HERCULES

High Efficiency and Rendered Colour Using LED Solid State Lighting

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 Obiettivo del progetto (Objective)

'Lighting accounts for 30% of all electricity usage in offices, homes, transport systems and retail. It is expected to be revolutionised by the widespread introduction of LED solid state technology. However, LED technology has some major problems to overcome on the delivered efficiency of multi-LED lights, cost, and the quality of the light colour produced.

HERCULES will produce solutions for LED lighting for a range of applications. It will build on a successfully demonstrated concept that combines the light from different LED sources to produce near perfect colour rendition at colour temperatures as low as 2500K. HERCULES will provide the normal benefits of LED lighting – high electrical energy to light conversion efficiency (reducing energy consumption), instant start-up and efficient dimmability, but will also allow tuneable colour rendering for applications such as food retailing.

It is essential that light sources produce high quality colour rendition, which has proved critical to the health and productivity of workers. High efficiency LEDs have very poor colour rendering and current approaches use multiple phosphors on each LED to generate a poor typically “blue rich” approximation to natural light. These phosphors can seriously reduce the efficiency of the LED, so more LEDs are required to achieve the light ouput. In a compact light source this has the effect of increasing the temperature of the LEDs, which has a very negative feedback as their efficiency decreases rapidly with temperature. The HERCULES solution will overcome this serious limitation.

The key developments in this project will be: • Characterisation and selection of suitable high efficiency LEDs • Novel electronic driver design • Optical design for several form factors, especially to de-image LEDs • Low cost injection moulding tool making technique for optical finish • Precision injection moulding of optical elements • Novel luminaire design for indoor/outdoor/specialist applications'

Introduzione (Teaser)

With EU support, scientists have delivered a light-emitting diode (LED)-based system that produces full colour rendering and has 95 % efficiency. The new lighting even allows you to programme a circadian rhythm of light fluctuation from your cell phone.

Descrizione progetto (Article)

Solid-state lighting using LEDs has taken a major market share from standard fluorescent lighting in recent years. LEDs offer higher energy efficiency and rapid start-up at a reasonable cost. However, poor colour rendering resulting in a bluish output can be unpleasant, stressful and tiring for the eyes. When used for surgical lights, they can impair the ability to discern skin, tissue and organ details, affecting the quality of surgery.

The EU-funded project 'High efficiency and rendered colour using LED solid state lighting' (http://www.hercules-project.eu/ (HERCULES)) sought major improvements in LED-based illumination with a key target being the medical sector. Scientists focused on increasing the efficiency, brightness and colour of a medical luminaire (complete lighting unit) while ensuring that it can be disinfected. Efficiency depends on LED selection, colour mixing, the electronic driving circuitry and the thermal design.

HERCULES delivered an advanced lighting system that combines light from different LED sources to produce near-perfect colour rendition across the full visible spectrum at extremely high efficiency.

Scientists showcased the technology in two demonstrators: a bed head light and an examination light. The bed light has controllable colour temperature to match the natural circadian rhythms of day and night. It comes with a dedicated programmer, but can also be programmed and controlled from a smartphone. The examination light is equipped with five colour settings ranging from cold to warm white light. The high R9 (saturated red) colour rendition enables greater resolution of tissue differences for surgical procedures, whereas the cold white setting supports general examinations and is particularly good for visualising veins, required for safe and painless drawing of blood.

HERCULES developed a highly efficient, full colour rendering and cost-effective LED lighting system with broad applications wherever good colour rendition is a necessity. The technology will significantly enhance the competitive position of related small and medium-sized enterprises (SMEs) in the EU. Partner SMEs have developed a realistic exploitation plan and are on their way to market. Reduced energy usage associated with lighting will have important impact on operating costs as well as emissions and global climate change.