ฝัง
- เผยแพร่เมื่อ 2 ต.ค. 2024
- Demonstrating how a backlit LCD actually works.
An LCD has a backlight, and a liquid crystal layer sandwiched between two linear polarizers oriented at 90 degrees relative to each other.
Typically, unpolarized backlight passes through the first linear polarizing filter. It then passes through the liquid crystal layers (for red, blue, and green), which selectively rotate the polarization based on desired intensity at each pixel. Then the front linear polarizer functions to block the appropriate color channels by the appropriate amounts based on the angle between its orientation, and the linear polarization angle of the light at the local pixel.
I've removed the front polarizer from the LCD monitor. So all you are seeing is the backlight. The on-screen information is encoded in the polarization rotation angles at each pixel, but it can only be revealed with a linear polarizer. Notice how the native filter orientations are 45 degrees relative to the screen boundaries. Try and guess why!
Also notice how intensities get flipped when I hold the polarizer at the wrong angle, giving us a negative of the intended image.
Top secret display... wear polarizing glasses to see it while nobody else beside you can...
Very great explanation in the description and sample of the concept. Thank you!
how I find the angle of the polarizing film? Would you help me? I need to buy film to make the switch, but do not know the angle.
If you are trying to buy the film to fit on a screen, just determine if the screen needs vertical, or diagonal polarization. It will most likely be diagonal. Use regular polarizing sunglasses, which only let vertical polarization through.
If you already have the film and are trying to determine its polarization, use naturally polarized sources. There are many ways.
Sky (blue) light is partially vertically polarized when your line-of-sight is perpendicular to sun rays. Or use reflection off of a water surface at Brewster's angle.
I am trying to change the poliriser film on my gameboy advance sp, but the replacement i bought is only showing inverted colors, no flip it or turn it and the other sides shows the same, whats causing this?
it happened to me with a casio camera watch with color display (no backlight). the screen was burnt (with sun) and i removed the polarizer and another white film that was all burned too. but then any polarizer shows a negative image. did you solve the problem? do you know what the other film is? they where both in front of the glass (glass, then white film and last the polarizer)
I tried to answer the question from the description "Why are the filters oriented at 45 degrees?" this whole evening. I came up with this: if the panel's orientation is 45 degrees, you can make two of these panels and if you rotate one of them 180 degrees you automatically get a 90 degree perpendicular set of panels, even for non square ratio panels. That isn't the case if you just had straight lines. When you rotate such a panel 180 degrees the lines would match. I might not understand polarizers correctly, so this is just a guess.
So I tried to see what the internet says about that, but found absolutely nothing. I may just be bad at googling, but I want a definitive answer to that question.
I'll give you a hint. Find out what the orientation is for polarized sunglasses. There is a standard direction for them.
xfce
@dileep vr A lot of videos on LCD show that the pixel colors are above the last polarization filter.
However according to the videos shown on how to create this secret display, I can see that the polarization filter is on top of pixel color.
Can you explain this.
The polarizer film is always above the pixel color. That's why when you take the film off, the screen will just leave blank white.
Wait a minute. I peeled off top layer (polarizer) from my BENQ G2450 (It was scratched) and found out that my display is dead. It has one plastic layer on top, sandwich of two (or more) glass layers in the middle and one plastic layer on the back, i'm not counting other layers that belongs to backlight. So... Can i still fix it?
@@Snoop.Driftera Did you throw it in dumpster?
i thought it works without that thing haha
great display
If I put extra polarizing film on my monitor it can make the black level better at the cost of brightness but not much reduced
I'm not sure you'd gain anything a contrast setting can't mimic. Modulo digital limits on dynamic range.
If I remove the polarizing filter of the tv screen as you have and then show a 3d film with the side by side configuration and stick a vertically polarised filter on the left hand side and a horizontally polarised filter on the right hand side and view the tv using polarised glasses with the same polarisation I.e. left = vertical and right = horizontal will I be able to see in 3d. The theory seems ok?. What is your understanding.
I don't know what the side-by-side configuration is. But I'd imagine you mean show the left-camera viewpoint in one half of the screen, and the right-camera viewpoint in the other. If this is the case, then it won't work.
For your brain to assume that something is 3d, and has depth, your eyes have to cross each other's line of sight at the object. Like a cup in front of you, placed right in the middle. Your left eye has to look slightly to the right and your right eye has to look slightly to the left to see the cup. Your brain takes the angles by which the eyes have to cross to compute the depth, or distance of the cup from you. The farther it is, the less your eyes have to cross.
The problem with side-by-side configuration is that your eyes aren't crossing their lines of sight to see the image. The two images are physically separated in space. So your brain won't interpret that as 3D.
I am wondering what would happen if you stick the horizontally polarized filter on the right-side of the screen and a vertically polarized filter on the left-side (as you suggested), but reverse the filters on the left and right eye. This would force them to cross a bit. I am not sure what the result would be, as you are trying to force the brain to think that the objects on screen are closer than the screen.. It would probably be something trippy.
You will also have to do a little less work though. As you can see, the colors get inverted depending on which filter orientation I use in front of a screen without it's own filter. Instead, don't remove the native polarizing filter. Just put your new filters on top of the original in-built filter. Orient your filters such that they are diagonal and anti-diagonal to the in-built filter's polarization-axis direction. If the in-built is already diagonal, then you can just choose vertical and horizontal for yours.
Keep in mind my other comment. I have no idea if this will work, even if you try my reversal trick. But if you have the filters, you can try it without destroying your TV!
Do you know what kind of polarizing film is that. I'm new to this. Maybe you guys know the specifications? Its it linear negative frosted polarizing film?
My answer to the question "Why are the filters aligned at 45 degrees?" is that the first monitor is pre-polarized by -45 degrees by the first polarizing plate and the second monitor is pre-polarized by 45 degrees by the first polarizing plate.
I would like to know if this is correct.
Yes. And the image colors are encoded in polarization rotations.
But the question was, why is it 45 degrees for these rectangular screens? Why isn't it 0 or 90 degrees, parallel to one of the screen borders?
@@dileepvr The second polarizing plate must be attached at a 90 degree angle to the first polarizing plate, as the light rays from crystals are rotated 90 degrees so that they shine optimally. So with a pre-polarization of -45 degrees, the rotation would be 45 degrees and not 90 to see the image
@@불타는불-h3z But why is the first plate at 45 degrees? Why did the manufacturer choose to put it in at 45 degrees? Think about everyday people using the screens.
@@dileepvr Because sunglasses are also polarized. The second screen shows that well. If you turn the sunglasses 45 degrees, the picture goes black. If the second screen were not pre-polarized, the screen would turn black at 0 degrees and sunglass wearers would therefore not be able to see the screen
@@불타는불-h3z Excellent answer! You get a cookie. And beer.
Bonus round: What direction are polarized sunglasses polarized? (It is obviously 0 or 90 degrees, but which one?) And why?
Assume 0 degrees means horizontal and 90 is vertical.
Vinegar disease...
Linux?
Yup. Arch w/ xfce.
@@dileepvr i am using arch with kde plasma