Chapter 5 - Output devices

Question 1

What is an output device?

Answer 1

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

Question 2

What are the 3 most common types of printers?

Answer 2

laser, inkjet, dot matrix

Question 3

How do laser printers work?

Answer 3

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

Question 4

How do inkjet printers work?

Answer 4

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

Question 5

How do dot matrix printers work?

Answer 5

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

Question 6

What are the advantages of laser printers?

Answer 6

very high quality of printing
relatively inexpensive to buy printer
large toner cartridges and large paper trays
very fast printing of multiple documents

Question 7

What are the disadvantages of laser printers?

Answer 7

can be expensive to maintain

produce health hazards such as ozone or toner particles in the air

Question 8

What are the advantages of inkjet printers?

Answer 8

high quality of printing
very suitable for printing photos
inexpensive to buy printer

Question 9

What are the disadvantages of inkjet printers?

Answer 9

ink is expensive to buy and runs out quickly
usually have small paper trays
can be noisy compared to laser printer

Question 10

What are the advantages of dot matrix printers?

Answer 10

not adversely affected by damp or dusty/dirty atmospheres
allows use of multi-part stationery (carbon copies)
allows use of continuous/fan-folded stationary

Question 11

What are the disadvantages of dot matrix printers?

Answer 11

relatively expensive to buy printer
poor print quality
very noisy and slow at printing

Question 12

What are 3D printers?

Answer 12

produce actual solid objects which work

built up in the printer in a number of very thin layers of varying materials

Question 13

What is binder technology in 3D printers?

Answer 13

the use of a binder (a type of glue) to form the solid layers

Question 14

Why are 3D printers referred to as additive?

Answer 14

they build up objects layer by layer

Question 15

What are 3D printers used for?

Answer 15

making prosthetic limbs
manufacture of aerospace parts
fashion and art
making parts no longer in production by conventional manufactering

Question 16

What are 2D/3D cutters?

Answer 16

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

Question 17

What are loudspeakers?

Answer 17

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

Question 18

What is the sampling rate?

Answer 18

the rate at which the DAC can translate the digital output into analogue voltages
usually 44 100 samples/second for a 16 bit system

Question 19

How do modern liquid crystal displays/diode (LCD) monitors/televisons work?

Answer 19

backlit using LEDs rather than cold cathode fluorescent lamps (CCFLs)`

Question 20

Why do LCD monitors need to be backlit?

Answer 20

the LCD does not produce its own light

Question 21

What are the advantages of LEDs rather than CCFLs?

Answer 21

reach max brightness faster
make whiter light
brighter colour = improved colour definition
much thinner and lighter
last almost indefinitely
consume much less power

Question 22

What are OLEDs?

Answer 22

organic light emitting diodes

produce their own light and do not need back-lighting

Question 23

What are the advantages of OLED over LED?

Answer 23

very thin and flexible screens
much brighter light than LEDs
don’t require any form of backlighting
much larger field of view

Question 24

What are the two types of light projectors?

Answer 24

digital light projectors (DLP)

LCD projectors

Question 25

How do DLP projectors work?

Answer 25

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

Question 26

How do LCD projectors work?

Answer 26

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