Tripping the Light Fantastic

The 1960s-era Bruce Nauman neon sculpture 100 Live and Die, was originally animated with mechanical switches, gears and cams. A replica was produced by Jacob Fishman that was animated with a modern microcontroller. Exhibition copy of 100 Live and Die, © by Bruce Nauman, 1985.

Since the advent of electric lights, there have been amazing and delightful examples of animated lighted displays. One very famous example from years past is the animated Anheuser-Busch neon eagle at the company’s Newark, N.J., brewery, which originally had 16 changes per second—the rate at which films of the day were shown—and achieved a fluid looking motion using mechanical switches, gears and cams.

Another example is the 1960s-era Bruce Nauman neon sculpture, 100 Live and Die, which was also originally animated with mechanical switches, gears and cams.

A few years back, Jacob Fishman built a replica of the piece for the Milwaukee Art Museum, and the replica is animated with programmable digital electronics. (The process was documented in an article by Brad Lash entitled “Perfect Timing”, published in the June 2006 issue of Sign Business (www.sdgmag.com/article/perfect-timing).

Countless other examples—Times Square and the entire Las Vegas Strip, for example—demonstrate how the art of lighting has evolved with the science, including in recent years the wide-spread adoption of LEDs as a major new light source.

Digitally controlled soft animation and color changing effects. Photos courtesy Kenny Greenberg.

CONTROL FREAKS

“There are two main choices in how to configure lighting controls,” says Kenny Greenberg. Greenberg specializes in stage lighting on Broadway as well as sports, film and architectural lighting. He owns Krypton Neon in Long Island City, N.Y., and is a long-time contributor to this magazine. For many typical sign applications, off-the-shelf devices are sufficient, Greenberg explains. They are relatively inexpensive and can provide a variety of pre-programmed options to control flashers and sequencers.

A more complex approach is to build an animation system and develop custom programming. Brad Lash used the Parallax Stamp (www.parallax.com) to control the Nauman replica mentioned above. A spin-off company of Parallax, EFX Tek, produces pre-wired boards, terminals, buffers and other electronic gadgets. There’s a world of resources on the web for animation control systems like these of all kinds for all purposes for all skill levels. In addition, most LED companies have proprietary software or software optimized to work with some other controller.

While the majority of signage animation is simple on-and-off flashing, a more sophisticated custom program might also include up and down dimming. On a grander scale is theatrical lighting, which has evolved into other mainstream applications, including architectural lighting and signage.

Today there are different kinds of computerized systems, the most popular of which is DMX, the stage lighting industry standard for digital communication networks. DMX is a serial protocol that allows one transmitting device to control a multitude of receiving devices. Greenberg goes on to explain that the way it works is relatively simple. A transmitter sends a burst of data with a start signal, followed by a burst of data telling the device what to do–usually simply setting levels, such as go up to 90 percent, or come down to 20 percent. The command can be more complex; for example, telling a moving light to rotate 20 degrees while it goes up to a 90 percent level. Last is the end signal, which signifies the end of that little burst. Thousands of such bursts can be squeezed into a microsecond and as a result, “a multitude” of devices can be controlled simultaneously using a DMX controller.

“A lot of work is done using DMX because it’s a versatile and reliable method,” says Greenberg, “and over time different devices have been optimized for DMX. I’ve done a lot of what you’d call soft animation, like swirling curved lines to make ellipses on a ceiling. You would use the same sort of mechanism with any kind of light source. For example, we were recently challenged to find a way to create a backlighting effect for a show that would cross fade back and forth from a warm color to a cool color. In the end we went with incandescent for the warm and neon for the cool.”

A “zipper” type LED screen, built and installed by YESCO, displays news and animated graphics on the Denver Post building.

LIGHT CHARACTER

Animation is achieved through turning switches on and off and by dimming; dimming up and down enables animation to appear more fluid.

Different types of light sources behave differently, so understanding their characteristics is rudiment to understanding how to animate them. Greenberg goes on to explain that neon, for example, is very responsive to changes in current but flickers at low levels, so a program needs to take that into account. The data in high resolution DMX theatrical systems can be split into 65,535 steps, so the eye doesn’t perceive those micro steps. On the other hand, an inexpensive low-resolution system splits data into only 255 steps. Because neon is very responsive, it could appear jagged using a low resolution controller. By contrast, other light sources such as incandescent could be described as having a little more “inertia”, meaning it takes a moment for them to come to full brightness but they will also still glow for a moment when the power is turned off, and thus not appear jagged.

One main difference between controlling LEDs versus controlling neon or incandescent is the voltage differences. But more important is the fact that LED lamps are DC devices and neon and incandescent lamps are AC devices.

AC dimming is generally done by what’s called “Phase Control”, in which a device is turned on at a time delay after the start of each cycle and power is thus regulated. There are also versions where power is turned off after a duration. Because there is no waveform for DC, control is usually achieved by what is called “Pulse Width Modulation” (PWM), through which power is rapidly pulsed on and off and the ratio between on and off is varied, which changes the power that’s delivered. (For a discussion of phase control and pulse width modulation fundamentals, read the two-part article by Dan Watts, published in the November 2006 and the April 2007 issues of Sign Business or online at www.sdgmag.com/article/led-power-supply-overview-part-1 and www.sdgmag.com/article/led-power-supply-overview-part-2.)

