With the summer months ahead, many are looking forward to bright and sunny days. However, to those who work with process instrumentation outdoors, the sun may seem a never-ending source of frustration. All too often the local displays and controllers they count on to do their job become unreadable from the bright and direct sunlight. There are many options available, however, to provide clear displays that can be seen even in the brightest direct sunlight.
While often the main cause of the problem, light emitting diode (LED) segmented display products can be sunlight readable. LED displays often wash out in the sunlight, appearing too dull to read. LEDs and faceplate assemblies are available that solve this problem, providing a display so bright it can be read even in direct sunlight, but this is not the norm. As a manufacturer of LED displays designed specifically for these tough, outdoor process applications, Precision Digital's Trident, ProVu, and ProtEX-MAX lines of LED-display products are all available with sunlight-readable LEDs. If an LED product is required, consider one of these lines of panel meters, controllers, and explosion-proof instruments as your solution.
Liquid Crystal Displays (LCD) are another great alternative. While usually not as bright as LED displays, LCDs are naturally sunlight readable. The digits on a standard segment-driven LCD block the light, as the crystals inside align like a shutter, shifting into a position that makes the glass appear opaque. Because the digits appear black, and the glass allows the light through, the brighter the light, the easier these displays are to read. When the features that come with LED display products are not needed, and especially if simple to wire loop-powered displays are a benefit, consider an LCD product such as the Loop Leader or ProtEX lines for a guaranteed sunlight readable display solution.
There are certainly other solutions, including the addition of sun shades. A sun shade is a plate that extends out from a panel or enclosure to provide shade to the display and block the sun from washing out the display. While effective, these shades add cost, complexity, and (perhaps worse of all) a troublesome inconvenience caused by having a plate or visor extending out from the panel. While this type of solution can work, it may not be as effective a solution to the problem as a sunlight readable display.
If not properly planned for, outdoor displays can cause a lot of frustration due to the effects of direct sunlight. However if planned for, there are a number of simple solutions that will have a dramatic effect on the ability of the operator to interact with the display or controller. Be sure to consider this whenever working on an outdoor application solution, and be sure you have an effective solution before the installation begins.■