Data Matrix Code
Data Matrix code is 2D type of code used at most in industry for marking different small parts due to its small size and high reliability. Data matrix codes are made of square dark and light cells with matrix dimensions from 10×10 to 144×144. Encoded information is a string containing characters or numbers. As more data is encoded in the symbol, the number of cells is increased. Data size varies from a few bytes up to 1556 bytes.
Additionaly data matrix code offers wide reading angles and high realibility due to error correction algorithm. Code damaged up to 30% can be reconstructed assuming the matrix if DMC can be properly located.
Modul size
Defines the smalles cell in data matrix code. Modul size has to be made out of at least 2×2 printed dots for bigger realibility. Also terms dot size or cell size can be used.
Finder Pattern
Bottom and left side of Data Matrix code refers to finder pattern. The L pattern is used locate and orient the symbol. Finder pattern is also used to correct distortion.
Timing Pattern
Dashed line positioned on upper-right side gives the reader information about Data Matrix code size. The sizes vary from 10×10 up to 144×144 depanding amount and type of data.
Quiet zone
A quiet zone is the area around Data matrix code, that does not contain any information. Quiet zone is separating DMC from its surroudings and should be at least one module wide.
Data area
Data area is boardered by finder pattern and timing pattarn. With selected position of dark and white cells, the desired information is encoded together with data correction code.
Size of data matrix code depends on the amount and type of information we want to encode. Type of data is important because encoding ASCII symbols is more complex as enconding only numerical values. When type and size of data is defined, size of matrix code depends directly on choosen modul width. With decresing modul size, the requirements for readers are increased.
Let us say that data matrix code is printed with resolution 300 dpi and one cell is represented with 4×4 dots. This results in modul size of 0.34mm. The following table represents data matrix code sizes and amount of data encoded with modul size 0.34mm.
|
Number of numerical characters
|
Number of ASCII characters |
Printed area size
|
Matrix size |
|
6 |
3 |
3.4 x 3.4 mm |
10×10 |
|
10 |
6 |
4.1 x 4.1 mm |
12×12 |
|
16 |
10 |
4.8 x 4.8 mm |
14×14 |
|
24 |
16 |
5.4 x 5.4 mm |
16×16 |
|
36 |
25 |
6.1 x 6.1 mm |
18×18 |
|
44 |
31 |
6.8 x 6.8 mm |
20×20 |
|
60 |
43 |
7.5 x 7.5 mm |
22×22 |
|
72 |
52 |
8.2 x 8.2 mm |
24×24 |
|
88 |
64 |
8.8 x 8.8 mm |
26×26 |
|
124 |
91 |
10.9 x 10.9 mm |
32X32 |
|
172 |
127 |
12.2 x 12.2 mm |
36X36 |
|
228 |
169 |
13.6 x 13.6 mm |
40X40 |
|
288 |
214 |
15.0 x 15.0 mm |
44X44 |
If we need data matrix code with encoded current date and time (mmddyyyyhhmmss) we need 14 numeric places. We need to choose data matrix size that matches or is bigger the string length we want to encode. In our example we need to choose dimension 14×14 which is capable of storing string or 16 numbers or 10 ASCII characters.