AMA Report Stirs LED Lighting Controversy
In recent years, municipalities around the world have begun swapping out existing street lamps for more energy-efficient varieties. The new primarily LED-based lighting looks different – it tends to be whiter and “glarier” than its mellower sodium-based predecessor. Coincidentally, this initiative is taking place at the same time that on a research level much is being discovered about the effects of light on human – and animal – health. Exposure to blue light, in particular at night, has been linked to a number of maladies, from poor sleep to greater chances of developing certain cancers. Since light is light, whether it comes from a street lamp or a glowing screen, displays are also a crucial part of this light/health balance.
A lighting “conversation” among various organizations began last summer, when the American Medical Association issued a report titled “Human and Environmental Effects of Light-Emitting-Diode (LED) Community Lighting,” in which the authors recommended the conversion of conventional street lighting to LED-based lighting.1 Additional recommendations included “the use of 3000K [as measured in correlated color temperature or CCT] or lower lighting for outdoor installations such as roadways,” proper shielding, and the reduction of blue-light emissions to the greatest extent possible.
Numerous publications picked up the report, streamlining and adjusting the main message as primarily anti-LED. A representative piece from CNN carried the headline, “Doctors issue warning about LED street lights.”2 In turn, agencies such as the Office of Energy Efficiency and Renewable Energy (OEERC) and the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute issued statements of their own.
From the OEERC: “Some media coverage of concerns about blue light, light at night, and dark-sky issues can give the impression that LEDs are the enemy when in fact they are a critical part of the solution, which the AMA acknowledges. It is important to remember that these issues have been around for decades, long before the emergence of LED technology.”3
The LRC issued an 8-page response to the AMA report,4 as well as a press release5 with the following bullet points:
• Predictions of health consequences from light exposure depend upon an accurate characterization of the physical stimulus as well as the biological response to that stimulus. Without fully defining both the stimulus and the response, nothing meaningful can be stated about the health effects of any light source.
• Notwithstanding certain sub-populations that deserve special attention, blue-light hazard from In-Ga-N LEDs is probably not a concern to the majority
of the population in most lighting applications due to human’s natural photophobic response.
• Both disability glare and discomfort glare are mostly determined by the amount and distribution of light entering the eye, not its spectral content.
• In-Ga-N LED sources dominated by short wavelengths have greater potential for suppressing the hormone melatonin at night than sodium-based sources commonly used outdoors. However, the amount and the duration of exposure need to be specified before it can be stated that In-Ga-N LED sources affect melatonin suppression at night.
• Until more is known about the effects of long-wavelength light exposure (amount, spectrum, duration) on circadian disruption, it is inappropriate to single out short-wavelength radiation from In-Ga-N LED sources as a causative factor in modern maladies.
• Correlated color temperature (CCT) is not appropriate for characterizing the potential impacts of a light source on human health because the CCT metric is independent of nearly all of the important factors associated with light exposure; namely, its amount, duration, and timing.
For additional feedback and analysis, Information Display checked in with Jennifer A. Veitch, Principal Research Officer at the National Research Council of Canada and Director of Division 3 (Interior Environment and Lighting Design) of the International Commission on Illumination (CIE). Veitch authored the article “Light for Life: Emerging Opportunities and Challenges for Using Light to Influence Well-Being” for the Nov./Dec. 2015 issue of ID.
Veitch said she agrees with the LRC’s response: “LEDs are not intrinsically more harmful to humans than other types of lighting, though they do have the potential of being harmful,” she says. She also noted that CCT is a poor indicator of a spectrum’s exact wavelength. “It’s a useful metric for indicating the general color appearance,” she added, “but simply to say that all lighting more than 4000K is harmful is wrong.”
ID asked Veitch if LEDs might be particularly suspect because people do not find them aesthetically pleasing. She replied: “As with most lighting installations, it is not the fault of the light source. It is in the way that you apply it.” And, she noted, that people tend not to be comfortable with new types of light sources. (Interestingly, the “warm” yellow glow of the sodium lights most of us consider normal dates back only as far as the 1970s and 1980s, when the older, and much whiter, mercury vapor lamps introduced in the late 1940s began to be phased out. The sodium lights were unpopular at first too.)6
One reason why LED lighting strikes so many people as harsh is that it is not being used to its best advantage. For financial and logistical reasons, towns and cities want to keep the existing physical infrastructure for lighting – the same number of poles spaced the same way, at the same height, etc. – and this arrangement often does not employ the new lighting technology to its best effect. “There are a number of products out there that are quite glary, but that has nothing to do with the spectrum,” said Veitch. “Any misapplied light source will give a bad outcome.” Veitch also made the point that LEDs are more controllable that previous light sources – they can be dimmed.
The important thing to keep in mind, she said, and this affects display makers and users as much as city planners, is that what counts is the lighting we are exposed to before we go to bed, not its source. “Your body does not care what the source is,” said Veitch, adding, “Of course, with street lighting, it is not only people who are affected but animals.” With the research – and the controversy – continuing, it is a pretty sure bet that in years to come, we will find ourselves looking more carefully at the light we expose ourselves to, especially that from laptops, televisions, and smartphones – and particularly before we go to bed.
Applied Materials Tailors e-Beam Review Technology for Displays
Applied Materials, Inc., recently introduced what it says is the first high-resolution inline e-beam review (EBR) system for the display industry. The new system is designed to increase the speed at which manufacturers of OLED and UHD LCD screens can achieve optimum yields.
Applied Materials, based in Silicon Valley, supplies hardware, software, and services to semiconductor manufacturers. The company is an industry leader in EBR, with more than 70% market share in 2015. (EBR and optical scanning are the two primary inspection
methods for wafers.) In order to reach display-industry customers, Applied Materials has combined the scanning-electron-microscope capabilities used in its semiconductor device review with a large-scale display vacuum platform. The result is an inline EBR technology designed to quickly and effectively discover and address the root causes of crucial defects in mobile and TV displays.
Applied Materials says it has received orders for its EBR system (Fig. 1) from six of the top 10 largest display manufacturers in the world (Tianma is one of these).
Dr. Jun Ma, Vice-President at Tianma Microelectronics Co., Ltd., said, “Applieds’ EBR system will enable us to reduce the start-up time at our Wuhan fab and accelerate our ability to bring more advanced display technologies to market.”
Fig. 1: Applied Materials has combined its semiconductor scanning-electron-microscope technology with a large-scale display vacuum platform to create a system to help display makers find defects quickly and accurately.
Merck Debuts Award for Young Display Researchers
Merck KGaA, Darmstadt, Germany, recently announced the recipients of its new Displaying Futures Award, which provides young display entrepreneurs and researchers with
individual mentoring, access to a global network, and funding. The inaugural winning teams are from the University of Central Florida, Kent State University, and the Eindhoven University of Technology.
According to Merck, the award was developed to help the company identify new applications for its materials and to support further development of these materials. In a pre-selection stage, more than 30 submissions were narrowed to 10 teams, who presented innovations related to liquid crystals. A jury from Merck, consisting of various specialists from different areas of the company, chose three winning teams. The winners were evaluated based on the criteria of novelty, business potential, and impacts on society and the environment. The awards were presented at the company’s headquarters in Darmstadt in September, 2016.
The winning project from the University of Central Florida focuses on e-skin displays. These highly efficient, thin, flexible displays utilize ambient light and can also be used in very bright daylight. Kent State University’s project involves liquid-crystal sensors to detect the presence of hazardous chemical gases and display the results visually on a surface. And the team from Eindhoven has developed “fresh strips,” a technology that changes color to indicate whether foods or medical supplies have been exposed to excessively high temperatures and can still be consumed or used.
The winners of the Displaying Futures Awards will receive mentoring from experts within and outside of Merck KGaA, Darmstadt, Germany, access to the company’s global network, and $50,000 each from Merck. •
– Jenny Donelan