Rambus moves into LED lighting

Rambus has moved into LED lighting with the introduction of an intellectual property (IP) portfolio called Pentelic.

The technology allows edge-lit light guides to provide both area and directional room lighting, typically in professional settings: offices, schools and retail, said the firm.

"Our IP space is to do with edge lighting a light guide with LEDs and the use of micro-optics embedded into the light guide providing ray angle control so light can be directed out of the light guide," Rambus director of business development John Langevin told Electronics Weekly.

Low losses are claimed.

"Efficiency is 92-95%, measured as the total flux from the light engine to the total flux from the guide," said Langevin.

This is a high figure. Even simple collimators rarely achieve much over 90%.

Under non-disclosure agreement, Langevin added, test reports can be provided to back up his figures.

The guides are made from moulded optical grade polymethylmethacrylate (PMMA), with light coupled in using a reflector and sometimes a lens moulded into the edge of the light guide. According to Langevin, anti-reflection and index matching coatings are not involved.

The shape of the guide is chosen for its aesthetics, then the array of lenses to be moulded into its surface is optimised by computer for each design to send light in the direction required, and to give the guide suitable luminous properties, said Langevin. Aesthetically, a uniformly lit appearance is generally desired.

Although the firm is licensing its technology, design will at least initially be done in partnership with the customer at Rambus own development centre in Brecksville Ohio - a centre that was acquired with the light guide technology when Rambus bought the IP and R&D arm of Global Lighting Technologies in December 2009.

Thermal, light-engine and electronic design services are also available.

The centre has prototype manufacturing facilities, then mass-production is up to the customer.

As Rambus is only interested in licensing for volume manufacture - income will come from per-unit royalties - it claims development cost will not be high for the licensee.

"Our goal is to get our customers into high-volume production. Typically, we don't want to front-end-load, although there are cases where there is NRE," said Langevin.

The firm is offering two other technologies under its Pentelic brand, acquired when it bought IP from Imagine Designs in January.

One is a way of extracting light from light guides using structures similar to collimators bonded to the guide surface - which concentrated light more than the microlens method, but only works at 90° to the guide.

The other has nothing to do with light guides and is a total-internal-reflection analogy to side-fed reflectors. It forms narrow beams from large-die (2x2 or 3x3mm) LEDs.

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