How Lightboxes Work

In commercial lighting, sometimes you’ll see different units of measurement when it comes to the brightness of the light source. The two most common units of measurement for light intensity are lux and lumens. Let’s take a look at each of these approaches, and see how they relate to graphic lightboxes for displaying duratrans backlit film

Lumens — In layman’s terms, the number of lumens generated by a light source is the total brightness or light intensity emitted by the source, regardless of size. One way to gain perspective on this is to imagine 1,000 tiny flashlights all clustered together at the eastern shore of a lake, to create a light source visible from the western shore. Now let’s place a single spotlight next to the cluster, to achieve the same result. Both sources may appear equally bright to the person on the western shore, even though one of the sources is really just a cluster of many not-so-bright sources. This is not a perfect analogy because no matter how many flashlights you add to the cluster, you may never reach the apparent intensity of the spotlight if you were to stare straight into it, but the amount of illumination that reaches the western shore from the cluster of tiny light sources could easily match that of the spotlight, if you keep adding tiny flashlights by the millions or however many it takes.

If we extrapolate this concept of lumens to backlit lightboxes, we must assume that larger lightboxes generally produce more lumens than smaller ones, and indeed this is the case. Of course this also depends on the brightness per same-size area, which is our next unit of measure to consider…

Lux (“light per area”) — Simply, the “lux” brightness value of one source can only be compared to another if the size of the source area is the same. For example, a value of 1 “lux” describes a certain level of brightness generated (or reflected) by 1 square meter of light source (or reflector). Lux is more difficult to measure than lumens, because of this requirement that the square area be made uniform, in order to compare different light sources. Also because of this difficulty, commercial lightbox fabricators generally do not scientifically measure the “lux” of their various lightbox models.

In practical terms, here are a couple of things you can keep in mind when shopping and comparing lightboxes in terms of brightness:

1. Ask for lumens ratings and you’re much more likely to get a number you can use.
2. Keep in mind that larger lightboxes produce more lumens just because there is more surface area, so if you really want to compare the brightness rating of two different lightbox models, they must be the same display size.
3. Multiple lightboxes placed adjacent to each other will also achieve an automatic lumens boost, since it’s an additive value. This will translate to an apparent increase in brightness, not so much as you view the lightboxes on the wall, as the ambient light that they reflect off their surroundings. For example we have a hotel chain customer who requires a certain number of lumens of ambient light in their lobby, and so if they are installling our lightboxes and need more lumens, they can just supplement the order with additional lightboxes. This will lift the general atmosphere in the lobby to an overall brighter level because there will be more light reflecting off more surfaces.

Thinking about super large lightboxes? At Blue River Digital, we’ve designed and built every conceivable size and shape of lightbox — but the really big lightboxes over 10 feet or larger — these are our favorite! There’s nothing quite like a vivid, high-energy lifestyle photo all lit up at 12 or 15 feet across or even 20 to 60 feet, there’s really no limit!

But what does it take to build a lightbox this large? Are there any limitations or special considerations? Let’s fly over a few quick tips on how to plan your Jumbo Lightboxes project!

1. TYPE OF LIGHTBOX. The first decision to check off your list, is determining which type of lightbox is going to work best for your project. Most ultra-large graphic lightboxes fall into one of three categories:

conventional "sandwich" design, with the backlit graphic film pressed between two plastic lenses;

tension fabric design, with no lens sandwich, just a swath of fabric that has some elasticity, stretched onto an aluminum frame; or

stretch vinyl design, with a vinyl "canvas" stretched across 2 or 4 edge rails (no lenses).

a. "Sandwich" lightbox models are the most popular for both indoor and outdoor, but they’re also the most limited in their adaptability to jumbo sizes over 10 feet, as we’ll see in the other tips below. The main justifications for sandwich lightboxes in jumbo sizes are:

- to match adjacent décor

- for easy graphic changeout

- for brightest, most saturated color

b. Tension fabric lightboxes are gaining in popularity for their efficiency in shipping and setup, as well as price economy. The main downsides with fabric lightboxes are that they do not perform well outdoors because of their absorbency, and also their lack of vandal-resistance.

c. Stretch vinyl lightboxes are especially designed for outdoors because of their durability and relative simplicity; no sandwich to trap moisture, plus the vinyl media does not absorb water.

2. MAXIMUM SEAMLESS GRAPHIC SIZES. Each type of lightbox has a general limitation as to how large of a full-color, digitally-printed, backlightable image can be produced on a seamless material:

a. Sandwich lightboxes use what is commonly known as "duratrans", which is the high-saturation, high-resolution polyester film you see in most lightboxes in retail applications. Industry-wide, the largest seamless duratrans on the market is approximately 6 x 10 ft., unless you opt for an inkjet alternative, which may enable longer prints in one dimension while restricting the other dimension even further. For example, most inkjet backlit prints are available up to 4 or 5 ft. wide by however long the roll of media is. Your backlit graphics printer (such as Blue River Digital) can let you know what their equipment and inventory limitations are.

b. Tension fabric is usually limited to a 10 ft. roll width by sometimes 30, 40 or even 100 feet, depending on the printer’s production limitations. At Blue River Digital, we don’t recommend seamless lengths of backlit fabric beyond 40 ft. due to production challenges and waste factors, but contact us for details.

c. Backlit vinyl boasts the largest available seamless sizes in the business, at up to 16 ft. (5 meters) wide by however long the roll of media is. This is the media you’ll find on the sides of skyscrapers, billboards and other ultra-gigantic color graphic applications. Plus, vinyl can be heat-seamed to create a virtual "seamless" canvas of unlimited size, with the only caveat (for backlit applications) being a slightly-visible darker line at the heat seam joint. At these sizes, your only enemies become high winds and the sheer weight of the vinyl.

3. MAXIMUM LENS SIZES. Jumbo-size conventional (sandwich) lightboxes come with one or two lenses, usually made of polycarbonate resin. The bulk polycarbonate is formed in sheets 100" wide x 150 ft. long. So technically, this is the maximum "seamless" size of a duratrans lightbox; although in practice, you’ll rarely see this type of lightbox longer than 10 or 20 feet per separate section.

Fabric and vinyl lightboxes are not subject to the lens-size limitation, since they do not use any lenses. This alone explains why fabric and vinyl capture a much higher percentage of the super jumbo lightbox market than they do the smaller sizes under 10 feet across.

Another workaround to the limitations on lens size is simply to place a series of large lightboxes adjacent to each other, for a jumbo backlit panorama that’s "near" seamless, such as this real estate sales office "overlooking" the bay:

4. MAXIMUM FRAME SIZES. In this regard, there’s no distinction among the three lightbox "types" discussed earlier. The main factor to be aware of, is the industry-wide threshold of 18 feet, where most extruded aluminum rails ship from the various extruders at 18 ft. length and not any longer. This means that any lightbox frame that has one side longer than 18 feet is likely to have a seam in the frame, regardless of the "type" of lightbox. Adding a seam to a lightbox frame is not a challenge structurally, although it may present challenges esthetically. If you need the exposed perimeter frame on your lightbox to remain unseamed from corner to corner, then you may want to take into account the industry’s 18-foot limitation on extruded aluminum rails.
5. POWER REQUIREMENTS. Again this consideration is irrespective of lightbox types. It’s a simple matter of planning to ensure that adequate wattage can be delivered to the install site of your jumbo lightbox. At Blue River Digital, we can provide you with the estimated wattage for any size of any given lightbox model on request, so that you can plan for adequate power.
6. LAMPING. All lightboxes use either direct-backlit or edgelit lamping to provide uniform brightness across the surface of your backlit graphic. Common sense dictates that the larger the lightbox, the more lamps are added to cover the increased square footage — and this is true: there is technically no limitation to the number of lamps that can be added as the size of the lightbox increases.

