Matching Registration Between 2 Machines (using igrid test files)

The Igrid files were developed to help realign any minor mainscan shift that occurred when the registration pins were reattached after an Electronic Registration Upgrade was performed. The files can also be used to align one machine to another so that a plate can be burned on one machine and then reburned on another with out any noticeable shift in the image. Image Igrid1 on a machine you want to set as a MASTER and then image the same plate on a second machine that you wish to adjust with Igrid2.

igrid1 test file (not available on service CD)

• igrid1.ps (Postscript)
• igrid1.zip (Zipped tiff)

igrid2 test file

• igrid2.ps (Postscript)
• igrid2.zip (Zipped tiff)

Note: Test files are not available on the service CD.

For information on how to use the PS files, and how to correct the GC in firmware, see Appendix D of the Electronic registration upgrade procedure

Theory of igrid Test Files

The files place the following shapes on a grid with 1 inch spacing in both the X and Y axis:

Notice that only on Igrid2, the crosshair marks extend past the circle boundary slightly. When both files are imaged on the same plate, the single circle fits in between the two circles and there is a small gap between the two sets of crosshair lines.

By looking at where the two sets of lines meet up under a loupe, it can be easily determined if the mainscan is out between the two machines. If the loupe has ruler lines built into the optics, you can tell exactly how many thou out the two machines are. The concentric circles make it quick and easy to see with the naked eye if the machines are aligned or not.

IMPORTANT: The corner of the plate that is used for registration of the image (corner of laser home edge and LEC edge) must be the same for both machines. This seems like an obvious point, but if the plate is rotated while it is being transported to the second machine the test is void.
For this reason, Igrid1 puts a half circle (consisting of two quarter circles) in this registration corner. The operator then knows how to orient the plate for the second image. Igrid2 fills in the missing quarter circles so the plate is marked complete and can be sent for processing.