A design of multiplexing liquid-crystal display for calculators

A numeric liquid-crystal display using the dynamic scattering mode has been developed for calculators by adopting a total system design through the integrated development of material, device, and system. A mixed Schiff-base nematic liquid crystal with the dopants of l-hexadecylpyridinum bromide and p-aminophenol has been developed for the 1:2 selection multiplexing drive over a wide temperature range (0-40°C). A reliable package has been achieved with new technology. A 1-chip CMOS driving circuit with a 42-lead package has been developed for 8-digit 7-segment numeric readout displays in order to eliminate the dc component of the applied voltage, to minimize variations in the drive voltage, and to reduce power consumption. The devices have passed severe reliability tests. Our displays have lasted 15 000 h under normal test conditions. Using the dichroic mirror approach, it has become possible to design color displays of yellow, green, blue, or any color which have high readability and wide viewing angle under severe ambient light conditions.