Output devices

Question 1

Output device

Answer 1

A device that allows the user to view/hear data from a computer system

Question 2

Inkjet printer

Answer 2

1. rollers are automatically feeds paper through the printer
2. a moving print head which consists of nozzles moves across the paper via stepper motor and belt
3. nozzles spray ink onto the paper from a cartridge filled with liquid ink(cyan, yellow, magenta and black)
4. different coloured inks are mixed to create the colours
5. technology can be piezoelectric or thermal bubble

Question 3

Thermal bubble

Answer 3

1. Behind hundred of print nozzles are tiny resistors that create heat
2. ink is heated, vaporised and forms tiny bubbles
3. as bubble expands, ink pushes through nozzle and is ejected onto paper
4. As it cools and condenses, bubble collapses and draws in fresh ink

Question 4

Piezoelectric crystal

Answer 4

1. At rear end of each ink reservoir of each nozzle is a piezoelectrical crystal
2. when the crystal receives a small electric current, it begins to vibrate in and out
3. As it vibrates inwards, ink is ejected onto paper
4. As it vibrates outwards, new ink is drawn in to replace it

Question 5

2 advantages of thermal bubble

Answer 5

less expensive

possible to use more print nozzles

Question 6

3 disadvantages of thermal bubble

Answer 6

produces larger droplets
only certain inks can be used because of high heat
more maintenance needed because of high temp

Question 7

3 advantages of Piezoelectrical crystal

Answer 7

precise, smaller ink drop sizes
wide range of ink types can be used
can run longer because less heat is generated

Question 8

2 disadvantages of Piezoelectrical crystal

Answer 8

more expensive

uses fewer print heads

Question 9

Printer interrupt

Answer 9

signals sent to processor which cause it stop to service the interrupt

Question 10

Printer driver

Answer 10

software that converts data to be printed in a form specific to given printer

Question 11

Printer bufffer

Answer 11

temporary memory which stores data until it is ready to be uses

allows processor to carry out other tasks whilst slow printing process continues in background

Question 12

Laser printer

Answer 12

1. uses toner(powdered ink)
2. drum is positively charged
3. laser reverses the charge on parts of the drum to create an image of the page to be printed
4. the positively charged toner stick to the negatively charged parts of the drum
5. the toner is transferred to the paper
6. the toner is fused by heated rollers

Question 13

2 advantages of inkjet printer

Answer 13

cheap to buy

print on many media types

Question 14

3 disadvantages of inkjet printer

Answer 14

frequent ink changes needed
noisy
ink is expensive

Question 15

4 advantages of laser printer

Answer 15

larger ink cartridges
cost per page is less
quieter
faster

Question 16

3 disadvantages of laser printer

Answer 16

produces particulates and ozone gas
maintenance is expensive
physically larger

Question 17

3d printer

Answer 17

used to create 3 dimensional objects from 3d computer model

computer model created by 3d scanner or CAD software

additive manufacturing - layering material from ground up

Question 18

5 uses of 3d printer

Answer 18

prosthetic limbs
reconstructive surgery
food
parts for items no longer in production
prototyping

Question 19

2D cutter

Answer 19

cutting holes or shapes into flat 2d surface

uses x-y plane

Question 20

3d cutter

Answer 20

cutting holes or shapes into flat 3d surface
rotates and cuts at many angles
uses x-y-z plane

Question 21

Speakers and headphones

Answer 21

digital data is sent from computer to DAC where it is converted into analogue signal
signal is boosted using amplifier and is sent to speaker

Question 22

Actuator

Answer 22

electromechanical device
e.g. motor, relay or solenoid
responsible for moving and controlling system or mechanism
used in many control applications involving sensors and microprocessors

Question 23

Liquid crystal display screen

Answer 23

1. Uses fluorescent lamp as backlighting
2. Contains groups of red, green and blue light filters to form each pixel
3. Liquid crystals are manipulated to allow different amount of fluorescent back light through individual RGB filters at front of screen

Question 24

Light Emitting Diode screens

Answer 24

1. Uses small LED bulbs to provide light

2. crystals are manipulated to block/ let light through to individual RGB filters at the front of the screen

Question 25

7 advantages of LED screens

Answer 25

allows delocalised dimming of screen( because can't be turned off) produces deeper blacks reach maximum brightness quickly sharper image with more realistic colours thinner more reliable -last indefinitely consume little power(produce little heat and lower costs)

Question 26

Organic Light-Emitting Diode screens

Answer 26

1. When an electric field is applied to the electrodes they give off light 2. Electrons flow from the cathode to the positive anode 3. Holes represent space for a missing electron 4. When the holes meet electrons they cancel each other out and emit energy in the form of light 5. A set of red, green and blue OLEDs work like a LCD pixel 6. No backlight

Question 27

6 advantages of OLED

Answer 27

``` thinner and lighter made of plastic - flexible brighter light is emitted generate own light so no need for complexity of backlighting larger field of view faster refresh rate ```

Question 28

3 disadvantages of OLED

Answer 28

increased production cost OLED layers wear out 4x faster affected by water and other contaminants

Question 29

LCD projector

Answer 29

1. lamp light is split from white into red, green and blue using dichroic mirrors 2. RGB light channels are passed through separate LCD screens, one for each of 3 colours 3. The screens determine how much RGB is present in final image 4. RGB light is then reassembled into single light beams 5. Magnified out of projector using lenses

Question 30

Digital light projectors

Answer 30

1. Strong white light passes through colour filters on rapidly spinning wheel 2. This converts light into red, green or blue light 3. DLP micro chip has millions of mirrors that correspond to a single pixel - tilted towards light = one - tilted away light = off 4. The mirrors switch between on and off thousands of times a second, creating different and changing shades of grey light 5. The coloured light and grey is combined to create different colours 6. The image is projected