Chapter 5 - Output devices Flashcards
What is an output device?
any piece of computer hardware equiptment used to communicate the results of data processing carried out by a computer
the device converts the computer’s digital information into a human-readable form
What are the 3 most common types of printers?
laser, inkjet, dot matrix
How do laser printers work?
rely on positive and negative charges on the print drum and paper; toner sticks to the paper in only certain areas and is permanently fixed using a fuser
How do inkjet printers work?
rely on liquid ink system which sprays ink onto the paper line by line as the paper advances; uses either thermal bubble or piezoelectric technologies
How do dot matrix printers work?
use a matrix of pins that strike an inked ribbon (either black or up to 4 coloured) to produce characters in a matrix on the paper
What are the advantages of laser printers?
very high quality of printing
relatively inexpensive to buy printer
large toner cartridges and large paper trays
very fast printing of multiple documents
What are the disadvantages of laser printers?
can be expensive to maintain
produce health hazards such as ozone or toner particles in the air
What are the advantages of inkjet printers?
high quality of printing
very suitable for printing photos
inexpensive to buy printer
What are the disadvantages of inkjet printers?
ink is expensive to buy and runs out quickly
usually have small paper trays
can be noisy compared to laser printer
What are the advantages of dot matrix printers?
not adversely affected by damp or dusty/dirty atmospheres
allows use of multi-part stationery (carbon copies)
allows use of continuous/fan-folded stationary
What are the disadvantages of dot matrix printers?
relatively expensive to buy printer
poor print quality
very noisy and slow at printing
What are 3D printers?
produce actual solid objects which work
built up in the printer in a number of very thin layers of varying materials
What is binder technology in 3D printers?
the use of a binder (a type of glue) to form the solid layers
Why are 3D printers referred to as additive?
they build up objects layer by layer
What are 3D printers used for?
making prosthetic limbs
manufacture of aerospace parts
fashion and art
making parts no longer in production by conventional manufactering
What are 2D/3D cutters?
machines used to cut into materials to form 3D objects and are controlled by computers and software such as CAD
materials include; glass, crystal, metal, wood, polymers
What are loudspeakers?
loudspeakers convert analogue voltages into sound
if the output is from a computer, the digital signals are first converted into analogue voltages using a DAC
What is the sampling rate?
the rate at which the DAC can translate the digital output into analogue voltages
usually 44 100 samples/second for a 16 bit system
How do modern liquid crystal displays/diode (LCD) monitors/televisons work?
backlit using LEDs rather than cold cathode fluorescent lamps (CCFLs)`
Why do LCD monitors need to be backlit?
the LCD does not produce its own light
What are the advantages of LEDs rather than CCFLs?
reach max brightness faster make whiter light brighter colour = improved colour definition much thinner and lighter last almost indefinitely consume much less power
What are OLEDs?
organic light emitting diodes
produce their own light and do not need back-lighting
What are the advantages of OLED over LED?
very thin and flexible screens
much brighter light than LEDs
don’t require any form of backlighting
much larger field of view
What are the two types of light projectors?
digital light projectors (DLP)
LCD projectors
How do DLP projectors work?
millions of miro-mirrors
turn on or off several thousand times a second creating various shades of grey
colour filters change the grey into colours
which are projected onto a larger screen
How do LCD projectors work?
use chromatic coated mirrors which reflect light at different wavelengths
light components pass through three LCD screens
recombined using a prism to produce the colour image onto a larger screen