The exception to this rule is the increasingly-popular "edgelit" lamping design, where LED lamps are placed along the edges of a translucent white diffuser lens which is oriented behind the backlit duratrans film, and these edge-mounted lamps shine "sideways" through the translucent substrate to make it glow and effectively backlight your artwork. Blue River Digital leads the industry in edgelit lamping technology, and our state-of-the-art edgelit panels are able to deliver solid, non-diminished brightness across the face of all sizes of graphic lightbox up to 6 feet across in the shorter dimension. So the bottom line is, if you are hoping to deploy a lightbox model that uses edgelit lamping, such as our EdgeLyte Premium line, you’re okay up to 6 ft. in the shorter dimension, but if you want sizes larger than that, you’ll need to switch to direct backlighting.

7. FREIGHT. No matter how large your lightbox, of course it needs to arrive safely and economically at your destination! With proper consultation with our custom lightbox specialists, you will be given a list of questions to answer before you get too far into the design process, such as, do you have a forklift onsite at the delivery point? Is there a receiving dock? Is inside delivery required? These types of answers will assist in your planning, as to how large of a lightbox you’re able to accept onsite. Often a jumbo lightbox will require a flatbed trailer for delivery, because the lightbox is too long to unload safely from a box trailer. We want to help you make sure there are no ugly surprises late in the process, after it’s too late to change your design.

The good news for fabric and vinyl lightboxes is, most of these models ship disassembled, which means you’re getting a larger lightbox in a smaller carton. This is often a justification all by itself, to switch to a non-lens lightbox type, for the hassle-free economy of a compact shipping carton.

8. CRANES AND ASSEMBLY. The sleeper in this checklist of challenges is, for ultra-large lightboxes, how to get them off the truck and into final position. Usually for sizes over 7 feet in the smaller dimension, if they’re to be delivered to an existing indoor install site, you’ll either need to select a non-lens model so that it can ship disassembled, or provide for crane delivery through a window or stairwell. The main reason we’re adding this tip to the list is to remind you to budget for cranes, dollies and/or special assembly tools and personnel. Small lightboxes can be handled and mounted with one or two workers, but lightboxes in the 15 to 60-foot size range need a whole crew plus special consideration for handling once they arrive at the delivery point.

Please let us know if you’re in the early stages of planning a jumbo lightbox installation, and we’ll be sure to help you think of all the right questions to formulate your ideal strategy, from which model, to how the graphics will work, to ensuring a beautiful complement to your space design!

Color temperature is an important yet often-overlooked detail, when ordering backlit display lightboxes. Blue River Digital offers quite a few different color temperature options, depending on the lightbox model you’re looking at. But before we discuss which models offer which color temperatures, first let’s chat about what color temperature means on a basic level.

Color temperature is a measurement of the “whiteness” of a light source. The classic reference point is for those of us who’ve browsed the Paint department at the local hardware store, trying to decide which version of “white” we want to paint our house trim with. There are so many “colors” that look totally white when we view any one of them by itself — but then line up all the variations on the same card and all of a sudden you can see all the different hues by their relative “color shift” from one color chip to the next — first you have a bluish white, then a greenish white, then a pinkish or orange-ish white… you get the idea.

This scenario is a good example of the reason we need to measure whiteness, or color temperature. Without color temperature ratings, two sources of white light that are slightly different “hues” from each other would be hard to describe without some subjectivity. Imagine trying to describe the color temperature of each set of headlights in oncoming traffic at night: “Let’s see, this car’s lights are kind of yellowish, and the next ones are kind of purplish, but the third car’s are kind of in between and maybe closer to…..” Good luck, right? So the scientific community has developed this universally-recognized scale as the first step in controlling which actual color temperature range we want to specify in a given context:

Oddly, the “warmer” whites were assigned lower numerical values than the “colder” whites, but once you get past this counter-intuitive anomaly, the Color Temperature scale is pretty common-sense. Reds and oranges are at the warm end of the spectrum, while the blues and violets reside at the colder end.

Now let’s talk about applications of light sources with various color temperatures.

To milk the earlier hardware store scenario a bit more, let’s take a stroll over to the Lighting department, where we’ll find lamps and bulbs of every type, and we’ll see that many are labeled with a color temperature rating. Even more, some of them will say “kitchen and bath” or “commercial” near the color temperature. This is because consumers generally prefer to install warmer color temperatures in kitchens and baths, and the colder temperatures in business environments. There’s a consensus that warmer color temperatures reflect more favorably on skin tones while imbuing a softer, more relaxed atmosphere — whereas colder color temperatures foster alertness, focus and a professional ambience. We’ll leave the veracity and psychology of these cultural assumptions to you the customer, but we do have one more extension of the “ideal color temperature” conversation to help you think about:

Which color temperature do we want for our backlit displays?

Extrapolating from the above general opinions as to which color temperatures work best for which situations, you can imagine why warmer color temperatures are more popular for model photos, portraits and skin tones, cosmetics, most fashion industry backlits, certain types of fine art, and other duratrans backlit artwork where the content is organic, softer, more mellow. On the other extreme, hi-tech product photos, machinery, jewelry, certain text and logo themes, and selective types of progressive or abstract fine art lend themselves to a colder color temperature. By now you probably know which category your own artwork belongs in, but if you’re still not sure, give our Lightbox Specialists a call at 800-706-4276 and we’ll ask you a few questions and chat about which color temperatures and which lightbox models may be ideal for your project.

Lastly, let’s briefly explore some of the standard color temperatures across the world’s largest selection of backlit lightboxes, found only at Blue River Digital:

To oversimplify things just a bit, the two most common color temperatures in the entire commercial backlit lightboxes industry are 4100°K and 6500°K (give or take a couple hundred degrees Kelvin). The 4100°K range temperatures are commonly labeled as “cool white”, but the 6500°K flavor are usually not given their own adjective, so you’ll usually just see “6500°K” and that’s it. Occasionally you’ll see a lightbox specification that says “warm white” and this usually indicates a color temperature in the 2700 to 3500°K range, loosely speaking. Before you get concerned about exact numbers, first be assured that two color temperatures within a few hundred degrees of each other are actually difficult to distinguish from each other; it usually takes between 500 and 1000° of separation or more before the difference is detectable to the naked eye.

To return to our Lighting department field trip once more, consider these common labels and color temperature ranges — but keep in mind these are not absolutes, just general ranges that the Lighting industry tends to follow:

COMMON LABEL	COLOR TEMP. RANGE
Kitchen & Bath	2700 to 3500°K
Cool White	4000 to 4400°K
Daylight	5000 to 5500°K
[numeric value only]	6500 to 8500°K

Now that we rambled off-track again, let’s try to get back to Blue River Digital’s line of lightboxes and color temperature options:

Almost every Blue River Digital lightbox model that uses fluorescent lamps defaults to cool white, because this is the most popular color temperature in the fluorescent lamps market. Also, almost every fluorescent model can be upgraded to warmer or colder lamps on request. The coldest fluorescent lamps generally available are in the 5000 to 5500°K (daylight) range.

For LED lightboxes, the default is usually 6500°K for the simple reason that this is the most commonly-available LED lamp color. Colder lamps are available for some models but rarely requested because this begins to skew the hue away from pure white and toward blue or violet. The most common color temperature upgrade request for LED lightboxes is to switch from 6500 to 4100°K, to get the warmer (or less cold) white for photos of people, nature scenes — anything that benefits from a less-harsh, less blue tone.

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:

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.
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.

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.

Have you noticed? Fabric-faced lightboxes are everywhere! Clearly, there’s a movement toward fabric as the medium of choice for commercial-grade backlit signs in every context from retail product promotion to institutional fine art display. Let’s take a look at the reasons discerning marketers and interior planners are turning to fabric for their LED backlit sign solutions:

THAT ORGANIC LOOK — Only lightboxes with a backlit fabric graphic can give you a zero-glare graphic surface and still deliver a bright, saturated color image. This is why you’ll find backlit fabric signage in TV studios, corporate lobbies, fashion and cosmetic retailers — any place where a softer, more humanic presentation may be desired without compromising color bandwidth.

