3D TV is still new. So new that the basic technology for delivering it is still in a state of flux. Most brands have gone for the ‘shutter glasses’ technique, in which the left and right eye perspectives on the picture are flashed on the screen in sequence, and the glasses only let each eye see the particular perspective intended for it.
But that’s not how it is done in most cinemas, nor how it is done in the new LG 47LW6500 LCD TV.
First, let’s look at this briefly as a regular TV. It has a thin (just under 30mm) LED backlit pane. I say backlit rather than edge lit, because somehow LG has managed to stuff the lights behind the panel, despite its thinness. Furthermore, there are 16 individually controllable LED ‘blocks’, so the TV can selectively brighten some portions of the screen while darkening others.
It comes with all the stuff you’d expect from a 2011 model premium TV. It of course has a HD digital tuner built in (and analog), supports a PVR function if you plug a USB disk drive into one of its USB sockets, and has extensive networking capabilities. Indeed, it supports YouTube and BigPond Movies and TV and both the ABC and Channel 7 replay channels. There are also a number of internet-based Widgets, including Facebook.
The 3D system uses ‘passive’ glasses of the kind used in cinemas. This makes them much less expensive, to the point that you get four sets in the box and can buy more in packs of two for $19. The LG glasses are, unaccountably, white framed.
Passive glasses work by means of polarised light. Light waves have a characteristic twist – either clockwise or anticlockwise. Filters can be applied so that only one or the other can get through. That’s what’s in these glasses. The TV screen has each horizontal row of pixels polarised either one way or the other. If you’re not wearing these glasses it makes no difference. But if you are, then each eye only sees every second row of pixels. The 3D processing makes sure that the picture for the left and right eyes goes to the matching rows of pixels.