TFT (Thin Film Transistor) Displays are the most popular multi-color LCD module in use today. They range in sizes from less than an inch to large screen TVs.
TFT modules can display up to 64 Million unique colors. Most contain a built-in controller for easy programming and a touch screen for customer interfacing.
The majority of TFTs have a transmissive polarizer and produce very bright illumination in darkness or dim lighting, but the brightness makes it difficult to read in direct sunlight. Think how difficult it is to read your tablet or cell phone in sunlight. You find yourself scampering off for shade or bending over to create a shadow.
What the heck is a polarizer? Click here to find out!
Transmissive polarizers project one hundred percent of the display’s backlight toward the user. This makes transmissive TFTs very bright in the dark but does not allow any sunlight to reflect.
There are two solutions to increase readability of TFTs in direct sunlight.
Option One: Transflective Polarizers
Transflective polarizers have appeared in the last few years and allow a TFT to be readable in sunlight without the backlight powered “on”. This is due to sunlight reflecting off of the Transflective polarizer and illuminating the display. This combination eliminates (or greatly reduces) the display from being faded.
This new technology does come with a price tag, but if your product is medical, aviation or any other industry where readability is first priority, then go with a transflective polarizer.
Option Two: Brighter Backlight
Transmissive TFTs contain a backlight that sits on the bottom layer of the display. The backlight must be powered “on” for the display to be read.
If the display becomes flooded out in direct sunlight, it is possible to increase the brightness of the backlight to ‘overpower’ the sunlight.
LCD manufactures measure brightness in nits. A nit is how much light one candle produces. As a general rule, an LCD needs to produce 700+ nits of illumination to compete with the sun.
One thing to note is that increasing the brightness of your backlight requires more power consumption. Therefore, a sunlight readable backlight is not a recommended solution for a battery powered product.
Sometimes excessive brightness can be detrimental in darker environments such as aviation or medical. In this case, the intensity of the display can be adjusted by the end user to reduce glare and save power.
Not sure which sunlight readable technology is best for your new design?
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