LIGHT WEIGHT — Not many people realize that the heaviest components in a conventional backlit sign are the two acrylic or polycarbonate lenses between which the duratrans backlit film is sandwiched and held in place. But not so with a fabric backlit sign, because the fabric graphic face is held flat via stretch tension from edge to edge, so no lenses are needed. This is only possible because of the tensile properties of fabric, as contrasted with the much more dimensionally-stable polyester film used for conventional backlit graphics. This can result in a weight savings near 50% in some cases, and it’s one reason backlit fabric signs are popular with trade shows, traveling exhibits and environments where handling and/or installing heavy, cumbersome display fixtures is at best inconvenient or at worst unsafe.

SECURE TRANSPORT — This is not the first thing that comes to mind for most people planning a backlit sign installation, but it may be the most practical, on three different levels: First, as mentioned above, your shipping weight with fabric lightboxes is always going to be significantly less than that of a conventional lightbox sign, due to the absence of plastic lenses as previously noted. Second, most fabric lightboxes can be shipped disassembled with the backlit fabric folded or rolled in the carton, so now the dimensions of your shipping container are a fraction of what they would have been for an aluminum backlit sign of the same display size. Lastly and most often overlooked is the relative damage resistance of a fabric lightbox — no heavy, flat, brittle lenses with sharp corners to secure!

PRICE PER SQUARE FOOT — And now for everybody’s favorite reason to opt for fabric backlit signs: the savings that can be realized. This is especially true for large or jumbo backlit signs, from 4 or 5 feet in one dimension all the way up to 10 feet or even 15 or 20 feet. As you can imagine, the incremental price to add a few square feet of mostly just a digitally-printed backlit fabric (since there are no “lenses”) is nominal compared to all the additions of metal parts and high-technology plastics required to achieve the same size in a conventional backlit sign.

Next time you’re in a public or commercial space such as an airport, shopping mall, casino, sports arena or any interior venue where large backlit messaging is found, take a close-up look and you’ll be surprised to find more and more tension fabric lightboxes such as Blue River Digital’s FabricLyte Econo LED with LyteStretch backlit fabric, which from more than a couple feet away, appears to have all the saturation, boldness and detail of any legacy backlit sign you’ve seen before.

Businesses choose backlit graphics with backlit signage for their promotional displays, instead of plain old posters, because they want brighter colors and therefore more “eye-catching and head-turning”. So of course, as the marketing person, you want the backlit artwork in your Duratrans to have lots of bright colors and compelling imagery, to compete for the attention of the passerby. But equally important as color and content, are (a) the amount of black areas in your artwork, and (b) the opacity of the solid blacks.

First, your backlit graphics will deliver more visual punch if they contain large black areas, by simple virtue of contrast. It’s similar to the principle of less is more — meaning, a backlit Duratrans that contains fewer brightly-colored areas intermixed with or surrounded by high-contrast black areas delivers more visual distinction, more “pop”. In comparison, if your entire lightbox window is fully and equally bright, then out of the corner of the eye it may just register as a big, boring rectangle. But if the colored content on the backlit film is silhouetted within an organic-shaped black boundary, or accented with medium to large-sized black (or very dark) objects, this breaks up the color field dramatically, demanding a second look.

Second, make sure the black areas are fully black, by imaging your artwork onto duratrans film (as compared to inkjet film) because duratrans uses a photochemical process to deposit a light-blocking layer of emulsion onto the film for your black areas, instead of just a semi-translucent ink, which is what inkjet processes give you. Black inkjet ink is semi-translucent by necessity, because it must also mix with other colors to yield process color. The true duratrans process leap-frogs the inkjet process when it comes to solid blacks, because instead of just spraying a murky-dark ink to achieve “black”, it builds a layer of opaque emulsion which actually blocks the light from transmitting through the backlit film.

In summary, you can spot a well-conceived backlit artwork by both the frequency of black areas, as well as the deep “car-paint” black coverage that is attainable only with the duratrans process.

Just by the names, you can see why there’s some identity confusion between the two products: (a) Electric Signs – or more definitively, “electrically-lighted signboxes”; and (b) Lightboxes for backlit graphic display.

Customers shopping for one or the other often interchange these phrases and similar, when referring to a related product. So the question is, is there really a difference between an electric sign and a lightbox — and if so, what is it?

The term ‘electric sign’ has been in use since at least the early 20th century, when roadside commercial signs powered by filament-electric lamps began to appear. And pragmatically, any product that can be categorized as a ‘sign’ — as long as it is powered by electricity — can be thought of as an electric sign.

Alternatively, the term ‘lightbox’ came into common use about the middle of the 20th century, as lighted cabinets that hold and display a sheet of backlit graphic film began to appear in commercial and retail environments.

Therein lies the defining difference between a an electric sign, generally — and a lightbox, specifically:
A lightbox is an electrically-lighted sign that contains the mechanism(s) to encapsulate, suspend, protect and display a discrete sheet of backlit film which embodies a print image, and which is designed to transmit light through the film for increased image brightness, contrast and color saturation.

So technically, the electric signs category is by definition a superset of fixtures that includes lightboxes as just one type. But in practice in the signage industry, the phrase ‘electric signs’ is often intended to exclude the subset of ‘lightboxes’, simply by describing any electric sign that does not fit the narrower ‘lightbox’ definition.

The reason for this exclusion in practice is simply a matter of convenience: Lightboxes have so many attributes that distinguish them from other electric signs, separating the two aids in clarification. What distinguishes a lightbox from other electric signs? Here’s a list of the main differentiators:

1. GRAPHIC UPDATING — Lightboxes are usually designed for frequent replacement of the graphic (such as a monthly or seasonal promotional message), so they provide a quick method for opening and accessing the graphic without tools. Conversely, (non-lightbox) electric signs are usually designed for long-term or permanent display of a graphic (such as the name of a store), so they don’t need such easy access to the graphic.
2. MATERIAL — Lightboxes are usually built of extruded aluminum, whereas electric signs are often constructed of steel, wood or plastic. Aluminum is generally considered to be more ‘upscale’ in both rigidity and elegance, but other materials are often more economical. The economy of steel, for example, is especially relevant because electric signs are often much larger than lightboxes, for building-mounted and highway signage that’s intended for viewing from greater distances. One might think rigidity should be more important at larger sizes, but (a) there are other more economical ways to strengthen jumbo signs besides switching base materials; and (b) rigidity is more critical for lightbox frames due to the unique, moving mechanisms they contain (see #3 below).
3. GRAPHIC SECURITY — Lightboxes usually sandwich the backlit film loosely (without glue) between two lenses so that it can be removed without wasting a lens, when the image needs to be updated. This is achieved via some combination of flip edges, slide frames, snap frames and/or hinged doors. Electric signs usually contain only one translucent lens layer, for the sake of simplicity, longevity, and also to decrease the need to manage moisture condensation. Most electric signs do not use a backlit film for their artwork, but they can — and if they do — the printed film must be glued to the lens, which renders the lens also wasted whenever the image needs to be replaced.
4. VIEWING DISTANCE — Lightboxes are more often intended for close-up viewing than electric signs; hence the basis for improved elegance.
5. SIMPLICITY — Lightboxes are almost always rectangular and generic in terms of any artwork or message or branding. This enables mass production, and puts downward pressure on unit cost. All the ‘customization’ of a particular lightbox application is fully executed at the graphic film level, by simply replacing one printed film with another. Electric signs are often custom-shaped, die-cut and/or fitted with custom-designed features that aid in the communication of the particular message or brand, such as a sign frame shaped to the letters that spell out the name of a store.

