LCD uses a backlight.
Plasma is ionized gas: gas charged by electricity resulting in ionized gas.Plasma Technology.
Between two plates of glass is a cell. The cell holds gas and phospor.
The dielectric is below the glass and holds the sustaining and scanning electrodes.
These electrodes discharge electricity into the protective m g 0 layer - the m g 0 layer sends electrons to the gas inside the cell ionizing the gas.
The charge from the m g 0 excites the gas in the cell, this sends ultraviolet light beams on the phospors; red, green, blue, that coats the inside bottom layer of the cell. When the phospor is lit up by the ultraviolet light, the phospors electron jumps up to a higher energy level and the atom heats up, then the energy level goes back down and this is when the phospor beams visible light back. The visible light is directly proportional to the number of photons randomly colliding with the coated surface.
When the phosphors energy level goes back down it beams visible light back towards the m g 0 and out from the glass towards the viewer.
The phosphors glowing time is called afterglow.
If the afterglow is still emitting when the next electrical burst is sent, the phospor didn't go to the energy level where it doesn't show light.
It acts similar to a seesaw (also known as a teeter-totter).
The ultraviolet light beams on the phospors, the phospors energy level goes up, then down, beaming visible light back towards the m g 0, instantly after the visible light dims the next ultraviolet light burst is sent raising phospors energy level again, and back and forth it goes: ultraviolet light, then visible light.
Phosphor persistence, also referred to as afterglow, may still show visible light when the other frames ultraviolet photons are sent to the phospor, this is what makes it show afterimage. The afterglow can last up to a minute, meaning the energy level of the phospor is still high enough it shows visible light.
In 3D TV's terminology afterimage is called Crosstalk: the image showing a persisting image of the previous frame.LCD Technology.
The backlight goes to the diffuser that distributes the light across the screen evenly.
The diffuser light then goes to the polarizers which hold two electrodes, The polarizers align the light sent through the electrodes.
Inbetween the electrodes is twisted liquid crystal.
The liquid crystal is given a electrical charge making them untwist, and when they untwist they block light from the diffuser.
The LCD Drive twists one by one.
While twisted they send light from the diffuser to the colored filter on top of the electrode and below the polarized panel resulting in a red, green, blue color.
The problem is the way color is shown: The LCD drive circuit uses Dithering.
Frame Rate Control (FRC) Dithering uses 4 frames to show more color than the RGB sub pixel can show.
2 frames are shown with different colors and they blend to make a new color in the third frame and this color is held into the fourth frame, making the 120Hz framerate show at 30fps after FRC dithering.
You may think that since 240Hz LCD TV's use 120Hz circuits in 240Hz LCD TV's this is the cause of the ghosting.
But, if they used true 240Hz circuits instead of 120Hz the liquid crystal would have to twist twice as fast as for the 120Hz circuit, one at a time instead of in parallel. Using true 240Hz LCD drive circuit is not the solution. The solution is something called Parallel LCD drive circuit architecture.
Parallel LCD drive circuit architecture refreshes pixels in parallel instead of one by one, shortening the whole refresh cycle.
"Such architecture requires more circuitry and digital frame buffer with parallel IO...No need for dithering when parallel." - Mathew Orman
One of the three problems of crosstalk in LCD monitors is due to the LCD Circuit twisting one at a time, by twisting many in parallel the problem is solved according to Mr.Orman.
Right now the LCD Drive is 120Hz and twists the liquid crystal one at a time.
The parallel LCD Drive keeps the same 120Hz as before but twists many in parallel instead of just one at a time.
This way by staying at 120Hz the pixel charge is not making the liquid crystal twist twice as fast, which is what would happen if the LCD drive went from 120Hz to 240Hz.
The second problem is capacitance, which is defined as the ability to store charge.
The Liquid Crystal when it shows Color, is twisted. Then it untwists and Black Frame Insertion is shown. If the Twist showed very bright color then the Liquid Crystal holds charge past the BFI.
The Third Problem is the Liquid Crystal is too heavy, and when twisted to show color has enertia that has to be overcome when the Black Frame Insertion is shown next.
If the weight of the Liquid Crystal is lowered it will twist faster when showing color, and showing the black screen.
So the Liquid Crystal itself needs the properties of low weight and low capacitance.3D Test Patterns.
Pattern one is looked at with one eye closed, and the open eye looks where the pointer says to look for that eye.
What's being pointed at is black and white bars. Look at the color of the black or white bar and compare it to the IRE scale of white to black squares next to it.
The black IRE square the black or white bar looks like is the amount of crosstalk your TV has.
Pattern 2 is only supposed to have white in one bar at a time, anymore than One white bar and your seeing crosstalk.
You'll need to either guess if the bar is too wide or use a dslr camera white the shutter speed at 1/1000 and take a photo of the screen white it's playing the 3D test pattern.
Both patterns are in side by side, 16:9 ratio, left eye first.
Pattern 3 is in 8x8 and 16x16 pixel squares.
It is in side by side 3D, left eye first, 16:9 aspect ratio 30 seconds long.
It has these three frame rates per eye: 50, 59.940, 60.
These are easy to use. Watch the 16x16 videos first, and look for the bars to become lit up wrong.
The bars aren't supposed to stay lit up when the white square isn't in it.
The white square is exactly 16x16 pixels, it's a square, so if you see a long white bar inside the pattern it's showing a error in the TV.
Or maybe you'll get color in the boxes, or maybe the boxes will get partially filled after the white box left it, these are all errors that it's not working properly.
I made these tests for the TV manufacturers to use so they could implement motion compensation, or the soap opera effect 120Hz TV' have.
But I don't mind at all if regular people use it to test 3D TV's in the store.
You don't need a camera to see the errors, you don't need to wear the glasses that 3D TV's use. Just put the pattern into the TV from a USB stick and watch the entire 30 seconds and look for any errors I told you about.
If the pattern is a square as it moves there is no crosstalk, if it's too fast to see then use the dslr camera method pattern 2 uses.Link to test patterns
This next test pattern is 1080p, 16:9, side by side left side first, 1 minute long.
To use these to test for ghosting/crosstalk. Wear the glasses and watch the videos in 3D on your TV.
Then, close one eye and see if the video is showing two images of the same pattern.
A double image would look like a rectangle rather than a square.
NTSCHigh Contrast version.High Brightness version.
PALHigh Contrast version.High Brightness version.
Link to quote.Link to test files
Originally Posted by icester
You can confirm it by playing a movie that has side by side configuration and contains left image with text "left image" and right image with text "right image".
By pausing the movie you can look through your DLP-Link shutters glasses with right eye closed and see if the image says "left eye" Then do the pay /pause sequence several times and see if you always get "left image" text when your right eye is closed...
16:9 aspect ratio, Side by Side Left side first, 1080p resolution - squished
Also these test files are good to test for ghosting.
While playing the test files close one eye and see if the text is doubled.
Ghosting is visible if "Right Image" and "Left Image" text is being shown at the same time with one eye closed.
You wear your 3d active polarized or passive polarized glasses for this test.