Lightbulbs lasting six years would be a fine thing, and Sharp believes that this is round the corner, now that that the declining ratio of $ per lumen and rising ratio of lumen per Watt is propelling LED into the general lighting market.
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"Cost is going down and efficiency is going up", says Sharp's Uwe Hock, who says the ratio of $ per lumen has dropped 3X over the last four years from $3 per lumen to $1 per lumen, while the ratio of lumen per Watt has risen to "close to 100 lumen per Watt, it was less than half of that four years ago", says Hock.
For general illumination, the market for LEDs is a mere $600 million today, according to Hock, however he reckons that the general illumination market will be worth $1.8 billion in 2011.
The benefits of LEDs over incandescent light bulbs are that they last for a lot longer, and produce much less heat. For the same amount of light produced, a 40W incandescent light bulb will last for 1,000 hours, whereas a 4W LED will last 50,000 hours, said Sharp. "Incandescent light bulbs require eight times the energy for the same amount of light", said Hock.
In terms of heat, incandescent light bulbs operate at 200 deg C whereas LEDs operate at only 50 to 60 deg C. According to Hock, incandescent light bulbs are only 5 per cent efficient, with 95 per cent of the energy used going into the production of heat rather than light.
Sharp is currently sampling a 540 lumen bulb at 6.7W and a 280 lumen bulb at 3.6W. Both come in an 18mm square module.
Currently it is mostly businesses which are switching to LED technology for power-saving reasons, but the declining cost will bring it into the home, said Hock.
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