	Electric Signs	lightboxes
definition	any powered sign	for backlit film only
frame construction	any materials	usually aluminum
shape	custom, organic	rectangular
graphics are changed	rarely/never	frequently
viewing distance	long distance/street traffic	up close / pedestrian

So, probably the main determining factor in choosing an electric sign vs. a lightbox should be — how often will the graphic be updated? If the graphic is intended to be changed every once in awhile (or more often), then consider a lightbox for convenience. Also — generally but not always, shorter-term graphics are smaller size and also intended for a shorter viewing distance than long-term graphics — these are two more reasons to choose an aluminum lightbox over a steel electric sign.

A customer recently asked if we have any information that sheds light on a set of claims by another backlit imaging firm, putting forth archival-quality inkjet printing as a preferred solution over duratrans imaging. Here’s the response we submitted:

First, let me clarify — duratrans is designed for transmissive light (backlit) applications only, not reflective. So comparing duratrans to archival papers is apples and oranges. Duratrans is not designed for or claimed as an archival solution. Some o the below comparative claims about archival media’s colorfastness may be true, but the main focus of our comparison should really be between backlit duratrans and backlit inkjet.

Here’s a point-by-point commentary on the claims that were set forth:

CLAIM	RESPONSE
Inkjet printing emerged commercially in the early 1990s.	This may be true for large-format applications, but smaller format solutions had been in play since the 80’s.
Inkjet printing emerged commercially in the early 1990s.	This may be true for large-format applications, but smaller format solutions had been in play since the 80’s.
‘Inkjet’ is a generic term referring to printers that ‘spray’ controlled amounts of ink onto specially coated media.	The first half of this is true, but it is not exclusive to “specially coated” media, as there are inkjet technologies that are designed to work with uncoated media as well
There are several technologies that fall under the inkjet umbrella.	true
Over the last two decades inkjet printing has become very refined, with great advances in print head and ink technology.	true
Because inkjet printing is essentially simple, it remains an affordable, as well as a premium choice for both commercial and fine art applications in all sizes.	It’s universally true that simpler technology contributes to affordability. But to say the simplicity of inkjet is one of the reasons it’s a “premium choice” is a classic non sequitur, because there’s no automatic correlation between ‘simple’ and ‘premium’.
Much fine art printing, including printing of b/w and color photographs, is now done using archival inkjet printers.	This may be true in reflective media, but it’s absolutely false (unless “much” can mean a small fraction) in backlit media, which is what duratrans is.
Quality inkjet is capable of far greater accuracy and subtle color rendering than Duratrans from the same files. Quality fine art and fine art reproductions are now printed using permanent archival pigment inks on high grade acid-free media.	There are several secondary untruths here, but the foundational problem is that archival processes and duratrans are not in the same field nor are they used for the same application. Duratrans is optimized for best-of-class performance in backlit commercial applications, and archival processes are optimized for best-of-class performance in reflective fine art applications. If you’re looking for reflective media, then of course duratrans is not in the conversation because it’s not reflective, it’s transmissive. If you want to backlight your fine art, the question remains as to which is more important for your application: long-term durability or color fidelity. For backlit, duratrans wins the color fidelity battle on every level. Most backlit projects are planned with the intent to optimize color bandwidth and brilliance; this is why the backlit medium was chosen in the first place, and it’s where duratrans excels above inkjet solutions. If your backlit project is more concerned with archivability, then other imaging processes may possess more UV-resistance than duratrans — although in practice, industry archiving protocols increasingly call for digital archives over hard copy archives, to keep record of color fidelity. In summary: if archival integrity is the main goal, nothing beats a digital file. If color brilliance is the main goal, nothing beats duratrans. And by the way, duratrans holds its original color for many years except under extreme UV exposure.
Most fine art photographic reproduction for exhibition and sale is now done using inkjet printing.	In this narrowly-defined market for reflective (not backlit) prints, sure no problem.
Inkjet permanent pigment inks now surpass Duratrans in fade and UV resistance. The underlying media have comparably long expected life spans.	Pigment inks may actually offer higher UV inhibition. This does not mean the color is more true, or the blacks are darker, or the saturation is deeper, it only means that the composition resists UV breakdown more. If you’re looking for the widest color gamut, highest contrast, deepest saturation, most tonal variation, highest potential resolution, lowest dot gain and/or deepest black opacity in a backlit medium – then a laser-exposed, chemically-developed, emulsified duratrans film process is the clear superior in each of these areas.
Inkjet printing is capable of extremely fine resolution. Our new equipment prints an extremely smooth and grainless look, unlike the visible grain of Duratrans reproductions.	If somebody visualized “grain” in a modern duratrans-grade backlit film, I suspect the original artwork contained a grain artifact, such as possibly a photo shot with a grainy film. The latest iterations of photochemically-processed backlit films (aka duratrans) do not possess any grain that is visible to the naked eye.

In closing:
We do not have a dog in this fight. Blue River Digital offers both duratrans and inkjet imaging. We just know which product is optimized for which type of project. Conversely, we wonder out loud if someone else may have an ulterior motive… perhaps some providers don’t offer one of the two products, hence a skewed devotion to the other…?

Comparing the light-generating properties among different models of backlit display lightboxes can be difficult when the lightboxes are not in the same room with you. Specifications such as measured brightness, color temperature and type of lamps can be helpful, but don’t overlook the value of lamp density in helping you evaluate competing lightbox models.

WHAT IS 'LAMP DENSITY' AS IT RELATES TO LIGHTBOXES FOR BACKLIT GRAPHIC DISPLAY?

'Lamp density' is basically how many lamps are installed in a given lightbox. More scientifically, lamp density can be measured 3 ways:

• distance between lamps, in inches
• number of lamps per square area
• total number of lamps in a lightbox, given its size

WHY DOES LAMP DENSITY IN A BACKLIT DISPLAY LIGHTBOX MATTER?

Lamp density can influence all of these:

• Intensity, which is really just brightness per square inch or square foot.
• Overall light output (aka ‘brightness’) of the entire lightbox — a larger lightbox will only have more light output than a smaller one if the lamp density is not reduced beyond a certain level.
• Diffusion — how uniform is the brightness across the display face of the lightbox?
• Color cast or hue, aka ‘color temperature’ – decreasing the lamp density may result in a modified overall color temperature.

Lamp density also influences these other non light related factors:

• heat generation
• energy consumption
• weight of the lightbox
• investment — increased lamp density in a lightbox is of course generally correlated with increased value

HOW IS LIGHTBOX LAMP DENSITY DETERMINED IN ENGINEERING?

Architects, general contractors and sign shops often ask, what is the engineering that determines lamp density for a lightbox designed for backlighting graphic artwork? Here are the primary factors:

• Chassis depth — the deeper the cabinet, the lower lamp density required to achieve adequate ‘coverage’ (aka diffusion) at the display face. Of course this may compromise brightness, but the reality is – not by much. The more significant downsides of a deeper lightbox frame for many customers are the issues with space planning and/or esthetics.
• Lamp orientation — lamps can be configured to directly backlight the display face from behind; or indirectly via a “light guide plate” which scatters the light generated by a single linear light source (gas tube lamp or strip of LED’s) across a two-dimensional backlit face.
• Focal dispersion — the wider the focal angle of the lamps, the fewer lamps needed to adequately illuminate the display face.
• Artwork — if the type of graphic artwork is known ahead of time, the lamp density can be optimized for it. For example, a solid light-colored background will be less forgiving of low lamp density than a busy, multi-colored background.
• Economy — of course, Lightbox Engineering always looks for the best combination of performance and economy – how can we get the best backlit performance for the most efficient price point?
• backlit performance for the most efficient price point? Energy efficiency — reducing lamp density as much as possible without sacrificing performance will of course save energy and at the same type generate less heat.

WHAT LAMP DENSITY SHOULD I LOOK FOR IN A BACKLIT DISPLAY LIGHTBOX?

