There are more and more TFT displays used in outdoor applications, such as automobile/two wheeler/tricycle display, digital signage and public kiosks.
There are various methods of improving LCD screens for sunlight readability.
High Brightness for TFT LCD
The most common method is to increase the luminance of the TFT LCD monitor’s LED backlight to overpower the bright sunlight and eliminate glare. When the brightness of LCD screen is increased to about 800 to 1000 (1000 is the most common) Nits, the device becomes a high bright LCD and a sunlight readable display.
Increasing the luminance is an affordable way to enhance the quality of display in outdoors. The first solution would be increasing the number of LED lamps. The more lamps, the higher the brightness. However, it also depends on the structure of the TFT high-brightness screen and power consumption, so electronic engineers need to design it accordingly. The second solution would be increase the brightness enhancement film material: prism film, light-increasing film, BEF. Currently, the mainstream process for manufacturing the brightness enhancement film is to use the UV-curing adhesive process technology to mold it on the finished roller.
Transflective TFT LCD
A recent technology falling into the sunlight readable display category is the transflective TFT LCD, coming from a combination of the word transmissive and reflective. By using a transflective polarizer, a significant percentage of sunlight is reflected away from the screen to aid in the reduction of wash out. This optical layer is known as the transflector.
While it does greatly reduce power consumption, transflective LCDs are much more expensive than high brightness LCDs. In recent years, the cost has decreased, but transflective LCDs continue to be more costly.
Anti-Reflection Film/Coating and Anti-Glare Film
It is also possible to make devices more sunlight-readable using surface treatments.
Comparison between uncoated glass and AR coated glass:
When anti-glare is used, reflected light is fragmented. Using a rough surface as opposed to a smooth one, anti-glare treatments can reduce the reflection’s disruption of the actual image of the display.
These two options can also combined together.
An external film with AR properties not only reduces reflected light, but also brings other benefits. For food industry application, shattered glass is a serious problem. An LCD screen with external film solves this issue nicely. As for automotive applications, in an accident, broken LCD with top AR film won’t produce sharp edge glass that could harms auto occupant. Nevertheless, a top film always reduces TFT LCD’s surface hardness. And it is susceptible to scratches. On the other hand, AR coating retains LCD’s hardness and touch performance. But it comes with a bigger price tag.
Summary
Compiling the various methods of improving LCD screens for sunlight readability, these devices can be optimized in high ambient light settings.
Post time: Mar-11-2025
