Screen parts hypothesis
There are very limited evidence that the following parts may create symptoms that are unrelated to flicker:
- front polarizer
- LCD matrix itself, presumably glass substrate with transistors
- BEF and similar brightness enhancing layers for a backlight
1. chahahc's post
Here is chahahc's post where he removed BEF or another brightness enhancement layer in five monitors and in every time it greatly reduced symptoms. But not totally. He also wrote this: 'I've removed antiglare coatings, removed entire front polarizer films, removed/ rearranged the various plastic panel diffusers, ccfl backlights, led backlights, janky diy incandescent backlights(which was actually pretty nice)'
2. infromerkh's story
I've met infromerkh at a huge Russian-speaking tech forum and he told me about his experience with screen layers.
I am translating it below.
For a very long time, I had an old safe 17 "LG monitor (LG L1717s, TN) and I didn't know LCD screens can bring me troubles. Then I broke it in 2017. By 'broke' I mean it became partially broken, I can turn it on. When I realized other screens hurt my eyes, I tried to purchase other monitors, not like mine, but also 17", and rearranged the LCD panels within them. I thought it might have something to do with the electronics of the monitor. When I realized that the electronics did not affect, I began to disassemble the panels, and I did not find any differences except for the BEF (which I did not have and in others it was most often). If I found BEF, I took it out right away.
Then I thought it was the front polarizer, but it can't be easily peeled off. Therefore, I simply rearranged only the matrix glasses with both polarizers from my reference (normal) monitor to others, and my sensations moved steadily with it. At first, I tried it with monitors from other companies, then with LG, but other models.
Then I got tired of all this and I just bought the same one as mine.
You can't imagine my level of disappointment.
It also turned out to be unsafe.
By swapping the glasses with polarizers in places, I was again convinced of the stability of the results. The next monitors, the same as my LG, I disassembled only to remove the BEF, there was no point in rearranging glasses. The matrix models differed by one letter at the end and the sensations were also different, somewhere there was a strongly pronounced 'directed lamp effect', somewhere there was a pain in the eyes and fake clarity, somewhere both.
I purchased this LG 5 times and all 5 screens turned to be bad. They all trigger my symptoms and my old LG doesn't. I still have my old LG, now it has lines running all across the screen, but you can look at it, just not for a long time, otherwise your eyes will hurt (differently). It later turned out that more than 20 LCD panel modifications for this monitor were produced simultaneously, and this is only by LG, while often monitors have a panel from a completely different manufacturer.
Eventually, I tried to rearrange polarizers. After stripping off the polarizers, the image looks bleached and scratched. I glued them back with scotch tape, but the quality of the image is not the same. But even like this, my old LG is different from everything else that I had. I really didn’t want to rip off the polarizers, but I was sure that the reason was in them and I would just move them to any other glass and the problem was solved (or at least the reason was found). But it turned out to be only 40% solved. The remaining 60% is the glass itself.
Tried a bad polarizer on a good monitor. It became bad, there was a pain in the eyes. The polarizer also plays a big role. But at least they can be replaced.
I also found a patent for 'improved polarizer' - here is translated post and my original post in Russian
- a good polarizer on top of the "bad" changes almost nothing (checked), it is necessary to remove the old one
- the polarizer is removed very reluctantly, the risk of breaking the matrix is large, it is better to check on a screen that you don't mind breaking.
Finally, I decided to break one of those bad matrices (also TN) and see what's inside. Matrix can't be fixed after this, it destroys it. So I broke the glass block, got two glasses and removed liquid crystals that were between them.
I found out that a lower glass substrate with transistors (it is not entirely clear as it some mirror-like effect) is troublesome.
I placed this lower glass on the window and looked at the street through it, the symptoms did not take long to appear. Even while I was removing the lower polarizer, my eyes suddenly hurt, I thought why? Then I realized that the table lamp was reflected from the matrix and the light, being 'bad', got in the eyes.
I also did this. The table lamp is directed to the ceiling, on top of it lies the bottom glass from the matrix. In a dark room, I lie on the couch and listen to music looking at the ceiling. The brightness in the room is low. After a couple of minutes, the eyes sensed something wrong, and after 10 minutes they asked to stop the experiment. Even when looking away, peripheral vision still catches this unpleasant light.
Later on, I tested BEF, similarly placing it above the table lamp, and found out that it also turns light into uncomfortable light. I have no idea why.
I also tested different barriers between me and the screen. It became slightly better, but not significantly with some films (20%), with silicone (25%), with a thin aquarium (0.5 cm) filled with oil (30-40%), but the aquarium should be kept close to the eyes and not to the screen.