Built in Britain: You will be hearing more of LED lighting firm PhotonStar

11dec13PhotonStarRoomWith factories in South Wales and Hampshire, PhotonStar designs, makes and tests professional and commercial LED light fittings in the UK, and is about to enter the consumer world with a wirelessly colour-tuneable LED light bulb, branded Halcyon.

“PhotonStar has a commitment to UK manufacture at a time when most LED products are manufactured in Asia,” said the firm. “Our products are modular and designed to be assembled with minimal labour.”

The light bulbs came out of an effort to see what was possible once a microprocessor is embedded in a light source, and early on it became obvious that such sources would have to be wirelessly controlled, company marketing director Fenella Frost told Electronics Weekly.

This is not the only wireless development within PhotonStar. For CES 2013 it worked with transceiver chip firm CSR to demonstrate a Bluetooth lighting system where smartphones and tablets were used as controllers.

Light mixing in the forthcoming bulbs is based on a professional colour-tuneable technology the firm calls ChromaWhite – which uses multiple different coloured and white LEDs to deliver flicker-free whites from 2,700 to 6,500K, with colour rendering that includes the frequently-ignored ‘R9′ reds. To maintain colour rendering index and intensity over the life of the product, feedback is used.

PhotonStar ChromaWhite

ChromaWhite capability

“ChromaWhite monitors itself in many ways: temperature, delivered light intensity and delivered colour. It gets used in things like filming, in TV, and in museums, and they are all quite happy to pay what it costs,” said Frost. Users can also be found in art galleries, shops, and medical situations.

Specifically, the technology behind Halcyon is ‘ChromaWhite II’, a variant of the original which uses a different mix of source colours and was developed with help from a Department of Energy and Climate Change grant, said Frost.

The LED mix inside the bulbs includes conventional blue-die-plus-amber-phosphor devices for maximum efficiency at high output levels, and LEDs of other colours.

Frost stresses that PhotonStar is not simply changing the intensity of red LEDs amongst ‘cool white’ LEDs to vary apparent colour temperature, or panning from cool white LEDs to warm white LEDs.

With ChromaWhite II “you can completely remove blue for night time use,” she said.

Why remove the blue?

Blue spectral content could easily become important in the selling of LED home lighting because blue light triggers recently-discovered photo-sensitive ganglion cells in the human eye. Although they form no images, they strongly affect levels of the sleep hormone melatonin. Seeing a spectrum including blue late in the evening can upset the body’s circadian rhythm (scroll down to ‘sleep’), causing a night of disrupted sleep.

11dec13PhotonStarTrack 310

Professional track lighting from PhotonStar

So ‘circadian’ may become a useful marketing term for light sources whose light can be made warmer (manually or automatically) as the evening progresses to ease people into sleep.

Due to the way the eye works, many combinations of colours can produce any particular colour temperature of ‘white’. An incandescent light bulb and a warm white LED can both produce 2,700K ‘white’ that looks the same to a human, but the LED spectrum has considerably more blue. And a nocturnal trip to the loo under light with blue in the spectrum can result trouble getting back to sleep.

Frost concern that circadian will get polluted as a word, and consumers put off, if manufacturers try to associate it with products that always emit a lot of blue, whatever their perceived colour temperature.

As an aside, the eye’s rods and cones are also active in regulating melatonin, so light at almost any wavelength can disrupt sleep if it is bright enough. Candles produces very warm (1,850K) white with a spectrum that has only a tiny fraction of blue, which could be one reason they are popular with those for whom evening relaxation is important. Dim deep red light is the least likely to alter sleep patterns.

Back with Halcyon bulbs, temperature feedback is retained but for cost reasons colour and intensity feedback is not included – although they may return in a mooted Halcyon Professional range.

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Halcyon

The system consists of individual colour-tuneable LED light bulbs, each with an ARM Cortex-M0 and a 2.4GHz 6LoPan (802.15.4) link; plus an ARM Cortex-A8-based wireless bridging box that connects the bulbs to the home’s Wi-Fi router by an Ethernet cable, and a web-based app.

Its lightbulbs form a self-healing tree network from the bridging box, said Frost, not mesh network.

Via Ethernet and the home wireless router, the box acts as a server and establishes communication to “allow any smart thing to control the bulbs”, she said. “It is browser-based so will work with anything: Windows, Android, iOS, Blackberry, KindleFire, …anything.” The app is still under development: “We have the raw bones; it is all about making it slick, lovely and beautiful.”

Communication is bi-directional and multi-user, so a number of people and remote sensors and automated devices can control the system’s state, and all can find out which lights are at what colour temperature and intensity. There is also a hierarchy so, for example, parents can over-ride their children. Security, secure authentication and device joining is covered by 128bit AES encryption in a way which is the subject of a patent.

No access to the Internet is needed for the system to work but, said Frost, set-up will be made considerably more straightforward by an on-line tool.

The roll-out of Halcyon products will include the demandingly-small GU10 bulb, from which Frost predicts 350lm will be possible.

Professional Halcyon products will deliver more light from a given size: “much higher outputs because we are in control of thermal management,” said Frost.

Consumer products will be “initially made in the UK”, said Frost.

Where did PhotonStar come from?

The company was established in 2007 by Dr Majd Zoorob (now CTO) and Dr James Mckenzie (now CEO), both who had a history in LED and chip design.

“When we started, it was originally going to be an LED chip making company, we thought we would manufacture die,” said Frost.

That is not what happened.

“We had some very unique IP, which we licence to LED die manufacturers, but we decided to go into good quality LED lighting. We have quite a lot of IP at system level, particularly involving colour-tuning and colour mixing,” said Frost. “We were recognised as a trusted adviser, with our first products at the ARC show in London, and we have won awards continually since then.”

As part of its development, PhotonStar made a reverse take-over of Enfis which was re-named PhotonStar Group, whose HQ, operations, and sales activities are in Romsey, Hampshire.

Within the group, there are three different businesses:

PhotonStar LED in Tredegar South Wales makes lighting. “Very much professional lighting,” said Frost.

PhotonStarCamtronicsVale

Camtronics Vale

Camtronics Vale is an electronic assembly sub-contractor with surface-mount facilities, also at Tredegar. The firm is not dedicated to lighting, and manufactures a variety of products, said Frost.

PhotonStar Technology manufactures LED light engines in Romsey.

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