Here are some more specific questions (with answers) to help you answer this bigger question:

• How large is your lightbox going to be? For lightboxes less than 4-5 feet in the smaller dimension, consider “edgelit” lightboxes, for their improved diffusion-to-lamp-density ratio and low profile frames. For larger lightboxes, look for premium edgelit LED and/or direct-backlit fluorescent models with lamp spacing of 7” or less, unless the application includes low-demand artwork and/or the desire for a less-bright backlighting system.
• How bright does your lightbox need to be? Almost all lightboxes on the market perform within a range of “adequate” brightness for most commercial applications. The brightest-available lightboxes in the general market usually share most of these features:
  - direct-backlit (as compared to edgelit or indirect)
  - LED-powered (as compared to fluorescent etc.)
  - high-density lamps, such as 1.5” spacing or less
  - low-profile chassis models, such as 3” or less total frame depth

If a lower-than-average-brightness lightbox model is desired, shop for a combination of at least some of these features:

• fluorescent lamps
• low lamp density, such as 7” spacing or more
• deeper chassis depth
• 'warmer' (lower) color temperature lighting, in the 3000° to 4200° Kelvin range
• 'warmer' (lower) color temperature lighting, in the 3000° to 4200° Kelvin range
• What type of artwork are you going to display in your new lightbox? If the artwork has a solid and/or light background, then look for lamp densities of 6” spacing or less. If your artwork is multi-colored and/or has large black or very dark areas, a lower lamp density can still perform adequately in terms of uniform diffusion, as apparent to the eye.

In summary, lamp density is just one of many parameters you can use for comparison as you shop, but it clearly gives you another tangible handle for isolating the ideal product for your backlit graphic display application.

Most people understand that backlit display lightboxes generally add a whole new, inviting dimension to a retail store’s ambience, but being intentional about how to deploy lightboxes and duratrans backlit graphics while still saving money, will benefit your overall strategy.

First let’s remind ourselves of the reasons when and why you’d want to use fluorescent or LED lightboxes instead of non-backlit signs or posters.

STANDOUT MESSAGING
Lightboxes deliver improved contrast from other visual media in a “noisy” space. For the shopper, there’s quite a contrast between your backlit messages and those that are not backlit, so plan accordingly. Not every message in the store should be in lightboxes; that’s like typing in all capital letters so that now everything is “shouting” instead of just the important messages. Lightboxes tastefully distributed around a shopping space do an amazing job of conveying the important messages that you want your visitors to come away with.

INCREASED PRODUCT ABSORPTION
Also, lightboxes more fully convey the color depth, texture, detail and/or beauty of the product being displayed, because backlighting a photo that’s printed on duratrans backlit film gives you increased color saturation, contrast and perceptible detail. This helps your customers more fully engage the product and appreciate its attributes.

IMPROVED SPACE ILLUMINATION
Thirdly, with backlit lightboxes, you can complement existing space lighting for a brighter, more positive shopper experience. Many retail spaces are beginning to replace standard commercial lighting with lightboxes and backlit graphics, so that they can kill the proverbial two birds. Why not use your space lighting fixtures to also deliver your important company and product messages — or conversely, replace some or all of your space lighting with enough large, bright lightboxes to yield the space illumination level you need? Most quality lightbox fabricators can specify the total light output in lumens for each model and size of lightbox sign you’re considering , whether fluorescent or LED, to help you ensure adequate light levels in your space.

EMOTIONAL CONNECTION
Lastly, professionally-produced backlit photos and graphics in lightboxes elevate your message to “near-real life”, with more realistic/vivid subject lighting than non-backlit messaging. If you’ve ever walked past a jumbo lightbox (in a shopping mall or other retail space) that contained a huge movie poster or a photo of a model wearing the latest cosmetic or fashion accessory, you’ve experienced the unique energy that a large, brightly-backlit photo delivers. This benefit of lightboxes is slightly different than point #2 above, because this is about the emotional trigger that well-planned lightboxes have a unique ability to activate, not just the detailed product information being displayed.

Whether you’re the architect, store designer or retail manager, keeping these four unique strategies for lightboxes in the back of your mind while planning your retail space will help focus your design.

Next, let’s think about what types of content are best suited to lightbox displays, whether indoor or outdoor, and whether small or large. Here’s a chart that gives you a list of “strategies” on one side, and on the other the type of graphic content that best promotes each strategy:

WHAT WE WANT TO ACCOMPLISH (STRATEGY)	WHAT WE SHOULD DISPLAY (LIGHTBOX CONTENT)
we want to create increased urgency	special promotions, offers that expire
our shoppers need more product awareness	closeup or detailed product info —features, textures, color choices, etc.
our shoppers need to be educated on the product’s practical application	photos of the product being used by people
our audience needs a positive perception of how our product is different or better	photo of the product with labels describing results/benefits of product use
our customers just need to know what all we offer	straightforward text menu with pricing and a few photos for clarity and appeal

The key with the above chart is to select one or maybe at the most two strategies for any given lightbox and the backlit film that you intend to place in it. Trying to leverage a backlit graphic to achieve more than one or two goals usually results in confusion and a missed opportunity for your message to be absorbed. Lastly, consider where in your space you plan to install your new lightboxes.This should be driven by which part of your overall store strategy you intend to boost using the lightboxes. There are generally four main “marketing zones” in a retail space, and each zone experiences a distinct visitor mindset, as well as overall store strategy (and therefore lightbox strategy), as follows:

DRIVE-BY/WALK-BY ZONE
Lightboxes displayed in these areas are best targeted to passersby who are not aware of either your company, or your product, or your unique value — or even if they are aware of all three of those — they’re not aware that you happen to be open for business at this site. The intent of these lightboxes should be to let passersby know one or two of the above points, and to intrigue them. This zone include the building façade, windowline and entry area. Keep in mind that any lightboxes that will be exposed to the elements such as daily hot and/or cold temperatures, will need special engineering for outdoor durability and to dissipate moisture (condensation) adequately, even if not exposed to direct rainwater. Ask your lightboxes supplier to recommend model(s) based on the exposure you anticipate.

PRODUCT DISPLAY POINT
If you think your best strategy from the above chart should be to convey a positive perception of difference, then lightboxes adjacent to this zone containing photos of product features and/or product in use will be most effective.

POINT OF PURCHASE
Lightboxes in the POP zone are best utilized for upgrade and cross-sell messages, because here you already have a committed customer and now’s your chance to add even more value to the transaction.

TRANSITION AND/OR NON-PRODUCT ZONES
Any part of the store that is not one of the above three zones is a great opportunity for backlit messages about promotions, value-adds and alternative products, departments, services and/or features of which the visitor might not already be aware.

Hopefully this summary of how best to deploy backlit lightboxes is a help to those who are planning a new retail store or remodel. At Blue River Digital, you can browse the world’s largest selection of lightboxes here, or for backlit lightboxes custom-built to spec, you may submit your request for custom quote here.

Most commercial retailers want their backlit display lightboxes to be as bright as possible, to increase impact and turn more heads, thereby generating more exposure and brand awareness. Still, once in a while a store manager or retail space planner will look at a lightbox after it’s installed and determine that it’s too bright for their needs — maybe the site is a nightclub with relatively low lighting, or the lightboxes are intended as a secondary accent to another more predominant display fixture, or maybe it’s just a matter of general preference.

If lightboxes have been built-to-order and delivered, it’s usually not cost-effective to return them to the fabricator for a “downgrade” in brightness. Not only does this triple your shipping costs, you also have the tentative situation of trying to re-package large, fragile display products properly to mitigate damage in transit. Plus of course, there’s the costs for either re-stocking the overbright lightboxes and/or retrofitting the units for dimmability or other brightness-reduction scheme.

When lower backlight intensity is desired, it’s best to engineer your new lightboxes from the beginning with low light in mind, so that the entire lightbox design can be optimized for this. However, the catch 22 is, since desired light level can be subjective (depending on viewing distance, type of graphic, and ambient light levels), you may not realize your new lightboxes are brighter than desired until after you’ve received and installed them.

