Backlite Printing of images for illuminated Signage

We print from most desk top publishing packages, computer files, scans, computer images, digital artwork and pictures on Apple Macintosh or PC format.

We offer a comprehensive in-house print finishing facility where prints can be mounted onto a range of boards: PVC / Foamex, MDF, Polyboard / Foam centred board, display board / card etc. and also laminated

Our synergy of advanced printing methods and systematized workflow ensure that your prints always come out on time and of unquestionable caliber.

The number of rear-illuminated displays is steadily growing, as is the variety and sophistication of the substrates required to produce them. Screen printers have become aware of this developing trend, and many are adding backlit-graphic production to their service offerings.

A large number of screen printers also are adding digital-printing systems to their operations. Digital-printing technology can be a great complement to the screen-printing process, providing screen shops with the flexibility to go after short-run business from new customers and offer new custom-decorating options to ex-sting customers. However, printers face as many options and challenges in producing backlit displays with digital-output devices as they do when using screen-printing materials and equipment.

To develop the highest quality backlit sign, graphics producers must realize the impact of the materials used on the graphic's final appearance. This article will provide an overview of backlit graphics, describe how they are produced with inkjet printers, and review what types of inkjet inks and substrates should be used for particular backlit applications. It also will address color matching by explaining the differences between reflected color in daylight and backlit color during dark periods and what printers can do to ensure color accuracy in both conditions.

Understanding backlit displays

Backlit displays are simply graphics that are illuminated from behind. They can be found practically everywhere these days, from retail-store aisles and hotel lobbies to trade-show booths and taxi tops. Backlit displays are not new; they have been around for many years. But recent advancements in digital-printing and media technologies have eliminated some of the production problems of the past, making it easier to produce high-quality, cost-effective backlit graphics. These developments, coupled with the boom in demand for promotional graphics, have resulted in a sharp increase in illuminated signage. A recent report from industry analyst firm CAP Ventures, Norwell, MA, bears this out. The group forecasts that large-format printers will consume 75.5 million sq ft of backlit film in 2003, growing to more than 83.8 million sq ft by 2007.

Digital printing has and will continue to have a positive impact on the growth of backlit advertisement. Because digital is suited for short- to medium-run lengths, more businesses can afford to include visual displays in their advertising budgets. Therefore, more local and regional venues find installing and leasing backlit space to be a profitable business decision. For example, a local store owner may see great value in placing promotional advertisements in backlit kiosks at a local mall, where foot traffic may be insufficient for a national retailer to consider advertising. The advantage for the print provider is twofold: First, this scenario presents a growing client base. Second, short-run graphics production can be very profitable and generate premium rates.

Different types of backlit displays

While the demand for backlit signage is increasing, it's important to note that not all backlits are created equal. The hardware and media requirements for backlits differ based on the application. For example, transit-shelter backlit displays generally require that the graphic be placed between two sheets of rigid Plexiglas. Complex and curved backlit signs, such as bus-side displays, vending machines, and taxi-top displays, require a printed, backlightable, adhesive film to be adhered to a single sheet of Plexiglas. The following is a short overview of the most common types of backlit formats and media:

Calendered vinyl with pressure-sensitive adhesive (PSA) on one side commonly is used for producing backlit signage. Vinyl is cheap, flexible, and durable. The adhesive enables graphics to be applied without the need for mounting hardware associated with rigid and non-adhesive media. The adhesive must be reworkable and aggressive, yet easy to remove at the end of the promotion. While on display, the vinyl must remain stable and not separate from the surface. Depending on the longevity of the promotion, the vinyl may be protected with a pressure-sensitive overlaminate.Ed McCarron, Larry Delesio, and Wendi West - InteliCoat Technologies

Polyester backlit films can be slid in between two pieces of Plexiglas for protection. Depending on the type of polyester media and the length of time the display will be exposed outdoors, the material may feature a water-resistant coating and may or may not require overlamination after printing. Polyester films also can be mounted to a pressure-sensitive clear backer for additional rigidity or to Plexiglas or acrylic panels with an optically clear pressure-sensitive adhesive.

Papers that have good uniformity can be used for backlit signage. However, paper products should be overlaminated, edge-sealed, and protected with Plexiglas. Papers are not as dimensionally stable as vinyls or polyester films.
Producing a backlit graphic

Backlit graphics are most commonly produced using one of three printing methods: screen printing, inkjet imaging, or photo laser printing. The type of printing technology used to produce backlit graphics depends on several factors, the most important being the life span desired from the printed graphic and the volume of graphics required.

For example, screen printing is the best method for producing a large volume of backlit graphics that are meant to have a long life span. Screen printing offers superior production speed and uses the most durable inks.

The new generation of grand-format and solvent inkjet printers has become a popular choice for screen printers who have committed to incorporating digital production. These machines also offer a good solution for producing long-lasting backlit graphics, particularly for outdoor displays such as transit shelters. Grand-format printers offer good resolution (in excess of 600 dpi, in some cases) and high print speeds, making them ideal for large graphic applications.

While grand-format and solvent inkjet printers are primarily designed for printing on uncoated vinyl, a growing number of substrates for producing backlit graphics also have become available. The production speed and outdoor durability of these systems, coupled with the new generation of specialty films and papers, can provide a great solution for outdoor backlit displays.

For a smaller quantity of short- or medium-term graphics, such as indoor P-O-P displays, a mid-format thermal or piezoelectric inkjet printer may be a more cost-effective solution. To choose the right type of substrate for your backlit graphics, it is important to know the differences between these inkjet technologies.

Differences between mid-format thermal and piezo inkjet printers

Thermal and piezoelectric inkjet printers both deposit ink droplets onto media by applying electrical signals to the printhead. What is different is the method used to expel the ink. Thermal inkjet printers use heat, whereas piezoelectric printers use a form of vibration.

Piezo printers enjoy several advantages over thermal inkjet printers. For example, piezo printers can use a wider range of inks, including solvent-based and aqueous inks that incorporate either dyes or pigments. In general, these inks are formulated to dry more quickly than the inks used in thermal inkjet printers, and consequently, piezo printers usually can print at more rapid speeds.

Thermal inkjet printers only use water-based (aqueous) inks, also in dye-based and pigmented formulations. These inks take longer to dry between print passes, affecting print speed. In addition, heat buildup in the printheads can cause color shifts. However, thermal inkjet is one of the most common printing technologies used in the market today. As a result, there is a wider variety of media choices available for thermal systems.

Choosing the right media

As film coatings and inks continue to improve, the opportunities to produce a variety of backlit display graphics with mid-format inkjets do as well. However, matching the media options with the right technology and intended application can be a challenge. The cost, output-quality, and finishing requirements of each job are key factors to consider when choosing a backlit media.

Some designers prefer to use paper rather than film as a cheaper way to produce backlit displays. This approach to saving money can backfire, however, because paper is less durable than film, even when encapsulated in Plexiglas. While films for mid-format inkjets may be more expensive (because they must be coated to accept the prints), they provide far more durability than paper, yielding greater economies in the long run.