Window displays and what you need to know
One of the most popular projection or digital signage applications we are asked about is the window display. 80% of these inquiries are about projecting onto outside windows and the accompanying challenge of sunlight. Most window projection systems are rear projection.
With any electronic window display, that must compete with the most powerful light source in our solar system, there are some basic questions to answer.
What time of day will the display be running?
How many hours of operation per day?
What direction is the window facing?
Is the window shaded by an awning or ledge?
Is the window glass tinted, and if it is, can the tint be removed?
How intense is the sun in your particular geographic location?
Answers to these questions will determine what size of window display is feasible and how many lumens your projector will require.
If you want a reasonably priced ($3,000 to $4,000) sunlight projection system, the size of your window display will probably need to be no bigger than 4’ x 3’. You won’t find any transparent projection screens that will work in this price range.
Proscreen Inc. sells a very good transparent screen and HoloPro works well also, but these will cost you anywhere from $8,000 to $12,000 including projector. That’s a bit pricey for most people and makes it very expensive if you plan on installing in multiple locations.
Our experience says the best reasonably priced projection material for full sunlight operation is the GlassVuE distributed by TRaC Associates, LLC. Make sure you get the “black shelves” surface - that is critical.
If you’re expecting to run your digital signage system for more than 4-5 hours per day, you will want to get a DLP projector. LCD projectors were not designed for long hours of operation day after day, and will likely experience technical problems within 9 -12 months.
Needing to use a DLP projector limits the size of display you can have because currently affordable DLP projectors cap out at 3500 lumens. Using a standard requirement of 2.8 to 3.5 lumens per square inch for full sunlight, a 3500 lumen projector limits the screen size to a 5’ diagonal.
A north facing window is best because your digital sign is not competing with sunrise or sunset, nor a southerly positioned sun during winter months.
The window projection screen’s size and projection power required will vary significantly between a northerly facing shaded window and a westerly facing un-shaded window.
If the window is tinted and you cannot remove the tint, it is unlikely you will be able to utilize digital signage in your window. It’s just too hard to power through while competing with the sunlight.
One final challenge is glare and reflections. Any glass based window display will have to contend with these image degrading phenomena. There is some good anti-reflective films on the market, but keep in mind that the more layers the light from the projector has to penetrate the less brightness will come out the other side.
If you need help determining what digital window signage will work for you, TRaC Associates, LLC offers a free consulting service with no obligation whatsoever.
Inside window projection systems are a lot less demanding. For example, mall stores and corporate lobbies can utilize a much wider range of front projection and rear projection screens without requiring as much lumen power from your DLP projector.