Hence here are some strategies for reducing the brightness of your existing lightboxes:

TUBE SLEEVES
quick online search on phrases such as “tinted sleeves for fluorescent lamps” will yield various suppliers who offer tinted sleeves that are easily slid over the fluorescent tubes in your lightbox. Blue River Digital has not tested these sleeves, but customers have reported success adding them to their lightboxes, either for a desired shift in color hue, or general brightness reduction. By the way – at the risk of stating the obvious – this strategy applies to fluorescent but not LED-powered lightboxes (unless your lamps happen to be “LED tube” design).

TINTED LENSES
Most lightboxes ship with a diffused white “back” lens and a clear “front” lens, between which the customer sandwiches their Duratrans backlit graphic film. Depending on the lightbox model and lens thickness / composition, tinted lenses with varying degrees of light-blocking properties can also be purchased from third-party suppliers. These tinted lenses can substitute for the original lens(es) included with your lightbox.

First ask your lightbox fabricator which “composition” and thickness is used for your lightbox model. Common lens substrates include acrylic (aka Plexiglas®), polycarbonate (aka Lexan®) and styrene. Also when you contact your fabricator, be sure to ask if the diffuser (back) lens is “etched” because if it is etched (a common feature of edgelit-design lightboxes), this lens is not replaceable, but the clear front lens still should be.

Then, locate a plastics distributor in your area, and visit their showroom with your original lens in hand, so you can compare translucence and thickness. They will usually offer advice and custom cutting services on the spot, even for small quantities.

THICKER OR MULTIPLE DIFFUSER LENSES A hybrid of strategy #2, this is simply replacing your existing translucent white diffuser lens with a thicker one of same or similar “translucence” (ability to transmit partial light) — or, adding a second diffuser to further reduce light-thru. However, it should be noted, our experience is that the brightness reduction achieved by this strategy is marginal. An important prerequisite to this strategy is to confirm if the lightbox design has adequate clearance to hold the thicker lens material.

DARKEN YOUR GRAPHIC
Using Photoshop® or similar software, you can darken the overall brightness of your artwork toany degree desired. If you choose this strategy to reduce your lightbox brightness, we recommend you print your graphic using the true, photographic “Duratrans” process, not inkjet. This is because the Duratrans process introduces a physical vector for opacity, which means darker colors will actually block some of the transmissive light, whereas the inkjet process only offers darker (muddier) formulations of translucent ink colors to achieve light reduction.

By the way, a really cool benefit of the Photoshop strategy is that you can selectively edit your graphic for brightness management. For example, what if you darken only the artwork’s background but leave the forward subject at “normal” brightness, for increased impact?

ADDITIONAL DURATRANS FILM
Our favorite brightness-reduction strategy is to add an additional sheet of Duratrans film behind your graphic. The “artwork” on the extra sheet is comprised of a solid, light gray field created by your graphic designer.

Not only is this the least invasive and quickest upgrade to apply, you can also easily adjust the brightness as desired simply by replacing the tint film with one of a different tint level. For example, say your Summer promotion graphic is way too bright so you add a 15% tint film behind it and now it’s just right. Then, maybe later you replace the Summer graphic with a Winter promotion graphic which already has a dark background, and now you don’t want the brightness reduced so much – so this time you replace your 15% tint film with a 5% film.

In addition to these workarounds for brightness management, there is still of course the idea of adding dimmable circuitry and lamps to your lightboxes. Most major fabricators, including Blue River Digital, offer dimmable upgrades to some if not all their lightbox models as new products, although the options for retrofitting dimmability to existing lightboxes are fairly limited, especially from a cost feasibility standpoint.

One of the most common problems people run into when selecting images for their lightboxes is getting one with the proper image resolution and file format. One of the biggest eyesores is when you select an image that appears pixelated once you print it out. However, the image you selected may have looked fine before you printed it out. So what happened? Let’s go over a few basics of digital photograph printing.

SELECTING THE RIGHT DPI
DPI is a common digital photography acronym that stands for Dots-Per-Inch and is a measurement of how many pixels (or “dots”) are packed into each square inch of print space. The higher the DPI, the greater the fidelity of the print job. To find out what your DPI is, simply right-click on the digital photo and click “Properties”. There’s a little tab on the top you’ll click on called “details.” From here, you can see all the properties the image has.

Take a look at the image properties here. The resolution is really high, which is really great. However, the actual resolution per square inch is only about 72dpi. You’re going to find that the image looks much better on your phone or computer screen than as a physical print with this resolution. An image that has an acceptable resolution will be around 300dpi. The good news is that the image we have isn’t necessarily lost. Since it has such high dimensions at 3264×2448, we can simply put the image in Photoshop or another professional photo-editing program and resize it, manually adjusting the DPI up to 300. This is not ideal, and many photographers recommend against this, but it is one of the very few ways you can save a low-resolution image. The only time you can really ever get away with this is when you have a sufficiently large photo like this. So, if 72dpi is so low and unusable, why do images usually default to this? Well, one reason is to save space. This particular photo example was taken with an iPhone 5, and we all know space is quite limited on phones. Another reason is that most photos taken with digital devices will be uploaded onto computers and will never be printed. At 72dpi, they may not look great printed, but on a computer screen, they look just fine. If you plan on printing photos, it’s best to go into the settings on your camera and select the appropriate resolution in which you want your photos to be taken in the first place.

The above picture is a pretty extreme example, but we wanted to demonstrate a little better what a low DPI does to a photo. The picture on the left, taken from our own site, is at a standard 72dpi that you normally see on web pages. The one on the right is set at 10dpi. Not only does the picture look fuzzy because you lose quite a bit of the sharpness and clarity, but the colors don’t seem quite “right” either. This also demonstrates that if we wanted to print the picture on the right, there’s no way to fix it in this state and print it at 300dpi. You can’t add quality that isn’t there. The only time this could potentially work is if you have an image that is sufficiently large in dimensions, and this image is, unfortunately, too small to work with.

SAVING IMAGES IN THE RIGHT FORMAT
Remember how we said that most images taken with digital devices will never be printed but simply uploaded to a computer? Well, one of the defaults that your digital device usually has is to save an image as a .jpg or .jpeg file extension. The purpose of JPG image compression is to save space on your computer. Once again, this is great for things like websites, sending email attachments, and uploading Facebook pictures, but it’s not so great for printing. JPG images use a much lower color bit-rate, which, in the simplest terms, means that there are fewer color choices. So if there is a color pixel that doesn’t match up exactly with its color selection, it has to “approximate” what color it is, which means that it has to settle for the closest match instead of the perfect match. The best image format to work with is generally images that are saved in TIF instead of JPG. If you absolutely insist on using a JPG, it will need to be a very low-compressed, high quality photo. If you have a photo that measures 11" x7" and is only 300 kilobytes in file size, it’s probably far too compressed for use in printing.

Q: What are the differences between lightboxes for backlit graphics display, that are designed for use indoors or outdoors?

