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PC, the symbol will fail Decode even if all other parameters pass. Decode is a
Pass/Fail parameter.
The Scan Grade is the lowest grade received out of the eight parameters tested
from a given scan profile. Even though an “A” grade might be achieved on most
of the parameters, if a “C” grade is received on one parameter then the Scan
Grade is a “C.” Scan Grade is a graded parameter.
ISO/IEC states that the overall Symbol Grade is the average of ten scan
profiles, and the average of their resultant Scan Grades as defined above. The
reason for averaging ten scans is purely for vertical redundancy. Quality levels
could change within the height of the bar code being verified. Symbol Grade is a
graded parameter.
In Quick Check
®
PC, the ISO/IEC grade is shown in the ISO/IEC window (upper
right section of the screen). This is a running average of all scan grades. Once
ten scans are completed, it is possible to scroll through individual scans to see
the effects of individual scans on overall Symbol Grade.
Note: because Scan Grades are averaged, a single failing Scan Grade
does not result in a failing Symbol Grade.
Traditional quality measures were based on reflectance and dimensional
tolerances. Although a crude gauge of print quality, they did not adequately
predict the scanning performance of symbols in many applications. They are
retained in Quick Check
®
PC because some companies still find these measures
useful.
Traditional reflectance measures were based on the reflectance of the lightest
bar (R
l
) and the darkest space (R
d
). This was termed Print Contrast Signal or
PCS. As implemented in Quick Check
®
PC, a PCS of 75% is a minimum passing
level.
PCS is calculated as:
R
l
– R
d
———
R
l
Dimensional tolerances are different for each symbology. The results of
dimensional tolerance measures are displayed by LEDs in the Dimensional
Parameters section of the Quick Check
®
PC screen.
Common Corrective Actions
Although it is not possible to provide complete remedial actions for all symbol
printing and marking problems, the following section outlines some of the more
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