Instruction manual

READING FEATURES

7.1 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, 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 (reading distance) and on external lighting.