wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

Radio Frequency Identification 8-3
8.2 Bar Code System
Inspired by the dots and dashes in a Morse code (Figure 8.2) [8], Joe Woodland drew the first linear bar
code of narrow and wide lines on sand when he was vacationing in Florida. Using a converted movie
projector with a 500.W bulb as a reader, Joe found that a bull’s eye pattern with circular lines was more
reliable. Unlike punch cards, the circular or the linear bar code is a noncontact method of data entry,
but it is vulnerable to smear and smash. Competing with the time-tested punch cards, little progress was
seen until the light bulb was replaced by a helium–neon laser in 1969. A linear bar code of 11 digits was
reinvented in 1972. Together with a laser scanner, the system regained competitiveness and prevailed
eventually. Other than minor augmentations, the revised version is virtually identical to the bar code
used today, such as Code 128 shown in Figure 8.3, because there has been no major change thereafter.
In the linear or the circular form, bar code reading is a slow process because the pattern must be properly
aligned with the scanner on the one hand, and on the other, it is read one by one, manually. Nonetheless,
it was a winner because printing a bar code on a box costs nothing and the helium–neon laser scanner was
affordable by most merchants in western countries at that time. Moreover, a bar code provides a primitive
method of authentication because it cannot be changed once printed on paper. It was welcomed by manufacturers,
distributors, retailers, and other merchandise handlers. The logistics management industry was
especially enthusiastic because tracking-and-tracing of lost cargo was made easier. With the arrival of the
low-cost solid-state laser scanner in the 1990s, the dominance of the bar code was established.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
1
2
3
4
5
6
7
8
9
0
FIGURE 8.2
Morse code.
6 1 4 1 4 1 0 0 0 0 1 2
FIGURE 8.3
Code 128 bar code.
© 2011 by Taylor and Francis Group, LLC