Why does 3DTV use glasses?
3D got thrown hard into the spotlight last year. With the help from James Camerons’ Avatar, 3D fast became the focal point of technology for 2010. 2011 is set to expand on 3D technologies even further. The hype makes sense, apart from Avatars terrible story, the 3D visuals we’re stunning, and it showed the world the possibilities of extending the entertainment capabilities of future televisions and home entertainment.
The major drawback of 3D at the moment is the need to use the glasses. If you seen any 3D movie at the cinema, and used a 3DTV you will notice a few differences in the glasses. The glasses at the cinema needed no battery, just put them on and watch, perfect! So why do 3DTV’s use powered glasses (Better known as Active 3D Glasses). The reason behind this is simple enough, at the cinema the picture for each eye is actually projected onto the screen simultaneously. The light of each picture (Left eye picture, Right eye picture) is polarized a different way, either vertically or horizontally, just like polarized sunglasses they only let light in which is polarised in it’s set direction.
3D TV currently uses a different method to produce the 3D effect. The glasses needs the batteries to run the two LCD panels inside the glasses, one for each eye. LCD panels have the ability to either allow light to pass, or block light all together. So what actually happens is, the TV will show an image for the left eye, then right eye, then left eye etc… As this is happening the television transmits a signal to the glasses to tell it which eye should be on, which off. Technically your only looking through one eye at a time, but because this all happens so fast your brain doesn’t percieve the difference and just renders both images together as a complete 3D image! What it does percieve, however, is a less vibrant picture, partly due to the flickering glasses, but mostly because polarized panels can’t be 100% clear.
The best news is, 3D Televisions won’t always require the glasses for too long. Infact, Toshiba and other companies are working on a 3DTV using a special lens which directs the left/right images into the appropriate eye. We’ll have to wait and see how this works out, until then, we can enjoy the occasional 3D movie or game on our Plasma TV by proudly wearing our unsightly goggles.