A display means to invert, to replace the colors of a monochrome display. The transparent background is black and the font will appear transparent, or vice versa. Made possible by the polarizing film, which is located on each LCD (Liquid Crystal Display). This film absorbs radiant light up, depending on the angle of the film. By turning this film can achieve this Invertierungseffekt. The inversion of a color display is not possible.

I'm doing this as an example based on the speedometer of my VW Jetta. On the expansion and opening of the speedometer, I will not go into because there are already enough guides on the net.

This requires a new polarizing film to get at several online shops or even alleged in the photo shop. Theoretically you could take the existing abknibbeln on any LCD film, and apply it rotated 90 ° again, but they are mostly stuck so much that they destroyed during removal or blind.
First you have to remove the display from the unit and expose. Here you have to make sure that the contacts remain intact on the back of the display. If you are now the small glass window in front, so you must remove the old film carefully. The best results I have, however, made with a sharp cutter blade and new, as if to fillet a fish. One should absolutely be patient, because the bonds are very strong and must be deducted sooooo laaaaangsam. But the best is yet to come: remove the adhesive residue on the glass! I have since worked through all the solvents. Glass cleaner can get in the bin, because alcohol is not much better and even nail polish remover brought with me only a slight smearing. With much persistence and nitro lacquer thinner then I can remove the glue with a cotton swab.

Now you can put the new film on the clean display and rotate until the desired Invertieungseffekt occurs. Possibly when the unit is reading the contrast control. In my case it was a bit difficult with the speedometer. That's about a 45 ° angle I had the best result that black was beautiful außenrum nationwide. Then one has to cut only the film in the form, again without changing the angle. It also helps the old film, simply lay out and cut around it.

Now hang the finished film to the glass display, do not stick anyway. Mostly, by the LCD still a kind of frame made of metal or plastic for protection. It is enough if the film is completely jammed with under this framework and not by slip.

That's it for now. Build everything back together and looking forward to a cooler display.