Basler Vision Technologies Sprint Series, Руководство пользователя

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Line Acquisition Modes
Basler sprint Mono Cameras 63
3.9.3 System Design Calculations
Our recommended approach for calculating system design criteria is tuned to matching the line of
view of the sensor to the width of your conveyor. The example below illustrates this approach.
Example
Assume the following conditions:
„
Conveyor width = 850 mm
„
Conveyor movement per encoder step = 0.09 mm
„
Center-to-center distance between sensor lines = 10 µm
(Each line in the sprint’s sensor is 10 µm wide and they are adjacent to one another. Therefore
the center-to-center distance is 10 µm.)
„
Pixel size = 10 µm
„
Length of sensor line = 40.96 mm (4096 pixels/line x 10 µm/pixel)
„
With an objective lens in place, the direction of travel of the object will cause the image to
cross the line A in the sensor first.
Step 1 - Calculate the magnification needed to capture the full conveyor width on a sensor line.
β
= 1 : 20.83
(
β
is the standard symbol for magnification and is usually expressed as a ratio)
Step 2 - Calculate the conveyor movement necessary to move the image 10 µm.
10 µm x 20.83 = 0.2083 mm
Step 3 - Calculate the number of encoder steps needed to move the conveyor 0.2083 mm.
Since the encoder only counts in whole steps, we have two options. We can move the conveyor
enough to generate 2 encoder steps or we can move the conveyor enough to generate 3 encoder
steps. In either of these cases, the movement of the conveyor will not result in the image moving
exactly 10 µm. Therefore, we will need to adjust the magnification so that exactly 10 µm of image
Sensor Line Length
Conveyor Width
----------------------------------------------------
40.96 mm
850 mm
-------------------------- 0.048 = =
1
0.048
--------------- 20.83 =
0.2083 mm
0.09 mm/step
------------------------------------ 2.31 steps =