Out in Front: November 9, 1995

Liquid, a new software package from Technology Modeling Associates, can help you design LCD panels by addressing the panels’ components and letting you simulate a flat-panel display. This technique allows you to perform design trade-offs to optimize the display.

An active-matrix LCD combines a thin-film transistor (TFT), a liquid-crystal cell (LCC), an electrical interconnect system (array), and optical polarizers and light filters. You input parameters for the different portions of the LCD to Liquid. Example parameters include current-voltage and capacitance-voltage characteristics for the TFT, which you can obtain from a parameter extractor or Spice simulation; geometry, including gap and pixel spacing, and medium of the LCC; metal dimensions and resistivity of the interconnect array; and polarizing characteristics, such as refractive index and wavelength, of the optical components. Liquid uses this information along with a reference image in a suitable graphics format, such as graphics image file, and produces a simulated image on the display of the workstation on which you are doing the LCD analysis.

An additional useful feature of Liquid is its ability to simulate an LCD as a function of viewing angle. As you specify increasing viewing angles, the simulated image loses contrast and color, as would a real LCD. Liquid also has an optical-analysis window, which shows a polar plot of contrast ratio as a function of viewing angle along with the electro-optic curve for the device being simulated. You can vary LCD parameters to determine the best combination for largest viewing angle. Liquid will be available in December. The software runs on Unix workstations from Digital Equipment Corp, Hewlett-Packard, IBM, and Sun, and prices start at $105,000.
—by Jim Lipman

Technology Modeling Associates, Palo Alto, CA. (415) 856-8862.