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    COMPANY PROFILE: OSRAM Opto Semiconductors - LEDs combine impressive economy and luminous intensity

    July 1, 2006
    For a long time the use of LEDs was restricted to indicator lights on electrical equipment, effect lighting and a few experimental light fittings for the home. Now, however, these tiny light sources are being used more and more in general lighting applications.
    Content Dam Leds En Articles 2006 07 Company Profile Osram Opto Semiconductors Leds Combine Impressive Economy And Luminous Intensity Leftcolumn Article Thumbnailimage File
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    New high-intensity LEDs can compete with conventional lamps in terms of their luminous intensity and completely outclass them in terms of economy. In many areas in which fluorescent, halogen and incandescent lamps have traditionally been used, such as architecture lighting, illuminated advertising and signage, security lighting and shop decoration, LEDs have now become a real alternative. The light emitting diode offers impressive economy, aesthetics and technology.

    Indoor use
    Imagine a room that is brightly lit but with no visible light fittings. Easy to do on a bright sunny day, but at night-time that is precisely what LED lighting can do – a real vision of the future. Although up to now a larger number of LEDs have had to be used to achieve the brightness levels of conventional light sources, their small size makes them extremely versatile and provides the impetus for new luminaire designs.

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    OSTAR Lighting LED

    Even large LEDs are significantly smaller than fluorescent lamps or light bulbs. The Ostar from OSRAM Opto Semiconductors, for example, is hexagonal in shape and can be used to create either two-dimensional or three-dimensional arrangements. It produces lots of light (420 lm at 700 mA) in a very small space.

    Powerful effects can also be achieved in furniture lighting. LEDs such as the 0.3 mm-high SmartLED or the slightly larger SideLED from OSRAM can be incorporated unobtrusively in furniture designs to produce small but impressive lighting effects. In such applications the LEDs themselves are no longer seen as light sources.

    Excellent heat dissipation means that the LEDs are extremely safe. Their long life of up to 50,000 hours and therefore their low maintenance requirements enable LEDs to be fully integrated, and there is no need to make sure they can be easily accessed. Glass cabinets can be lit more effectively with LEDs than with fluorescent lamps. OSRAM MultiLED, for example, has three individually controllable colour chips in red, green and blue which can be mixed to produce any colour.

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    Playmobil Funpark LEDs are driving forward a revolution in so many different areas, particularly in luminaire design. Up to now, most people have associated artificial light with relatively large light fittings. With high-intensity LEDs, however, a table light with a light source measuring just a few square centimetres is all that is needed to provide enough light to work or read in comfort. The largest version of the high-output Ostar Lighting LED from OSRAM Opto Semiconductors, for example, offers 420 lm at an operating current of 700 mA, which is more light than a standard 20 W low-voltage halogen lamp can provide. Economy is therefore another important aspect. The values for Ostar are better than those of any energy-saving lamp.

    The right white for any situation
    LEDs can do much more than provide light year after year after year while consuming very little electricity. They can create moods with crisp cool spotlighting or by simulating the cheering effect of natural sunlight – both are possible with modern converter technology.

    The OSRAM Golden Dragon LED, for example, offers three different white tones with colour temperatures of 3250 K, 4200 K and 5600 K corresponding to warm white, neutral white and daylight white.

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    Turning Torso tower With appropriate lighting control, a single table light can adapt to the various needs of users throughout the day and night. If the table light is equipped with LEDs such as Golden Dragons with different white tones, it can be used throughout the day with cold white light, making it ideal for working, and then switched to warm white LEDs in the evening to provide atmospheric background lighting or a pleasant light for reading. Coloured LEDs can also be combined to make the light more red or more blue for example.

    This is a useful option not only for the domestic market but also for shop windows. During the day, the white light ensures that products appear in their natural colours. In the evening, coloured LEDs can create an eye-catching display all of their own. White LEDs such as the Golden Dragon or the Power TopLED from OSRAM can be mixed with coloured LEDs of the same type, which can be switched on and off as required.

    Museums are another ideal application for light with different colour temperatures. Works of art can be highlighted without a spotlight to be seen. Thanks to the optimised heat dissipation of the SMT package there is no thermal stress on the illuminated objects, and sophisticated lighting solutions can be set up so that the lighting mood can be actively changed.

