Ok Folks.. Perhaps I didnt explain the process well enough..
Although I refer to it as a mod, its not an electronic modification. Its a physical one..
The actual LCD glass plate is a sandwich of things..
First comes a polarized filter. This is a VERY thin strip of plastic with adhesive to...
Second comes a layer of glass coated in silicon dioxide to help the liquid crystals align.
Then comes a layer of indium tin oxide on which the actual pattern of the characters is photo etched.
Then comes the liquid crystal itself.
Then another layer of Indium Tin oxide,
Then another layer of Glass coated in Silicon Dioxide and finally
A layer of polarizing filter film
In simple terms,
Polarized filter, Glass, Polarized filter.
What I do is to strip off the front layer of plastic filter using a sharp razor blade (trust me, my fingers know just how sharp the blade is.)
I then clean off the adhesive from the glass with Alcohol etc.
If I was to apply power at this point, I wont see anything displayed.
Its at this point I find out if this is a new LCD or an old one
If Its an OLD display the little letters that say HS, LO ME , the word Frequency, Time, CH BAND etc etc are printed onto the GLASS surface.
If its a new display those same words etc are printed on the plastic I just stripped off..
What I then do is cut some new polarized filter which is High contrast, anti glare and anti scratch at about 45 degrees to the original polarization, remove the protective layers over the adhesive and place it on the glass carefully smoothing it out to not trap any air. Once Im happy, I'll remove the protective layer over the front of the film and then re-assemble the LCD module with the frame, the perspex light diffuser and reflective paper that lives behind the LCD glass and tighten it all up and re-install back into the nose piece of the radio with the buttons and cassette door.
Because those little letters are painted onto the glass in the case of the original LCD glass, they cannot be reversed so they blend in with the black background.
This is the most obvious method of reversal. There MAY be an electronically reversing the display by inverting the voltages.
By default, the background has a 0 or negative voltage to keep it "clear" and each individual segment has a positive voltage to make it go "cloudy"
To invert the background is simple, but to invert the segments would require substantial hacking of the electronics as there are so many.
Gene.. Brilliant Idea... If I could master the electronic inversion, then it would be really nice..
Let me take a longer look at the actual LCD driver chip and see if there is anything I can do..
