quantity of RAM and can
support different types of screen resolution.
Monitor
would be
plugged
into the
socket
Specialised user interface
Questions
Internet cafe
1. Jill has some systems set up with voice output
capability. Describe a situation where this might be
useful for a customer to use.
2. What output device is required for voice output?
3. What does LCD stand for?
4.What does TFT stand for?