Barcode Scanners

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Barcode Scanners

• By
• Jason Shotwell
• Shotwell_at_u.arizona.edu

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What is a scanner?

• A scanner is a device that uses a light source
  and then measures the light reflected back to it.

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What is a bar code?

• A barcode is a combination of spaces and bar of
  varying widths that comprises a record for a
  computer to decode.

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Types of Barcodes

• 1-d and 2-d barcodes

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How are barcodes ordered?
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How are barcodes ordered?

• Diagram showing spacing and how they are
  organized.

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Check Digit

• Tells the scanner if the barcode was scanned
  correctly

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Barcode Scanners

• Now that we know what a barcode is how do we add
  a scanner?

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What is a Barcode Scanner?

• A barcode scanner usually has three pieces
• Scanner - which reads or captures the code
• Decoder - which translates the code
• Computer Interface- Which makes use of the code

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Types of barcode scanners
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Wand or Pen Scanner

• Includes a light source and a photodiode next to
  each other on pen tip
• Measures reflected light intensity and generates
  a waveform according to bar widths

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Wand scanner pros and cons

• Pros
• cheapest type
• can read any size barcode
• small in size
• Cons
• Need steady hand when scanning
• Needs to be touching the barcode

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Laser scanner

• Uses a laser light source
• Usually have mirror or prism to scan light back
  and forth
• Uses a photodiode as detector

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Laser Scanner Pros and Cons

• Pros
• can be used at a good distance
• can read large barcodes easily
• Cons
• High Priced

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CCD scanners

• Uses CCD array
• measures the emmitted and not reflected light
  from the target

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CCD Scanner Pros and Cons

• Pros
• No need to swipe barcode
• Cons
• Like a camera, has certain focal position, and
  cannot read all sizes of barcodes
• Need close proximity to the barcode

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Camera scanners

• Uses small video camera to capture image of the
  barcode
• Employs Digital image processing techniques also.

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Any Questions?

• References
• www.howstuffworks.com
• www.simplyscan.com
• www.semicron.com
• www.emediaplan.com