The façade at the Louis Vuitton store in Las Vegas constantly sparkles with cool white light. The façade also displays video. Photo courtesy John Fox.

The characteristics of the LEDs and how they are spaced affects how fast video can move through the façade. Photo courtesy John Fox.

SOMETHING NEW

The Louis Vuitton store in the Crystals shopping complex at CityCenter in Las Vegas features a façade that pushes the envelope for state-of-the-art lighting control technology.

The façade emulates the Eiffel Tower at night, in that it produces a random sparkling, paparazzi flashbulb effect. It is also capable of displaying video. John Fox says there were several design challenges to overcome in order to achieve the final result. Fox’s company, Fox & Fox Design, in collaboration with Lighting Science Group recently completed the simple, elegant and innovative façade at the Louis Vuitton store in Las Vegas.

Fox’s first challenge was to find the right light source that had the necessary characteristics and would perform as conceptualized. His search ended when he found a sample of a Dynasty white LED lamp, manufactured by the CAO Group.

DESIGN FOLLOWS FORM

“The design stems from the specific LED and working around its limitations and performance capabilities,” says Fox. “The rest of the system evolved from that point.”

The Louis Vuitton façade represents a significant departure from typical Las Vegas Strip video displays and what controls them. First, instead of full color RGB LEDs, the display uses only white LEDs. This was a “bold decision” made early in the design process when Louis Vuitton’s director of design determined that full color wouldn’t add value to the image the company wanted to project.

A Dynasty white LED lamp, manufactured by the CAO Group.

Additionally, unlike most video walls, this display would not be accessible from the back, which meant that the control system and all the associated electronics had to be in a remote location.

The resulting wiring configuration is a spider web-like network that required more actual wires than simply daisy-chaining each LED, but efficiently solved the problems of keeping the electronics dry, accessible and away from the heat (temperatures on the south-facing stainless steel façade can reach up to 180 degrees F).

Fox explains that at the heart of the system is a constant current driver about the size of a ream of paper that can drive 60 independent LED channels. “The LED is literally bare. The drivers plug into the DMX and it’s all daisy chained that way.”

The wide-spread adoption of LEDs as a major new light source has greatly added to the realm of architectural lighting. Traxon Technologies developed this Imagic Weave media façade in Germany at Haver & Boecker’s office building in Oelde. 10,656 high-performance LEDs display stunning lighting effects in up to 16 million different colors.

IMAGES AND CONTENT

Part of the design process for the Louis Vuitton façade was also to evaluate the limitations of the system in terms of what kind of images it could display.

One of those limitations is that the LED has some ramp-up time. “You can run electricity and light the LED in 1/60th of a second, but the LED will look dim at that point,” says Fox. “You need to allow the LED to be on for a certain amount of time for your eye to see it and also for the LED to come to full brightness. What’s that duration and does it affect how fast you can move video through it?”

Another limitation on the Louis Vuitton façade is the size of the space and what could actually be done with regards to shapes. There are 8,000 holes in the 80' by 80' façade but only 4,600 are filled with the Dynasty LEDs. The rest are filled with blanks. With 4,600 points of light randomly located throughout the façade, but densely populated in the middle, another limitation is the kinds of shapes that can be displayed before it looks like LEDs are burned out and edges are not complete.

“We worked out a lot of content criteria based on these limits,” Fox explains. First, the wall can’t display solids. Second, shapes can’t move too fast because they will blur and lose definition. Third, shapes can’t move too slowly because they will show those incomplete edges.

A final content design criterion was that the wall would always be flashing. This criterion was a result of observing the dynamics and characteristics of the light source. Because the LEDs are relatively small and the pitch (the distance between light points) is relatively sparse at one foot by one foot, visually the LEDs work better in groups of three or four. Doing this also reinforced and strengthened the paparazzi flashbulb effect.

An analog mechanical wheel timer compared to a Parallax Stamp 2p40 microcontroller. Photo courtesy Brad Lash.

Another very critical element of the façade’s design process was choosing the color temperature of the light sources. The color temperature on most camera flashes is in the 6,000-8,000K range, so to get that flashbulb effect, Fox recommended using LEDs in the 5,700K range, which would mimic that flashbulb effect. By contrast, most of the dots of light on the Las Vegas Strip are very warm incandescent bulbs, in the 2,000-2,700K range.

In terms of energy usage, the design departs dramatically from other Las Vegas media walls because it uses only 5,000 watts, compared to others that use 10 times that.

“The technology is dictating where we’re going,” says Fox. “Eventually we’re going to have to rethink electrical systems for lighting in general. The system we created can be used for anything. This driver, which we built on a large scale, can be done at any scale. To me, that’s the neat part of this.”

Sign & Digital Graphics

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