Input Devices

Question 1

Two dimensional Scanners

Answer 1

• Used to hard copy documents, converted to electronic form for storage
  *Uses OCR
• If the original document was a photo it will be scanned as a jpeg

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Question 2

What is OCR

Answer 2

Optical Character recognition. A software which converts scanned documents to text file format

Question 3

How does a Two dimensional scanner work?

Answer 3

• Place document
• Light illuminates
• scan head is moved acrossed the document
• Lens focus image
• The image falls onto a charge couple device which consists of a umber of integrated circuits
• Software creates a digital copy

Question 4

Three dimensional scanner

Answer 4

• Can scan solid objects
• Can be used in Computer aided design (CAD) or to a 3d printer

Question 5

Applications of 2d scanners at airport

Answer 5

• Produce digital images which respresent passport
• Text can be stored as ASCII
• 2D photograph can be saved as JPEG
• Passengers face is photographed
• Key parts of face are compared (Distance between Eyes)

Question 6

barcode readers

Answer 6

• Numbered parallel lines are thick or thin of varying thickness
• numbers 0-9 are represented by a unique series of lines
• left and right are just guard lines
• Lasers are redirected depending on dark or light areas
• pattern is converted to digital

Question 7

(QR)

Answer 7

Quick Response

Question 8

QR codes

Answer 8

• Another barcode
• Matric of dark squares on a light background
• hold up to 7000 digits
• can store website addresses

Question 9

digital cameras

Answer 9

• Controlled by a microprocessor, which automatically adjusts the shutter speed and focuses the image
• light is captured onto a light sensitive cell
• cell is made of pixels
• number of pixels determine size of file

Question 10

Keyboards

Answer 10

• Conntected to computer wired or wireless
• Each character has an ASCII value and is converted to a digital signal
• slow
• prone to errors

Question 11

Pointing devices

Answer 11

Mouses use red LEDS to detect movement

Question 12

Microphones

Answer 12

• used to input sound
• picks up a ound, a diaphram vibrates producing an electrical signal
• signal goes to sound card
• voice recognition

Question 13

Types of touchscreens

Answer 13

• Capacitative
• Infrared HEAT
• Infrated OPTICAL
  Resistive

Question 14

Touchscreen

Answer 14

• Medium cost
• layers of glass creating electrical fields
• when touched current changes and co-ordinates are determined by on board microprocessor

Question 15

Infrared HEAT

Answer 15

• Expensive
• Uses glass
• needs a warm object to carry an input

Question 16

Infrared OPTICAL

Answer 16

• Expensive
• Uses glass as a screen
• Array of sensors in grid form
• Point of contact is based of co-ordinates

Question 17

Resistive

Answer 17

• Inexpensive
• Upper layer is polyester
• Top and bottom touch to complete a circuit
• signals are then sent and processed

Question 18

Sensors

Answer 18

• Devices measure physical properties
• Data needs to be converted to digital
• Analogue to digital converter

Question 19

Control of street lighting

Answer 19

• Light sensor sends data to ADC
• If data is less than specific value, signal is sent and lamp is switched on