Signs of the Times - July 2012 - (Page 28)
THE MOVING MESSAGE
By Bob Klausmeier
Digital-display consultant Bob Klausmeier brings 34 years of firsthand professional experience to all digital-sign markets; his home and office are in Las Vegas.
The Evolution Continues
Today, you have the choice of many formats.
In the not-so-distant past, when one spoke of a color, LED-lamped
display, the conversation typically regarded a flat screen of arrayed pixels with one red, blue and green diode. Today, the “LED display” phrase connotes numerous and different technologies – the only common element is the use of addressable pixels to create images. Examine LED displays today, and you’ll find dissimilar LED formats. The traditional, evenly spaced, threediode pixel configuration (also known as discrete pixels) remains most common, but other options are becoming fashionable. Pixel-sharing technology (also known as virtual pixel) distributes the LED firings across an even pattern of individual diodes, each equidistant from their neighbors. The individual diodes then interact with multiple others to create the image. In this technology, an additional diode, either green or
red, is added to the RGB mix. Some manufacturers offer a shareddiode technology that comprises three LEDs configured in a pixel pattern, but shared with neighboring pixels. Daktronics’ (Brookings, SD) Optimized Technology series typifies this system. LED Surface Mount Device (SMD) technology integrates three RGB diodes into a plastic wafer that illuminates the combined colors in a single light point. Originally available for indoor technology, new and brighter SMDs are now configured for various outdoor applications. Why all of the options – and how do you choose the right technology for a customer’s application? Here’s a basic primer that explains the best uses for each. Pixel-sharing technology The pixel-sharing concept, perhaps the most difficult to explain, is con-
troversial because it applies individual diodes in multiple pixel configurations (Fig. 1). In this type of application, the entire screen comprises evenly spaced diodes, but they’re electronically arrayed in a color pattern that allows each to be used (borrowed) for multiple pixel configurations. The result is an image that appears to have a higher resolution than possible with the physical number of diodes. Display-screen engineers developed pixel sharing as a method to heighten resolution perception without adding diodes. I’ve seen many side-by-side demonstrations, and the apparent resolution increase is noticeable. It definitely enhances the image quality without adding to the board cost. However, I think it works best with smaller still images and/or video content. Surface mount device (SMD) technology SMDs, a technology once reserved for indoor applications, was developed as an alternative to discrete pixel systems, which are handicapped by minimum-size, fabrication limits. Therefore, the SMD, which fits into smaller areas, allows manufacturers to produce displays with more diodes per square foot, hence higher resolution. Five years ago, we considered a 10mm-pitch SMD display as high resolution. I now see many 4mm-pitch displays installed in short-distance, pedestrian-type applications, such as indoor casino signage. And, at recent ISA and National Assn. of Broadcasters (NAB) exhibitions, I saw a new, Chinesemanufactured, 1.7mm-pitch display. The U.S. distributor said it was designed for use in TV broadcast situations, where it would be filmed in close proximity to news anchors
Fig. 1: Typical pixel-sharing display face. Each circle represents one virtual pixel. The pixel-sharing phrase comes from the use of every diode in more than one pixel. 28 SIGNS OF THE TIMES / JULY 2012 / www.signweb.com
Table of Contents for the Digital Edition of Signs of the Times - July 2012
Signs of the Times - June 2012
The Moving Message
Vehicle Graphics Contest Extension
The American Sign Museum Opens!
An Electric-Sign Company Snapshot
By Print or by Paint
Lessons for the Boss
The Value of Signs
Signs of the Times - July 2012