Liquid Crystal Displays
Liquid crystals are organic substances that reflect light when voltage is
In a watch display, the liquid crystal material is sandwiched in between two
layers of glass. A transparent electrode pattern has been applied on the inner
surfaces of the glass in the shape of the digital bars used in the time
display. The integrated circuit applies voltage to the appropriate segments of
the display, which reflect the ambient light to display the time. These
molecules are affected by the voltage in such a way that they contrast sharply
with the molecules in the rest of the display that do not receive current.
Because LCDs reflect, rather than emit, light, the voltage requirements are
Scientists have known about liquid crystals since the 1880s.
Scientists have known about liquid crystals since the end of
the 19th century, but applications appeared only in the 1960s.
Friedrich Reinitzer and Otto Lehmann
first noted their behavior
and named them in the 1880s. European laboratory scientists came
to understand the physics and chemistry of liquid crystals during
the 1930s, but it wasn't until the 1960s that investigations began
in the United States in both basic research and practical uses
for liquid crystals.
LCD watches first appeared in 1970, but the display required improvement.
The first liquid crystal displays were developed in 1968 by a research group
at RCA's David Sarnoff Research Center, headed by George Heilmeier. This display was based on the dynamic scattering mode. In 1970 Nunzio Luce, Louis Zanoni, George Graham, and Joel Goldmacher left RCA and joined Optel Corporation, where they developed the first LCD display for commercial purposes, including the digital watch display.
Because the DSM LCDs suffered from relatively
high power consumption, limited life, and poor contrast, the search
continued for a workable LCD.
James Fergason at Kent State invented
an improved display based on the twisted nematic field effect in 1969.
Fergason left Kent State and formed ILIXCO Corporation to manufacture his
display. The first LCD watch with an ILIXCO display was marketed by Gruen. The
field effect display is the kind most frequently found in today's LCD products.
Time Displays ~