Transflective vs Transmissive LCD Module

Transflective vs Transmissive LCD Module
March 8, 2017 Eric Hawkins
In Journals

When selecting a LCD with backlight, there are two types of LCD polarizers to consider: Transflective vs Transmissive.

Transflective vs Transmissive | Which is Best?

Transmissive polarizer: Transflective Polarizer:
Advantages:

  • Backlight is brighter without drawing more current (power)

Disadvantages:

  • Very poor in direct sunlight (that is why most cell phones and tablets are hard to read on a sunny day)
  • The display can only be read when the backlight is ON which makes it a poor choice for battery or solar powered products.
Advantages:

  • Is still readable when the backlight is OFF
  • Easy to read in direct sunlight
  • Ideal for battery powered products.

Disadvantages:

  • Dimmer backlight

Transflective vs Transmissive Visual Aid:

Below are two photos comparing a Transmissive polarizer to a Transflective polarizer.

These segment displays (below) are shown in different color backlight options. They are built with the same LED backlight and driven at the same current. In all photos below the transmissive polarizer is on the left side and the transflective polarizer is on the right side. As you can see the display with the Transmissive polarizer is brighter.

All Photos are Positive mode. For more information on Positive mode LCD module and Negative mode LCD displays, please see Positive-and-negative-mode-lcd-display-modules/.

White Backlight | transflective vs transmissive LCDBlue Backlight | transflective vs transmissive LCD

Red Backlight | transflective vs transmissive LCDYellowGreen Backlight | transflective vs transmissive LCD

Which polarizer to choose?

Transflective vs Transmissive… The choice is simple. If your product is battery powered or you need it to be readable in direct sunlight, then choose Transflective; otherwise choose Transmissive.

There is no difference in cost or lead-time between LCDs with a Transflective and Transmissive LCD polarizer.

Note: There is a third polarizer option: Reflective and is covered in the article : what-is-the-difference-between-reflective-transflective-and-transmissive

LED vs EL backlights

Once you choose the polarizer type (Transflective vs Transmissive), you will need to select the type of backlight. There are two technologies: LED vs EL.

LED backlights:

  • LED (Light-Emitting Diode) is the most popular and accounts for about 98% of all new LCDs that require a backlight.
  • LEDs are DC driven with a half-life ranging from 50K to 80K hours depending on how hard they are driven.

EL backlight:

  • EL (Electroluminescence) backlights are available, but not recommended for new designs.

This type of backlight is being phased out due to several reasons including:

  • A short half-life of only 3K hours
  • They are AC driven which requires an inverter and produces electrical interference. (aka noise)
  • MOQs (Minimum Order Quantities) are much higher.

What does half-life mean?

‘Half-life’ is a way to measure when the brightness of a backlight is half (50%) as bright as when it was first turned on and is measured in hours. This is not the amount of time for the backlight to burn out.

Questions about LCDs?

Want to talk to a human about your LCD needs? Contact us at 480-503-4295.

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