DENSO ADC QR Code White Paper - BlueStar

QR Code Essentials
How the QR Code works
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The QR Code is a
2-D matrix
barcode that
contains
information in
both the
horizontal and
vertical
dimension.
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Unlike 1-D barcodes, the QR Code is a 2-D matrix code that
conveys information not by the size and position of bars and
spaces in a single (horizontal) dimension, but by the
arrangement of its dark and light elements, called “modules,” in
columns and rows, i.e. in both the horizontal and vertical
directions.
Each dark or light module of a QR Code symbol—a specific
instance of a code—represents a 0 or 1, thus making it machineintelligible.
The QR Code modules perform several functions: Some contain
the actual data itself, while others are grouped into various
function patterns that improve reading performance and allow
symbol alignment, error correction and distortion compensation.
The timing pattern lets the scanning device know the size of the
symbol. There is also a required “quiet zone,” a four-modulewide
buffer area containing no data, to ensure that surrounding
text or markings are not mistaken for QR Code data.
Conventional 2-D matrix codes required a considerable amount
of time to be spent searching a symbol’s code to determine its
angle of orientation, position (x and y coordinates) and size.
To address this problem, the QR Code was designed with
special position-detection patterns located in three corners of
each symbol. The patterns have a symmetrical scan-line ratio of
1:1:3:1:1, which allows them to be scanned from any direction
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