A compact image display system in which the optical pathway is folded and thereby extended between the image source and the imaging optics of the system. The image display system may be used in place of computer or television screens, and may further be affixed to a frame so that it is wearable...http://www.google.com.hk/patents/US5777795?utm_source=gb-gplus-share專利 US5777795 - Optical path extender for compact imaging display systems
