I/O Flashcards

1
Q

What are the 4 main types of barcode reader?

A

Pen-style readers, laser scanners, CCD, camera based

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2
Q

How does a pen-style barcode readers work?

A

Physically looks like a pen that you drag across the barcode.
Contains a light source and photo diode in the tip.
The diode measures the intensity of light reflected back as it passes over the barcode.

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3
Q

How do laser scanner barcode readers work?

A

A laser is reflected of a moving mirror to read the barcode

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4
Q

How does a charge-coupled device (CCD) work?

A

Has an array of tiny light sensors in a row, that measure intensity of light

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5
Q

How does a camera based barcode work?

A

Uses a camera and image processing software

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6
Q

What are the 2 sensors in a camera?

A
CCD = high quality, more power  
CMOS = lower quality, less power
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7
Q

What happens when you take a photo on a digital camera?

A
  1. Shutter opens
  2. Light enters camera
  3. Image projected on to sensor in the lens
  4. Each tiny sensor measures brightness
  5. Turned into an electrical signal stored in binary
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8
Q

How is a coloured image produced in digital camera?

A

The sensors are placed behind coloured filters. RGB

Can either be mosaic or mirrors

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9
Q

How does a laser printer work?

A
  1. Ink stored in cartridges
  2. Print software generates bitmap
  3. Drum is negatively charged
  4. Laser draws a mirror negative onto the drum
  5. Laser light cause areas of drum to loose their charge, then rotates
  6. Charges particles are attached to areas of page not layered
  7. Particles then bonded to the page with heat and pressure
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10
Q

What is an RFID card?

A

They store information without being in line of site i.e dog tag

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11
Q

What are the 2 types of RFID?

and what are their properties?

A

Active tags - Larger, contain battery, constantly transmit signal

Passive tags - smaller, rely on radio waves to provide electromagnetic to energise antenna coil

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12
Q

Why would QR codes be used over barcode readers?

A

It can encode more complex information

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