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Each LCD has two polarizers, the front and rear polarizers, applied
accordingly across the front of the display viewing surface and across the
rear of the display to determine how the infuse light into the display. The
front polarizer is always transmissive and not selectable by the user,
however the rear polarizer has three choices and two grades for each choice.
Reflective Polarizer
Reflective displays have an opaque rear polarizer that includes a diffuse
reflector, such as brushed aluminum. This layer reflects polarized ambient
light that has entered the front of the display back trough the LCD cell.
Reflective displays require ambient light to be seen. They exhibit high
brightness, excellent contrast, and wide viewing angles. They are
particularly suitable for use in battery operated equipment where an
adequate level of light is always available. Reflective LCD's cannot be
backlit, however they can be front lighted in some applications.
Transmissive Polarizer
Transmissive displays have a clear polarizer on the front and the back. The
display therefore depends on light coming through from the back of the
display toward the observer in order to be seen. Most, but not all
transmissive displays are negative image, and we sometimes add colored
filters to different areas of the display to highlight different
annunciators. Another example of a transmissive polarizer display would be a
transparent window where you could see the segments superimposed over your
line of vision through the display window (this assumes a sufficient ambient
light source exists on either side of the window).
Transflective Polarizer
Transflective displays have a rear polarizer which includes a translucent
material which reflects part of the ambient light, and also transmits
backlighting. As the name implies, it is a compromise between the
transmissive and reflective viewing mode. Used in reflection, it is not as
bright and has lower contrast than the reflective type LCD, but it can be
backlit for use in low light conditions. This polarizer is the best
selection for a display that can be used in all lighting conditions with a
backlight.
Commercial Grade Polarizer
The grade of a polarizer determines its operational and storage temperature
range. The commercial grade polarizer operates typically between -10°C to
+60°C.
Industrial Grade Polarizer
The grade of a polarizer determines its operational and storage temperature
range. The industrial grade polarizer operates typically between -30°C to
+80°C. Other temperature ranges are also available. |
