There are three primary types of display polarization technologies, they are the Reflective, Transmissive, and Transflective.

Reflective

This polarization technology is most commonly found on calculators and some inexpensive digital wristwatches. Since Liquid Crystal Displays are non-emissive type of displays (does not generate their own light source), they rely on a light source, either using the sun, the ambient light, or a backlight, in order to see the characters on the display. Example, if you took a digital wristwatch into a dark room and do not press the light button, you will not see anything on the display. But as soon as you press the light button on the watch, you are then able to see the time, or if you turn on the lights in the room, you too will be able to see the time.

So, when a display is "Reflective" it means that is needs to have a light source in front of the display in order for you to read the display...thus “reflecting” the light. A typical application for this technology is a product that is used in an office environment where the office lights are sufficient, a product that is used outdoors in the sun, etc. Where the light source is supplied by the environment. (See Diag. 3.0)

In addition, with the reflective technology, the background color of the display is fixed as a grey/silver color background (click here to see a picture of the reflective technology) and you CANNOT install a backlight for illumination.

The reason you cannot install a backlight onto a reflective display is due to the construction of the rear polarizer...its basically a solid material that has no Transmissive properties, so no light can pass through it.

Transmissive

This polarization technology is the opposite of the Reflective technology. This type of technology can be found in Medical devices, test and measurement instruments, automotive audio, laptop computers etc. This technology requires a backlight in order to see the image on the screen. There are exceptions to this rule, but only in very specific designs can this be achieved. In addition, most Transmissive displays are negative mode, meaning that the text will be light color and the background of the display is dark colored.

With this technology, the light source must be behind the LCD panel, so that the light shines through the display as the pixels are activated, this will allow the light to pass, thus you see an image. (See Diag. 3.0)

To see a picture of the Transmissive technology,click here.

With this technology, the key element is the backlight...without it, the image on screen will either not be visible or extremely low on contrast. The backlight must be ON.

Transflective

This is probably the most commonly used polarization technology. Most cellular phones, PDA, GPS, Fish finders, etc. use this type of polarization technology. The best way to understand how the Transflective works is to think about the windows of an office building in a downtown skyscraper that look like a mirror. During the day, you can't see through the window, instead, there is a reflection. Then during the night, when you look at the same building, you can see what's inside the office. Are you confused with this analogy?

To explain another way, with the Transflective technology, the characters on the display are visible because of its dual nature, the ability to reflect light and transmit light through (from the backlight source). Basically, where the light is the brightest, whether its the backlight or the ambient light, you will still see the display. If you took this display into a dark room, the backlight would shine through the display and allow you to see the characters (as if the display was transmissive), whereas if you were outside in the sun, the sunlight would be reflected and again (as if the display was reflective), you will see the characters. (See Diag. 3.0)

This polarization technology also offers two different background colors, yellow and nuetral/grey. To see pictures of the Transflective technology, click here.

Diag. 3.0