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Scanning

 

Types of scanners    Capabilities    Selection Process    Resolution     Ergonomics    Throughput

 

 

Types of Scanners:

  • Hand Held  - Wands, CCD's, Laser Scanners, Imagers
  • Fixed Position  - Laser Scanners, Imagers
  • Hands Free - Laser Scanners, CCD's, Imagers
  • Conveyor - Laser Scanners, Imagers
  • Flat Bed (Slot Scanners) - Laser Scanners

Most of these come either in hand-held and/or fixed-mount (position) versions. Some, such as presentation scanners, fixed-mount conveyor scanners, imagers, and some hand held laser scanners will be able to scan the bar code in any orientation (omnidirectionally).

Capabilities:

Different types of scanners have different capabilities:

Wands

A wand is a pen-type scanner that requires physical contact with a bar code when scanning. The wand is simple to use but requires the user to keep a constant scanning motion at a consistent speed across the barcode. It is usually the least expensive (and least accurate) scanning device. Best angle to hold the pen and scan is typically 60 degrees.

CCD's
 
Charged Coupled Devices (CCD's) are either contact or short range non-contact scanners that need to be in close proximity with the barcode when scanning. Its use is simple. Just cover the barcode with the head of the scanner and the barcode is read.  Some CCD readers employ a trigger to activate the reader.
 
Laser Scanners
 
Laser scanners are non-contact scanners which typically use a visible diode laser to read a barcode. Laser scanners can be activated by pulling a trigger or by sensing an object when it is placed in front of the scanner. Laser scanners are aggressive scanners that are better at reading barcodes from a distance. They also read poorly printed bar codes better than other types of scanners.
 
Imagers
 
Imagers are non-contact scanners that take a picture of a barcode and are designed to read two-dimensional matrix symbols. They read all barcodes omni-directionally. Imagers can be activated by pulling a trigger or by sensing an object when it is placed in front of the scanner. Imagers are fairly agressive scanners that have a shorter reading range than laser scanners.

 

Scanner Selection

Here are some things to consider when selecting a scanner:

  • What is the minimum and maximum distance between the scanner and the bar code?
  • Which symbologies will you be scanning?
    • Do you need a scanner that can read two-dimensional symbols?
  • The "X" dimension of your bar codes will determine the resolution of the scanner you need.
  • Do you need to scan more than one symbology? If so, select a scanner with autodiscrimination capability.
  • Ensure that the scanner interface connects to your host system.
  • What environmental characteristics does the scanner need to meet your production environment?
    • Indoor; outdoor; noise; dust; sunlight; heat; cold; wet
  • Long range scanner for distance scanning
  • Does the application require a fixed-position scanner, a hand-held scanner, or a hands-free scanner?
  • Do you need to send and/or receive data in real time?

A specific point to remember for 2D:

  • 2D symbols have specific requirements; make sure your scanner is capable of reading your symbology.

A scanner that reads Data Matrix will also read the other 2D symbologies and the linear symbologies. A scanner that reads PDF417 may not be able to read the other matrix symbologies but will read all linear symbologies.

Scanner Resolution

The optical qualities of the scanner determine the resolution of the scanner. No scanner can read every possible resolution, but all of them can read the range of resolutions allowed within an application standard. In order to pick the correct resolution you need to know the following:

  • The minimum and maximum "X" dimensions for the bar codes used in the application
  • The minimum and maximum widths of the bar codes used in the application
  • The minimum and maximum scanning distances required by the application

When you have a large number of data characters to read, you must make sure that the entire symbol is in the scanners field of view at the required reading distance.

Scanner Ergonomics

Your application will not succeed if your workforce cant operate the scanner productively because the ergonomics make the scanner difficult to use.

  • Is the scanner comfortable to use?
  • How heavy is the scanner?
  • Will you require accessories such as shoulder straps, holster, etc.?
  • How well does it balance in the hand?
  • Is the trigger (if available) easy to use?
  • If it is tethered to a portable terminal, is the combination easy to use?

Scanner Throughput

Typically, a low throughput application uses a hand-held scanner and an extremely high throughput application requires an unattended fixed-position scanner. How often will the bar codes in the application be scanned? At the same time, determine if you require unattended or attended scanning and hand-held or fixed-position scanning.  Ask yourself the following questions:

  • What are the maximum number of scans per hour?
  • Do you need to take the scanner to the bar code?
  • Will the item be delivered to the scanner?
  • What are the minimum and maximum dimensions of the packaging?
  • If this is a conveyor application, what is the conveyor speed?
  • Does the height of the packaging vary?
  • Do variations in the dimensions of the packaging make hand-held or fixed-position scanning difficult?