Solar Radiation on Digital Signage

I attended an outstanding webinar on digital signage given by Peter Kaszycki of MRI. In the webinar he mentioned that the morning or evening sun in winter can be as bad for an LCD as the noon day sun in summer. I found some interesting data to back that up.

The chart comes from Research Needs: Glass Solar Reflectance and Vinyl Siding by R. Hart, C. Curcija, D. Arasteh, H. Goudey, C. Kohler, S. Selkowitz in the Environmental Energy Technologies Division of Lawrence Berkely Labs. Solar radiation can be a much larger contributor to the display temperature than than the ambient temperature. In fact data from the study shows that for black vinyl siding, solar radiation can raise surface temperatures to 70 degrees F higher than the ambient. Further, if the display is near a window and gets surface reflections from that window, it can get a double dose, or more, of solar radiation.

This picture shows the side of a house on a winter day when the ambient air was 24 degrees. The light on the side of the house is a reflection from the windows of a neighboring house. The issue of solar radiation and reflections has been well studied in the vinyl siding industry as it is a common cause for product replacement. The LCD being new to outdoor environments will experience the same conditions.

An important additional point to consider... because solar radiation is delivered at the speed of light rather than being conveyed by air currents or thermal conduction, the surface of the vinyl siding or the LCD can equilibrate with the current level of solar radiation within 10 minutes. Unlike heat transfer from the ambient, there are no thermal conduction issues or boundary layer effects. So, if some other surface happens to reflect directly on your digital signage installation for only twenty minutes; but the wrong time of day 20 minutes; that can be enough to cook your installation. Further, as contact burns can be almost instantaneous above 145 degrees and everyone assumes that every large LCD within reach is a touch panel, there could be some consumer complaints as well.

"But all we've discovered is that the blaze was started from a great distance through the refraction and convergence of light." from "Limoney Snickets: A Series of Unfortunate Events"


Norm

Microsoft Becomes a Display Maker

A New Vista for the Display Industry

Microsoft has purchases Perceptive Pixel. As computing has become more and more graphic, Microsoft has increasingly been increasingly involved in display technology. It began with Microsoft Vista, when Microsoft intruded upon what had been Intel's domain in specifying the desired resolution of notebook displays. Microsoft added a different touch in changing the specs from from just a raw resolution (e.g. 1024 x 768) to a desired dots per inch (dpi or pixels per inch.. ppi), more commonly used in the print industry. They also promulgated color fidelity standards, modified their operating system to embrace touch panels, and produced the first "Microsoft Surface" (later renamed when Microsoft introduced its own tablet using that same name).

Perceptive Pixel is a maker of large sized touch panels commonly used by television commentators for weather or for on-camera telestrating. As such, my own impression is that that business might have been a better fit within Cisco with its studio telepresence business. So, there are two questions, first, what is microsoft going to do with Perceptive Pixel? It could be an intellectual property (IP) play in order to gain better control of the direction of touch technology in general. It could be specifically a move to strengthen the position of the Microsoft OS in the digital signage and public information displays market. It could even be part of some greater move into hardware.

The second question is will any of Microsoft's potential competitors respond by purchasing their own touch panel companies or maybe even other display technologies. As the marketing emphasis of new devices is increasingly wrapped around what kind of display the device has, will the major hardware OEMs or others in the market be content to buy common technology from display companies or will they want to own either the IP or or the supply chain to grant them unique competitive advantage. In the initial part of the touch revolution, Apple secured a great advantage by contracting for much of the available production capability (interestingly from a company called Touch Revolution). However, as the industry grows and touch panel production grows, large supply contracts will have to face even larger supply capability. So... how do you maintain competitive advantage for the technology used on your device displays?

Norm