Looking Backward

The 1990s previewed a new millennium in which technological development will advance at the fastest pace in human history. During the past decade, huge improvements have been made in computers, software, electronics, optics and machine-control systems. As the speed of innovation increases, less time is required for new technology to impact business planning.

To appreciate the shrinking horizon for incoming technology, remember that, as recently as 1980, the concept of signs being mass-produced by computer-aided equipment seemed like pie-in-the-sky to many sign professionals. Twenty years ago, LEDs, lasers and fiber optics were widely viewed as expensive curiosities.

Today, these technologies have become mainstream industrial tools. Laboratories around the globe compete aggressively to unlock new secrets of physics that will serve myriad practical applications. In the world of electronic signs, this race yields products with better resolution, greater durability and lower operating costs. Although technology might be fascinating, concrete benefits are what people buy and sell. Electronic-signs are high-visibility, promotional messengers that stay on the job 365 days per year. For many businesses, this represents a priceless advantage.

Given the current rush of innovation, it’s difficult to predict any long-term winners in the clash of electronic-sign technologies. It’s a safe bet, however, that moving message signs of the year 2020 will be quite different than the products we see today. This evolution is not only good news for product manufacturers and their customers, but it also promises to help keep vagabond technical editors off the streets. The following is an overview of the main types of large-format electronic displays.

E-ink

Although current product applications are confined to p-o-p posters that automatically change textual messages (see "P-O-P Industry Keeps Up with the Times," page 113), electronic ink is a technology with the potential to rewrite the book on electronic signs. Manufactured by a process that its creators compare to "making salad dressing," electronic ink is a high-tech coating that creates electronic displays when applied to almost any substrate.

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E-ink displays combine excellent visibility, a wide viewing angle and very low energy consumption. Product development, however, has not reached the stage of direct competition with other types of moving-message signs.

Electron-Emitter Displays

Field-emission displays (FEDs) and surface-conduction electron-emitter displays (SEDs) represent a new wave in large-format-video products. Although a few of these products are already in production, most are still under development.

FEDs incorporate a substrate coated by a thin diamond film and sealed inside an evacuated cell covered by a plate of phosphor-coated glass. When current is applied, electrons emitted from the diamond film strike the phosphor, producing light. By altering the type of phosphor, FED pixel elements can be produced in red, green and blue versions for bright, efficient, full-color displays.

Canon (Tokyo) and Toshiba (Tokyo) recently announced plans to jointly develop large-screen displays based on SED technology. An SED operates similarly to an FED, but the structure of its electron-emitting component is different. Whereas FEDs emit electrons from the entire coated surface of the glass-encased substrate, SEDs confine the electron-emitting area to a narrow, linear tunnel between two electrodes placed on the substrate’s surface. It’s estimated that SEDs will consume approximately half the power of CRT displays, and only one-third the power of plasma displays.

Flipper Displays

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Electromechanical flipper displays are prominent in many traffic-control and mass-transit applications. The operating principle is the same as flash cards used at college football games. Each pixel is either on or off, and the displays present only text and simple graphics. Flipper displays are preferred for mobile applications like buses or trains because they consume minimal power and offer excellent resistance to shock and vibration. For fixed installations, flipper displays present lower-cost alternatives to light-emitting displays.

Incandescent Displays

Although some electronic signs incorporate large floodlight bulbs, smaller, wedge-based, xenon lamps illuminate the majority of incandescent message signs today. These signs are available in monochrome, grayscale or full-color models. To create a full-color pixel using incandescent lamps, a colored lens is placed in front of each wedge-based lamp.

Although energy consumption and maintenance costs for incandescent displays are higher than comparable-sized LED displays, the lower initial cost preserves a significant market for these products. Also, various design improvements make today’s incandescent message signs more reliable than ever before.

Laser-Based Displays

This very complex technology creates high-resolution, full-color video images by encoding red, green and blue laser beams with the pixel components of a video input signal. A galvanometer-driven scanning mirror projects the image line-by-line onto a display screen. Most of the laser-based displays currently in use are installed at indoor sports arenas.

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LCD Displays

Although numeric liquid-crystal diode (LCD) displays like those found on digital wristwatches and calculators do not require integral light sources for daytime visibility, an LCD display may also be projected (with a powerful light source) onto the front or rear of a large screen. This produces full-color video images with excellent resolution for indoor or nighttime outdoor applications.

LED Displays

Unlike incandescent lamps emitting white light filtered through colored lenses, LEDs are colored light sources. By adjusting the composition of an LED’s light-emitting semiconductor chip, manufacturers produce a full range of visible colors. As manufacturers improve the diodes’ brightness and outdoor durability, LED displays make inroads to markets formerly dominated by incandescent displays. Particularly in retail applications where monochrome, text-only displays are required, LEDs compete aggressively with incandescent products.

In the high-end market for large, full-color video displays, LEDs have moved into a dominant position. With outdoor visibility better than ever, these products are increasingly specified for stadium applications as alternatives to energy-guzzling, CRT displays.

Plasma Displays

Plasma panels operate on the same gas-discharge principle as neon tubes. A mixture of neon, argon and xenon gas fills millions of tiny evacuated cells (pixels) sealed between two glass panels. When electrical current is applied via a complex network of tiny electrodes, the pixels emit light to create an image.

Plasma displays have excellent resolution and a wide viewing angle, but require extremely careful handling. For this reason, the displays are used primarily for permanently installed, indoor applications.