DEK 265 horizon Engineering Specification page 17

Fiducials
Chapter Issue 1 May 00
The Horizon uses the vision system to capture and process alignment marks or
fiducials to align the stencil to each board before it is printed. The alignment
marks or fiducials are produced as part of the artwork of the board and stencil, in
the same relative position. The information processed is used to correct stencil
to board alignment.
The Horizon has a library of synthetic fiducials of the most commonly found
shapes. The dimensions of these fiducials can be tailored by the operator to fit
the fiducials on the board and stencil. The fiducial on the stencil can be can be
different from the fiducial on the board. After the vision system has been taught
these fiducial parameters, it is able to search the field of view of the camera and
recognize any features which resemble fiducials.
After finding a shape it is assigned a score comparing its shape and size to the
shape and size of the fiducial in the vision system library. This score is set
between 1 and 999, the better the fit the higher the score.
The fiducial shapes available is shown below:
CIRCLE CROSS
Shaded Areas: No Printing and No Fiducials
Board
Width
Engineering Specification
ENGINEERING SPECIFICATION
DIAMOND TRIANGLE
Board Length
3mm Must Be Free
of Underside Components
KEY FEATURES
RECTANGLE DOUBLE SQUARE
3mm
3mm
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