Slashdot Mirror
LEDs Lighting Up the African Darkness
Peace Corps Online writes "In a non-electrified society, life is defined by the sun and little is accomplished once it sets around 6 pm. Only 19 percent of rural areas in Ghana have electricity. The rest use foul-smelling kerosene lamps to light their huts, which pollute, provide little light and are major fire hazards. But now Philips has partnered with KITE, a not-for-profit Ghanaian organization, to bring artificial light to villages that have no electricity. The new Philips products include a portable lantern which provides bright white light where it is needed, the Dynamo Multi LED self-powered (wind-up) flashlight that provides 17 minutes of light from two minutes hand winding, and the 'My Reading Light,' which is a solar-powered reading light with built-in rechargeable battery. 'People can now do things in the evening,' says Harriette Amissah-Arthur, KITE's director. 'If you could only see the joy these products bring the villagers. You look at their faces; you have to see it to believe it.'"
This isn't the first product Philips have produced for developing countries.
See wood-burning stove: http://www.research.philips.com/newscenter/archive/2006/060227-woodstove.html
I wish they would make them available to buy in the developed world though. I'd love some of this gear for outdoor pursuits.
It is as if the frequencies in its spectrum just miss the the ones my photoreceptors are tuned into...
:-)
Well, that's because the LEDs actually are missing (large) components of the spectrum!
Even when your eyes are tricked into believing the light is white (by equally stimuling the three kinds of color-sensitive cells), the light reflected off of objects isn't "correct".
Imagine two green objects. One has true green pigment, the other has a mixture of yellow and blue pigment. Both look the same under incandescent light, because the light from a glowing filament emits a full spectrum .
When an LED doesn't emit a full spectrum the two objects don't like alike. The "true" green objects only reflects "true" green, not yellow + blue. The "yellow + blue" object doesn't reflect "true" green.
That's why it's hard to see in such light.
Your eyes (or brain) can adapt very well to changes in color temperature (yellowy incandescent light, or the blueish halogen light), but it can't cope with holes in the spectrum.
This goes for compact fluorescent lights as well, even as they keep getting better. The cheap ones are really crappy in this respect.
For fluorescent tubes there is a rating for color temperate and color rendition. It isn't used (as far as I know) for compact fluorescents as they score way to low on this scale. That would make the public relations department of the manufacturers unhappy.