Electronics > Repair
Transflective LCD polarizer orientation
<< < (3/5) > >>
wraper:

--- Quote from: shakalnokturn on January 20, 2020, 08:42:02 pm ---@ wrapper: What paper is that an extract from please?

--- End quote ---
https://books.google.lv/books?id=zmlQDwAAQBAJ&printsec=frontcover#v=onepage&q&f=false
wraper:

--- Quote from: Lomax on January 20, 2020, 11:05:48 am ---
--- Quote from: wraper on January 20, 2020, 03:16:42 am ---Guess I found why this happens. Probably display is STN but you are using film for TN.

--- End quote ---

That does indeed sound like a very likely explanation, thank you! Anyone have any idea where I might find polarizer films suitable for an STN LCD panel? The supplier I bought from only has one type of film.

--- End quote ---
After giving some more thought, I think that polarizer films are the same. But when removing polarizer, you likely removed retarder film(s) as well which likely come as separate film layers. In description of some polarizer films at 3DLens.com it's mentioned they are suitable for STN.  IMHO try placing new film on the back of LCD and old original front film in front and see what happens.
Lomax:

--- Quote from: wraper on January 20, 2020, 09:01:09 pm ---After giving some more thought, I think that polarizer films are the same. But when removing polarizer, you likely removed retarder film(s) as well which likely come as separate film layers. In description of some polarizer films at 3DLens.com it's mentioned they are suitable for STN.
--- End quote ---


Thank you, that sounds reasonable. A quick search for "retarder film stn lcd" indicates that this is known as an FSTN LCD (Film compensated Super Twisted Nematic). Reading a bit more about how this stuff works it sounds like I wasn't far off suspecting some "dichroic magic" might be involved. Also explains the identical appearance of the naked polarizer films when viewed without the LCD panel.


--- Quote from: wraper on January 20, 2020, 09:01:09 pm ---IMHO try placing new film on the back of LCD and old original front film in front and see what happens.

--- End quote ---

With apologies for the damaged and dirty pieces used (the removal was messy), here's a photo of what the different combinations look like (at 45 degrees and in negative orientation):



Note the difference in the dark portions indicated, where you can see the old front polarizer on top of the old and the new rear polarizer. The old rear film gives a darker and more purple "black" compared to the new film's lighter and bluer "black". So the rear films are not quite the same either :(
Lomax:
Confirmed: FSTN LCD displays need a retardation film on the front and on the back. 



What chance do I have of finding these films?
shakalnokturn:
Did you get any further with this?

I'm looking around as I also have a front polarizer to replace on a C-STN display now.
I'm thinking the "A" suffix references at 3dlens.com could be worth trying.
https://3dlens.com/transflective-polarizer-film-200x250mm-with-adhesive.php
https://3dlens.com/linear-polarizer-film-200x250mm-with-adhesive.php

I tested their P200 reference on a Tektronix TDS220 some years ago, it wasn't adequate for the job.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod