Variable Message Sign (VMS)

Light Emitting Diode (LED) have a permanent place for the transfer of VMS (VMS) applications. After opening a little happier in the 1980s, the LED has become the preferred source of VMS for the new millennium. Virtually maintenance-free LEDs offer many advantages over other available options RCC today.  LEDs used first commercially developed in the 1960s. LEDs appeared on variable message signs in the 1970s. These variable message signs began mostly used for commercial advertisements. Their popularity has increased rapidly due to reliability, maintenance without service on high resolution and excellent readability.

 LED variable message signs are initially restricted to indoor applications, the limited brightness. Technology LED, although it is almost 15 years at the time yet reached a level where it is visible in high ambient light. LEDs began to move outside in early to mid 1980. Technological progress improves the brightness of the LED point at which messages were read outdoors in most conditions.

Red LEDs

The red color was first light, which could be used effectively to meet outdoors. The development GAALAS (aluminum gallium arsenide) technology LED, LED brightness brought a new level. First foreign commercial applications, particularly time and temperature displays in front of a bank or advertising in Marquis. It was not long, however, found their way to market red LED VMS.  Initial attempts to variable message signs for traffic applications with red LEDs met with mixed results. First, there is an important part of the population is colorblind. Unfortunately, the red because the wavelength of the upper end of the spectrum of visible light is usually lost first color to color blindness. In addition, part of the population has difficulty focusing on a red background, a phenomenon which the chromatic aberration. This results in an obligation to characters appear in a vague, uncertain. To solve these problems, LED VMS leading some mixed red and green LED in the cluster. These colors, when mixed in correct proportions, income Yellow LED / Amber LED color we see today, in characters. This effort, and has seen its share of problems. Green LED not yet caught the technology with red LED lights illuminate the higher currents and therefore had to run in a performance of appropriate brightness. The red LED, and sometimes have higher power than that recommended for optimal brightness. This saturates the LED brightness caused premature deterioration and failure. The results of this failure are common symptoms of almost all shades between red and green.

 Although GAALAS was a significant achievement in technology, LED, there were other significant disadvantages GAALAS material. First, it is only a red 660 nm wavelength. Second, the degradation of GAALAS light intensity is higher than the level of technology. This removed a misconception long tube LED, the light output by 50% after 100,000 hours of operation. In fact, some GAALAS LEDs can be reduced by 50% after only 50,000 to 70,000 hours. This is especially true at high temperatures and / or very wet environment.

Technology LED LED VMS common today, large and fixed installations and portable work zone signs, use InGaAlP (indium phosphide, gallium and aluminum), technology LED. Solid state diode laser technology InGaAlP LEDs were introduced in 1990 and since then it has become possible to have almost all the deficiencies have been known since the LED traffic VMS applications.

Traffic VMS Systems

LEDs have a technology of choice for VMS Since today our roads more congested, we can expect a proliferation of VMS systems as an alternative to the prohibitive cost and environmental impact of new roads to the settlements. It became imperative to make effective use of road infrastructure, we are able. The Traffic VMS systems currently used to guide motorists with a maze of road maintenance and repair of detours, peak-hour congestion, weather problems and delays caused by traffic problems. For this challenge, the VMS units must be clearly should be in all weather conditions, cheap and reliable as possible.  Today InGaAlP LEDs are perfectly suited for this task. With the establishment of the RCC in all possible weather conditions, the constant vibration and the effects of dirt, dust and salt led technology is the obvious choice. Design reliable, solid state LED, is very resistant to adverse weather conditions and mechanical vibrations and shocks. LEDs documented best facilities in the warm and cold climates as acceptance for use in demanding automotive applications for interior and exterior lighting. 

LEDs, and even in the same production of incandescent and halogen. However, they are not covered by the maintenance of conventional lighting technologies and the shutter speed. LEDs have MTBF (mean time between failures) of hours over a million. This level of reliability of services, eliminating the need to replace light bulbs or repair parts of a mistake. This will ensure that the desired message is still clearly readable, and reaches the driver. A burnt-out lamp or shutter speed that can cause the driver's attention distracted from driving to the interpretation of the message. The readability of the LED VMS is further improved by using different levels of brightness. As solid state devices are easily controlled compared with LED lighting. It is not unusual for an LED VMS for more than a hundred levels of brightness are controlled automatically to provide optimal viewing in virtually all lighting conditions and weather.

LEDs, Cost Effective Solution

Besides all the advantages of LED technology providing a cost effective solution as well. The cost savings is in many ways, first is the most energy-efficient LED technology achieved. The LED VMS Zone work today, nearly all solar eliminating the need for diesel generators and support and maintenance costs. Large, solid LED VMS also realize significant savings in energy costs. Moreover, the ongoing maintenance units for both large and stationary and portable LED VMS cleaning and maintenance of electronics, which is required for all types of units reduced. Finally, an LED-VMS unit can be expected this year, many low cost investment services. InGaAlP LED life (hours, until the LED goes half of original brightness), expectations are more than 100,000 hours of use.  InGaAlP LEDs provide a reliable and cost effective for the increasing demands of highly mobile our society has placed variable message signs. Not expected to overcome the problem of alternative technologies to provide reliable LED VMS, long term, low consumption and excellent readability in all applications VMS signs mobile workplace in large, fixed installations, the costs generally.