RGB Backlight | TFT and FSC LCD displays

The RGB backlight on TFT displays and custom FSC color LCDs

RGB (red green blue) macro pixels – extreme macro shot of a LCD computer monitor

The RGB backlight combines the three colors to generate all other possible colors. The exception to this is the color black.

Two of the more popular types of custom color LCD modules are TFT LCD Displays and custom FSC LCD modules. Both TFT LCD Displays(Thin Film Transistor) and FSC LCD Modules (Field Sequential Field Color) require a RGB (Red, Green, and Blue) LED backlight.

The half-life of TFT displays and custom FSC LCDs

One concern many customers have with a TFT LCD display and a custom FSC LCD module is the half-life of the LED backlights. In other words, how long before the backlight starts to dim?

Let’s start by explaining what the term half-life means. Half-life is an engineering term which simply means “How many hours can the backlight be on before it is half as bright as when the backlight was first turned on?” This term is measured in hours. This does not mean it burns out at this time, but only dims. Half-life for many LED backlights can average between 50,000 hours and 70,000 hours.

An example of this is a 3.5 inch TFT. The half-life of the RGB (Red, Green, and Blue) backlight is rated at 50K hours. When 50K hours rolls around the light will be half as bright as when you first activated the display. When the same display runs for an additional 50K hours, that is a total of 100K hours, the brightness of the backlight is now half of what it was at 50K hours or one quarter, 25%, as bright as when it was first turned on.

Replacing the RGB backlight of TFT displays and custom FSC LCDs

It is close to impossible to replace the backlight on a TFT LCD display or a custom FSC LCD module once it is out in the field. Taking the display apart is not difficult; putting it back together is a whole different subject. LCD display modules need to be assembled in a clean room environment.

At this time the only other option is to replace the entire LCD module. This introduces issues that can be expensive. LCD modules have a tendency to be discontinued every few years. This means you may try to purchase replacement displays, only to find they have become impossible to locate. At this point the only option you have is to build a custom LCD display module. This can also be expensive and time consuming.

Extend the half-life of TFT displays and custom FSC LCDs

One possible option to obtain a longer half-life on your TFT LCD display or custom FSC LCD module is to build a custom display when you first design your product. The custom display would contain two RGB backlights. The concept is that the customer’s processor would turn on RGB backlight #1 for 1,000 hours, and then switch to the second RGB backlight for 1,000 hours. This rotating between the two sets of RGB backlight would double the half-life of the TFT LCD display custom FSC LCD.

We do not offer this option on any of our standard LCD modules, but have partnered with a supplier to engineer and design this display on LCD custom modules.

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