Fooling the Optical Sensor

Plotter Cutting Prints on High Gloss and Reflective Media

Some printer manufacturers, such as Mutoh, Summa and Mimaki, have systems that utilize a separate plotter to contour cut the printed graphics. To ensure accurate cutting of the printed graphic, the plotters utilize an Optical Positioning System called OPOS.  The electric eye or photo sensor of OPOS scans the black register marks printed along the outside edge of the print, so the cutter can plot the knife cut.

Some plotters have difficulty reading the registration marks printed on some films. These films include mirror finish vinyl films, such as the RTape VinylEfx® films, reflective sheeting and high gloss laminates. The glare from these films has blinded electronic eyes and  frustrated sign makers. Clear films on clear release liners or carriers can also be problematic, because the electric eye sees right through the film and liner, and determines that no film is present.

Many sign makers have had to resort to hand cutting printed graphics. That’s a non-productive use of valuable shop time. So what’s the solution? Try covering the registration marks with a ¾” strip of RTape paper application tape. It’s not just the register marks that need to be taped, but the entire path to each mark. You can’t just tape over the registration marks, because as soon as the eye leaves the tape, it’ll cause an error. After applying the application tape, trace the OPOS  registration marks using a pen.