Code Reader 1200 Manuel d'installation télécharger pdf (Page 30)

TC1200 REFERENCE MANUAL

2.4 DYNAMIC CODE READING APPLICATIONS

2.4.1 Line Speed vs. Exposure Time

The Exposure Time defines the time during which the image will be exposed to the reader's

sensor for acquisition. 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)

for dynamic reading applications, the essential condition to avoid blurring effects

between two adjacent elements is:

LS  T

exp

 X

For TC1200, the maximum exposure time is 300 s in a dark environment (no ambient light)

using Strobed Exposure Mode. This value, and therefore line speed, is affected by the

following environmental conditions:

 Code Resolution: a decrease in code resolution, (i.e. 2X) allows an increase in

maximum line speed. There is a decrement of overlapping effects between two adjacent

elements.

 Code/Background Contrast: a decrease in image contrast (poor quality codes,

reflective transparent coverings, different supports and printing techniques) requires a

decrease in maximum line speed.

 Ambient Light: an increase in external lighting conditions allows an increase in

maximum line speed.

 Reading Distance: an increase or decrease in reading distance with respect to the

center of the focal distance for a given code resolution, (see reading diagram), requires a

decrease in maximum line speed.

These environmental conditions are automatically compensated for by one of the selected

Reading Condition Recipes (see par 5.2.5. for more details), as well as by the Exposure

de parameter (see par. 5.2.4 for more details).

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Code Reader 1200 Manuel d'installation Page 30