Current display research—A survey

Recent display research will be reviewed and related to displays which are available commercially. For many devices, the focus of current work is on materials. New liquid-crystal formulations offer lower-voltage thresholds and thus wider viewing angles and higher contrast, both of which increase with voltage above threshold. New materials are making possible liquid-crystal-and-dye devices with potentially better performance than twisted-nematic liquid crystals. In electrochromic devices, much effort is going into understanding the failure mechanisms. Further improvement in life and lower-voltage operation have been reported for low-voltage DC electroluminescent phosphors. Some new forms of gas-discharge devices have been described. The introduction of memory to positive-column displays should eventually improve both luminance and efficiency. So far, only increased luminance has been attained; the, duty factor and resulting lower peak luminance has not yet been translated into higher efficiency. For many displays, the drive electronics is substantially more expensive than the display device itself, so there is incentive to reduce the cost of the drive circuitry. Much of this work involves conventional semiconductor technology: new circuitry, less-expensive packaging, and lower-cost interconnections. Reducing the requirements on the drive circuitry by modifying the device characteristics can also lower circuit costs.