Dolev 4press; Dolev 4news
Linearity Registration Correction Using the Strobe Tables

Product Family: Imagesetters / Platesetters

 The Strobe board in the Dolev 4press can be used for Linearity correction by using the Grid setting utility.

Note: It is recommended to use the "Remote Mode" for this procedure. It will be faster to insert the measurements into the table.

The correction procedure:

1. Create a Grid file with the size: H=700mm and W=550mm.
   Each rectangle in the Grid Should be with the size: H=115mm and W=67.5mm.
   Create second grid to use as a ruler. Each square should be 67.5 x 67.5 mm.
   On both grids it is recommended to use resolution 100 and the lines will be from one pixel ( 10 microns width ).
   If you use a Brisque the grids can be exposed after copying them from a CD that contains the two grids.
2. Expose the two Grids and make sure that the overall size ( 700x550) is correct.
3. If the overall size need correction use the LD and/or the LS functions.
4. Using the LD & LS:
   Enter the Service Utilities
   Setup -> Service -> Dimension setting
   Make sure that in the table you will have:
       Grid step Height = 115
       Grid step Width = 67.5
       LD = 1.00
       LS = 1.00
       Number of Rows = 7
       Noise = Yes

If the overall size is not correct adjust the LS and/or LD as needed.

Theory: LD is the overall factor in the drum width direction and LS is the overall factor in the Leadscrew direction.

If the overall size of the grid is 541 mm and not 540 please insert LD=541/540 = 1.002
If the overall size of the grid is 739 mm and not 740 please insert LS=739/740 = 0.9986

5. Expose two new Grids ( After the LS & LD correction ).
6. Enter the Strobe table in the service utility. ( Setup -> Service -> Grid Setting )
   The table will start with the 0 ( Zero ) line in the height and the numbers will be as the grid width line: 0, 67.5, 135, 202.5, 270, 337.5, 405, 472.5, 540.
   
   The same will continue on the 115 line, 230 line and so on.
   
   We will measure the 67.5 x 115 mm grid and use the 67.5 x 67.5 mm as a ruler. The ruler is in the height direction ( Leadscrew direction ).
   
7. Please note that the 0,0 place on the Strobe table is the front left corner of the film.
   It is the TL corner on the drawing. ( Home position and loading side of the film )

8. Use one grid as a reference and measure the other one. You have to rotate the reference grid! ( Remember to use the leadscrew direction as the ruler ).
   
   Please tape the first grid to the light table ( grfield.lw ) and use the squared one as the ruler ( grflrf.lw ).
   
   The numbers in the table refers to the left line of the column.

9. Measure the Grid. Please measure the left line first and put the numbers in the strobe table. All the numbers in the strobe table are from the 0 line so if for example the fourth line of the grid ( default value of 202.5 ) is shorter than the ruler line by 50 microns enter in the strobe table the value 202.45. Expose and make sure that you did the right correction on the left line.
   
   Continue only if you are sure that you understood the process. If not read the instructions again.
   
   Example for a corrected line can be:
   0, 67.52, 135.04, 202.56, 270.06, 337.54, 405.02, 472.5, 540.
   
10. Continue with the second line ( the 115 line ) and then correct one by one and check each time that the corrections are in the right direction.
    
11. In the Grid Table change only the Width ( The Height, Bow, Can not be corrected )
12. Expose the Grids again and verify the correction.
13. Note: Do not try to correct linearity less then 50 microns!