Outdoor Viewability

Many factors converge when attempting to create a display solution that is sunlight viewable or legible in an environment of high ambient illumination, which can be either direct sunlight or under high ambient lighting. One of the first aspects to consider is where and how the display will be mounted and oriented with respect to the illuminating source. The amount and angle of the ambient light that strikes the display are key factors that must be considered while developing the display solution.

Display Reflectance and Contrast Ratio

In high ambient conditions the light striking the display surface degrades the displayed image contrast ratio perceived by the human eye, because as the ambient illumination falls on the display it is reflected by the display surface, the display’s internal layers, and from the surrounding area. An AMLCD itself typically has a reflectance from 4% to 6%. If other optical elements are installed over the display (such as a resistive touch switch or protective window) the total reflectivity can easily climb above 20%. When there is a high amount of ambient light from the environment, the light output from the display backlight is quickly "overpowered" by the reflected light and the displayed image is obscured.

To overcome high ambient conditions it is just not as simple as adding a more powerful backlight. While adding a more powerful backlight can certainly help to overcome high brightness environments, it also adds a good deal of complexity, cost and thermal load to the display system, which is usually undesirable. It can be very effective to design a system that first reduces the reflected light as much a possible, and then has sufficient backlight luminance to deliver an image that is clearly recognizable but does not exceed the target product cost or thermal budget. Reducing the reflections created by the incident light can be much easier, and more cost effective providing a solution that is truly satisfying.

We utilize both passive enhancements such as Max-Vu and active AMLCD enhancements to arrive at a display solution that is simple, cost-effective and robust.

The display design consideration form can help you to assess and refine your display requirements and operational expectations. The completion of this form will facilitate a high-value discussion and allow us to accurately and efficiently match your display requirements with the right suite of display enhancements.

You can also phone 503.690.2460 during business hours and ask to be connected with one of our application engineers to discuss your particular application and the display enhancements that might be right for your application.