This article covers the LCD polarizer differences between the Reflective polarizer, the Transflective polarizer, and the Transmissive polarizer. 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 (alphanumeric) LCD modules, Segment (static) LCD displays, and graphic LCD displays.
LCD Polarizer Differences: Reflective
Reflective Polarizer - 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. The light comes in from the front and bounces off the mirror in the back. There is no backlight from behind, but edge lighting can be used.
A backlight mounted behind the polarizer, will not work on this type of application. It will work just like a flashlight behind a mirror. The light will be blocked and not shine through. This is used where there is high ambient light and no need for a backlight, such as outdoors with strong sunlight or in a well lit factory.
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.
LCD Polarizer Differences: Transflective
Tranflective Polarizer - 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.
This is kind of like a two-way mirror. The light comes in from the front and a backlight placed behind it will shine through. This is used in all types of lighting conditions. This makes it possible to read the LCD with the backlight ON and with the backlight OFF. This is the most common polarizer for any backlight. If the customer is not sure what they want, and they have a backlight choose a transflective.
Advantages: The LCD can be used with or without the backlight being ON.
Disadvantages: The contrast is not as sharp as a reflective display.
LCD Polarizer Differences: Transmissive
Transmissive Polarizer - A Transmissive polarizer allows all light to pass through the display. The backlight must be ON for the user to read the display. The backlight on the transmissive polarizer is very bright. The LCD is difficult to read when the backlight is OFF. But it is still possible to read the characters.
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 of LCD Polarizer Differences:
Choose the polarizer based on the type of lighting conditions your display will operate in. There is no difference in cost or lead time between Reflective, Transflective and Transmissive polarizer. Note: It is possible to build any of the three polarizer’s as a TN display, STN display or FSTN display
If you have any questions regarding LCD polarizer differences, feel free to contact Focus Displays Solutions for US-based support. You can call 480-503-4295 or simply fill out the contact form to the right of this article.
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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
Character LCD module (aka: alphanumeric LCD display, character LCD, numeric LCD displays) The majority of character LCD modules listed below are STN
8x1 LCD display, 8x2 LCD display, 16x1 LCD display, 16x2 LCD display, 16x4 LCD display, 20x2 LCD display, 20x4 LCD display, 24x2 LCD display, 40x1 LCD display, 40x2 LCD display, 40x4 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 ordered in STN.
122x32 graphic LCD display, 128x128 graphic LCD display, 128x64 graphic LCD display, 240x64 graphic LCD display
Custom LCD displays Can be ordered as TN, STN and FSTN. Also, LED backlight, EL backlight (with 500 MOQ), but no longer available in CCFL backlight.