Bullough Receives Fire Protection Research Foundation Award
John Bullough ’91, senior research scientist at Rensselaer’s Lighting Research Center, has received the Ronald K. Mengel award from the Fire Protection Research Foundation, National Fire Protection Association, for his presentation at the Research Foundation’s March 2012 symposium, titled “Characteristics of Light-Emitting Diode Sources: Relevance for Visual Signal Detection.”
Bullough also presented a paper at the Research Foundation’s February 2013 Suppression, Detection and Signaling Research and Applications (SupDet) symposium, titled “Influence of Visual Signal Flash Intensity and Duration of Perception” on the topic of LEDs for emergency signaling lighting, specifically, the intensity of the light and the duration of the light flashes, and how those impact their effectiveness.
As LED lighting technologies continue to improve in efficiency and light output, they are being considered for an increasing number of lighting applications, including emergency lighting. Bullough’s SupDet 2012 presentation gave the attendees an overview of the properties of LED sources from a human visibility perspective. Fast on/off times, wide range of available colors, and ability to be dimmed easily, in conjunction with their durability and long operating life make LED sources attractive for visual alarms and warning systems.
At the latest SupDet symposium, Bullough described how the duration and the intensity of flashes of light impact perceptions of brightness and urgency of the light. Most visual fire alarms use xenon strobe lights that produce very brief (much less than a millisecond) but high intensity flashes. Bullough showed that for a visual alarm signal within a person’s field of view, the intensity of the flash could be reduced if the duration were increased proportionally up to about 25 milliseconds, without reducing the effectiveness of the signal light. This information could be used by visual alarm designers to optimize the flash characteristics of LED systems to maximize reliability and maintain visibility.