Datalogic Scanning Compact 2D Reader Matrix-2000 - Manual (Page 76)

MATRIX-2000™ REFERENCE MANUAL
7
7.2 MAXIMUM LINE SPEED CALCULATION
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.
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 maximum speed is greater.
Assuming:
• X: Code Resolution (mm)
• Texp: 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 x Texp ≤ X
The maximum (theoretical) line speed (LS) can be calculated as follows:
X / Texp (min) = LS (max)
Texp (min) is the minimum Exposure Time value obtainable for the specific application. It
can be evaluated in static reading conditions and may depend on code printing quality,
reader position, etc.
Using the formulas previously explained it is possible to calculate the theoretical maximum
line (target) speed expected for the application, based on the maximum code resolution and
the minimum suitable Exposure Time value.
The minimum Exposure Time value depends on the Matrix reader model selected for the
application (internal lighting system, optical lens, diaphragm aperture, reading distance) and
on any external lighting system.
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