Mechanics of Video Glasses
How do these gadgets give you the illusion of sitting in front of a big-screen television? The patents filed for a few of these cutting-edge video glasses offer us some helpful insight.
The displays typically use liquid crystal displays (LCDs) or organic light emitting diodes (OLEDs). A lens magnifies these tiny displays so viewers feel as if they're sitting in front of a large screen. Video glasses come equipped with audio equipment, often in the form of earbud headphones that hang from the headpiece. A battery pack and media player connect to the glasses through wires.
The mechanics of video glasses are designed to capitalize on an amazing function of our vision perception. Most video glasses display two images -- one for each individual eye. When aligned correctly, video glasses allow our brains to make a composite image of the two displays. This allows us to sense depth. Putting together images to form one 3-D image in our brain is known as stereopsis.
The advanced video glasses that strive for this 3-D illusion are binocular. Simpler, two-dimensional varieties are biocular. Whereas binocular glasses display two slightly different images to each eye, biocular head-mounted displays (HMDs) project one image that is seen by both eyes. Hybrids, which use a combination of binocular and biocular methods, split the video image into two parts. From these parts, your brain creates a single composite image. The more well-known video glasses on the market are hybrids.
Among HMDs, many video glasses fall into the immersive category. Immersive glasses take the viewer completely out of his or her surroundings. When you have on an immersive HMD, you won't be able to see anything around you. Other glasses are nonimmersive, meaning that the viewer can at least partially see his or her surroundings.
When you want an immersive video experience, most agree that bigger is better. This is one fundamental drawback to watching video on portable players with small screens such as iPods and cell phones. Developers are working to increase the field of view (FOV) of video glasses. Our eyes have a natural horizontal FOV of about 180 degrees, but video glasses offer smaller FOVs (ranging in the 20s, usually). This is partly due to the technology used to film videos in the first place [source: Tang]. When the image contains only so many pixels, enlarging them too much will result in poor resolution [source: Cakmakei].