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<< Click to Display Table of Contents > Optimize Line Shift |
  
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<< Click to Display Table of Contents > Optimize Line Shift |
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After marking the bitmap with calibrated contrast, the Line Shift parameter can be adjusted. Since the shift errors are primarily visible in bi-directional bitmap marking, we now enable bi-directional. In some cases, the bitmap lines do not begin and end at the same position. Therefore, the Line Shift has to be adjusted.
Picture |
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Bidir. Shift Effect: |
Double image at the bitmap edge and within the bitmap. The effect was intensified in the picture. |
No double image at the bitmap edge, but double image (blurry) within the bitmap |
Distance of the double image at the bitmap edge [mm] |
0.35 |
- |
Line Shift [µs] [*] |
0 |
221 |
Table 32: Line Shift and Power Shift values
[*]: Mark Speed = 790 mm/s and bidirectional is enabled
We did the following steps to optimize the bitmap marking:
•At the edge of the image, we measured a Line shift of 0.35 mm. With this value, we can determine the Line Shift parameter according to the Shift Equation. The example result was a Line Shift value of 221 µs. Now, the next marking can be done to check the adjustment.
•Our marking result is good and the system is now well calibrated to mark black&white bitmaps.
For higher resolution of bitmap images, the line shift and the power shift are visible even at the the level of single bitmap lines.
•The Line Shift does not manifest as a blurry double image but as distinguishable fringes at the edges of a bitmap lines (see Figure 241).
Figure 241: Bidirectional fringes at the bitmap edge change with variation of the Line Shift parameter from left (large fringes) over middle (small fringes) to right (no fringes)
In the beginning, the Acceleration Ramp value has been set to 2000 µs. This parameter is important for the marking, but can be optimized to reduce the marking time.
