Datalogic Matrix 120 - Maximum Line Speed and Exposure Time Calculations

Maximum Line Speed and Exposure Time Calculations
Product Reference Guide 117
Maximum Line Speed and Exposure Time Calculations
The Exposure Time (or Shutter) parameter defines the time during which the
image will be exposed to the reader sensor to be acquired. This parameter
depends heavily on the environmental conditions (external lighting system,
image contrast etc.).
In general, a longer time corresponds to a lighter image but is susceptible to
blurring due to the code movement; a shorter exposure time corresponds to a
darker image.
Assuming:
• X: Code Resolution (mm)
• T
exp
: Exposure Time (s)
• LS: Line Speed (mm/s)
The essential condition to avoid blurring effects between two adjacent elements
in a dynamic reading application is:
LS  T
exp
 X
The maximum (theoretical) line speed LS can be calculated as follows:
X / T
exp (min)
= LS
(max)
T
exp (min)
is the minimum Exposure Time value obtainable for the specific
application. It can be evaluated in static reading conditions and depends on the
Matrix reader model selected for the application (internal lighting system, optical
lens, reading distance) and on any external lighting system. It may also depend
on code printing quality, and reader position.
Example:
A Matrix 120 using:
Internal Lighting Mode = Very High Power Strobe
Exposure Time = 200 s
Code Resolution (X) = 0.254 mm (10 mils)
has a maximum line speed of:
0.254 (mm) / 0.0002 (s) = 1270 mm/s
NOTE
The following considerations must be applied only when the internal lighting system
and 2D codes are used. The Maximum line speed allowed for linear codes or postal
code reading applications heavily depends on the direction of symbol movement.
When the direction of movement is parallel to the elements of the code, the maxi-
mum speed is greater