A: The easiest way to characterize the differences between indoor and outdoor lightboxes, is to discuss outdoor-rated models, because almost all the differences occur as “upgrades” to make a lightbox outdoor-capable. So here is a list of features that distinguish outdoor models:

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:
2. FULL UL LISTING. Most building codes require that any electric sign (including backlit lightboxes) that is to be permanently installed outdoors, must be fully UL-approved as an electric sign. This means that product that only contains UL-listed components does not qualify for outdoor installation, unless the finished, complete lightbox comes with its own UL certification, in the form of an external, serialized sticker stating such.
3. WEATHER STRIPPING. Ask your lightbox vendor if the outdoor model you’re considering includes weather stripping to seal the enclosure, to minimize interior moisture and contamination.
4. DRAIN HOLES. Even a well-sealed lightbox needs drain holes at the bottom of the frame to allow excess moisture to escape from the light chamber.
5. UV-RESISTANT LENS. Not all outdoor-rated lightboxes include UV-resistance at the display face, and even those that do, can’t fully eliminate any UV impact to your graphics, but this can be another option to ask for, with many outdoor models.
6. CLEAR POWDERCOAT FINISH. Even if you want your lightbox to be silver or aluminum color, ask about a clear powdercoat to protect your aluminum frame. Even though aluminum won’t rust,it can “white” with age, resulting in a possibly undesirable look, which a clear powdercoat will forestall for many years.
7. HARD-WIRING. Some building codes require that outdoor-installed electrical signs be hard-wired, which means the electrician brings the source wiring all the way to the interior of the lightbox and terminates directly with the lightbox’s internal wiring, instead of via a plug and socket.
8. EXTRA SPACE BETWEEN FRONT CLEAR LENS AND WHITE DIFFUSER LENS. Even the tightest outdoor lightbox can develop internal condensation, mainly because air always contains a certain amount of water and then as the temperature drops, the moisture in the air will condense onto the surfaces inside the lightbox. For this reason, it is important with outdoor-rated lightboxes, to allow an extra space between the front clear lens and the white diffuser lens, so that condensation can dissipate over time. Not all outdoor models have this feature, but well-planned models do. This extra space will serve to help your graphics perform better longer, with less visual impairment resulting from condensation.
9. EXTRA INTERNAL BRACING. For areas with severe climate exposure, some outdoor lightbox models can be configured with internal reinforcing poles for extra rigidity.
10. SECURITY ACCESS. Outdoor applications experience increased likelihood of unauthorized access attempts, so tamper-resistant screws or key locks are optionally available on some outdoor lightbox models.
11. POLYCARBONATE LENSES. Standard lightbox lenses are usually made of acrylic, commonly known as Plexi-glas (plexiglass). But polycarbonate, though more expensive, yields greater shatter- and crack-resistance by a significant factor. Also polycarbonate lens stock is available in much larger sizes than acrylic, which means a larger display. (Acrylic lens stock typically maxes out at 10-foot lengths, and polycarbonate, depending on the thickness, can be 12 feet to 100 feet maximum length.)
12. “NO-GLARE” OR GLARE-RESISTANT LENSES. Some outdoor applications benefit from a glare-resistant clear front lens, in order to more effectively display their messages, depending on the environment and type of lighting.

Some indoor models may contain one or more of these normally “outdoor-only” features, but the goal is usually to only order (and of course, invest in) features that will help your backlit display lightboxes perform as needed in the environment for which they are being purchased, and outdoors is clearly the more demanding environment in almost all circumstances.

There are two types of lightboxes used for displaying backlit graphic film. There are what we call direct-backlit lightboxes, and then also what are known as edgelit lightboxes. Here we have a direct-backlit lightbox, which is designed the way most people would expect a lightbox to be. You can see that its lamps are oriented behind the viewing surface, so that the light shines directly forward, through your backlit graphic film.

Over here, we have what we call an edgelit lightbox. In this design, the lamps shine sideways thru the translucent panel behind your graphic film, thereby indirectly lighting up your graphic message.

So… which of these two lightbox designs will work best for your project? Let’s take a look at the pros and cons of both direct-backlit, and edgelit, lightboxes.

First, direct-backlit lightboxes are usually brighter than edgelit ones, because the light is transmitting directly from the lamps to the graphic surface, not shining sideways. This does not mean that edgelit lightboxes are not bright enough for most applications. Consider it like this: most direct-backlit lightbox models have the potential to be slightly brighter than average — depending on some other factors such as how many lamps are used — whereas most edgelit lightboxes usually give you more of a standard-level brightness.

Another difference between direct-backlit and edgelit lightboxes is — a direct-backlit lightbox requires more cabinet space behind the graphic, in order to transmit the light uniformly through the empty space. Usually two to four inches deep is the minimum cabinet depth required to achieve adequate diffusion of light. On the other hand, your average edgelit lightbox can often be less than one inch deep, since the light is transmitted indirectly from the side edges, as we see here.

The next thing to consider when comparing direct-backlit and edgelit lightboxes is what we call “uniformity of diffusion”. Uniformity of diffusion is basically the question of, how uniform or even is the brightness — or intensity — of your lightbox, from one corner of the display to the other. A direct-backlit lightbox will always have the potential to deliver better uniformity than an edgelit one.

For example, check out this direct-backlit lightbox and notice how even the light intensity is spread across the entire face. Now take a look at this edgelit lightbox and notice the slight “glow” along the edges where the lamps are positioned. Almost all edgelit lightboxes exhibit this characteristic. In addition to this, as you increase the size of an edgelit lightbox, the brightness toward the middle of your graphic may start to drop off and get dimmer. This is because the larger the lightbox, the further away the lamps are from the center of the backlit graphic film.

The final consideration between direct-backlit and edgelit lightboxes is your investment. A direct-backlit lightbox needs many more lamps to light up the display surface than an edgelit one, if it’s using LED lamps. For example, a medium-size direct-backlit lightbox may contain approximately eight hundred LED lamps while a similar edgelit lightbox may contain only about one hundred lamps.

This means there will be higher startup and operating investments for the direct-backlit option — that is, unless you choose fluorescent lamps. Considering all these factors, both Direct-Backlit and Edgelit lightboxes have their advantages and disadvantages. But hopefully this will enable you to make the best selection for your project.

	direct-backlit	edgelit
brightness	x
low profile frame		x
uniform diffusion	x
jumbo display sizes	x
energy use		x
upfront investment		x

As business people, we sometimes impulse-kick to get the latest and greatest, so we can stay ahead of the other guys. But when it comes to messaging platforms we depend on to optimize exposure for our businesses, sometimes we need to step back and ask, “Do I really want to replace a tried-and-true messaging platform with a more-fragile, higher-maintenance and high-cost replacement?” Clearly there are times when a digital sign is the right medium for certain types of messaging, but before you write that monstrous check, review this quick list of three cases for a simple, high-brightness LED lightbox, adorned with breathtaking, high-saturation duratrans backlit film:

1. IT’S THE SCIENCE. The “science” of lightboxes has evolved in a lot of ways, but the tech feature that stands out the most in a backlit lightbox, is the high resolution potential of the imagery. A digital sign typically offers between 30 to 90 dots per inch, whereas a lightbox with commercial-grade duratrans backlit film can achieve up to 4000 dpi. This exponential improvement is obvious with any hard-edged artwork in terms of “smoothing” the edges, but what if for example, you also want to draw attention to the subtle changes in color tones on a piece of fine jewelry, or varying degrees of dark gray vs. black textures in an ominous movie poster? In addition to superior crispness and smoothness, a backlit lightbox delivers color tone bandwidth on a scale digital signs can only dream of, for the simple reason of resolution
2. IT’S THE ART. Saying a lightbox sign limits your options in commercial imaging is like saying still photography limits your options in wedding memorabilia. The same essence of art and beauty that exude from a stunning, aptly-shot still photo also command the spectator’s appreciation in a well-conceived lightbox application. There’s something about a special moment frozen in time, for the observer to contemplate whatever relationship, struggle, victory or other dynamic is symbolized in the still imagery. This powerful messaging technique speaks to our basic humanity, but it’s fully lost on digital signage.
3. IT'S THE MONEY. Every campaign to promote your message must be weighed for its efficacy as a ratio against cost. There are two fairly obvious ways a backlit lightbox display delivers relatively compelling ROI, plus a third idea you may not have thought of:

a. Cost of Setup — Let’s just take an example of an average-sized lightbox in an average retail space. Blue River Digital’s EdgeLyte Econo LED lightbox model at 27x40" graphic size is Internet-discount priced at $369.00 USD for qty. one lightbox. Add a duratrans backlit graphic film plus shipping, and your electrician’s time to mount it on the wall and plug it in, and your total investment is likely to stay south of $500.00 after all is said and done. On contrast, a similarly-sized commercial grade 48" digital sign with media player like this popular Samsung model, with wall mount, wi-fi connection and power cable, once you add shipping and professional installation, is going to demand somewhere in the $1500.00 range and up. And this is before we even step up to the “starting line” of deployment.

b. Cost of Maintenance — Digital signs are not only more fragile and sensitive, they also consume more power, generate more heat, and due to their complexity – generally require more maintenance to keep running. Most retail operators are looking for ways to reduce maintenance overhead, and this is where a tidy backlit or edgelit LED lightbox can deliver a “set it and forget it” experience unmatched by any digital sign. No wi-fi connection, no extreme sensitivity to moisture or warmer temperatures, and minimal impact from both direct sunlight and workplace contamination all remind us why a conventional lightbox offers a compelling, zero-maintenance case.
…and now for the third economy factor that’s easy to overlook:

c. Cost of Content — Awhile back I was staying at a hotel in Las Vegas, and every day I rode a driverless light rail tram to and from another nearby hotel where a trade show was hosted. The tram cabin contained a digital sign that played an ad loop over and over, every 1 to 2 minutes, to the tune of a catchy Abba song which I actually used to like, until then. By the time I’d ridden the tram twice, I was committed to never buy tickets to the show that was being promoted on the digital sign, for the sheer insanity it had pushed me near, and for its general disrespect for my senses.

