Omron V440-F User Manual page 35

2 Quick Start
2-2-1 Determining the Optical Setup
The following four-step process determines the optimal lens focal length, field of view, and camera standoff to
read the intended code successfully.
Step 1: Determine the minimum element size of the code (usually expressed in mils).
For a 1D barcode, this is the size of the thinnest bar of the code. For a 2D code, this is the size of a single square
element in the code. The element size is usually known by the customer.
1D Barcode
Step 2: Use the guidelines below to determine the approximate PPE (Pixels Per Element) required to read
the code successfully.
Pixels Per Element (PPE) is defined as the number of pixels that span the smallest feature of the code. A certain
minimum number of pixels is required to read successfully. For 1D codes, PPE refers to the number of image
pixels across the narrowest bar in the barcode. For 2D codes, PPE refers to the number of image pixels across a
single cell within the 2D code.
The following are general guidelines for typical PPE requirements based on the code type and application. It is
acceptable to have too many Pixels Per Element. It can however slow down the read time.
Code Type
1D Code – High Contrast Label
1D Code – Direct Part Mark
2D Code – High Contrast Label
2D Code – Direct Part Mark
Step 3: Based on the suggested PPE from the above table, use the table below to determine the ideal
field of view that delivers the required PPE.
The Readability Table below shows, for all common code sizes, the maximum field of view that will result in the
required PPE. Results for 2, 3.5, 5, and 10 PPE are given.
Thin Bar or 2D Cell Size
0.5 mil (0.0127 mm)
1 mil (0.0254 mm)
1.5 mil (0.0381 mm)
2 mil (0.0508 mm)
2.5 mil (0.0635 mm)
3.3 mil (0.084 mm)
5 mil (0.127 mm)
7.5 mil (0.19 mm)
10 mil (0.25 mm)
13 mil (0.33 mm)
15 mil (0.38 mm)
20 mil (0.5 mm)
30 mil (0.76 mm)
40 mil (1 mm)
50 mil (1.25 mm)
2-4
2D Code
Minimum PPE
1.6
2
2.75
3.5
FOV Size (mm) to Achieve a Specific PPE for all Common Code Sizes
PPE = 2 PPE = 3.5
15.6
31.3
46.9
62.6
78.2
103.5
156.5
234.1
312.9
406.6
469.4
625.9
936.3
1251.7
1564.6
Preferred PPE
2
2.5
3.5 to 5
5
PPE = 5
8.9 6.3
17.9 12.5
26.8 18.8
35.8 25.0
44.7 31.3
59.1 41.4
89.4 62.6
133.8 93.6
178.8 125.2
232.3 162.6
268.2 187.8
357.6 250.3
535.0 374.5
715.3 500.7
894.1 625.9
V440-F C-Mount Code Reader User Manual
PPE for Code Grading
5
5
8 to 10
8 to 10
PPE = 10
3.1
6.3
9.4
12.5
15.6
20.7
31.3
46.8
62.6
81.3
93.9
125.2
187.3
250.3
312.9