1. بنام خدا کاربرد کامپیوتر در مهندسی صنایع (21774( Lecture 9 The barcode

2. Barcode SYMBOLOGIES

3. Bar Code Scanner (Most Commonly Used) Input Devices
Wands
Lasers
CCD
Fixed Mount

4. Wands Advantage Low Cost Disadvantage Low Read Rates Acceleration
QZ violation
Scanning fast
Scanning slow
Hand Held, Contact Reader
Scanning motion provided by operator
Illuminates with light focused through aperature (spot), then reflected back

5. Laser Hand Held or Fixed Reader Most Popular
Scanning provided by internal electromechanical system
Fast Scan Times (< 1 sec.)
High Read Rates (> 40 scans/sec)

6. Long Range Scanner
Long Range Scanner

7. CCD Scanners (Charge-Coupled Device)
Scans the received light path as a whole
Image of BCS is optically transferred to a linear array of multiple adjacent photodiodes
At least two photodiodes are covered by one narrow element (one Z length)
Scans by electrically scanning each individual photodiode in a sequential manner

8. CCD Array of Photodiode Sensors Advantages Disadvantages
Linear or Matrix
Advantages
No Moving Parts (Rugged)
Less Expensive than Laser
Smaller than Laser
Disadvantages
DOF < 1’’

9. 2D CCD Reader

10. Fixed Mount, Moving Beam Scanners
Used in untended environment (auto sortation, Mat. Handling)
Internal scanning ( scans/sec)
Factors to control for 4-5 complete scanning opportunities
Scanning line length
Scanning rate
Bar height
Symbol orientation
Conveyer speed

11. Fixed Mount Scanner

12. Reader Selection Criteria
Number of Readers
Cleanliness of Environment
Cost
Basic Reader Requirements
Recommendation:
Test various readers
Read Rate - Read Time
Ruggedness - Ergonomics

13. Two Dimensional Symbologies
Module 6

14. Linear Symbologies Scan Path: Single Continuous Line
Length = f(x, amount of data)
Standard height equals 15% of the symbol’s length
Problem: Required data exceeds physical space
4-20 characters
“License Plate”
Error Detection

15. Two-Dimensional Symbologies
MaxiCode
DataMatrix
PDF417
High data capacities
Space efficient
Stores data file rather than lookup key
Error Correction
Currently over 24 2-D symbologies

16. Premise of 2-D Symbologies
“To encode and print the largest amount of machine readable information in the smallest possible area”

17. 2-D Main Issues How to keep track of rows.
How to handle scan lines that cross between rows.
How to detect and/or correct localized errors.

18. Structure --Stacked--
Data encoded in Linear Fashion
Multiple Rows
Often Rectangular Shape
Scanned with Conventional Scanners S T A R L 1 O P d
n-1
n-2 c
k-1
k-2
QUIET
ZONE
ERROR CORRECTION AREA
LEFT ROW
INDICATORS
RIGHT ROW
DATA CODEWORD AREA

19. Structure --Matrix-- Represent binary code Array/Checkerboard Pattern
Square in shape
Perimeter Border/Center Target
Read by determining color of each cell
Uses CCD Reader Technology

20. Structure --Composite-
Short and long messages
The linear symbology decoded by conventional laser scanners
the 2-D component decoded by CCD or rastering laser scanner
Two different components of the overall symbol are linked

21. 2-D Symbologies --Features--
Data Capacity
Error Correction
Orientation Independence
Edge Independence

22. Data Capacity
May contain up to 1800 characters in much smaller symbol

23. Error Correction Allow up to 50% of the symbol to be destroyed
Typically utilize
Reed-Solomon
Algorithms for
Error Correction

24. Orientation Independence
Read at any angle
(Matrix Symbologies only)

25. Edge Independence Do not depend on element thickness
Allows printing/reading tolerances to be reduced
Can print at microscopic level

26. 2-D Symbology Standards
MaxiCode
DataMatrix
PDF417
Currently over 24 different 2-D symbologies

27. MaxiCode Developed by UPS for Automatic Sortation & Tracking
1 in. square array with bullseye Finder Pattern
92 Characters: Fixed length, 596 bit with substantial redundancy
Read Rate ==> 14 symbols/second
Conveyor Speeds ==> 500 ft/min.

28. PDF417 Defacto standard for most hand held 2-D scanning applications
Capacity: 3 to 90 rows; 1 to 30 char/row; 1,850 alphanumeric Characters
Error Correction: Eight Levels
Scan Time: < 1 second for many applications
Used when Symbol Size is less of an issue

29. Typical PDF417 Applications
Driver License Registrations
U.S. Military ID Cards
EDI Transactions
Quality Conveyance
Configuration Management
Material Safety Data Sheets
Warranty Claims

30. DataMatrix Checkerboard Arrangement of Black & White Squares
Perimeter Border to id. symbol, cell location, orientation
Can be read with contrast as low as 20%
Two versions: ECC and ECC 200
ECC 200: a 144 module square holds either 3116 digits or 2335 alpha chars
Used for Small Component Marking
Standard for the electronics industry

31. Commonly Asked Questions
Are 2-D symbologies really useful?
Do they, or will they, make linear bar codes obsolete?
What are the 2-D symbologies good for?

32. Attributes of 2-D Symbologies
Symbology
PDF-417
Maxi Code
Data Matrix
AIM Standard
Yes
In Process
ANSI MH10.8 Selected
Configuration
Rectangle
Square
Element Magnification
Variable
Fixed
Error Detecting
Yes, strong
Error Correcting
Selectable or Fixed
S, 9 levels
S, 13 levels
Data Capacity
1850 A/N
93 A/N
A/N
Minimum Printed Element Size
0.0075²
0.0035²
0.006²
Min. Etched Element Size
0.001²
Label Printer
Yes, many

33. Attributes of 2-D Symbologies
Symbology
PDF-417
Maxi Code
Data Matrix
Fixed Scanner
Yes
H-Held Scanner
Yes, many
Prototype
Auto-distinguish with
linear codes
Yes, demo
Design Focus
Port. Data File
General Purpose
Handheld Scanning
Sortation
Small Components
Strength
AIM std.
Strong Sponsor
Exclusive for HH
30² DOF
500 ft/min
Installed App.
Recent Improv.
Weakness
Not for short data
Not best suited for
automatic scanning
Fixed size
Fixed Capacity
No strong corporate sponsor