Visual performance for incandescent and solid-state cap lamps in an underground mining environment.
IAS '07: Conference Record of the 2007 IEEE Industry Applications Conference: Forty-second IAS Annual Meeting, September 23-27, 2007, New Orleans, Louisiana. Piscataway, NJ: Institute of Electrical and Electronics Engineers, 2007 Sep; 4:2090-2095
Miners depend most heavily on visual cues to recognize underground mining hazards; consequently, illumination plays a critical role in miners' safety. Some hazards are located in the miners' peripheral field-of-view (10 degrees to about 60 degrees off-axis) or on-axis (0 degrees). The objective of this research was to determine if there were visual performance improvements when using solid-state cap lamps with light emitting diodes (LEDs) as compared to incandescent light bulbs commonly used in miner cap lamps. Recent research has indicated that an increased short-wavelength content of the spectral power distribution of LEDs relative to incandescent lamps improves peripheral visual performance for low-light (mesopic) conditions. The visual performances of nine subjects were quantified by measuring the subjects' speed and accuracy in detecting floor objects located on axis and at +/-20 degrees off axis. The objects were located near field (1.83 meters) and far field (3.66 meters). Upon presentation of the objects, subjects would count and point to each object using a red-laser pointer. The object detection response time and number of missed objects were recorded. The results of the visual performance comparison for an LED, a prototype LED, and an incandescent cap lamp are presented. There were no missed objects when subjects used the LED-based cap lamps but, there were three missed object occurrences when subjects used the incandescent cap lamp. The mean detection time when using the incandescent cap lamp was 55.3% greater than the prototype LED cap lamp and 43.5% greater than the LED cap lamp. It can be inferred from this data that the spectral distribution of LED-based cap lamps could enable significant visual performance improvements as compared to incandescent cap lamps.
Mining-industry; Mining-equipment; Light-source; Lighting-systems; Underground-mining; Visual-fields
National Institute for Occupational Safety and Health, 626 Cochrans Mill Road, PO Box 18070, Pittsburgh, PA 15236
IAS '07: Conference Record of the 2007 IEEE Industry Applications Conference: Forty-second IAS Annual Meeting, September 23-27, 2007, New Orleans, Louisiana