MicroOptical Corp., Westwood, Mass., is field testing a monitor clip-on information display. It's the company's model C-1, which provides quarter-VGA (320- by 240-pixel) color at a 60-Hz refresh rate (Fig. 4). It fits most adult frames and safety glasses. The input is a standard VGA, female DB-15 connector, and a standard National Television Standards Committee (NTSC) RCA plug. Power requirements are 100 mW for the display and backlight, 2.9 W for the VGA interface, 1.9 W for the NTSC interface, and 300 mW for an RS-170 interface. The RS-170 is the Electronic Industries Association standard for the combination of signals that are required to form NTSC monochrome video. Head-supported weight is less than 50 g.
Likewise, the company has field-tested its model EG-6C, which has VGA color or monochrome resolution, with a 60-Hz refresh rate. The field of view is approximately 10° on the diagonal corresponding to a 6.5-in. diagonal display, three feet away. The focus range is from 20 cm to infinity. The power required is 100 mW for the display and backlight, 2.9 W for the VGA interface, 1.8 W for the NTSC interface, and 300 mW for the RS-170 interface. The head-supported weight is 100 g. (See "Candidates For Head-Mounted Displays," p. 112, for a discussion of the three microdisplay technologies that are likely to end up in HMDs.)
Summing up, McLaughlin remarks, "The issue isn't the microdisplays. It's the optics, the power, and all the other stuff." The innovators haven't yet turned the corner from a price/performance point of view. He further says, "I'm optimistic about what they're trying to do, but rather skeptical as to how fast they're going to get it done. An audio headset weighs in at 14 g, so a 100-g HMD isn't going to do it. Do you want to wear a 100-g headset all day?"
Probably not. "I just hope that the developers are looking for new and exciting architectures and designs to try to meet the performance and price points for the consumer market. There's no doubt that over the next year substantial market opportunities are going to develop for HMDs," concludes McLaughlin.
Recommended reading:
Sorsby, A., "Biology of the Eye as an Optical System," Clinical Ophthalmology, vol. 1, chapter 34, Duane, T.D. (editor), 1988.
Bergstrom, N.; Chuang, C.L.; Curley, M.; Hildebrand, A.; and Li, Z.W., "Ergonomic Wearable Personal Display," Digest of Technical Papers, Society for Information Display International Symposium, vol. XXXI, May 16-18, 2000.