History of the light bulb: early days to LEDs
Image credit: A photo agency
With its evolution in the 19th century and its terminal decline in the 21st, the incandescent light bulb dominated both domestic and public lighting for the entire 20th century. It was a technology that changed the way we lived, worked and were entertained.
Part one: early developments
Without the technological and business flair of one man - Thomas Edison - the world would look a lot different today. Back in the 19th century, the journey into light was a shadowy sequence of events.
Such was the importance of the light bulb - or lamp, as it is known to engineers - that the expression has entered into the language as a synonym for invention. Yet its road to supremacy was an untidy street fight dominated by one man - Thomas Alva Edison - who, for all his visionary prowess and business acumen, could not have predicted that a century later, his development of an idea that lit up the world would be rendered virtually obsolete by the emergence of light-emitting diode technology.
In one of the neatest twists of technological fate, the so-called ‘invention’ of the light bulb never had a ‘light bulb moment’. As with so many critical innovations that had far-reaching effects in the commercial and cultural development of humankind, the light bulb - or more specifically here, the ‘incandescent’ light bulb - was the product of a series of independent and incremental breakthroughs by engineers and scientists separated by both time and geography. Although it is the great American inventor and entrepreneur Edison that is conventionally given the laurels for bringing the bulb into the world, Smithsonian Institution curator emeritus Bernard S Finn says we’ve been refining one of our most important discoveries ever since early humans learned that controlled fire could produce light as well as heat.
Edison’s role in bringing light to the modern world was as a developer of other engineers’ ideas that went before him in the 19th century. “It was Thomas Edison who came up with a commercially viable solution,” says Finn. In 1879, on New Year’s Eve, Edison lit up his laboratory at Menlo Park - a display visible for more than 20 miles - and the era of electric lighting was quite literally switched on. Always ready with a sound bite, Edison predicted that electric light would become “so cheap that only the rich will burn candles”.
The real value of Edison’s achievement was that it marked the end of a tentative phase in creating light from electricity by establishing the incandescent lamp as the front-runner technology. In Edison’s Electric Light: The Art of Invention, historians Robert Friedel and Paul Israel cite 22 inventors of incandescents ahead of Edison and yet still place him firmly at the head of the family. This is due to the combination of three critical factors Edison got right simultaneously: the incandescent material, high vacuum levels and high resistance.
It was the last of these three that Edison really understood better than his predecessors. With high resistance, heat (and therefore light) would build up in the element instead of the feed wires coming from remote electric generators. After testing hundreds of materials, says Finn, “he settled on a thin strip - or filament - of carbon”. Because the carbon filament would burn if exposed to air, the glass enclosure, or ‘bulb’ needed to be evacuated by a vacuum pump. Early versions of the incandescent (the word comes from the Latin ‘incandescens’, meaning ‘glowing’) bulb have a ‘tip’ showing where the pump was originally connected. By 1881, there was a standard connector at the electrical end, where the bulb could now be screwed into a socket and could be switched on and off.
It was by standing on the shoulders of those who went before him that Edison could see so far into the electric light future. He relentlessly refined innovations of other scientists such as Humphry Davy, James Bowman Lindsay, Moses G Farmer, William E Sawyer, Joseph Swan and Heinrich Göbel, whose ideas were commercially impractical. Realising that platinum was too expensive a commodity to be used in electric lighting, he pursued the avenue of a carbon-coated bamboo filament (anecdotally, he had the idea of using bamboo from observing his fishing rod while on a field trip to watch an eclipse).
He also wheeled and dealed, scooping up patents of other engineers, while forming strategic alliances, especially with his British competitor, Joseph Swan (who, in many ways, was a player of equal importance, whose house was the first to be lit by a light bulb). Edison secured substantial financial backing from both the Vanderbilt family - the richest in America, having made their money in shipping and the railway - as well as the corporate financier J.P. Morgan. Yet it was mostly by sheer visionary ingenuity that the man with more than a thousand patents to his name became the driving force behind lighting up the 20th century.
Part two: market dominance
For much of the 20th century it seemed the incandescent light bulb had no serious challenger. Yet with growing pressure to improve energy efficiency, in the closing decades the writing was on the wall.
Way back in 1835, Scottish inventor James Bowman Lindsay demonstrated his early version of constant electric light with the claim that by using such technology he was able to “read a book at a distance of one-and-a-half feet”. He could hardly have expected that, within a century, the incandescent light bulb to which he had contributed so much would be turning night into day. It would illuminate our lives, extend office hours and make football stadiums glow in the dark. It would provide security and illumination for public buildings and searchlights to guide wartime anti-aircraft weaponry. Roads would be lit to accommodate the relentless rise of the automobile and night-ready airports would revolutionise international freight.
