M20_Ope_E - 第232页
Chapter 5 Libraries 5-82 BB A A: Model X B: Search area Model Search ar ea Define the Search Area setting based on the print offset or expansion/contraction, or board po sitioning offset in clamping. Normally about 1mm i…
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Sometimes the fiducial may not be captured clearly at this location
depending on the mark material or ambient lighting even under the
best adjusted illumination. In this case, while in teach mode, try to
shift the camera 1mm in X and/or Y direction to where the image is
clearly seen.
* Increment : 0.01mm
Note: The field of view of the teach camera is as small as 5mm. Using the “Distance X/Y” function is
not so effective within such a small field of view. Therefore, do not use this function. Use the
standard center recognition whenever possible.
X offset
Y offset
Viewed at the center of the camera.
(Not clear image)
Viewed at slightly shifted position
(Clear image)
Action:
To avoid problems, follow the procedure below to use [Distance
X/Y].
①Open the Mark Image Editor, and perform “Model centering” to
move the camera center to the Fiducial mark center without
inputting any values for [Distance X/Y].
②Open the Program Edit screen, and acquire the camera position
where is just on the mark center to the Placement&Mark data. (If
you have CAD data of the mark position, input the values
unchanged. If you do not have CAD data, teach and acquire the
mark center with the teach camera.)
③Add [1.00](mm) to each of XY coordinates for mark center, and
modify the coordinates in Placement&Mark data.
④Open a teaching screen on the Placement&Mark data, and move
the camera to the coordinates specified at step③ using “Move”
command.
⑤Go back to the Mark Image Edit screen, and input [-1.00](mm) for
each of Distance X/Y.
⑥Perform “Model centering” command to move the camera center
to the mark center.
⑦Acquire Model when using Pattern Matching.
⑧Perform [Image test] to check, and save the data if OK.
NOTE: Depending on the condition of mark or neighboring pattern, adjust
the offset value accordingly within “+/-1.00”. However, be sure to
follow the same procedure above. If the amount of offset are
different between [Distance X/Y] and the addition of mark
coordinates, that may cause placement shift. (Their absolute values
should be same, but plus/minus orientation should be reversed.)
Search Area: Search area means the area within which fiducial search is
performed. The center of the search area corresponds to that of the
fiducial model.
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BBA
A: Model X
B: Search area
Model
Search area
Define the Search Area setting based on the print offset or
expansion/contraction, or board positioning offset in clamping.
Normally about 1mm is adequate.
A fiducial can be in varying location relative to the programmed
coordinates for its purpose. Accordingly, you should suppose the
following case should occur:
Model
Search area
When the model is fitted over the fiducial,
it is contained within the search area.
OK
However, when the model fitted over the fiducial falls out the
search area, the fiducial cannot be detected.
The T
Model
Search area
The model fitted over the fiducial
falls out the search area.
Captured imageModel
In the above case, the model and the captured image do not fit
completely to result in process failure. To prevent this, define the
search area size large enough to cover the variation in fiducial
location.
* Increment : 0.01mm
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Match. Threshold: The threshold value that compares the images between the fiducial
model and the actual fiducial image. Enlarging this setting makes
the criteria more severe. Specify “600”(default value) normally.
For example, when the model is hexagonal and if a similar round
object exists in the search area, it may be mis-recognized as the
fiducial if the threshold setting is too low (not severe enough). In
such a case, you must raise the setting.
On the other hand, when there is no chance of confusing objects that
appear in the search area, it is recommended to make the criteria
less severe to reduce possible fiducial error. Fiducial mark generally
has diverse reflectance. As the result, the mark may be distorted
when captured as an image. With too severe criteria, the system
fails to detect the mark even though the mark exists.
In the latter case, it is not recommended to change the default
setting.
Search Interval: This parameter implies the intervals to search the target mark in
search area. Default value is “4”(pixels). If there are any similar
objects in the search area, that may sometimes found as the target
mark wrongly, try smaller value, 4 Æ 3 Æ 2 Æ 1, to perform more
precise check by smaller intervals. However, the smaller value will
make the recognition time longer.