1.00 and later
Caution is required when using white barcode stickers on
white card.
The decoder uses an infra-red light source and what appears to be
white to the human eye might appear as black to the decoder.
As long as the sticker looks whiter than the card it will operate
correctly. If the sticker looks darker than the card then
the decoder will not operate correctly.
We recommend that a dark coloured card, such as blue, be used.
The gap between the bottom of the barcode stripes and the bottom
edge of the card must not exceed 6 mm. This includes any lamination.
To enable a decoder to distinguish between the wide and narrow elements
a minimum wide to narrow ratio is needed. Depending upon which resolution
has been used for the
printing
of the bar code, the width of the wide element should be at
least two times greater than the narrow element. A ratio of three
to one is better. All elements of the same type should be printed
the same size. (The width of a narrow bar should be the same as
a narrow space.)
We recommend a four to one ratio be used.
Please refer to the article on the Hewlett Packard web site from
more detailed information.
www.hp.com/HP-COMP/barcode/sg/Misc/code_39.html
At least one bar code manufacturer has called this specification
Code
3 of 9 MARK(3) SPACE(1) |
