A polarizer allows some light to pass through the liquid crystal display and some light to be reflected back towards the user of the display. There are three types of polarizer’s used in LCD display modules. These include character LCD module (or alphanumeric LCD display), Segment Display (or static display) and graphic LCD displays.
Reflective mode LCD
In the reflective mode, ambient light (the light that is available from the sun, office lights, etc) is used to illuminate the display.
A reflective LCD module works the same as a mirror. It will reflect all the light it cast on it, but it will block any light that is placed behind it.
It is possible to use a reflective polarizer with a side lit display.
Advantages: The contrast is sharper then transflective LCD displays and transmissive LCD modules.
Disadvantages: It is not possible to use a backlight behind the display. This type of display is best used where light will always be available.
Transflective mode LCD
A Transflective polarizer is a combination of both a reflective polarizer (no light may pass through) and a Transmissive polarizer (all the light can pass through).
The Transflective mode LCD allows the user to read the display when the backlight is off. When necessary a backlight placed behind the polarizer can be turned on. This allows the user to read the display when in a dark location or ambient light is very dim.
Advantages: The LCD can be used with or without the backlight being on.
Disadvantages: The contrast is not as sharp as a reflective display.
Transmissive mode LCD
A Transmissive polarizer allows all light to pass through the display.
The backlight must be on for the user to read the display.
Advantages: The backlight will be brighter in a Transmissive LCD display than in a Transflective LCD module.
Disadvantages: The display is very difficult to read when the backlight is not on.
Summary:
There is no difference in cost or lead time between Reflective, Transflective and Transmissive. It is possible to build any of the three polarizer’s as a TN display, STN display or FSTN display.
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Segment Display module (aka: static LCD displays, seven segment display, glass only LCD display) The majority of segment displays listed below are TN, but they can be ordered in STN
7(seven) segment LCD display, 14(fourteen) segment LCD display, 16(sixteen) segment LCD displays, multiplex, mux, common mode LCD.
Character LCD module (aka: alphanumeric LCD display, character LCD, numeric LCD displays) The majority of character LCD modules listed below are STN
8 x 1 LCD Display, 8 x 2 LCD Display, 16 x 1 LCD Display, 16 x 2 LCD Display, 16 x 4 LCD Display, 20 x 2 LCD Display, 20 x 4 LCD Display, 24 x 2 LCD Display, 40 x 1 LCD Display, 40 x 2 LCD Display, 40 x 4 LCD Display.
Graphic LCD displays (aka Monochrome Graphic LCD Displays, dot matrix LCD module) The majority of Graphic Displays listed below are FSTN, but can be order in STN
122 x 32 graphic LCD display, 128 x 128 graphic LCD display, 128 x 64 graphic LCD display, 240 x 64 graphic LCD display
Custom LCD displays Can be ordered as TN, STN and FSTN. Also, LED backlight, EL backlight, but no longer available in CCFL backlight.
