Passive LCD Technology
For passive LC displays a variety of technologies are available. They differ in viewing angle, colour, maximum multiplex rate and temperature range.
The lowest-priced technology is TN which is used for segment LCDs and alphanumeric modules. This technology suffers from a very constricted viewing angle and a maximum multiplex rate of 1:8.
Used mainly for alphanumeric modules and graphics modules, the STN technology features higher multiplex rates (>1:8) than TN and higher contrast ratio as well as a wider viewing angle.
LCDs can be produced in positive and negative mode. In positive mode the segment driven is darker than the background. LCDs use ambient light and/or a backlight. In negative mode the driven segment is brighter than the background. It is used especially if a high contrast with backlight is required.
The following table shows the colours of the segments or dots and the background colour of the LCD for possible modes:
|TN||black / grey||transparent / black|
|STN||blue / yellow-green||transparent / blue|
|STN||blue / grey||blue / transparent|
|FSTN||black / white||white / black|