Procedure developed by S. M. Condren and G. C. Lisensky.
This experiment deals with the disassembly of an inexpensive liquid crystal display (LCD) watch and testing several of the properties of the LCD panel.
Remove the front or back plate to access the interior. Your watch may
be slightly different from the one shown here. If screws are removed,
place them in a small container for safe keeping since tiny parts can
be easily lost.
Remove the watch assembly from the band.
Slowly rotate a polarizer above the LCD panel. Does the orientation make
a difference?
Remove the four tiny screws holding the printed circuit board and battery
retainer to the white plastic inner case. Remove the electrically conducting
pad and the LCD panel. Place the screws, switch contacts, and battery
contacts into a small container for safe keeping.
Examine the LCD panel and find the contact area of the panel on the bottom
of the wider glass plate. Use a battery snap connected to 9-V battery.
Hold one of the leads against the contact area at one end of the panel
and rub the other lead along the contact area to address various segments
of the LCD panel.
Under pressure liquid crystal materials, such as used in LCD watches,
undergo dramatic color changes.
When a liquid crystal melts, the molecules become less ordered and the
display appears black. The change is reversible if the heating is not
too severe.
The temperature for the liquid crystals to liquid phase transition can
be measured using a hot water bath and a thermometer.
This step is not totally reversible. Remove the top polarizer
by carefully prying up one corner and then gently peeling it away.
This step is not totally reversible. Cut the polarizer in half
with scissors. Place one half back on the panel in its original orientation.
Place the other half back after rotating 90 degrees. Use a battery snap
connected to 9-V battery. Hold one of the leads against the contact area
at one end of the panel and rub the other lead along the contact area
to address various segments of the LCD panel. Does the orientation make
a difference?
With care, the watch can be reassembled in working order.
Materials
An inexpensive LCD watch (not necessarily functioning)