Stop and think about the cost to conceive, produce and deliver dynamic video content that’s always moving, always changing. You’ve got to pay for scripting, lighting, acting, shooting, editing and post. And after it’s all done, the general public’s elevated expectation for your digital sign demands that the content will not insult their intelligence. For example, say you invest several hundred dollars to get a professional-quality, impactful product video of 90 seconds length, and you’re really proud of this presentation on what is so great about your product. Now, are you going to loop that clip every 90 seconds, all day every day — or are you going to try and backfill time slots before and after the clip, with cheesy weather reports or entertainment news? …Just like my story, think of the times you’ve ever seen a promotional video that was painfully repeated ad nauseum.

Compare that to the investment required for a head-turning, dramatic still photo with or without overlaid text message and/or logo, for a lightbox display. All you need is a good stock or custom photo, plus a bit of your graphic designer’s time to put it all together.

In summary — digital signs, like live video, deserve a clear carve-out in the commercial messaging landscape; we just want to reaffirm the applications of each of these technologies within the domains where they serve best. A digital sign is great for wayfinding, informational, line-item menu and similar uses; whereas a backlit display lightbox often still maintains an edge with jumbo-size, dramatic detail/still photo and branding/lifestyle types of messaging.

As backlit LED lightboxes increase in popularity for commercial and fine art applications as compared to legacy fluorescent models, so does the need to find ways to smooth out the LED light intensity and deliver more uniformity of brightness, to meet the expectations of the viewer. In our previous article 7 Tips on How to Improve Diffusion in Lightboxes, we talked about how to improve lightbox diffusion generally, regardless of lamp type. Here, we’ll specifically focus on LED lightboxes and the unique ways to optimize their light diffusion properties.

1. LAMP BRIGHTNESS — Conspicuously missing from our original article is the idea that variations in lamp brightness may contribute to or detract from uniformity of diffusion. In fact, our own research here at Blue River Digital has concluded that adjusting the brightness of fluorescent lamps has little to no detectable influence on how well a lightbox diffuses. However, this cannot be said of LED lamps, and the reason is simple: LED lamps generate a highly focal pattern of light output, as compared to fluorescent tubes, whose light output is highly diffused at the very outset. This difference in light output pattern between fluorescent and LED lamps is responsible for the differing results obtained when you increase or decrease the intensity (aka brightness) of the two lamp types.
2. To illustrate this, consider a spotlight on a foggy night, compared to a line of store windows that are lit up. If you dim or brighten the spotlight, its “diffusion” also changes, even if not in a linear relationship to brightness, it still changes from modestly diffused at its “dim” setting, to barely diffused (more “focal”) when bright. Conversely, a set of store windows that is indirectly lit up from within, or possibly a large rectangular electric sign with a lightly-colored graphic face, when adjusted to a dimmer or brighter setting, does not result in the same degree of change in diffusion level. Whether dim or bright, a large, somewhat pre-diffused light source changes very little in its “diffusive” property — unlike the spotlight — or in our case, the LED module.

So our conclusion here is that when LED lamps are dimmed, they diffuse better than when at full brightness. Or more accurately, the more the light from an LED lamp is intensified, the more focal or pinpointed its light output pattern becomes, making it more difficult to mitigate that focality, aka “diffuse” the light output.

Blue River Digital carries tens of lightbox models specifically fitted with LED lamps, plus several other models that are upgradeable to LED. Of all our LED models, at least half of them are also upgradeable to dimmer-controlled circuits, which in turn can deliver an improved diffusion for critical lightbox projects.

3. LAMP ORIENTATION — Because of the intense focality of LED lamps by their nature, lightbox designs that contain edge-mounted lamps which cast their light “sideways” through an etched diffuser plate are especially popular with LED-powered systems. This is because the side-throw design boosts diffusion simply by delivering an indirect transmission of light, first laterally through the etched plate, and then forward to the display face — instead of direct, unhindered, straight-line from lamps to display face

For this reason, if you want the best of diffusion in an LED lightbox, it’s hard to go wrong with an “edgelit” design. Edgelit LED lightboxes are the most popular lightbox configuration these days for several reasons, and uniform diffusion is near the top of the list.

4. LAMP BUBBLES — Not many LED lightbox manufacturers offer lamp “bubbles”, but several of Blue River Digital’s premium models include these miniature, translucent lenses by default. A lamp bubble, as seen here, is simply a mini-diffuser mounted on a single LED module. The bubble serves to scatter light as soon as it emits from the module, thus making it easier for the diffused face lenses and/or diffused graphic film to finish the job of smoothing out the light intensity, with the ideal goal being an unquestionably uniform glow at the display face.
5. SPACE BETWEEN LAMPS — Back in the ‘ancient’ days of mostly fluorescent lightboxes, since fluorescent tubes stretched the length of a lightbox in one direction, the only axis left to worry about was the 90° opposing one,in terms of how many tubes, or what “lamp density” was found. Now with LED lightboxes, we have to think about both “X” and “Y” axes, because each LED lamp is so tiny that of course we need a two-dimensional “matrix” of them to adequately illuminate the display face of your lightbox.

Most direct-backlit LED lightboxes are fitted with linear strips of LED lamps all in a single-row per strip. LED lamp strips are available in all ranges of lamp density, from several lamps per inch, up to one lamp every couple of inches or more. The spacing between lamps on an average lamp strip in a direct-backlit LED lightbox is between 1.5 and 2.5 inches. Of course the closer the lamps, the less “light drop-off” can occur between lamps at the display face, thus reducing hot spots or variations in brightness.

Next we have the spacing between strips of LED’s, and here’s where you get all manner of variety from one lightbox model to the next, depending on depth of lightbox cabinet, intended overall brightness, and of course budget.

If you’re shopping for LED lightboxes and you have a particular requirement with regard to overall brightness, uniform diffusion and/or budget, find out what variations of models — and also flexibility within a particular model — are available from your suppliers.

6. DISPERSION ANGLE — Our last tip on how to improve light diffusion for your LED lightboxes, and perhaps the least intuitive, is the dispersion angle of the LED modules. Dispersion angle is the degree of spread of light as it leaves the lamp and fans outward, similar to a floodlight vs. a spotlight. Some LED modules have wider dispersion angles than others(these are commonly called “wide angle LED’s”), and this property functions hand-in-hand with lamp density to either improve or degrade diffusion uniformity. As a matter of fact, a good test of the detail and quality of your lightbox source is to inquire about dispersion angle. If your supplier is not able to provide specification on dispersion angle, chances are you’re dealing with narrower angles, plus parts and materials that generally require lower investment on the part of your supplier.

Usually you don’t see a consumer-level option for dispersion angle, but if you have a super-critical diffusion application, and you’re having your lightboxes built-to-order, dispersion angle is an important part of the formula, in addition to lamp spacing and distance of lamps from display face.