How 3D Glasses For 3D TVs Work
The history of 3d glasses is an interesting one, and actually is longer than you might think. They were actually invented quite a long time before they had a mass release in the 1950s. After becoming popular again for a short time during the 70s, the market for them soon dropped away though. Much of that had to do with the fact that the 3D technology of old was not actually very good.
With the old red-blue glasses, as you probably know, they didn't always work and even when they did they made the image blurry. This has managed to be eliminated by the modern glasses, which are much more precise. However they still work by the same principle, which is to separate two images that are shown, so that each eye will only receive one of them.
The reason this has to be done comes down to the way that we are able to perceive depth in the real world. This comes down to a question of coordinates. For objects in a three dimensional space, to pin point their location we need three coordinates, the x and y coordinates for the length and height, and then the z coordinates for the depth, or how far away it is. To calculate the z coordinates, however, you need to be able to see the object from two different directions. We are able to do this because we have two different eyes.
In the real world, therefore, we are able to do this because we have got two eyes and so two points of reference. That's only because there are actually three dimensional objects in the real world though, but when we are looking at a flat screen they don't actually have any depth to them. Therefore the illusion of depth has got to be created by giving a different image to both eyes, just like we get in the real world, enabling the brain to calculate depth properly.
One solution to this is to display both images simultaneously and then have the glasses filter them out. This is what the old glasses used to do, using the different colour spectra to do it. The same principle is involved with the polarising, passive 3D glasses that we have now as well. These are the kind which are used in cinemas, but are rarely used with 3D televisions.
Instead, most 3D TVs utilize the active shutter 3D glasses. These sorts of glasses do not do any sort of filtration, they are much simpler than that although it actually requires a lot more to be going on electronically. What happens is that each individual frame is broadcast for one eye or the other, and then the LCD screens in the glasses black out one of the eyes to correspond with the different frames. Of course you cannot notice this flickering effect because it is happening at the same speed that the frames are changing.
The major benefit of using active shutter 3D glasses as opposed to the passive, polarising variety, is that you do not lose any of the resolution. At any one time, each eye is going to be seeing the entire screen. This means you will be getting the HD image in its full glory with this effect. The major drawback, however, is that these sorts of glasses are more expensive due to the active technology involved.
When you are buying 3d glasses for your 3D television, you can cut down on the cost by getting universal glasses. They work across most sorts of 3D televisions, whereas the manufacturer's own will generally only work on their own make of television. If you only want glasses to be able to watch 3D films at the cinema, however, or to watch the 3D televisions in pubs, then you can go for the cheaper polarising variety.
With the old red-blue glasses, as you probably know, they didn't always work and even when they did they made the image blurry. This has managed to be eliminated by the modern glasses, which are much more precise. However they still work by the same principle, which is to separate two images that are shown, so that each eye will only receive one of them.
The reason this has to be done comes down to the way that we are able to perceive depth in the real world. This comes down to a question of coordinates. For objects in a three dimensional space, to pin point their location we need three coordinates, the x and y coordinates for the length and height, and then the z coordinates for the depth, or how far away it is. To calculate the z coordinates, however, you need to be able to see the object from two different directions. We are able to do this because we have two different eyes.
In the real world, therefore, we are able to do this because we have got two eyes and so two points of reference. That's only because there are actually three dimensional objects in the real world though, but when we are looking at a flat screen they don't actually have any depth to them. Therefore the illusion of depth has got to be created by giving a different image to both eyes, just like we get in the real world, enabling the brain to calculate depth properly.
One solution to this is to display both images simultaneously and then have the glasses filter them out. This is what the old glasses used to do, using the different colour spectra to do it. The same principle is involved with the polarising, passive 3D glasses that we have now as well. These are the kind which are used in cinemas, but are rarely used with 3D televisions.
Instead, most 3D TVs utilize the active shutter 3D glasses. These sorts of glasses do not do any sort of filtration, they are much simpler than that although it actually requires a lot more to be going on electronically. What happens is that each individual frame is broadcast for one eye or the other, and then the LCD screens in the glasses black out one of the eyes to correspond with the different frames. Of course you cannot notice this flickering effect because it is happening at the same speed that the frames are changing.
The major benefit of using active shutter 3D glasses as opposed to the passive, polarising variety, is that you do not lose any of the resolution. At any one time, each eye is going to be seeing the entire screen. This means you will be getting the HD image in its full glory with this effect. The major drawback, however, is that these sorts of glasses are more expensive due to the active technology involved.
When you are buying 3d glasses for your 3D television, you can cut down on the cost by getting universal glasses. They work across most sorts of 3D televisions, whereas the manufacturer's own will generally only work on their own make of television. If you only want glasses to be able to watch 3D films at the cinema, however, or to watch the 3D televisions in pubs, then you can go for the cheaper polarising variety.
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