With the dawn of the 20th century came an unprecedented opportunity for developers of the newly established incandescent light bulb. Applications were limitless, ranging from the extremely modest (such as bicycle headlamps) to national infrastructure (such as road lighting). The field was open and the market was soon awash with manufacturers hoping to cash in on the gold rush in artificial lighting.
Yet, by Christmas 1924, household names such as Osram, Philips and General Electric were becoming nervous. This was because the market, while booming, was becoming unpredictable. After seeing his sales tumble from 63 million units in 1922-23 by more than half in the following year, the head of Osram, William Meinhardt, proposed that he met with his competitors to agree on trading principles that would safeguard their future. While Christmas tree lights festooned the Swiss city of Geneva, on 23rd December 1924, the top brass of the global incandescent manufacturing community colluded to form the Phoebus Cartel to establish quotas and territories, share knowledge and agree on standards (such as the Edison screw-in connector).
Yet the hidden agenda was revenue protection in a market where manufacturers were becoming victims of their own success. Even back in the third decade of the 20th century, light-bulb manufacturing was so advanced that units had an operational life of 2,500 hours, meaning that it was years before units needed replacing. One of the major (and yet lesser-broadcast) outcomes of the ‘Convention for the Development and Progress of the International Incandescent Electric Lamp Industry’ was that life expectancy was to be reined in to 1,000 hours. To ensure companies complied with the new obsolescence regulations, they were obliged to send their products for independent testing in Switzerland. If the products displayed unwanted longevity, manufacturers faced heavy fines.
Despite the cartel deliberately stagnating technological development, the incandescent bulb gained traction as one of the great innovations of the time. By the end of the First World War, with cost of electricity plummeting, it was also presenting a serious alternative to gas lighting.
Edison had not been wrong when he said only the rich would burn candles. According to research data published by Fouquet and Pearson, the cost of artificial light had fallen over the centuries from thousands of pounds per lumen hour to fractions of a penny as we evolved from the use of handmade candles to mass-produced light bulbs. This fall in cost led to consumption of artificial light in the 20th century being 100,000 times more than it was in the 18th century.
Energy and light was so abundant the market could afford to, and did, become complacent. The tungsten filament could absorb the hit from emergent fluorescent ‘strip-light’ technology that appeared in factories and offices. The cost of powering artificial light was such that there was no real pressure to change the status quo until the oil crisis of the mid 1970s. This triggered the emergence of the compact fluorescent light bulb (CFL), which with energy efficiency five times greater than the incandescent technology made it a serious challenger. With Philips and Osram bringing them to market by the early 1980s, the first cracks in incandescent supremacy appeared.
Efficiency became the buzzword. New technologies were queuing up to be the next big thing. The unthinkable was starting to happen: governments were passing legislation to phase out the incandescent light bulb.
Part three: the LED revolution
With the incandescent light bulb now effectively a dinosaur and all eyes on emergent LED technology as an environmental panacea, the next evolutionary phase of lighting is all about efficiency and legislation.
According to light bulb manufacturer Philips, today lighting accounts for 19 per cent of the world’s electricity consumption globally. Given that incandescent light bulbs effectively waste as much as 95 per cent of their energy producing heat rather than light, there is massive potential for energy-saving in a world where alleviating demand on resources is increasingly legislated. Looking at the US light bulb market in 2010 - around the time when phase-out legislation of incandescents was drafted around the world - there were eight billion lamps sold, of which half were incandescents, with barely 10 per cent LEDs.
At the time, consumers appeared to be unprepared for the LED revolution despite research coming out of the University of Cambridge predicting potential energy savings for switching to LEDs to be “huge”. Iterating the base-line energy-saving figures, the research paper, entitled ‘Lighting for the 21st century’, says that in the UK lighting consumes over a fifth of all the electricity generated at power stations and LEDs have potential to reduce this figure by at least 50 per cent. Statistics from the US Department of Energy agree, estimating that by 2025, “solid state lighting such as LEDs could reduce the global amount of electricity used for lighting by 50 per cent and could eliminate 258 million metric tonnes of carbon emission, alleviate the need for 133 new power stations and result in cumulative financial savings of over a hundred billion dollars”.
With universal agreement that there are massive energy savings to be gained, the world seems set for spontaneous change in how we illuminate it. Yet that predicted market revolution has been slow and reluctant, causing governments to step in to accelerate the change in our manufacturing and consumption patterns. The EU has progressively banned various incandescent product types over the past decade, with this September seeing the phase-out of halogen and compact fluorescent lamps (CFLs) - effectively the end of the incandescent light bulb as we know it.
The Energy Saving Trust uses more measured tones, saying that while historically we might have had “little concern” over the fact that “light bulbs were only 10 per cent efficient... a very different attitude to lighting has emerged in the past few years”. In its white paper ‘The Right Light’, the Trust says that this new attitude is only partly driven by legislation, with goodwill from the “growing public appreciation of the role good lighting can play in the improvement of their homes” supplying the remainder of the market shift.
