Along with Key Patent 8456745 COMPACT EYEPIECE USING AN IMMERSED FIELD LENS, Obtained the Same Day: Collimating optical member for real world simulation

And why the Oculus Vomit Comet Makes People Sick and why eMagin's iHMD won't:

The problem stems from the fact that the simulated scene on a display is located a relatively finite distance from the user, perhaps 40 cm. Accordingly, head movement of a few centimeters causes radical disparity between expected image position and actual image position. Nonetheless, such systems do enjoy a large measure of popularity in the civilian world, because the human brain is well trained by television to accept such displays. Nevertheless, such displays, while accepted by the human brain, fail to provide the numerous visual cues such as image movement, parallax, image size and the like, that inform and then guide reactions.

http://www.google.com/patents/US20070070508