    Use in outdoor lighting
    As soon as the sun goes down, spotlights come on in every major city to bathe important buildings in light. Up to now this has involved high maintenance costs. The long life, low maintenance costs and low power consumption of LEDs make them particularly attractive not only indoors but also for outdoor applications. Compared with neon tubes they can save up to 80 percent of operating costs.

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    Nutcracker at Boston Ballet With LEDs, there are virtually no limits on how “creative” lighting designers can be. The small size of LEDs and the ease with which they can be installed means that they can be used in innovative lighting concepts in areas of building facades where access is difficult. Whatever the application, suitable LEDs are available. OSRAM Opto Semiconductors offers products that cover all levels of brightness and all colours. During the day, there is little or nothing of the LED lighting system to be seen because it is so inconspicuously integrated into the fabric of the building. Thanks to their low weight, LED systems have a negligible effect on building loadings. This means that these innovative lighting systems can be installed in existing buildings with no problems at all. Another benefit of LEDs is that they are so robust. They will operate reliably at temperatures from minus 20 to plus 60 degrees Celsius.

    It is not just on façades that LEDs can be used outdoors, they could revolutionise street lighting. Because LEDs are so small and weigh so little, the fittings do not have to be as bulky, either to accommodate the LEDs or to protect them from the weather. If equipped with a photo-voltaic system, LED path lighting need not be connected to an external power supply. This would also have an impact on operating costs. Again, the long life of LEDs would mean that there would be little or no need for maintenance work.

    New technology for more light
    Despite the many benefits, LEDs have only recently come into the reckoning for general lighting applications. For a long time, LEDs were not bright enough to warrant their use for room or façade lighting. A combination of new technologies has now overcome this weakness.

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    Travelling Light The problem was that the substrate used for growing the semiconductor crystal in the LED remained in the diode and swallowed up much of the light generated. OSRAM Opto Semiconductors developed thin-film technology to counter this.

    The process uses the substrate exclusively for growing the crystal and then it is removed. All that is left is a thin light-generating layer that is so close to the surface that almost all the light escapes at the top. With thin-film chips, numerous LEDs from OSRAM Opto Semiconductors have been given a huge boost in brightness. The Golden Dragon for example achieves a typical luminous efficacy of 40 lm/W in the cold white colour, 36 lm/W in neutral white and 32 lm/W in warm white, in each case with an operating current of 350 mA. This and the Ostar are two high-power LEDs that are now suitable for general lighting.

    New technologies alone are not enough however to achieve maximum performance. The right combination is needed. Several chips connected in series ensure a much higher luminous efficacy. If a lens is then added to the LED, performance is improved still further. The best example is the Ostar Lighting high-power LED. This has six chips connected in series, producing a luminous flux of 300 lm. Combined with a suitable lens, peak output is boosted to 420 lm.

    Producing coloured light the direct way
    As in the case of conventional light sources, LEDs can bring colour to general lighting applications. The benefit of LEDs in this respect is well documented. They produce colour directly without having to filter them out of the visible spectrum. The result is much higher colour saturation than with other light sources, which in turn means more brilliant vibrant colours. Unsaturated colours, in other words white and mixed colours such as magenta and ice blue, can be created by a process known as luminescence conversion.

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    Bostonian shoe store In this process, for example, the light from a blue LED excites a fluorescence phosphor that then emits yellow light. The mix produces white light. For luminescence conversion, OSRAM Opto Semiconductors uses a blue chip in manufacture in combination with red, green and yellow phosphors. Luminescence conversion can be used to create all the colours of the spectrum – including custom colours.

    The light source of the future
    In just a few years, LEDs have managed to gain a firm foothold in the general lighting market. Their enormous flexibility and impressive economy mean they can be used in an extremely wide range of areas and applications. What’s more, they are particularly kind to the environment. They contain no lead or mercury and comply with RoHS and WEEE directives.

    New developments have not only closed the gap in brightness between LEDs and conventional light sources, they have given LEDs properties that surpass those of their rivals. However this is just the start for LEDs. Over the next few years they are expected to get better and better and better.