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Mine Illumination and Solid-State Lighting. Dr. John J. Sammarco NIOSH Pittsburgh Research Laboratory. Agenda. Why is lighting important? Age and vision History of lighting Lighting safety & accidents High brightness light emitting diodes (HB LEDs) NIOSH lighting research.
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Mine Illumination and Solid-State Lighting Dr. John J. Sammarco NIOSHPittsburgh Research Laboratory
Agenda • Why is lighting important? • Age and vision • History of lighting • Lighting safety & accidents • High brightness light emitting diodes (HB LEDs) • NIOSH lighting research
Why look at mine lighting? Mining…“the most difficult lighting environment in the world” Illumination Engineering Society of North America, 2003.
Why look at mine lighting? • Miners depend heavily on visual cues to spot hazards • Aging workforce • Accidents
Age Effects on Vision • Night vision decreases with age • Smaller pupil • Eye less able to adapt to light • Fewer rod receptors • Cloudy eye lens
Average miner 43 yrs old 40% less light than 20 yrs old Age Effects on Vision Yellowing of Lens(age in years) Degradation of lens decreases effective light level and effective contrast (due to scatter)
Why look at mine lighting? • Improved lighting may help miners avoid accidents: • Slip/trip/falls • Falls of ground • Striking/pinning • An MSHA study of metal/nonmetal mining concluded that current lighting systems are inadequate.
Safety & Lighting The percentage of accidents declines as illuminance is increased in industrial (non-mining) work areas Source (Walton et al., 2005)
A Brief History of Lighting Candle holders with candles
Oil wick lamps improved safetyby containing open flames. Costswere also lower, and minersfound them easier to use thancandles. Oil Lamps Photos: Royal BC Museum, British Columbia, Canada, http://www.royalbcmuseum.bc.ca/
The transition to helmet-mountedlighting began with the introductionof the carbide lamp. Carbide lamps Photo: Royal BC Museum, British Columbia, Canada, http://www.royalbcmuseum.bc.ca/ Quotation: Where the Sun Never Shines, Priscilla Long, Paragon House, New York, 1989.
The introduction of theincandescent lamp eliminatedconcerns about openflames within the mine. The light from a small, steadilyburning incandescent filamentwas much more controllablethan the light from an openflame. Enclosed within adirectional reflector, it becamethe standard, unchanged tothis day. Incandescent Lights Photos: Royal BC Museum, British Columbia, Canada, http://www.royalbcmuseum.bc.ca/, Cape Breton Mine Museum, www.minersmuseum.com
Light Spectrum • White light from LEDs • Shorter wavelenghts • Bluish-white light • Better depth perception • Better color rendering • Better visual performance
Lighting technologies • Lower specular color temperatures indicate a yellowish light; • higher temperatures indicate a whiter light.
Light Emitting Diodes (LEDs) LEDs are semi-conductors; they don't have a filament that will burn out. They are illuminate by the movement of electrons in a semiconductor. Luminaires LED’s
Light Emitting Diodes (LEDs) • Advantages: • Lower power requirements • Long Life (>50,000 hours) • Small size • Sturdy • “White, shorter wavelength” light
Reducing underground mining mishaps by improving mine illumination
Project Scope Underground lighting: • Cap lamp (coal) • Preblast lighting (metal/nonmetal) • Machine lighting (coal)
Cap Lamps Additional Personal lighting LED Cap Lamp2 lb. battery, 5 year LED life 5 lb. battery
Preblast Lighting • inspect roof & back • loading of explosives
Specific aim summary • Does the color (spectral power distribution) from white LEDs: • Improve visual performance? • Reduce glare? • Can advantages of LEDs (small, robust, high efficiency, etc)enable new designs to: • Improve visual performance? • Reduce glare? • Realize new safety applications?
Mean time to detect an objectIncandescent cap lamp was slowest