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Invention and innovation: An introduction
Invention and innovation: An introduction

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5.14 Compact fluorescents and new developments

In the case of the electric light there were a series of incremental product innovations (metal filaments, gas filled bulbs, frosted bulbs) as well as process innovations (some of which were mentioned above), which steadily improved performance and reduced price until, by the 1930s, the incandescent light was mature and diffused in many nations.

Then in the mid-1930s a new invention appeared that was to challenge the incandescent lamp – the fluorescent lamp. This was the culmination of around 70 years’ research into fluorescence (the conversion of one kind of light into another). In the modern fluorescent light a heated electrode emits electrons into a tube of mercury vapour causing the vapour to emit ultraviolet light, which is invisible to the human eye. This causes the phosphor coating on the inside of the tube to emit visible white light. Another cycle of innovation was under way when the new lamp was first introduced commercially in 1938.

Gradually the fluorescent light began to encroach on the market captured by the incandescent lamp, first in the workplace and then increasingly in the home, especially after the introduction of compact fluorescent lamps (CFLs) onto the domestic market in the 1980s (Figure 18). Compact fluorescents last 10 times as long as incandescents and use 20 per cent of the electricity. By 2004, with the unit cost falling, CFLs had broken through the 10 per cent barrier achieving the status of having a substantial market share (10–20 per cent) rather than being a niche market (over 1 per cent). Some projections expect them to achieve a 15 per cent share by 2010. This would still not be sufficient for CFLs to achieve the ultimate status of becoming the industry norm or the dominant brand.

Figure 18
Figure 18 Domestic compact fluorescent lamp, 2005

Box 1 Race for the future of lighting

The problem with filament bulbs like those made by Edison and his successors is that they generate more heat than light – only about 10 per cent of the electricity becomes light – and turning them on and off shortens their life. The next generation of electric light is under development at the moment, based on more recent scientific discoveries and more advanced technological applications. But will it be one technology that wins or will several find their own niches in the lighting market? Along with fluorescent lighting there are currently (2005) at least two other competing technologies.

Electrodeless induction lamps

In the early 1990s an invention was revealed that might be the subject of the next cycle of lighting innovation – electrodeless induction lamps. The device, from a small Californian firm, Intersource Technologies, used a magnetic coil to generate radio waves that excited gases in the lamp, causing the phosphorous-coated interior surface of the glass cover to glow. The company estimated that the operational life of the lamp would be 15 000 to 20 000 operating hours, compared with 750 to 1000 hours for a conventional incandescent lamp. Without a filament or electrode, lamp failure is most likely to be due to the gradual degradation of the gas. Repair would then require the replacement of the glass cover only, rather than the expensive base and electronic components, making the system even cheaper to run.

Further electrodeless lamps were subsequently developed by Philips (QL system, Figure 19), General Electric (Genura) and Fusion Lighting (Solar 1000 sulfur lamp).

Figure 19
Figure 19 Philips QL 85-watt electrodeless induction lamp system (Source: Philips Lighting BV)

Although all of these lamps have proved significantly longer lasting than incandescent and compact fluorescent lamps (for example Philips claims 100 000 hours for the QL), there are several factors that explain why we aren't all using them in our homes at the moment. They are all being tested in different environments and technical improvements made in response to the users’ feedback – in other words the technology is still being developed and hasn't reached a stable enough state for mass manufacture. Current small-scale manufacture also means that the unit cost of existing versions of these lamps is high. In fact Philips’ QL and Fusion's lamp are complete systems rather than replacement bulbs and are expensive on first installation. High purchase prices mean the product isn't taken up by consumers on a large enough scale to ensure its commercial success and to enable manufacturers to reduce prices.

So this technology is stuck in the vicious circle common to many innovations. Some of the companies developing these new lamps are hoping for assistance from government legislation on energy efficiency. Pierre Villere, chairman of Intersource, hopes the US government's Energy Policy Act will provide the incentive needed to interest buyers. Villere thinks, ‘We will see … the same thing happen in high-efficiency lighting that we saw in terms of safety and emission control in the automobile industry’ (quoted in Rensselaer Polytechnic Institute, 1998).

White LEDs

Light-emitting diodes (LEDs) are devices that generate light when electrons pass between two kinds of semiconducting material. Normally the diodes emit a single colour depending on the amount of energy an electron is losing during its transition. You will be familiar with LEDs used in the displays of digital clocks, watches, and electrical appliances. They're also used in remote controls (emitting infrared light) and increasingly in car brake lights, traffic lights and giant TV screens. They convert about 90 per cent of their energy input into light and are very hard-wearing.

The challenge has been to find a way of getting LEDs to make white light for general-purpose use. One approach, first adopted by the Nichia Corporation of Japan in 1996, has been to coat the inside of the light bulb with a phosphorescent coating that gives off white light when hit by the LED's particular wavelength. But the phosphor wears over time – present (2005) estimates are for a 100 000-hour life. Another solution is to try to mix the appropriate primary colours but it's more difficult to make blue light than red and getting the balance right is difficult. However solutions have been found and the devices are being improved. White LEDs are being used in some specialised products such as torches and cave lamps.

As with the electrodeless lamps above, the technical performance of white LEDs is steadily improving and their cost is coming down as the price of semiconductor devices has fallen. However they are still much more expensive than incandescent and fluorescent lights, although arguably cheaper over the lifetime of a typical bulb. In 2003 the UK gadgets company EFX launched a range of white LED downlighters to replace halogen lighting for domestic and commercial use. EFX is using the slogan ‘Global lighting to halt global warming’.

By the time you read this the situation will have moved on and its outcome may be clearer. Or maybe a completely different technical solution will have emerged – that's the nature of the innovation process.