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CS > 4 > Flashcards

4 Flashcards

1
Q

Input devices

A

transfer data from the source in the outside world to the computer

Examples include:
Keyboards
Mice
Digital cameras
Microphones

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2
Q

Types of Touchscreens

A

Resistive
Capacitive
Infra-red

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3
Q

Resistive touchscreens

A

Resistive touchscreens are made up of a layer of conductive polyester and a layer of conductive glass
- your fingers make those 2 layers touch

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4
Q

Capacitive touchscreens

A

Capacitive touchscreens are made up of glass layers
-When the screen is touched by a finger, there is a change in the electric field at that position. That position is then calculated by a microprocessor
-can be touched in more than one place at a time

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5
Q

Infra-red touchscreens

A

LEDs shine infra-red light across the screen from the edges and the infra-red rays form a grid across the screen
-When the screen is touched by a finger, the infra-red beam is interrupted

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6
Q

advantages and disadvantages of

A

-Capacitive screen have a smooth surface
-They are very easy to press
-They are highly accurate

-Capacitive screens don’t work if the
user is wearing gloves

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7
Q

Barcode readers

A

UPC-A systems:
This uses long guard bars to show the start and end of the barcode
Left hand codes- odd number of black bars.
Right hand codes- even number

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8
Q

Digital cameras

A

Digital cameras focus light onto a CCD sensor

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9
Q

3D scanners

A

3D scanners use a laser to
scan across an object

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10
Q

2D Scanners

A

These are used to convert documents or photographs into a digital format.
Examples:
Multi-function printers
Photocopiers
They can contain:

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11
Q

Describe how barcodes are used within supermarkets today.

A

Each product has a barcode located on it.

The barcode is scanned by a handheld scanner / at the checkout.

The computer processes the barcode to find its barcode/ID number.

The item is looked up to find the product name and price.

The stock in the shop is automatically updated.

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12
Q

Give two other applications of barcodes.

A

Uses may include:
Library books and library cards.
Tracking luggage at airports.
Tracking packages.

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13
Q

Why use barcodes?

A
  • It is faster to scan products than enter a price in to a till
  • no stock control necessary
  • Barcodes reveal a number that identifies each product. This allows a shop to determine how many items are sold
    -Saves the need for shop workers to manually check stock levels
  • Prices can be changed without needing to update the price on each product
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14
Q

QR codes

A

QR codes are 2D barcodes and can be read by smartphones or tablets
They contain:
Links to websites or
Information

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15
Q

Uses of QR codes in society

A

Tracking packages
Restaurant menus
Mobile concert tickets
Tourist info

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16
Q

uses for 3D sanners

A

Checking parts for faults.
Tomography
MRI scans.
Medicine

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17
Q

Gas sensor

A

Detecting CO2 levels
Detecting O2 levels
Detecting CO (carbon monoxide) levels in a home alarm

18
Q

pH sensor

A

Detecting the acidity of soil
Detecting the acidity of liquids

19
Q

Light sensor

A

Automatic turning on of car lights
Turning on street lights

20
Q

Level sensor

A

Finding how much fuel is left in a car
Finding the amount of grain stored

21
Q

Pressure sensor

A

Detecting if someone is standing on a special mat at an entrance
Detecting how much air is in a car tyre

22
Q

Infra-red sensor

A

Security lights
Detecting movement in alarm systems

23
Q

Moisture sensor

A

control or monitor the dampness of soil in a greenhouse
measure water content in a lawn for an automatic watering system

24
Q

Humidity sensor

A

monitor the humidity in the air of a greenhouse
control a dehumidifier in a home

25
Q

Flow

A

measure how quickly a chemical is moving through a pipe in a chemical plant
measure the speed of water in water pipes

26
Q

Magnetic field

A

used in smart phones so they know which direction it is pointing
used in the motors of CD players

27
Q

Acoustic

A

pick up noise levels (e.g. footsteps) in a burglar alarm system
detect the noise of liquids dripping from a pipe in an oil refinery

28
Q

Output devices

A

transfer data produced by a computer and turn it into a human-readable form
Examples include:
Displays and projectors
Printers
Speakers
Actuators

29
Q

Speakers and headphones

A

Digital data is sent from the computer to a Digital to Analogue Converter (DAC) where it is converted into an analogue signal

30
Q

Actuators

A

Actuators are output devices used to move mechanisms or systems
examples include:
Central locking on cars
Opening and closing valves on pipes

31
Q

LCD screens

A
  • Liquid Crystal Display (LCD) screens are made from millions of pixels.
  • The pixels are switched on or off very rapidly to make the moving colour picture
    -LCD screens are backlit with a fluorescent backlight
32
Q

LED screens

A

LED screens use LEDs (light emitting diodes) to light them

33
Q

advantages of LCD

A
  • cheaper to produce
  • better contrast / sharper image
  • more energy efficient.
34
Q

advantages of LED

A

-very bright
-suitable for outdoors
-good for shows with big screens

35
Q

There are two types of technology that are used in projectors.State what each technology is and describe how it works.

A

DLP uses millions of micro mirrors on a small microchip within a single projector. When these micro mirrors are tilted towards the light source, they are on, if they are tilted away from the light source, they are off. The micro-mirrors can switch between ‘on’ and ‘off’ thousands of times a second creating different and changing shades of grey light.

DLP projectors have a mirror for each pixel and a rotating wheel with the colours red, green and blue

As well as LCD works in a way where screens are made from millions of pixels, each pixel separates red, green and blue lights that can be switched on and off electronically using liquid crystals. They are switched on and off very fast to make moving colour pictures.

LCD projectors use three LCD screens, one for red, green and blue. The three images are then combined into colour

36
Q

Laser printers

A

A laser scans across a print drum and apply electro change
The drum will pick up the dry powder know as toner, and the toner sticked to paper
The heated fuser makes sure that toner does not come of the page
A page is printed quickly and the quality is high for text.

37
Q

3D printers

A

A plastic is squeezed from the head (the nozzle) .
A 3D model is built up in layers from top to bottom going side to side and up and down.

38
Q

Inkjet printers

A

Thermal bubble:
Droplets of ink are produced using a thermal bubble
- behind the print nozzles there are resistors that create heat
- The heat causes tiny bubbles to form inside
- As each bubble
expands, ink is ejected onto the paper
- As it cools, the bubble collapses and draws in fresh ink and the process continues until the page is printed

Piezoelectric crystal:
small piezoelectric crystal is located at the top of each ink reservoir of each nozzle
- When the crystal receives a small electric current
- As it vibrates, ink is ejected onto the paper
- new ink comes to replace
-this is repated until page is printed

39
Q

Benefits and drawbacks of thermal bubble

A
  • Less expensive technology than piezoelectric
  • Possible to use more print nozzles
  • Produces larger droplet sizes
  • Only certain inks can be used because of the high heat
  • More maintenance needed because of the high temperatures involved
40
Q

Benefits and drawbacks of Piezoelectric crystal

A
  • Very precise ink drop sizes can be produced
  • Wide range of ink types can be used
  • Can produce very small ink droplets
  • Can run for longer since less heat is generated
  • More expensive technology than thermal bubble
  • Can use fewer print heads
41
Q

State two other uses for 3D printers.

A

Spare parts (such as for cars)
models for houses
prosthetics
medicine

CS (7 decks)

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