Sharp believes that the declining ratio of $ per lumen and rising ratio of lumen per Watt is propelling LEDs into the general lighting market.

"Cost is going down and efficiency is going up", said Sharp's Uwe Hock, speaking at the Sharp Innovation Forum in Seeon, near Munich today.

The ratio of $ per lumen has dropped 3X over the last four years from $3 per lumen to $1 per lumen, said Hock, 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", said Hock.

For general illumination, the market for LEDs is a mere $600m today, according to Hock, however he reckons that the general illumination market will be worth $1.8bn 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.

Colour coding LED info
	Driving into the blue
	Organic - grow your own
	Green chandeliers
	Into the black?
	Display Trilogy
	Headlight glare
	Phosphorous
	Sensing light
	Grey area
An alternative look at the hues and shades of LED technology

"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° 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.

See also: Mannerisms, the blog of David Manners. Updated twice daily, it's the distinctive, entertaining, authoritative and never dull commentary on the semiconductor industry, from someone who knows. Sign up for the Mannerisms eNewsletter.

See also: Electronics Weekly's roundup of content related to LEDs, with a special focus on both white LEDs and coloured LEDs:

LED technology - White LEDs

LED technology - Coloured LEDs

LED technology - LEDs general