3D display with dual backlights

Posted February 5, 2006

There's all sorts of interesting things going on with display technology, so to keep with the backlighting theme of my last entry, here's another innovation along those lines. This patent is the best description I could find of a neat technique for doing 3D displays with only minimal modifications to existing LCD panels.

To make a 3D display generally boils down to somehow presenting a different image to the left and right eye of your user. If you can do that by any means, either by having the user wear polarizing glasses, by putting two different displays right in front of his eyes inside a VR helmet, or by clever optical systems, you're golden, and the rest is just making those two views synthesize a three-dimensional scene.

So in this case, the method chosen is to have two backlights for your LCD panel. Each one shines horizontally from the edge of the screen onto a separate layer of little microprisms which bounces the light up through the LCD panel, but at a small angle. So one backlight illuminates a little to the left, and the other illuminates a little to the right... with the user directly in front of the display, that means one is shining into his right eye and the other his left.

Flash the two backlights alternately and have your LCD panel present the two eye views sequentially, and poof, you're done: you're giving the user's two eyes two different images. Granted, the user has to be in exactly the right place for this to work properly, but the huge advantage is that this is essentially a drop-in replacement for existing backlight assemblies, so you can turn a cellphone display into a 3D imager without a lot of hassle... aaand if you want to drop back down to normal 2D behavior without restricting the user's positioning so much, you just turn both backlights on and run the screen normally.