The reality is that industrial and domestic are only now seriously beginning to undergo a step change, driven by the desire to phase in energy-efficient emerging technologies such as LEDs at the expense of incandescents and, now, halogen and compact fluoresecents, too.
Today, despite its prolonged arm-wrestle over Brexit negotiations, Britain is still a member of the European Union and we are facing what the media has chosen to describe as a ‘bulb ban’, with the more excitable daily newspapers routinely reporting on the (largely non-existent) public stockpiling of incandescent bulbs as a safeguard against a future lit by LEDs. The objection to it is unclear, apart from a vague feeling that LED lighting is not as ‘warm’ as incandescent. This ‘bulb ban’ is actually a set of draft European regulations over efficiency that will see the removal of tungsten halogen and CFLs as light sources by 2020.
As part of its review of its Ecodesign laws, the EU has published the necessity for replacement light sources to have minimum efficiency requirement of 85 lumens per watt and a maximum standby power of 0.5W. Ecodesign requirements are mandatory for all standard bulbs, fluorescent lamps and spotlights sold in the EU. These regulations set energy-efficiency requirements and other factors such as bulb lifetime, warm-up time and energy labelling. According to the EU, “with energy-efficient lighting, household electricity bills could fall by €25 per year. By substituting a halogen lamp with an LED, you could save up to €100 over the product’s lifetime of around 20 years. Energy-efficient lighting could save enough energy to power 11 million households for one year and avoid the emission of 12 million tonnes of CO2 in Europe.”
Yet not everybody is quite as enthusiastic about the benefits of LED replacement technology or the Ecodesign requirements, with the entertainment industry saying the EU directive will sound the death knell for dramatic lighting. The CEO of German stage lighting company GLP, Udo Künzler, is predicting “extinction for theatres, concert venues and other sections of the performing arts, since no tungsten fixtures and many LED-based entertainment fixtures don’t appear to meet these requirements”.
In order to protect the professional stage lighting industry, he is hoping to “succeed in convincing the European Commission to ratify an exception for our industry. There is no time to lose. We need to act as a united industry to prevent these proposals from becoming enshrined in law”.
The long road to the 20th-century light bulb
Ebenezer Kinnersley demonstrates incandescence from a heated wire.
Humphry Davy uses a "battery of immense size" to create incandescent light, by passing an electrical current through a platinum filament.
James Bowman Lindsay demonstrates constant electric light by which it was possible to "read a book at a distance of one and a half feet."
Marcellin Jobard invents an incandescent light bulb with a vacuum atmosphere using a carbon filament.
Warren de la Rue devises and encloses a coiled platinum filament in a vacuum tube. Development shelved due to cost of platinum.
Frederick de Moleyns is granted the first patent for an incandescent lamp, a design using platinum wires contained within a vacuum bulb.
John W. Starr acquires patent for his incandescent light bulb involving the use of carbon filaments.
Jean Eugene Robert-Houdin publicly demonstrates incandescent light bulbs on his estate in Blois, France.
Moses G. Farmer builds an incandescent bulb with platinum filament. Thomas Edison purchases Farmer's later light bulb patent.
Russian Alexander Lodygin invents an incandescent light bulb using nitrogen in the glass enclosure and obtains a Russian patent in 1874.
Canadian patent is filed by Henry Woodward and Mathew Evans for a lamp consisting of carbon rods mounted in a nitrogen-filled glass cylinder. Patent later sold to Edison.
Thomas Edison begins serious research into developing a practical incandescent lamp.
Joseph Swan gives working demonstration of his carbon rod arc lamp. Mosley Street in Newcastle upon Tyne becomes the first highway in the world to be lit by an incandescent bulb.
Edison files US patent for an electric lamp using "a carbon filament or strip coiled and connected to platina contact wires."
The Oregon Railroad and Navigation Company steamer Columbia becomes the first application for Edisonís incandescent electric lamps.
London's Savoy Theatre, lit by Swan's incandescent lamps, becomes first electrically lit public building in world.
Edison and Swan's companies merge to form Edison and Swan United Electric Company (later Ediswan) and later incorporated into Thorn Lighting.
Heinrich Gobel claims to have designed the first incandescent light bulb in 1854, with a thin carbonised bamboo filament of high resistance, platinum lead-in wires in an all-glass envelope, and high vacuum.
US Patent Office rules that Edison's patents are based on "prior art" of William Sawyer and are therefore invalid.
US judge rules that Edison's patent for "a filament of carbon of high resistance" is valid.
Arturo Malignani patents method of mass production of light bulbs. Patent bought by Edison in 1898.