78 |
78 User Manual
Appendix 1:Installations & Setting Up
PRINTHEAD TYPE / RASTER RATE (kHz)
Raster
7 GEN STD
16 GEN STD
24 GEN STD
Midi 60um
5.714
1.5
0.895
EJ117
Where:
Pitch Factor is a whole number.
This will probably require trial and error; first select an encoder/gear combination and then multiply it
by whole numbers to get the actual pitch. This is then compared to the required pitch:
For each encoder pitch you try, the starting point for the pitch factors can be:
rounded to the nearest whole number.
Using the example from Step 1, the required raster pitch is 0.373 mm. A standard EC-JET encoder and
wheel will be used to try to achieve this.
The actual raster pitch from Try 3 is close enough to the required raster pitch to be used, particularly
as the required raster pitch is the maximum. Therefore, a 5000 ppr encoder and a 200 mm wheel will
be specified. The pitch factor will be 9.
It can be seen that the higher the encoder pulses per revolution, the closer the actual pitch will approach
the required pitch. This also gives the possibility of accommodating changes in the required pitch.
However, the cost of the encoder will be higher and there may be limitations in terms of speed (this is
covered in later sections).
Step 3: Check the Expected Print Performance
Any difference between the required raster pitch and the actual raster pitch will influence the print
performance. There is also a limitation due to the frequency of the encoder signals. In particular, the
printed message length and the maximum line speed must be checked. If there are any problems with
these then the selection process must be repeated.
Printed Message Length (mm) = Number of Rasters x Actual Raster Pitch (mm)
Where:
Number of Rasters = as calculated in Step 1
Actual Raster Pitch = as calculated in Step 2.
Max. Line Speed (m/s) = Actual Raster Pitch (mm) x Raster Rate (kHz)
Where:
Actual Raster Pitch = as calculated in Step 2
Raster Rate = Maximum Rate of Raster Production.
The raster rate varies with printhead type and raster:
Encoder
/Gearing
Try 1
Try 2
Try 3
Encoder Pitch x Pitch Factor
= Actual Raster Pitch
EJ115
Encoder/Gearing
Encoder Pitch x Pitch Factor
= Actual Raster Pitch
2500ppr/200mm
0.080mm
0.320mm
4
5
9
5000ppr/200mm
0.040mm
0.400mm
0.360mm
2500ppr/200mm
0.080mm
EJ116
Try 1
Try 2
Try 3
Too Low
Too Low
Pitch Factor
Required Pitch (mm)
Encoder Pitch (mm)
=
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