7 tips on how to improve diffusion in lightboxes

In a perfect world, every backlit display lightbox that’s being used for back-lighting posters and promotional messages would deliver perfectly uniform brightness from one corner to the other. But the reality is – light intensity always varies to some degree across any surface, including a lightbox or backlit menu board. So the next question is – how can we get the light to be the most uniform possible, within a reasonable budget? Let’s look at seven things you can do to help your lightboxes deliver the best possible diffusion:
1. ARTWORK — Does your graphic have a solid, pale background – or, is there a lot of variety to the colors and shapes? The more variety in color and/or contrast that you can build into you artwork, the more forgiving it will be, of variations in light intensity. Look at these two artworks and notice how this one does a better job of hiding the lamp variations:
artwork and color distribution
Of course you can’t always re-design your whole graphic just for diffusion – but it’s a good trick to know.
2. LENSES — Check the diffusive properties of your lightbox materials to ensure optimal performance. For example, the white lens in one lightbox model may deliver more or less light diffusion than another. Also, the thickness of the lens can vary as well – and generally, thicker lenses yield slightly better diffusion. For new lightboxes, of course you can ask about these options before you buy – but for existing lightboxes, they may or may not be upgradeable, depending on the model.
3. LAMP TAPE — Actually, this should be tip number two-and-a-half, because lamp tape is only available for fluorescent lightboxes, even though more and more customers are switching to LED. Anyway, if you’re ordering a fluorescent lightbox, some models offer the option of added lamp tape. Some lightbox suppliers – such as yours truly – even offer lamp tape by the roll, for customers who want to add it to the lamps in their existing lightboxes.
4. MEDIA — Be sure to use a graphic print film that is specifically designed for backlit display. Regular paper, transparent films, and other non-backlit media are not designed to evenly scatter the light source – but true Backlit Film comes with its own diffusive property which helps smooth out the brightness.
Okay so that’s four down and three to go – but before we go on, let us just throw out a little disclaimer here – these next tips are all pretty much for new lightbox purchases only, as it’s pretty difficult – or, cost-prohibitive – to apply them to existing lightboxes, as you’ll see. So – we could be like a new car salesman, and just expect you to spring for a whole brand new set of lightboxes – but we’re not like that.
5. DISPLAY SIZE — Most people aren’t aware of this, but smaller lightboxes generally diffuse light better than larger lightboxes. The reason is, there’s more light bouncing around at various angles before it fades away. Again we’re not assuming you can just change your whole lightboxes plan and re-design all your new lightboxes to be smaller, but it gives you a reference point to keep in mind.
display size and light distribution
6. LAMP DENSITY — As you can guess, the closer together your lamps, the less chance of visible shadowing in between them. This is true for both Fluorescent and LED lightboxes. The lamp density thing also applies not only to Direct-Backlit lightboxes where the lamps are positioned behind your backlit duratrans, but also to edgelit lightboxes, as we see here:
Your lightboxes supplier can help you determine which models have higher lamp densities.
7. CABINET DEPTH — This one is probably our favorite around here. For direct-backlit lightboxes, as you can imagine, the deeper the cabinet, the better the diffusion. As a matter of fact, of all the tips we’ve discussed, it’s fair to say that increased cabinet depth is the most effective factor by a long shot, for achieving uniform diffusion in a lightbox. Another way to look at it is simply, “distance” – because the further the lamps are from the graphic face, the more uniform the light intensity. And at the risk of the obvious, if you’re looking at edgelit lightbox models such as our EdgeLyte Premium LED, then the cabinet depth factor doesn’t really apply, since the lamps are not behind your backlit film.
cabinet depth and light diffusion
That’s it for our Seven Tips – but there’s one more twist to the whole diffusion question – having to do with the choice between Direct-Backlit and Edgelit lamping – and we have a video on that subject, here.
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